Coolant Temp Warning - pegged to red. Holy crap.
 

2003 X5 3.0

Every new yorkers nightmare, getting stuck in the lincoln tunnel. Luckily the coolant temp warning came out just as I was getting out of the tunnel. I then pulled over and shut the car off right away. I got out and looked in the engine bay, no coolant leak, nothing smoking. I got back in the car, turned it on and went to see if the large radiator fan was turning, it was - so i got back in the car and watch the temp sensor go right back to the middle, exactly where it always is for 16 years. Car then drove fine for next 15 minutes, I parked it, then drove again another 15 and then another 15. No more issues.

So - any suggestion on what is going wrong here... thermostat was replace already by me, a few years ago. Do you think the water pump is going? Could it be the big fan control? I have not replace the hoses, but they look okay, nothing looks crushed (but I think there are some hoses that run under the exhaust manifold that I cannot see).

Thanks. Definitely need this sorted out. Can't risk getting stuck!

A couple of things to look at would be the mechanical fan (clutch) might not be engaging properly. They wear out. Was your AC on at the time?

Waterpump is a high failure part on every I’ve ever had.

All sorts of things to check. Are the upper and lower radiator hoses really tight? Or just spongy? Do they stay tight several hours after you have stopped driving? Or relax as it cools?

Others can add their input.




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AC was definitely on at the time...

when you say mechanical fan clutch, are you referring to the big fan, that I pull out when working on the car? Are you saying that big fan might not be running properly or starting to fail?

How can I determine if the water pump is going?

Car has 144.7k miles. Been real good to me!

How old is the coolant temp sensor? It's not common, but they do fail.

I forgot if the sensor is built into the thermostat and comes with a new thermostat which you replaced already. I also don't remember if there are two coolant temp sensors as there are on some BMW's. Hopefully someone more familiar with the m54 can come in.

Once it cools down of course, check the coolant level.

The sensor is in the lower radiator hose on the starboard side of the radiator. I would at least consider a problem with that.

Air bubble is another thing to consider.

So far, your symptoms indicate nothing at all wrong other than the gauge, so hopefully the engine did not really overheat.

This post from crowz + overboost shows what temperature the gauge needle actually points to:
PA Soft 1.4 | Crowz Nest

So 115*C would still be pretty much straight up, and 125*C is pegged hot, in case that makes you feel any better.

I don't know what pressure 125*C correponds to with your antifreeze mix (50/50?), but your expansion tank has a 2-bar (about 30 psi) release valve. If the coolant actually got to that pressure, you would definitely see the aftermath of that sprayed out of the expansion tank cap.

Yes, the spinning fan.

The center part of the fan reacts to heat and as the viscous fluid inside heats up the fan spins faster and pulls more air across the radiator. On cool startup the fan will lope but as the car heats it will spin faster. The test is to put a rolled up newspaper into the spinning fan after it’s warmed up. If the fan doesn’t seem tight then the clutch needs replacing. Obviously, not something you want to do without taking care.

Also, look around for coolant leaks. Maybe put a cardboard underneath the radiator, look for drips overnight.

Lastly, once cooled off, open the coolant cap and check the level. If way low, good chance it has air in the system.

Check utube for bleeding procedure. Air in the cooling system can definitely cause overheating.


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If I remember correctly, the coolant system is self purging of any air. Unlike an e30 for example, where bleeding the coolant system was required after making any alterations with that oversized plastic philips screw on the top of the expansion tank.

Have you thrown a multi-meter on the temp sensor to see if it is within specification? All you do is unplug the wiring harness and read across the connectors on the sensor. Actual numbers +/- you’re gonna need to source.

Bad thermostat? Once your rig is nearly up to operating temp, there will be a distinct change in temperature at the return hose to the radiator as the thermostat opens. Just don’t lose any fingers on any belts or your fan. Ideally if you had a digital infrared thermometer you could watch the coolant hoses safely. If there is no change, ie one hose is super warm and the other is luke warm, your thermostat isn’t opening.

If the temp dropped right back to "noon" then you may have just had an occurrence of a known bug in the DME that will randomly set the temp needle to max.

It happened to me once. I pulled over and put my hand on the radiator hose without difficulty I knew it wasn't actually overheating so I figured was a bad sensor.

Turned the car off and back on and needle went back to normal.

The dial on the dash is not a proper gauge. It for all intents and purposes is a three position idiot light:

Cool, normalish, overheated.

I'm willing to bet your case was like mine.

Use the hidden menu to monitor ECT (engine core temp) to confirm the cooling system is behaving properly.

I think it might be test 7. It will show the engine temp in °C

I agree with this. If it had really overheated, the temp would have increased while it was off. From engine residual heat soak.

I think you’re safe, but keep an eye on coolant level.

Correct. There is no way the temp was pegged into the red and then a minute later be normal again. As Andrew pointed out, there is a known DME glitch that has happened to a few cars before.

trying to digest that all... I struggle being able to accept this was just some random "big" that just appeared out of nowhere and then simply went away. I do agree it was odd that the coolant temp cooled down right away once I restarted the car, yes, in like less than 15 seconds, it went back to the noon position.

Why would it matter if the AC was on? I am curious about that question.

If the waterpump goes, does it get intermittent? If that stopped working and then restarted, with the fan blower on, would that not cool down the coolant temp right away. There is no engine/oil temp gauge. Same goes for the fan, if the fan stopped working, wouldn't the coolant temp go right up and then come down if the fan started blowing again?

thanks.

Engines hold a lot of heat. It would take 30 minutes for a stopped overheated engine to cool to normal running temperature.

AC can cause an engine to overheat if the condenser (like a radiator) is in front of the engine radiator. If it’s side mounted, then it won’t.

Water pumps fail at the bearing, causing leaks, or the plastic impeller can disintegrate causing loss of water flow and over heating. But it’s not intermittent. If you remove the overflow tank cap and water is flowing, then the pump is working.

Fans help move air at low speed driving, but don’t contribute much at freeway speeds.

The AC question was to eliminate the Aux fan that comes on with the AC as a potential failure point. You have two fans, one is mechanical, spins with the engine rotation. The aux fan (electric fan) comes on with the AC compressor,also comes on if the coolant temp gets too high. Not sure but likely your AC won’t come on if the electric fan is not functional.


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thanks. I checked the coolant level tonight (since last DIY I did on the car was replacing the coolant expansion tank). coolant level was perfect, not low and not leaking. hmm. well heading to the beach this weekend, 100 mile drive and back home. lets see how it goes.

Seems to me you got the temp sensor glitch. But the conversation will get you ready for the next time.
Happy motoring.


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Since it is intermittent at best at this point and there is no coolant leak, I would not expect it to be a water pump issue, or low coolant. Suggest a check if belt is in good shape. A bad thermostat usually sticks open which would not cause overheating. I test a mechanical fan after the engine has been at operating temp to see how easily it turns by hand. Should be some resistance, won't spin even a full turn and feels smooth. First let the engine run at operating temp for 10 minutes or so without the air on and again with it on. The higher the outside temp the better. If it overheats when not running carefully remove the cap and confirm temp. I think more troubleshooting is in order before buying parts and easy to this before your trip.

It's "laws of physics" impossible for the car to do what the instruments displayed that can. ONLY mean the instruments were wrong. I'll see if I can find the tsb from bmw


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https://www.m5board.com/vbulletin/e3...ture-gage.html

Here are the details about the problem. The M5 and X5 have very similar brains and the X5 has a nearly identical tech service bulletin.

FYI, I wasn't suggesting the cause, just simple troubleshooting to confirm or eliminate previous suggestions.

Head gasket/cracked head also possible.

I meat to +1 on your diagnosis ideas. All good stuff everybody should know those things.


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What does this tell you?

Still short drive testing after head gasket and a went for a more spirited drive- 50mph for 10 mins or so. Temp got up too high just as I made it home.

Opened the hood and getting some coolant from the reservoir area and when I opened the bleed screw and steam was coming out. Uh oh.

Here’s the deal:

Running with no spinning fan or shroud attached.
Temp- as high as 121 degrees C engine coolant temp, on 65 degrees C radiator outlet temp. Upper radiator hose hot and tight, lower hose not hot but tight.

Must be radiator or something clogged?

Yesterday I did about half as far, temps were good, hoses both hot and full. What broke?


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Coolant Temp Warning - pegged to red. Holy crap.
 

No flow usually means t-stat not opening properly. Next bet the water pump. If outlet temp too cool means not enough flow rate.

Coolant above about 105C means you will get stream if you open the vent so that is just normal.

Coolant Temp Warning - pegged to red. Holy crap.
 

Yep, damn coincidences again? WP fails on second run? Hmmm? Wouldn’t thermostatfail open?

Got up to 90degrees yesterday on short, slow drive. Outlet was 73 and hot to touch. Frustrating.

Neighbor said go “straight to Carmax and take their off.”
Thinking he might be right.

Would the mechanical fan make that much diff in 10 mins?


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When not moving you need a fan or you'll overheat very quick but inlet and outlet temps will be almost the same.

The in/out much different means low flow. I've seen very recent thread xo that had a stuck closed t-stat they fail either way.

More likely to be an air lock, given the recent work...?

Thinking that too, just refilled the coolant let it idle up to op temp in the driveway.- scanner shows 82c engine coolant 75c radiator exit coolant. Upper and lower hoses fairly tight, hot. Squeezed on both to push any air through. Still no fan connected so it will likely not cool properly.

I assume the engine temp should read a little higher than the coolant exit temp if the radiator is cooling a little.

One odd thing. Other day I drove it a few mins up to temp and all was fine but the next AM the coolant hoses had sucked in on themselves. Some said it’s a bad rad cap. Replaced it with a different but same spec cap.

That mean anything?


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Yeah - I think it means there's air in there somewhere... :confused:

You don't mention bleeding the air using the bleed valves? I'm not familiar with the M54 - I have an M57 - but bleeding the air is a MUST do task when refilling the coolant....

Did the bleed screw prior, nothing but coolant. Can’t park at an angle with other car behind it so I’m improvising.


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Filling with ignition on but engine off (KOEO) might help - as long as the electric pump is running. You should see a small stream of coolant coming back into expansion tank.

Air bubble might affect heat shouldn't affect rad outlet the water pump is low enough air pocket can't stay there.

T-stat best bet. Same symptoms another member had just a few months ago. T-stat wouldn't open properly.


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Yes, with the ign on but not running I see the constant stream.


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It's bled. The problem is with the mainm flow. When there is a big difference in goesin vs goesout of radiator you have no flow


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Logical. Should it be nearly identical temp?


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Yes, hose(s) sucked in is an indication radiator cap is malfunctioning which results in a coolant circulation problem. Are you sure the other cap is the same?

Was gonna post, changed caps, new saw hoses sucked I also (after short drive).

Hmm, what causes that? Other than cap fail.


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Testing without the fan or shroud attached is not a valid test of cooling system performance.

Agreed.


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Are you sure the other cap is the same?

Should also have heater on.

Both caps are 200’s. Look identical.


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Coolant Temp Warning - pegged to red. Holy crap.
 

I'm used to seeing maybe 10-20C Delta. 95 in 70/75 out I can't recall.

Something is very confusing here, the topic being discussed has nothing to do with the thread headline. A new thread should be started not related to the software bug that causes an erroneous overheat needle.

It doesn't take long to overheat if there is a flow problem. I recently replaced an electric water pump on an E90 and it would kick on the fan full speed in an attempt to air-cool the water cooled engine within a few minutes of starting.

The electric fan runs based on the output temp I believe so if you don't have the mechanical fan installed it wouldn't be surprising to have an overheat situation if the car isn't moving to get airflow through the radiator however:

If the water pump is moving the coolant and the t-stat is open the in and out of the radiator will become the same temp without airflow through the radiator.

Since a hose sucked in is so often the cap I would be positive they are the same even if I had to purchase a new cap to do so. Perhaps there is a difference in how they seal.

Good point, may do that. Any other possible cause?

Ironically Before I did the head gasket one of the symptoms was the hoses would stay really tight overnight....


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Vacuum suggests high temp difference and/or too much air in the system. I think if you open the system while hot you can expect collapsed hoses when cool. Level must be set cold engine off key on engine off to bleed.


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I can't tell from your posts that the system has been bled properly. What was your process? I would purchase an infrared thermometer. IMO It is one of those must have DIY testing tools. I would like to eliminate one of the new head gaskets as the problem. Have you had to add coolant since you filled it to proper level the first time. If so, smell the exhaust when it is running for a sweet smell or any trace of white smoke or merely for wet soot inside a tailpipe.

Never sure about bleeding. Turnedthe key on position and let the aux pump pull the coolant into the hoses and heater core. Minute and a half or so. Added coolant and purified water until it was near reservoir top. Cracked bleed screw until no air bubbles. Didn’t take long. Not able to get on a slop with wife’s car behind me but I think it’s bled.

Constant stream from the squirt hole. Heat is hot.


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On level ground, engine cold and not running, fill expansion tank until the float is fully extended not to the top of the expansion tank.
Replace the cap.
Let it run for about ten minutes with the heater at highest temp.
Slowly open the bled screw about 1 turn. Close the bled screw so very little fluid escapes and let fluid continue to come out until you haven't seen an air bubble for a minute or two.
Close the screw. Let the engine cool.
Without starting the engine, remove the cap and add fluid as necessary. Put the cap back on. System is bled.

Thanks. Will do that.


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Back to the OP... Drove my call all of the holiday weekend, well over 300 miles and the red signal on the temp gauge did not return... I guess at this point, do you all think i should leave well enough alone for now until it happens again? I have many other things to work on, main one being change of valve cover gasket. I will tackle that and go from there.

I'm quite sure you experienced the bug. If it happens again you'll know it is the bug because the temp will magically become normal when you power cycle the engine.

Perform a reality check (expansion tank didn't explode, no puddle of coolant and no steam coming out etc) after turning off the car then start it back up and the needle should be at noon again.

My car did it once in 40,000 miles.

Just check coolant level every day for 3-4 days and see it you are losing coolant. If you are you will need to find the leak.

OP said no leak implied coolant level is full but didn't say explicitly.

Definitely confirm coolant is full but I'm quite confident you just tripped the non-gauge bug. I can try to pull my DME firmware number you can compare with to see if they are both original. I couldn't find the fixed DME firmware for the X5 not sure how compares to the M5 /5 series mentioned in the bulletin linked above.

I had thought the bug was tripped when ambient was cold as what happened to me but I think it can happen at any time.

Symptom is simply that the temp "dial" indicates overheating when nothing else corroborates this and simply turning off the car and restarting it will set everything back to normal. It's a known issue that can be resolved with a DME firmware flash but with the fix as simple as every 50-150,000 miles turn the car off then back on it's pretty low on my to-do list.

Again, I am not addressing the cause of the problem. Only the troubleshooting and precautions to take until the cause is confirmed. I understand your position is that the cause has been confirmed. I am not agreeing or disagreeing. Since the problem is no longer present, I don't think there is anything that must be done other than, as a precaution, monitor the gauge and coolant level.

Yup I know. I'm not sure if he made sure coolant is full just was suggested. I'm just a little annoyed at the seeming lack of understanding that this particular incident was almost certainly resolved by my first reply but there are all sorts of tangential trouble shooting etc. Not that those aren't general purpose useful things.

The issue that started the thread "random erroneous overheat on dash but engine not hot" is a known (not well known) bug in the DME of more than one BMW model line and was pretty clearly what happened in this case.

People who drive X5 should be aware that this bug exists and if the temp shoots up to red to check to make sure the coolant didn't just blow out but if the car doesn't have secondary indication of being over heated simply reboot the DME and the bug will clear and the temp non-gauge will report normalish (straight up pointer).

After 1 minute of verifying the car didn't vent the coolant it's laws of physics impossible for the temp to drop to normalish so if that set of conditions has passed you just experienced the overheat "gauge" bug. It will likely never happen again I don't know if even BMW knows what condition will bring it on.

OP here.

I drove several hundred miles and had no issue. Coolant is full. So guess what, I am driving again in the Lincoln Tunnel and about 3/4 of the way through, not thinking about it, I hear ding! and sure as sh!t, its the coolant temp and gauge pegged to red, again in the same exact place as the first time. I get out of the tunnel (in less of a panic) and pull over. I pop open the hood and make sure the main fan is turning, blowing on the rad. It was. Temp gauge went back to noon very quickly.

I do not believe this is a random bug. The air temp in the tunnel was HOT, like in the 90s, it felt hot. When the cooler air hit the radiator outside the tunnel things went back to normal. So what does this mean? Something about my cooling capacity is weak? Poor circulation, weak pump or a crushed hose??? Is my fan not spinning up fast enough? Air in the line?

Just a reminder, I did recently replace the expansion tank before this happened the first time. I also changed the tstat below the tank with a BMW factory part.

Coolant Temp Warning - pegged to red. Holy crap.
 

There is a huge difference between went back quickly and instantly recovered.

If the bug happens the actual engine temp is normal the gauge is just reading wrong and will instantly return to noon upon restart.

If there is an actual problem with the cooling system a restart will not reset the temp gauge. If the needle is right of noon upon restart and it takes any time to recover it's a different problem.

Temp high that recovers on its own hints at a sticking thermostat.

Use test 7 to monitor temp live and drive that same route to try to reproduce.

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yes - I think I said it went back down over like 15 seconds or so, once the colder air was hitting it. Okay, tstat sticking could restrict flow.

I am not really sure about how to get into test #7, which you and other keep talking about. Thanks.

The thermostat in the bottom of the expansion tank is for your automatic transmission so don't assume that will affect your engine temperature. The ambient air in the tunnel compared to outside the tunnel should not affect the cooling either.

Here is a video explaining the hidden menu. Go to test number 7
https://youtu.be/cO_tBe58ew8

Why would the temperature of the air blowing on the radiator now impact how well the system can cool the coolant and the engine? I might agree that a difference of 20 or 30 degree in the air temp might not make a difference, if that is what you meant.

So where does this leave me? Poor flow for some reason?

What temperature should the engine be? I can see if the engine is running hot? It night be because i know I have a crack somewhere in the intake side and I am getting the occasional Lean Bank error code. I also have a leak in my valve cover gasket.

3.0 motor should be about 90-95° normally.


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There are many X5's running around in the desert with ambient temps above 120F and they do not overheat so my point is the tunnel temperature has nothing to do with your issue.

The thermostat would be the first component I would validate. So you will need to get an exact reading on your temps. The stock gauge will show straight up anywhere from 75C to 115C so you need to not rely on that.

There are several ODBII apps you can install on your phone that will take a simple OBDII interface plugged into that port or you can get the temp through the hidden menu.

My advice would be to get the OBDII interface as it will have the ability to look at live measures, CEL codes and the option to clear them.

https://www.obdsoftware.net/software/obdfusion

yes, I have an OBDII scan tool in the car, never used it to read engine temp, just to clear and review the occasional code. yes, makes sense what you are saying about cars in the desert etc, but if I have restricted flow then perhaps a 30 degree change in temp would make a difference. thankyou for your help and support, really appreciate everything for all of the community.

Getting a problem to repeat is the best way to find out the cause

that might quickly become a reality as summer creeps in. My car might overheat or run hot once the temperature here goes up... its no coincidence that the same issue happened twice at the same place on warm days, with very hot air in the tunnel. I agree that for a normal working system, the hot air should not be an issue. I might swap out the thermostat and then see how things progress. Will take some engine temp readings first and maybe try and fix my lean bank/valve cover gasket too (before the summer comes) - its just I have virtually no free time in June, eh...

Most spring days in the northeast will have close to a 20 degree swing from day to night. I would think if that was the problem, you would see it every day.

How many miles on the X and given the traffic in NYC I am wondering what kind of speeds you were traveling before entering the Lincoln Tunnel and how fast in the LT?

Thermostat or viscous fan clutch would be my best guess. :dunno:

BTW, I had a 1992 348 TS. Loved that car

it was a long ride home in traffic for like 2 hours... in the tunnel it was slow, crawling, like 5 MPH. car has 145k on it, I replace the tstat two years ago b/c it was stuck open. when i pulled out of the tunnel, I parked it and checked to see if the main fan directly in front of the radiator was blowing - and it was. hmmm.

Counter intuitive but next time it does that turn the heat on full blast, sorta sounds like you may have air trapped in the system.


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It's not an air trapped thing. If the electric fan kicked on indicates that the output temp is hot and registering.

I'll bet on the t-stat


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On a really hot day here in the south I can hear my viscous fan clutch locked up and turning the engine fan but only for a minute or two. That fan moves a lot of air and given the temps you saw, your engine fan should have been noticeable by ear. If you don't remember hearing the "roar" from the mechanical fan when she was hot I think a simple test would be to roll up a newspaper and try to stop the mechanical fan. It should be locked in at temps above your center point on your gauge (115C) and you should not be able to stop the fan.

From the Bimmerforums:

1. Start the car (cold) with the hood open and note if the fan is turning, increase the engine RPM and note if the fan turns faster and the noise increases, if it does, first good indication, if it does not increase speed/noise, clutch is bad and needs to be replaced. (Remember, this must be tested after the car has been off for and extended period, over night etc.)
2. Leave engine running and note if the fan starts to slow down after 2-5 minutes, speed/noise should diminish and even raising the RPM, the fan should not make as much noise as when first starting, if it does slow, this is the second good indication. If speed/noise does not decrease, clutch may be “frozen” and should be replaced.
3. Leave the engine idle and watch the temperature indicator. When normal operating temperature has been reached, some increase in fan speed/noise should be noted, in particular when the RPM is increased. If temperature is fairly stable and the fan noise/speed increases or cycles, third good indication. If temperature indication continues to increase, with no increase in fan noise/speed, clutch is defective and should be replaced.
4. After the engine is at normal operating temperature or above, is the only time that the “rolled up newspaper” test that many people talk about should be performed! Take some newspaper and roll it up into a long narrow tube. Be carefull, keep hands and fingers away from the fan while performing this test! With the engine at full operating temperature and idling, take the rolled up paper and insert it on the back side of the fan and try to reach the hub of the fan avoiding the blades until close to the hub. Push the rolled paper at the fan increasing the friction to the hub area of the fan. If the fan can not be stopped easily this is the fourth good indication, if it can be stopped the clutch is defective and should be replaced. Again, this test can only be performed when the engine is at or above full operating temperature.
Testing can be performed in any order but just make sure the conditions during testing are those that are specified for that specific test.
Do not continue to operate the engine if the temperature continues to rise and certainly stop if the temperature approaches “redline”.

Yes, my sons z-3 would heat up in traffic, viscous fan clutch had very little “bite.”


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I am getting confused, viscous fan, engine fan and electric fan? I am talking about the giant fan directly in front of the radiator, the one I have to take the blades off and remove the housing to work on things. I think this is the viscous fan/clutch.

My current guess, is that this is going. Rationale is its blowing weak, so if it blows weak cool air, things are stable, if its blowing weak hot air, then the coolant starts to overheat. Or the t-stat is restricting flow and again the warm air is just not sufficient with the weaker.

I'' get to work and report back with the solution.

The viscous fan clutch is the center part of the spinning fan with blades. As the temp increases the fan spins at a higher rate as the viscous materials tightens the hub. When you first start the car cold the fan sort of lopes along, once the temp rises the clutch “ bites” more and the fan spins higher pulling more air over the radiator and increasing the cooling effect.

These thing fail so that if it doesn’t tighten enough the fan doesn’t spin fast enough. Usually in bumper to bumper traffic. But, never seen one fail to the extent you would get a quick over heat.

To test carefully stick a bit of rolled up newspaper in the fan after its at op temp. Ease it in. If the newspaper causes the fan to stop or even slow significantly the clutch is bad.

Safer way is with the engine hot but off try to spin the fan by hand. If the fan spins then the clutch is bad. If it resists, not your problem.


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Yes, confusion for sure. On the 3.0L M54 engine the fan in front of the radiator is the electric fan used mostly for A/C operation. Behind the radiator attached to the engine is the viscous fan. If you didn't hear a jet engine when your X was overheating, your viscous fan clutch is bad. Believe me, you can hear it when it is functioning. That fan moves A LOT of air when the clutch is engaged.

Indeed loud and windy if you open the hood.


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Loud and windy sitting in the driver's seat with the windows up and A/C on full song. But then I listen to every little sound my ole girl makes... ;)

I'm about to replace my viscous fan clutch - it works correctly but the bearings have shat the bed... :-(

https://youtu.be/kdhRraCZorA

Got a Hella Behr (OEM) unit for a decent price in the UK.

done, ordered a new fan clutch... if that doesn't eliminate my issue as we head into summer, I will change out the thermostat again, not a big deal. I like that I can work on this car, makes it kind of fun for someone who is inclined. I really need to get in ad do my valve cover gasket and the intake boot. thank all. I will report back.

Intake boot is way harder than it looks. Mainly due to the Metal clamps being hard to get a tool on.


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If replacing: CUT off the old one.

Clearly they are installed at the factory with engine not in the car!


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This is excellent advice OP. As Andrew points out, once you have the old boot cut off then the awkward clamp positioning is easy to get at to remove. :thumbup:

Of course when I did it the replacement was a crap copy I couldn't use however super glue did a fine job of putting the old back together until my OEM replacement came.


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I don't think that the air temp is your problem as I get into bumper to bumper traffic and the temperature here can get up to 60c (140f) although normally it's around 120f in the shade...

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OP here with my final recap!

So was coming back to the city yesterday and instead of taking the George Washington Bridge, I took the tunnel. About half way into the tunnel the gauge started to climb and then about 3/4 of the way in, ding - Coolant Temperature warning. When I got out of the tunnel, it took longer for the needle to move back - it was hotter out yesterday than any other day.

I now think i was lucky to have a nice warm Lincoln Tunnel to find this issue. Had the outside temp went to 90, I would have started to overheat with no way to cool it back down other than turn off the car.

I didn't have the courage to stick something into the spinning fan, but I read another way to test the fan clutch. Turn the car off and watch the fan, if it spines for several seconds after the car is off, then it is toast. Sure enough mine spun.

Last night I swapped in my new fan clutch... took longer to find my fan clutch removal tool than to do the rest of the job. LOL. You need a 5mm allen to remove the fan clutch bolts from the blades, I had 3 bolts on my 2003 X5. Amazon part Hella Behr was $80, with 2 day free shipping.

After the swap, I checked the fan when the car was turned off and it basically stops in 1/2 turn or less. Totally different from what was seen before. I am sure this was my issue, but like the first guy said, who responded to my initial posting. Thank you and thanks to everyone else who helped out.

Other comments: Getting the fan nut off is always a guessing game, but at least I know you can move the nut around to try and get better position to take it off... putting it on always sucks too, takes me many tries, but always gets back on.

Now I need to do my valve cover gasket and lower boot (which I actually taped up yesterday), it has a HUGE crack in it, but at least now my lean error codes have gone away...

Congrats! Thanks for posting the conclusion.


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You may have one more problem. If the car doesn't get enough cooling from the mechanical fan, you should have the electric fan kick on before the temp hits the red. Do you remember if that happened? The foxwell scanner will let you engage the fan on command to test it's function also when you start the car I think it will turn like 1/2 a turn to self test

I did not notice the electric fan turning on at any time when looking at the fans in the overheat state. I will take a look. Does that fan do anything when the AC is on? thanks again for your help specifically.

The electric fan program is such that it turns on at lower temp when ac is running. That's why the mention of ac being on in early posts.

The usual first symptoms of fan clutch worn out is not the fake gauge hitting red usually it's complaint of the electric fan turning on too frequently or fast. (It can sound like the car is trying to hover).

Any time the mechanical fan doesn't do its job the electric fan should kick on.

Usually on a hot day at idle the engine will get warm enough for the fan to cycle on and off when AC is on and car is not moving.

A month ago or so I took a video to demonstrate how to stop the mechanical fan and when I did that it took mere seconds before the electric fan kicked on. I let the fan spin back up to speed and the electric fan turned off.

When your car cooled off quickly when out of the tunnel, perhaps did the electric fan finally come on? You definitely want to confirm the fan is working. I believe it uses the outlet temp sensor so it would be good to know that is reporting a valid reading ;use an IR thermometer to confirm the temp is similar to the computer temp.

It feels like your elec fan is not working and that led you to discover that also the mechanical fan wasn't. If either one was working properly you'd probably have never gotten the overheat situation. The elec fan should turn a little bit when you start the car but also typically on hot days with AC going it will cycle on and off when car is idling and not moving.

Glad you got it sorted. Hit the tunnel again for total validation.

The electric fan should run whenever the A/C is on.

Coolant Temp Warning - pegged to red. Holy crap.
 

Doesn't "always run" only when needed:

When it's hot out it might always run. When it's 75F it might never run. Like I mentioned above I had the AC running it was maybe 75F outside, I stopped the mechanical fan with some cardboard and within seconds the electric fan kicked on. When I let the mechanical fan free the electric fan stopped within seconds.

Correct Andrew. Only when needed and will assist the A/C condenser cooling when hot.

I just wanted to make sure people don't think their fan is broken because it doesn't immediately turn on with the AC.


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If OP wants to check his fan operation he can disconnect the high pressure switch and the fan should go full song :dunno:

overboost, I recall doing that once before... but which "fan" are you talking about? the electric fan, right? too many fans, LOL

$500+ for the Aux fan, dang... if mine is broken, not sure I would replace it knowing it wont cause my car to break down.

Coolant Temp Warning - pegged to red. Holy crap.
 

There are decent third party fans available. Yes he's talking about the electric fan but I'm not sure which connector needs to be pulled to force it to run. He said high pressure switch maybe means coolant output sensor. If the DME can't read the temp it may assume it's max and kick on the fan.

Maybe that is what I did last time, pull off the coolant temp switch to see if the engine fan would blow like mad... ill check out the electric fan.

later today I will be in the Brooklyn Battery tunnel, it is about twice as long as the Lincoln Tunnel. I don't think the temp will rise, I am pretty sure it is fixed now.

I think the AC has been weak, thought it just needed a little recharge, but maybe the fan is shot. hmmm.

Open the hood, look straight down on the passenger side next to the A/C compressor. The hard line going to the compressor running along side the frame rail has a high pressure switch in it. Start the engine and disconnect the plug on the sensor and the fan will start and within 10 seconds it is wide open.

I thought that was the low pressure line that's why I was confused. Does the AC button need to be pressed for the fan to run? When I bought my car that connector was loose and I had no AC. I did not notice the fan spinning all the time but I didn't try to run the AC since It wouldn't engage.


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You may be right Andrew, I am no HVAC specialist. I assumed it was the high side as it is the hotter of the 2 hard lines but anyway, start engine, turn A/C on and disconnect that sensor plug. The aux fan will slowly ramp up to full speed over 10 seconds if it is operational.

Successful trip through the Lincoln Tunnel last night. No overheat.

I pulled the plug on my high pressure line and the electric fan did nothing.

I am leaning toward the fact that it is dead given that it also never came on when I was experiencing the overheat condition.

I am considering to not change it and just let things be with the engine fan.

Well double issue as Andrew expected. At least we know why she would overheat so easily. Does your A/C work? When my aux fan went out the A/C compressor would not turn on.

yes, the AC works very good... so I wonder if maybe the Aux fan is not dead... can we say for sure if I disconnect the high pressure line on the AC, it should work, and if not then it is dead? So it turn on when the car starts up for a few seconds? I have not looked for that yet.

So - what if I do not replace it? Being that my AC works and the engine fan is new and working strong to keep the coolant low. I live in the Northeast so temp does not really get much above 100 at the most.

Your call but most of us want things working the way they were designed. When you did the fan test was the engine running with A/C on?

of course I want things working, but $450 (for a good fan, not one that will break in two months) and also it looks like a pain to install it with risk of cracking the tabs on the front bumper... not sure how worth it, it is. I guess I can see how I get along over the summer without it, see if the car is running hot or if the AC is not cooling.

I put the AC on MAX when testing the fan.

Coolant Temp Warning - pegged to red. Holy crap.
 

If the elec fan is not working the only real risk is overheating when in traffic jam and high ambient.


That's exactly when you want AC the most so definitely fix the fan of it's broken but since it's not used 99% of the time I have no probs with using a high rated knock off

True!

How hard is it to pull off the bumper and get the old fan out?

It takes about 2 hours start to finish. My wife and I did ours several years ago together. (Bonding time) :rofl:

You can test the Aux. fan via the activation menu in INPA and via a few other tools too. It takes the guess-work out of it. ;)

I've heard and read that the aux. fan should "kick" or turn a little at start-up but I've never actually seen it do it. But when I fire it up via INPA it spools up to full RPM with no issues. It's very noisy when running at full speed!!! :yikes: