Thermostat
 

The shop is saying that my thermostat need replacing, this from their computer, no indication on the dash, living in S FL, I never noticed any malfunction, is this a huge $$ job, are they scamming me?, I no longer trust even the indie's after a few screwups that they have done...
Unfortunately I just can't do my own work anymore....gettin' too old...

I assume it failed in open position (if it's indeed failed) since you notice no malfunction. Is the temp needle in 12 o'clock position or does it go down to 11o'clock when you're on the hway? That's an indication of opened Tstat.

Check your local BMW club. Perhaps a member can assist. Or you can host a get together and thy topic will be thermostat replacement and you can provide food and beer.

I have helped many Lotus owners this way.

On our 4.8is, the tstat has a sensor. That sensor technically measures when the tstat fails. I know this because I had it happen. It was a ridiculously simple job on the 4.8.

That being said. Does your car take a really long time to warm up in the morning. That is also an indication of a failed Tstat.

I also question how these mechanics know you have a failed tstat. If there is no code for it, how did they come to this conclusion?

You need to do what tmv said.

BMW t'stats fail open, drive it for a few miles on the hwy after warming it up.

If the gauge doesn't get to 12 o'clock, it's time for a new one. No pun intended!

The car(truck?) seems to be operating 100%, warms up to needle straight up. It almost never sees the highway, as it's my wifes daily driver...

I recently had the same code; interestingly enough just before it happened I had noticed it was warming up a bit slower than normal.

I cleared it, and it hasn't happened since - since it fails "open" I am not particularly worried about it, and will probably just replace it during a planned job including coolant & water pump change as I get closer to 100,000 miles.

Seems a fairly easy job, dealer quoted an outrageous price though.

If it gets to normal operating temp in a short amount of time (5 to 10 mins) and gauge stays at 12 o'clock during hwy operation, the shop has no idea what they're talking about.

^^^ +1...

If it is as the OP says, I might do/have a good Indy shop do a coolant flush and fill, and give the cooling sys components a look.

It might be nothing or it might be 'something', and if it is the CEO's dd, I would rather have her trust the car and happy/content, than not. ;)

If the OP doesn't like/trust his current Indy, there are others to choose from, in his area.
GL, mD

Oh fyi. When my Tstat died. I had a check engine. Somehow forgot that you had nothing. Thats the check engine that made me buy a scanner. Yea i doubt your tstat is dead.

I'm thinking I'll let it go for a while and see what happens, she's never more than 10 minutes from the house....and I'll make sure she keeps an eye on the temp gauge.
Probably with the next service I'll have the coolant changed...(it's now only at 68,000 miles, not a lot for an 06)

Doing a bit of research, as mentioned by others the thermostat mostly fails by keeping the engine TOO cool.

Do you have the high instrument cluster and unlocked the OBC? I would monitor the engine temps via test 7 (or 9, I cant recall exactly which ATM).

As per various BMW forums the M54 runs at around mid to high 90's. Failed 'stats cause temps to be consistently at the low to high 80's from what people have reported.

Sometimes the classic symptoms of failed thermostats like long warmup or temp needle below middle dont show.

A lot of people do report poor gas mileage as a common symptom though. Not that it'll sip fuel like a Prius, but there is reportedly a noticeable diff. :)

If he's in Florida and it's stuck open I doubt it would ever take that long to heat up.. The car will normally always run fine with a faulty thermostat UNLESS it's stuck closed that's more of a problem because of overheating.

In general though normally thermostats are very easy to replace , on some cars you just have to make sure to get all of the old gasket off to have a nice smooth surface for the new one. If not leaks will develop.
I'm pretty sure I located mine just by a glance without even looking it up online , if it is where I think it is it's not that hard to get to. (whenever I get a new car I look for these sort of things it's a common thing to go)

Someone mentioned:
New Water pump after 100k? This is normal routine maintenance????

BMW waterpumps don't use a surface gasket that needs to be scraped off, they seal with an o-ring seated in a groove, that "tight slip fits" into the engine block waterpump bore.

Yup OP the waterpump on these motors is easy to get to.

Pretty much at the top front of the block.

Ah ha, I have noticed that when I fill it (as I said I don't drive it much, but I don't like my SO going to gas stations, so I fill it) I have noticed that it has gone from about 16 mpg (80% local driving) to about 14....maybe I should just change the t-stat anyway if it is that easy!

Yes a dead thermostat throws a code but you need diagnostics for it. It wont throw a dash light

Yeah, when the t'stat allows the engine to run cool MPG drops about 20%.

This what the OP stated

The shop is saying that my thermostat need replacing, this from their computer, no indication on the dash

A failed thermostat will not set off a check engine or service engine soon light, but it will be logged into the DME as a problem, which can be retrieved if you have the proper software connected to the car.

Nope you are wrong. My check engine light got set off. Thermostat is directly related to emissions. Car can't warm up fast enough, means it is running rich, and will throw a check engine. I got an error something like cooling below threshold/thermostat stuck open, with a basic OBD2 scanner. Something more advanced with INPA, but check engine definitely lit up for this error.

Sorry I don't think that I'm wrong and neither is the OP's mechanic. He read the error code as stuck open thermostat.

I read my DME and it told me that the thermostat was stuck open. No check engine light.

The error code that you received was for a " I got an error something like cooling below threshold/thermostat stuck open".

There could be several reasons why you have that code including a stuck thermostat. But that code is not a stuck thermostat code.

http://www.obd-codes.com/p0128

interpretive breakdown lol
 

I wasn't referring to the water pump gasket , I was clearly talking about the thermostat gasket :)

My question/inquiry still stands unanswered though. Replacing a water pump is standard maintenance around 100k miles?
That's somewhat discouraging for a german engineered machine lol

I wouldnt suggest that a waterpump is "part of a routine maintenance" But they do fail and when they do, they usually start by leaking fluid, then maybe a bit of bearing noise. When they do, I change them! and for what ever reason, its usually around 100k
as posters have said, its an easy job, the toughest part is getting the fan and rad shroud out of the way, and the belts off. after that, its drain and replace, the gasket is an O-ring which is how every car should be built! no wondering if its gonna seal until its too late! The water pump isnt an expensive part (BMW speaking!) and its peace of mind knowing its not going to fail for another 100k!
(that said, mine is going to be changed in the next few weeks, when i do my serpentine belts and tensioners! :))
:thumbup:

Going to chime in here.

Can confirm thermostat DOES in fact set off an engine code. ie p0125. It will actually give 2 codes under BMW specific diag.

Thermostat, 28$. Fix takes an hour.

They fail (as mentioned) OPEN. Don't bother trying to fix the unit. it has some wax inside and a circuit as far as I have been told?

Haha yeah, I meant thermostat though, sorry. :)

A lot of people replace the water pump when they do a cooling system overhaul. I did get a waterpump with the intention to replace it along with the hoses but with a few anecdotes on line indicating these are relatively long-lived, plus it being relatively accessible, I held off for now. I've read reports of these OE water pumps reaching beyond 100,000 miles, so at 45,000 now, I'm (hopefully) still a ways off. :)

I dont know why you seem stuck on this. Like i said before, it does give a check engine light on the dash. And Persian confirmed it. Maybe your perticylar BMW doesnt, but i know sure as shit mine did. A replacement tstat fixed it.

Persian never stated that the ses or cel came on with the code. He only stated that it throw off a couple of codes. You need to re-read his posting.

I know that a stuck open thermostat will give a DTC but not a SES or CEL as the OP's mechanic found out and as I have stated in my case.

This was my experience when my old 3.0i had an opened Tstat:
- NO SES on the cluster
- Take very long time to warm up/have little bit of heat.
- Temp needle drop down when driving on the hway vs. local streets
- Mpg went down
- Scanner showed one pending (that's why it's not triggering the SES) code: P0128

@ Slick GT1

Daka 3.0
Persian 3.0
Upallnight 3.0
TMV 3.0 (old X5)

All experience a stuck open thermostat with no SES light. You need to read the owners car model before telling them they are wrong.

It sounds like you had your X in for something else and indy mentioned thermostat or did you have symptoms that tied to cooling system?



Since you are only driving short distances it should not harm the engine and it is possible it does not get to proper operating temperature with good or bad thermostat anyway. Regardless, it is not something that has to be done right away.

I would think if the indy wanted to scam you they would have chosen to repair that costs a lot more and requires many hours of labor.If you are concerned about integrity of shop either unlock the OBC and monitor temperature or ask the shop to do so. Then let the engine idle for 15 minutes to monitor temperature before making a decision to replace the thermostat. If indy is trying to put one over on you it will do no good to ask him how he knows it is a bad thermostat. I would either monitor the coolant temp or get a second opinion and prices from to do the repair.

Code or no code, light or no light you will have your answer.

It sounds like you had your X in for something else and indy mentioned thermostat or did you have symptoms that tied to cooling system?

Since you are only driving short distances it should not harm the engine and it is possible it does not get to proper operating temperature with good or bad thermostat anyway. Regardless, it is not something that has to be done right away.

I would think if the indy wanted to scam you they would have chosen to repair that costs a lot more and requires many hours of labor. If you are concerned about integrity of shop either unlock the OBC and monitor temperature or ask the shop to do so. Then let the engine idle for 15 minutes to monitor temperature before making a decision to replace the thermostat. If indy is trying to put one over on you it will do no good to ask him how he knows it is a bad thermostat. I would either monitor the coolant temp or get a second opinion and prices from to do the repair.

Code or no code, light or no light you will have your answer.

lol Okay thanks :)

It will trip p0125 generic: INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL. in the winter. This will turn on SES.

Under the bmw hidden codes, you will have open thermostat.

Maybe I am paranoid but I believe on my car, this has greatly affected adaptations due to me taking 5 mo. To fix it (busy).

Exactly. Happened to me in winter too. It is a general P code. I am telling you it was the first ever code I read off the car, with SES on. And like I said before, maybe because it is a 4.8is and we have a sensor right on the tstat, but it sets off the SES.

Oh and my friend has a 3.0, had the same error during the polar vortex, it has not returned. Persian has a 3.0 as well. The winter condition is news to me.

The X5 was in for an OIL service and to check that the shop that replaced the Steering Angle Sensor had coded the repair properly...they found a "problem" with the t stat and also the brake light switch(?) that they said was causing my adaptive headlight problem...(they used to move slightly right and left as you turned the wheel, which they no longer do)....I am loosing faith in this new shop as well as the shop that I used for over 20 years...the one that replaced the SAS and told me that they had done the oil change when in fact they had NOT done it...(oil was dirty and 1/2 quart low the day after they serviced it)....
Makes me want to start leasing new cars and not having any "REPAIR SHOP PROBLEMS"
tnx Daniel

Someone here has a list of recommended shops around the U.S. That might be helpful.
If I have something I can't do I always check with the local BMW club for what shop is currently on the good list. If there is a cars and coffee in your area that would also be a good place to talk to BMW owners.