Coolant Temp Overheating
 

Hello All,

So for starters I definitely missed out on the Midnight run a little while back but now I've moved from queens to jersey which gives me space to actually work on my car now rather than doing everything on the street.

So here is my dilemma:

Yesterday I was driving back from work which is approximately 25 miles. Somewhere in between I get a check coolant sign while I'm driving approximately 45-50 mph. Immediately after that maybe 2 minutes later I get check coolant temperature sign. Now the car starts overheating so I pull over immediately at the first chance.

The last thing I changed on this was the lower rad hose from engine to the radiator. Now I remember how hard it was getting that hose off and then getting the new one to get in there. Anyhow that hose came off from the radiator and had spewed all the coolant out. I was able to hammer it lightly and get it to be in there again and re-filled the coolant that I picked up from a Sears nearby. (Originally when i had flushed and re-did this job I have only used the BMW coolant but I had no choice and bought the prestone and put that in). Turn the car back on all seems normal the temp gauge is right in the middle and so I start driving immediately it shoots to the red area and I pull over again. So luckily I was only a few miles from home and crawled home letting it cool every 1/2 mile - mile before it shoots to red. Now I re-checked that hose and its still connected and no coolant dripping after I re-filled it. Also at this point now before I get home I also have the SERVICE ENGINE SOON light on which im guessing might be from turning it on and off or probably a sensor.

I am wondering if the sensor that is attached in that hose that I also replaced is the culprit. I wonder if it fried when it detached itself and started overheating.

I do not have warranty so I'm on my own on this. My first guess is to change that sensor or perhaps the sensor and the entire hose itself.

Please give me suggestions as to what I should do. Again the car keeps overheating but I do not see any coolant loss.

Recent changes:
New Expansion Tank with thermostat
New hoses all of them

In my recent post i posted pics of all the changes

When you refilled the coolant, did you bleed the system? You might be overheating because there is a ton of air in there.

That hose coming off is not good. How did it do that anyway. Did you put the clip on when you installed it? You should read the codes, and see what is going on. Maybe your t-stat is busted again.

there are multiple problems - first you need to properly bleed the system, and as a matter of fact you can look up the procedure either here or on E39 forums - the engine is the same between the platforms.

once you bleed the system, read the codes from the engine to see what threw the code...

report progress, we will help you from there on...

I think that might be the problem I did not bleed the system. The air might be the issue. I know that the last time I was bleeding the system I made sure the temp was to max 90 and at the lowest setting. Then adding coolant with the vent open and I started getting coolant flying out of the vent at which point it seemed clear of bubbles. I did not do that this time when filling it up. I will do that as soon as I get home.

The hose was in tight for sure because i could not do it with bare hands so i used a rubber mallet to slowly push it in all the way until it was on just the way the previous one was. Then i closed the clip and did not have trouble until this.

As far as codes go I can read the one on the obc but I do not have a reader. Any suggestions on one that I can pick up from perhaps a pepboys? or an Autozone?

I am gonna research again the correct procedures on bleeding and make sure its done the right way and see what i get back on it.

The "codes" you need to read are not associated with the car's OBC. You need an OBD II scanner/reader that will give you the codes for the vehicle's electronic emissions system (which OBD II is federally mandated to be installed in ALL car mfg's vehicles in the USA).

Once you have the OBC II "DTC" (diagnostic trouble codes)...you can usually find the code, its meaning, and possible fixes online. There is so much OBD II info online its not even funny. For instance, just type "OBD II codes" into a google search box and see what I mean. :)



Since OBD II is a federal mandate for the same criteria for all car MFGs...in most states you can go to places like AutoZone, Advanced Auto, Pep Boys etc...and most will read your OBD II codes for free. All they need to do is hook up to the OBD II connector on the lower left of your instrument cluster (between the steering wheel and driver's door...there's a small flip down door).


And now that your over in Jersey...consider picking up a simple OBD II code reader (as a Xmas present for yourself) :) ... you can find simple ones on eBay or Harbor Freight for approx $25. You can also pay much more money if you desire more info etc...but a simple $25 reader works fine for quickly hooking up and finding out what any OBD II code(s) that may pop up...and allows you to reset them if possible.

This is the one I have (Autel Maxi Scan MS300)...and keep in my trunk tool kit in case needed...again, I paid approx $25 for it a few years ago on either eBay or Amazon.com. I just checked and it's going for $19 on Amazon :wow::

Your best bet is to fill it with an Air Lift:

Air Lift Cooling System Refiller : Amazon.com : Automotive

You do need shop-air to use this. It uses the shop air pressure to create a vacuum, and it will then suction in the pre-mixed BMW Coolant/Water mix. Don't forget to use only distilled water, not tap water.

I'm gonna try to bleed it without this for now and see where it goes and then take it to a local spot for diagnostics.

Well, the auxiliarly cooling system pump can circulate the water a bit. Turn it on while filling the car, (hit the Max button when the car is off and key out, I believe there is a time limit from when the car was shut down. I think it will also go on with the ignition in ON but car not started as well.)

But these cars can be quite difficult to get out all the air pockets without an Air Lift. And if you run the car with an air pocket, you do run the risk of overheating the car.

Nah. Key in position 2, heat at 90, slowest fan speed. I can actually hear the pump, and hear it circulating water. It will do this as long as your battery has juice. So ridiculous easy to bleed system fully without anything special. Never had an issue.