running hot, not overheating

A

Athos

Member
Hello All,

i have been having a strange problem and I am looking for help.

My car has been running hot lately, not overheating but when caught in traffic, the needle will the the middle mark and begin to slowly rise upward but not overheat and then return down to the middle mark.

I replaced the water pump, and thermostat thinking that might have been the problem.I took the car on a long drive (6 hrs) and it ran perfectly all the way there. Then after driving for 40 minutes in traffic, I experienced the same symptoms.

I do not appear to have any leaks, and can find no water in the pan. I have also replaced the coolant sensor and several of the hoses.

All the fans appear to function correctly sooo do I just keep replacing parts i.e. the radiator and expansion tank ? Any other things to check?

Thanks in advance

2006 3.0SI Auto
 
Try and bleed the coolant system, make sure you don't have pockets of air in the system.
I have the opposite problem; mine runs cold (75-85deg C) at motoway speeds, indicating sticking open stat.
 
What bleed procedure did you use? I’m guessing you are aware there is an automated electronic bleed process on the N52.
 
I read that post and followed the bleeding procedure exactly. I an near certain that I have no air in the system but am having a hell of a time trying to figure out what is causing the problem. It only seems to happen in start stop traffic.

I am going to bleed the system again and try that. Then check for leaks again!

J
 
Usually a sign of a leak or steaming. Run the car up to temp and look under the bonnet whilst running, see if you can smell coolant or see wisps of steam. Plastic reservoir is the common one, also could be that the cap is not sealing properly anymore.
 
Understood that it's a different motor, but is the bleeding procedure different for a n52??

I will check for steam leaks , and report back..

J
 
Athos said:
Understood that it's a different motor, but is the bleeding procedure different for a n52??

I will check for steam leaks , and report back..

J
Click to expand...

The M54 has a traditional mechanical water pump, the N52 facelift motor has an electric water pump that has to be activated with the ignition switched on, but engine OFF to self bleed properly.

Good how-to instructions with pictures can often be found on the Pelican parts site, in your case the e90 instructions which should be the same as your car as they are both N52.
https://www.pelicanparts.com/BMW/techarticles/BMW-3-Series-E90/WATER-Draining_Filling_Cooling_System/WATER-Draining_Filling_Cooling_System.htm
 
Athos said:
Understood that it's a different motor, but is the bleeding procedure different for a n52??

I will check for steam leaks , and report back..

J
Click to expand...

That’s right, with the ignition on you have to fully press the accelerator for 10 secs to start the automated bleed process just like ewazix link above describes.
 
I followed the proper procedure for the n52, and bled the system 3 times...

The coolant level is fine, and I have yet to find leaks...but will keep checking..

Thanks all

Ps no error codes...!
 
Same thing with mine, but that was coolant leak (so easy fix). Good luck sorting :thumbsup:
 
This is driving me mad...

I have bled the car and am near certain that there is no air in the system. The car is using no coolant and I can find a leak anywhere, steam or other wise.

The car will not overheat if on the freeway and moving, when driving free the temp stays dead in the middle of the gauge...

If however you slow down or move onto city streets the guage begins to climb, and then will go back down to normal, and swing back up again, intermittently. I cant seem to trigger it to happen and have tried both the A/C on and the A/C off which does not effect the issue.

Also just as a side note my A/C has been blowing warm air intermittently as well...could the two be related?

HELP!

J
 
Both the ac and obviously the main radiator cooling rely on the radiator fan to kick in at the right time to function properly. Are you sure the fan is working?
 
It appears to be work, I turn on the A/C and the fan will immediately engage. I am wondering if the fan might be intermittently cutting out?
 
So if you leave running stationary, revving a bit to encourage it, have you actually seen the fan come on to cool and when that happens does the needle move back down then ?

I am not surprised in free driving the temp does not move, in my experience the N52 needs to get quite hot to move the needle, so on normal journeys the stat will do the work alone with the cooled air even at slow speed

Also as said before these fans are electronic and so have speeds - not just off and full. So maybe it gets hots, triggers fan at low speed, that fails, getting hotter, triggers more speed until it finds a level it works, then it cools down. The a/c just triggers a static spin.

Anyway thats what I would do, watch the fan as it gets hot. Jumping straight to full blast and something is wrong.

INPA lets you trigger the % full speeds to test. At 100% it sounds like a tornado
 
Yeh, INPA is great for testing fan. If that all checks out ok you probably might need to start thinking about a sludged up radiator.
 
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