BimmerFest BMW Forum banner

Hello everyone, Serious need of help here. Engine is overheating. e39 528i 1999

1K views 14 replies 7 participants last post by  pjamrisk 
#1 ·
Hello everyone,
I been reading a ton of posts on how to change the several different parts for the water pump and thermostat.
My question however is the following. when the car is running, I can see how it overheats slowly, but the front fan does not turn on at all. the pulley from the water pump is working correctly and there are no leaks. I have not replaced the thermostat yet, but wanted to see if anyone has some pointers before I endeavor on changing the whole thing here.

Thanks again!
Patrick
 
#7 ·
Awesome Guides thank you!
Anyways, no one helped me with a concise answer. Does the fan in the front does not work because of a faulty thermostat? The reason why I am asking is when I get the job done, I don't want to have the surprise that something else is the problem as well, and I am going to have to put the dang thing apart for the second time after I am done with the job.

Thanks again!
Patrick
 
#8 ·
Are you referring to the Auxilliary fan (pusher, in front of radiator) or the main fan (belt-driven)? The auxiliary fan turns on in some conditions, but usually turns on if it's warm and the a/c is on. The main fan should spin at all times, just more slowly if the engine is cold. You should be able to stop the fan with a rolled-up newspaper if the engine is cold. If it's not spinning, but the belt is, you need a new fan clutch.

As you'll have numerous bits and pieces out of the car to replace virtually any cooling system component, you're best-off replacing it all at once, to minimize the labour involved. You will replace everything in CN90's writeup eventually.
 
#9 ·
Thank you for your quick reply. Yes the fan with the clutch is working as the belt rotates, so that is not the problem. is the other fan not turning on. The AC fan I believe in this case, but then that one has nothing to do with the whole system then
Regardless, if it is not the waterpump the problem, it is either the radiator or the thermosthat.

Long story short the front part of my car caught fire for an electrical problem (the mechanic said he was not sure how it happened). so in the process they replaced most of the front of the car, but I am unaware if they replaced the thermostat or anything else in that sense.
So I will go ahead and start the process and get back to the forums if I get stuck somewhere. I am sure someone will have some good pointers.

Thanks again everyone!
Patrick
 
#10 · (Edited)
It does seem like that the thermostat is stuck open. If you drive on the highway and the temperature drops below normal, the thermostat is most likely stuck open. Usually that results in a fault code, scan the code if you have a reader. If the fan infront of the radiator is not turning on when the engine passes the normal operating temperature, you should check out the fan as well. Maybe the fan is bad, or the coolant temperature sensor is faulty.
 
#12 ·
Scott, as a reply to your post (sorry didn't see if before) the temperature started to rise while driving for a split second, then the temperature started to drop back to 50% while driving on the highway. if I drive it on the regular streets then the temperature started to rise again and it kept going up to red... I just checked the fan fins, and they are fine after the removal. Also the old water pump seems to be in perfect shape. The only thing left is the thermostat and that sensor I will post the picture later and see if one of you can tell what it is.
Patrick
 
#11 ·
Hello again guys and gals!
well I was able to put the assembly apart and cleaned the radiator. The thing is still brand spanking new. I removed the housing of the thermostat and replaced the water pump. I am waiting on my new thermostat to arrive and put it all back together. Indeed an easy job.

However, I do have a question. On the right lower end looking at the car. The plastic frame has what looks like another sensor. I will take a picture of it and post it over later today as I just got back from work and need some sleep, to see if you guys have any ideas of what the hell this is. I don't know if this one helps on a temperature differential calculation of some sort.... maybe another culprit.

Patrick
 
#13 ·
How many miles on the car? As others suggested, you should do a cooling system overhaul regardless of mileage for a 11 yr old car, especially on the E39. But to fix the problem at hand for now, i suggest you to change the water pump, thermostat, top radiator hose and the coolant temperature sensor (mounted in the lower radiator hose). You should scan for any fault code if you have a scanner.
 
#15 ·
Scott,
The car is 145k miles. I am doing the whole overhaul, just waiting on the parts to arrive tomorrow.

The cause of the fire my mechanic said was a electrical failure and a leak of power steering fluid. besides that nothing else he could note. And it was extremely weird as it started with the car being parked.
The insurance covered all costs, so I was happy on how it turned out until today of course.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top