Overheating when idle...

[jrusso628]

my car seems to be heating up when stuck idling in traffic. It is only during long idles, such as stuck in traffic, rather then just a red light. it will immediately cool down once i am in gear, moving and getting air through the radiator. I had the fan clutch replaced just this february so i'm hesitant to think that is the problem even though thats what it seems like. Replacing the fan clutch seems like a pretty simple job so i doubt it was botched when done? What is my next step to figuring this out?

Engine is a m50 also.

[1996 328ti]

Stuck thermostat?
Air in the system?

[jrusso628]

I'll try bleeding the lines.

Is there a easy diagnosis for thermostat?

[1996 328ti]

Originally Posted by jrusso628

I'll try bleeding the lines.

Is there a easy diagnosis for thermostat?

But it in boiling water with a thermometer?
If i was going through the trouble of removing to test, I'd probably just replace it.

[zoner]

When you say 'cool down', does the temp. gauge ever go below the half-way mark on the gauge when you are driving or on the freeway (once the car is at operating temperature, of course)? If so, I would say it is the thermostat. If it never goes below half-way, but only goes higher when stuck in traffic, it is possibly your fan or fan switch. Either way, I would start with bleeding the system, as it is relatively easy and does not require tearing into the engine or cooling system, but only requires removing the bleeder screw next to the filler neck and going through the steps to correctly bleed it.

If the thermostat is stuck shut, the car is only going to overheat, regardless of whether the car is moving or standing still. If it is stuck open, it may run hot when you are in traffic or standing still, but it would normally run cold (gauge below the half-way mark) once you start moving at any significant speed.

[zoner]

Originally Posted by 1996 328ti

If i was going through the trouble of removing to test, I'd probably just replace it.

+1

[cooljess76]

6cyl e36's typically don't trap air as badly as 4cyl models due to the expansion tank placement. However, since your car is swapped, it's possible that the PO reused the 4cyl radiator. I'll 3rd the stuck thermostat theory though, symptoms point towards that being the culprit. Probably wouldn't hurt to replace it and bleed the system, they're relatively cheap.

[1996 328ti]

While swapping out a t-stat, aren't there aluminum t-stat housings for the M50?
It's so easy to spend other people's money.

[jrusso628]

temp gauge locks midway like normal, only goes above mid during long idle, never below. Is the fan switch the same as the fan clutch? if so i had it replaced in February. I've noticed upon initially starting the car and accelerating the fan sounds like a jet engine for the first few seconds. Not sure i'm hearing the fan turn on when the engine heats up either.

[zoner]

Originally Posted by jrusso628

temp gauge locks midway like normal, only goes above mid during long idle, never below. Is the fan switch the same as the fan clutch? if so i had it replaced in February. I've noticed upon initially starting the car and accelerating the fan sounds like a jet engine for the first few seconds. Not sure i'm hearing the fan turn on when the engine heats up either.

My above comments pertain to the M42/44 motor. If yours is swapped, you would have a belt driven fan, not an electric puller fan.

[jrusso628]

Decided to go with a whole coolant flush, don't know when the previous owner last did one if ever. Replaced the thermostat and put on a new aluminum housing. Finished up and pressure tested the system and both radiator seems were leaking, passenger side far worse. So come monday new radiator will be going in. pretty sure air pockets in the system was causing the overheating problem, but glad i found this radiator leak. Bit surprised i haven't been noticing any coolant left under the vehicle during rest.

Was hoping to spend that money on a new valve cover, the gasket is leaking leaving a bit of a mess down the front of the engine, not to mention the ugly chipping paint. replacing the gasket is the next to do. followed by transmission ouput and shift seals.

Gonna be a spendy month, but she is well worth it, never had a car more fun to drive.

[1996 328ti]

It you want to spend even more money, you can opt for an aluminum radiator.
I don't think the t-stat and housing was a waste of money though.

[jrusso628]

When replacing the radiator i noticed that one of the plastic fan shroud clips on the driver side of the radiator had been snapped off. The fan clearance to that same clip on the new radiator was about 1 cm (keep in mind i have no fan shroud do to it not fitting with a m50), i decided to leave it be. Next day while stopping hard heard a loud noise, engine started to vibrate hard and a rattle coming from the engine started. Opened the hood, first thing i notice is my fan is missing blades and several others are chipped and damaged. Thankfully radiator was fine and water pump was also fine. The rattle turned out to be ac pulley tensioner, since ac is dead removed it. After all this couple questions, Could the engine shift a cm forward from a hard stop? (checked engine mounts) If i can't fit a shroud is it ok to run without a fan? (already bought and replaced broken one, Engine vibration gone)