Why do I keep overheating?

[bigmansM]

I have replaced:
Water pump and thermostat 2,000 miles ago. Auxilary fan fise and switch.
Temp.109
A/c was on and my water temp gauge read 250 and i had to shut a/c off. this is the third day this has happened. It is too hot to drive without a/c

Next:
Even at night when it is much cooler, and the a/c is off, my water temp. is just pased the 210 mark on the gauge.

I think its time for a new fan clutch?

I am using the edge motorworks gauges to read the numbers. I talked to one of the guys at edge and he said everything is pretty acurate on those guages

whats my prob?

[M3_boogie]

Barring getting some faulty new parts, my guess is you've still got air in the cooling system. Try re-bleeding it by opening the bleed screw on the radiator and running the engine until no more air bubbles come out (then close it).

[techno550]

Could also be a partially plugged radiator or a faulty aux fan. What were you doing while the temps were so high? was this at 55 ;) on the highway? or stop and go traffic?

if you have an IR temp gun, check the temp on the radiator. It should be relatively even top to bottom, and cooler only when sweeping from driver side to passenger side. If its got cold areas between top and bottom, then it is partially plugged.

[M3_boogie]

Could also be a partially plugged radiator or a faulty aux fan. What were you doing while the temps were so high? was this at 55 ;) on the highway? or stop and go traffic?

if you have an IR temp gun, check the temp on the radiator. It should be relatively even top to bottom, and cooler only when sweeping from driver side to passenger side. If its got cold areas between top and bottom, then it is partially plugged.
Good point. A bunch of people had issues with the "fan delete" because their aux fan fuse was blown and the fan wouldn't come on. Check that out too.

[douglee25]

Also make sure your underpanel is installed. If it's missing or has a hole it in, this will creat a low pressure area causing the air that's supposed to be reaching your radiator to be sucked out under the car. No good :mad

Doug

[bigmansM]

Also make sure your underpanel is installed. If it's missing or has a hole it in, this will creat a low pressure area causing the air that's supposed to be reaching your radiator to be sucked out under the car. No good :mad

Doug

Actually I dont have my underpanel on, because it kept coming off.
Ill check the radiator today for cold spots, that things is original and probably needs to be changed.
The high temps are in stop and go traffic, on the highway the temps. lower

I dont think i need to bleed it because i had already done that. But ill check that as well. Thank goodness it is sprinkling this morning. Crazy CA weather

[DeeM3]

Probably air bubbles in the cooling system.

[techno550]

If you are ok on the HWY but not in the city, I'd suspect fan issues moreso than radiator issues. You can test the low and high speed settings on the fan by jumpering the pins in the fan switch plug on the side of the radiator.

[mikeinsanmarcos]

Also make sure your underpanel is installed. If it's missing or has a hole it in, this will creat a low pressure area causing the air that's supposed to be reaching your radiator to be sucked out under the car. No good :mad

Doug

Is this a fact or opinion?

[douglee25]

Is this a fact or opinion?

Fact! Physics don't lie :redspot Faster moving air will cause a low pressure area right under the pressure stream. This is the same principal that causes an airplane to fly or why the soda rises in a straw as you blow air across it. Check out Bernoulli's concept in a google search.

Doug

Edit: Here is the concept applied to a carburetor.

[mikeinsanmarcos]

:nono you need to quantify the low pressure experienced without the panel for you to state this as fact. Many, many people here run without the panel and do not experience ANY overheating issues. I ran without one for about a year even with the fan delete and never had any problems either in stop & go or on the free way.

Soooo much misinformation on the internet :eyecrazy

[douglee25]

:nono you need to quantify the low pressure experienced without the panel for you to state this as fact. Many, many people here run without the panel and do not experience ANY overheating issues. I ran without one for about a year even with the fan delete and never had any problems either in stop & go or on the free way.

Soooo much misinformation on the internet :eyecrazy

This is a fact that a low pressure area is created. Like I said, the physics don't lie. Whether or not you personally experienced overheating or not, isn't the issue. This could contribute to an overheating condition which is why I stated to check out whether or not the underpanel was installed. How is that misinformation?

Doug

[techno550]

I agree that the underpanel is important, but it would not be the factor that would make an E36 overheat. Especially when stopped. ;)

[Balthazarr]

I agree that the underpanel is important, but it would not be the factor that would make an E36 overheat. Especially when stopped. ;)

I would think if attached, the panel would exacerbate the problem.

I seriously doubt that Bernoulli's eqn comes into play significantly in the above case.

[mikeinsanmarcos]

This is a fact that a low pressure area is created. Like I said, the physics don't lie. Whether or not you personally experienced overheating or not, isn't the issue. This could contribute to an overheating condition which is why I stated to check out whether or not the underpanel was installed. How is that misinformation?

Doug

Lol, I am not saying Bernoulli's concept is wrong, I am saying it is not relevant here.. You do not know for a fact that there is low pressure generated without that panel unless you have measured it, this is an assumption on your part. The underside of an M3 is nothing like the inside of a carbarator or a straw. Misinformation is someone stating opinion as fact.

He is having overheating issues when stuck in traffic, not when moving on the freeway.. Lets concentrate on his problem at hand..

My vote goes to air trapped in the radiator..

[rfc2307]

I struggled thru this when my 1997 ///M3 2 door hit about 90K miles. Among other things, the mechanic mixed BMW blue and K-Mart green anti-freeze which turned to a nice milky goo in the radiator. Needless to say, cooling went thru the floor.

I did the following:

1. Flush radiator with standard radiator flush. Run engine ten minutes, open radiator drain and put garden hose in top of radiator and let it run ten minutes with the engine on.

2. Remove overflow hose from engine block (under intake manifold, behind Power Steering Fluid reservior. Drain water.

3. Add another container of radiator flush, close drain pepcock in radiator, put garden hose in engine, fill with water, run ten minutes.

4. Open radiator pepcock, turn on garden hose and flush ten minutes.

5. Repeat step #2 above.

6. Put in two bottles of Red LIne Water Wetter and fill with 100% distilled water.

[M3_boogie]

I think your problem is still air stuck in the system. Sometimes you need to bleed it, drive around, (let it cool down) and bleed it again. Sometimes 3-4 times.... eventually you'll get it all out.




I struggled thru this when my 1997 ///M3 2 door hit about 90K miles. Among other things, the mechanic mixed BMW blue and K-Mart green anti-freeze which turned to a nice milky goo in the radiator. Needless to say, cooling went thru the floor.

I did the following:

1. Flush radiator with standard radiator flush. Run engine ten minutes, open radiator drain and put garden hose in top of radiator and let it run ten minutes with the engine on.

2. Remove overflow hose from engine block (under intake manifold, behind Power Steering Fluid reservior. Drain water.

3. Add another container of radiator flush, close drain pepcock in radiator, put garden hose in engine, fill with water, run ten minutes.

4. Open radiator pepcock, turn on garden hose and flush ten minutes.

5. Repeat step #2 above.

6. Put in two bottles of Red LIne Water Wetter and fill with 100% distilled water.

rfc - yes, it is a no-no to mix "green" crap with the BMW antifreeze.... but using straight water (even distilled) without any kind of anti-corrosivies (like those in the BMW stuff) isn't a good idea for the long term. Racecar's do this, but they also do a lot of other things daily drivers should not/don't need to do.

[speshuled619]

If you are ok on the HWY but not in the city, I'd suspect fan issues moreso than radiator issues. You can test the low and high speed settings on the fan by jumpering the pins in the fan switch plug on the side of the radiator.


everyone is giving the right advice. also check by hand when the car isnt on if the fan clutch is alright by spinning it. it should have a fair amount of resistance. and once again you can never over bleed your system so check it once more.


techno - how would i check for a faulty high speed fan relay? my fan doesnt come on when the car gets hot. it only comes on when the a/c is on.


ed

[bigmansM]

okay i checked the radiator temp. with my temp. heat gun and the temp is even throughout. I will try bleeding the system again.

I jsut flushed the radiaotr not too long ago. I didn't do such an ellaborate process as stated above but Ill do this last.

one thing no one has consider is:
this only happens when te a/c is on. other then that the car runs pretty much at the proper temp. like i said myabe it runs at 220 instead but i can live with that. I think there is something with the a/c unit

[techno550]

techno - how would i check for a faulty high speed fan relay? my fan doesnt come on when the car gets hot. it only comes on when the a/c is on.

ed
The temp switch is on the side of the radiator. (passenger side.) There is a plug on it with 3 wires. If you view the plug as if the wires come out the back and go *down*, thus looking at the pins/holes with wires going down, and jumper the bottom pin to the left or right pin, you should get low or high speed on the fan.

you can also check for continuity between certain pins on the sensor that is still in the radiator at this point at various coolant temperatures. (checked on the core with a temp gun is easiest/best.)