coolant system problem still

[kansas-ix]

Okay hopefully this time my problem can be solved, The car overheats when sitting still, yes I bled the system, yes I have flushed the system, yes I have put a new water pump and a new auxillary fan, and a new fan clutch on the car, and it still overheats sitting still and also the top hose from the radiator to the thermo is full of pressure along with the water pump bypass hose, does this mean head gasket?, I have clean coolant and clean oil, I can drive the car to school 30 miles on the highway no prob of overheating, driving 400miles a week, but today my concern grows the car had jolting hesitations on the highway, rpm dipping and catching again. Pressure in hoses was very high also. Thanks for your help in advance, Bryant.

[nando]

maybe try a different temp thermostat?

The pressure is probably not good, maybe you should have a compression check done to see if maybe there's something wrong with the head?

as far as the jolting on the freeway/loss of power/rpm dip, replace your O2 sensor.

[kansas-ix]

I'm running a wahler 80* ,
I'll check compression tommorrow, just got a summer job a repair shop in town, I'm sure I can get them to peek at it tommorrow.

[65Matt]

Back from the dead to add some good information:

- Make sure your car has the plastic undertray installed. It bolts underneath the car, and attaches to the wheel wells. It makes a big difference in cooling, especially when the car is idling.

- If your guages are acting strange in the least way, replace the SI batteries. My temp guage would twitch and go up. It was giving incorrect readings.

[M-technik-3]

Have you check the thermostate itself? put it in pot and boil water to see if it's opening correctly? Miles on the car? How often was the coolant changed by previous owner?

Was phosphate free coolant used by previous owner? Head and water passages could be clogged.

[LennysEleven]

I am having the same problem. I bought the car after it had the water pump replaced and it overheated on the way home. Head was cracked. So I got a used head, new head gasket and flushed the coolant. Oil is clean but the coolant could be better, I was thinking I would flush it again and replace it with water wetter. No one had mentioned the undertray before ill go check that out right now.

ANYWAYS, its the same exact problem, runs fine when moving but the guage will go up when sitting. And it takes awhile to get up the normal op. temp but once it does it will start going past halfway.

[LennysEleven]

I had an undertray but its metal, sits under the trans, and is not attached to the wheel wells.

So am I missing the plastic one? I have a 90 325i. How does this undertray help keep the engine cool when idling?

thanks
NIck

[65Matt]

Well I cant find the undertray in my ETK. It functions as a fan shroud, keeps the air moving. It fills the gap from the front valance panel/ spoiler to the oil pan.

I couldn't find a picture of one, but here is an aftermarket version for the E36. This will give you an idea of what to look for (I'd look in the junkyards or make your own):

http://store.yahoo.com/jtdesigns/body.html

All I know is that my car was getting hot when sitting still. When I started moving, it would cool down. I thought it was the fan clutch, but it passed the 'shredding newspaper' test. Once I put the undertray back on, it runs cool like it's supposed to.

[M-technik-3]

The under tray also helps aerodynamics.

[Digitalwave]

I have an undertray for sale if you want it.

[LennysEleven]

SO there are two? A plastic one under the engine and a metal one under the trans?
How much are you selling yours for?

thanks
Nick

[Digitalwave]

Yeah, there are 2, I have both if needed, I was talking about the plastic under engine one. $20 plus shipping.

[LennysEleven]

Ill take it, my email address is Lennyseleven@aol.com

Email me and we'll get this in order.

thanks
Nick