Cooling System HELP!

[kylekrueger]

Hi everybody,

I have a '89 325 with a b35 swap from a 1992 e32. I have been having cooling issues with the car ever since I bought it about a year ago and now finally the cooling system has gone to hell. I need some major help because I cannot diagnose the problems it is having.

Here is what happens to the car.

1. I turn on the car, everything seems fine so I start to drive.

2. After the first 2-3 minutes the engine temp rises at an unsettling rate until it is almost at the red zone. Mean while, if I turn on the heater it will not blow hot it will only blow ambient air.

3. The engine will stay at this high temperature, but when I rev the engine at this point to above 4-5k something happens and the engine temp will go back down to a normal running temperature (just below the middle of the gauge).

4. After the engine has returned to a normal running temp the low coolant light comes on, on the check panel so now there is no coolant in the res. tank but the engine is still operating at a normal temp.

5. When I shut off the engine, but then turn it back on (engine is still hot) we start back at #1.

So, this has been going on for a few weeks and finally 2 days ago I came back to my car at a shopping center and i noticed a river of coolant coming from under my car. At this point I say, that enough is enough and I call a towing service to get it towed back to my house.

Now, that brings us up to today. I have pulled out the entire cooling system. That means all the hoses, res. tank, thermostat, thermostat housing, thermostat inlet cover, everything accept the radiator.

Here are some known things:

I know of one leak coming from the return hose to the radiator. It is at the hose clamp on the thermostat housing

I found a hole in the thermostat inlet cover (from calcium build up and corrosion)

I noticed also that there was a lot of calcium build up on the third from front of engine coolant hole on the block (the brass coolant plugs on the intake side of block, sorry I can't remember what they are called). The build up could just be because of the coolant that leaks onto the block or is it possible that coolant is leaking out of the plug?


SO, what I need help with is if anyone can help me solve the cooling problems I am having. Why does it over heat like that then go back to a normal temperature? And is it possible for those brass plugs to leak like that?

Any help is wanted and sorry for the long post.

some pics:


thermostat cover with a hole in it


thermostat seems ok


found some antifreeze build up around temp sender


modified thermostat, I drilled 3 holes in it so there would constantly be fresh coolant flowing into the engine



general layout of hoses


build up around radiator outlet hose into the thermostat cover (where the hole is)


build up around brass block plug

[JoeMadoo]

I would start by fixing your leaks, getting a new t-stat housing or one from a junkyard and replace any funky looking or leaky hoses.

Test your t-stat, one way is to set it in a pot with water on the oven and see if it opens as the water gets to boiling point.

Make sure to BLEEEEED all the air out of the system from the bleed screw and that your reservoir is the highest part of your cooling system.

Maybe clean the freeze plug and see if thats leaking under normal temps.

There needs to be pressure in your cooling system to work properly and can't be any air in the system other than the reservoir.

Give those a shot.

[kylekrueger]

Thanks for the response Joe.

What happens if I just ran the car with out a thermostat? Is that a bad idea, or is it mostly just there for the warm up period when the engine is cold?

Do, you think you could send me some pictures of your hose routing, I'm not really sure if mine is correctly routed. If it isn't too much trouble.

[msinger]

make sure you dont put the thermostat in backwards, like me, for shame....

[DivineStyler]

I was wondering why would why you want to put holes on the thermostat? Does that adversely effect the proper function of the thermostat? just curious... thanks.

[dannyyisntt]

Sounds like you've got yourself a bad t-stat.

[down_shift13]

Also when you replace thermostat, make sure its the right temp coz they sell them in varius degrees. Mine was always above the halfway point on the temp gauge despite bleeding and fixing all leaks. Once i got the lower degree one my gauge stayed between 1/4 - 1/2 of the gauge.

[Dude]

I was wondering why would why you want to put holes on the thermostat? Does that adversely effect the proper function of the thermostat? just curious... thanks.

Apparently it auto bleeds it or something, its a track thing from what I hear

[DivineStyler]

Apparently it auto bleeds it or something, its a track thing from what I hear

my thermostat is running cool just below to the left of 12 O'clock... it's not right in the middle and seems to run fine... I wonder if the holes in the thermostat is keeping it slightly cooler than the normal middle temp gauge...

if so, I heard that it will have adverse effects on the engine and gas mileage...? true?

[LowR3V'in]

Why exactly did you drill holes in it?

The hole that's already on the thermostat
bleeds air when you're filling the system only.

Good crutch for people that don't know how to bleed
or have a blown head gasket . :P

[DivineStyler]

my question is will the 3 holes you drilled on the T-stat make the car run slightly cooler? or affect the temperature at all?

what exactly is the purpose of the holes or it's advantages... I would think it would interfere with the proper temperature that it was designed to work for...?

[Danny]

All drilling holes does is let a little bit of coolant into the radiator when the thermo is closed. Makes for easier bleeding.

[weaksauce]

yeah, we drilled ours like swiss cheese on our 6 series race car.
if you ran it without a t-stat it woudl overheat, our t-stat was bad, so bam, drill holles all around the outside of it fixed the problem. Now it runs just a tick to the right of the blue all teh time on teh track.

[slammin.e28]

yeah, we drilled ours like swiss cheese on our 6 series race car.
if you ran it without a t-stat it woudl overheat, our t-stat was bad, so bam, drill holles all around the outside of it fixed the problem. Now it runs just a tick to the right of the blue all teh time on teh track.

Wrong. It wouldn't get to operating temp because the coolant would ALWAYS be flowing through the radiator, thus cooling it.

Just park it on an incline with the front facing up, open the heater core (turn the temp knob all the way to the red) and open the bleed screw. Start filling the reservoir until coolant comes out of the screw. Simple. There's another way, but I don't feel like typing it out. Go to mye28.com and read the tech sticky.

[Doughnut]

wrong. It wouldn't get to operating temp because the coolant would always be flowing through the radiator, thus cooling it.

+1