dumb overheating AGAIN

[lolcantturn]

No, nothing? I'm starting to think it's a faulty thermostat.. but I just got a new thermostat. Grrr.

[lolcantturn]

Sorry for the double (well, triple post), but just to clarify my previous post, I know it's not related to the heatercore or valve in any way because when I had a faulty coolant temp sensor that made it read cold, my heat was still pretty freaking hot.

[lolcantturn]

Well I kind of have another problem now..but I'm sure it's related to my original overheating

So I drove my E30 around and I noticed that with the heat on blast and I'm on idle sitting at a light, the heat is actually cold..then when I'm driving in gear, it gets warm. Warm, but not hot, just "acceptable" for this weather.

Hmmmm? I checked in the Bentley but that doesn't seem to have helped.

[LJ851]

Not bad, perfectly normal. When your engine is running , your functioning , circulating cooling system is constantly removing the heat generated by the engine. When you turn off the engine the cooling system not functioning (well barely) so all the heat energy stored in the metal of the engine "soaks" into the coolant raising its temp until they are equal and then the temp will start to go down.

[lolcantturn]

Its called heat soak. All engines do it .

Oh I was unaware. Hmm...Is this..bad?

[LJ851]

Its called heat soak. All engines do it .

[lolcantturn]

It seems like it's working mighty fine now! It hasn't gone over the halfway mark not even a little. The only thing that weirds me out is that when I shut my car off and leave it off for about 5 minutes and come back, I turn it on and the needle is at the 3/4ths mark? then in about 4 seconds it's back to halfway point and staying there..

How can my car be producing overheating while it's off haha

[lolcantturn]

When you re-bleed after driving the car do you get more than a few bubbles out? If so and if the prior bleed was done properly you have a leaking head gasket. When you had the head off the car did you have a shop check it for warp and cracks?

Definitely not more than a few head bubbles..I'd say it was a quick short burst and then just a steady stream of antifreeze. Thanks!

[jlevie]

When you re-bleed after driving the car do you get more than a few bubbles out? If so and if the prior bleed was done properly you have a leaking head gasket. When you had the head off the car did you have a shop check it for warp and cracks?

[lolcantturn]

There is an electrical problem for sure. The gauge is moving too fast for that to be real temperature. You may also have a mechanical problem as well. Do you have access to another cluster to try ?

Nope unfortunately I don't right now. I think however I fixed the mechanical part of my overheating problem.. I drove around hard, let it cool down, and rebled. I just left the bleeder screw open all the way. closed it, squeezed every hose (not sure if that would do anything but) and then opened it again and rebled. Filled up my coolant, drove around, and it stayed in the middle. There were some fluctuations in the first 4 minutes but then it died down and stayed in the middle. On idle I saw it creep a HAIR over to the right, the needle was still ontop of the halfway mark but towards the left. It never went passed there, and once I was on the gas again it moved back to being dead center.
For such a simple cooling system the M20 sure has weird mood swings.

However, I'm going to get a new cluster soon (my ODO doesn't work anyway), so I'll see what's up.

[LJ851]

There is an electrical problem for sure. The gauge is moving too fast for that to be real temperature. You may also have a mechanical problem as well. Do you have access to another cluster to try ?

[lolcantturn]

Earlier in this thread you stated that you removed the thermostat and found that it failed to open in boiling water. Have you replaced that thermostat with a good unit? If the thermostat is missing or not opening there will little to no flow through the radiator and thus the bottom hose will be cool.

I don't know what your bleed procedure is but what's below will work almost as good as a vacuum fill system.

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500 for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

Oh yes, I did your bleeding procedure jlevie, but to no avail. I literally did that procedure for an hour this morning. I drove the car around 4 minutes ago pretty hard, so I'll re-bleed after it cools down and post my results.

My thermostat seems to be working, My lower radiator hose gets hot.

[jlevie]

Earlier in this thread you stated that you removed the thermostat and found that it failed to open in boiling water. Have you replaced that thermostat with a good unit? If the thermostat is missing or not opening there will little to no flow through the radiator and thus the bottom hose will be cool.

I don't know what your bleed procedure is but what's below will work almost as good as a vacuum fill system.

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500 for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

[lolcantturn]

Anyone ?

[lolcantturn]

that may just be your gauge cluster spasing out, and not real temp fluctuations

I'm not sure, but I don't want to take the risk if it's actually correct.

I had a Victor-Reinz head gasket fail on my M20 in the same manner as your describing your problems to be occurring. It was spontaneous, but the problem provoked itself rapidly through the course of one day until it failed. Keep an eye on your coolant level. Something may have gone awry through the course of putting your new head gasket on.

I was reading in a popular mechanics mag about some catalyst you can add to your overflow tank, it changes color with the presence of exhaust fumes. I'm sure you can find this crap at your local auto parts store. If your still having issues, it would be a cost effective way to figure out if you've got a bigger problem on your hands.

I don't have a victor-reinz head gasket on my car, I forgot which one it is.
My coolant level is fine, I highly doubt its my HG because I would know all the signs as it's happened to me before already.

Can you link me with further information on that? That would really help down the road haha.

Thanks!