Sorry Guys Possibly Repetitive Thermostat Problem

[Paul in NZ]

have you verified that the thermo stat is good?.Even though new it can be faulty.Place in a pan of water and heat.At some point(and if you have a thermometer you can verify that temperature)it will begin to open,but the main thing as the water heats up the thrmostat should open fully.Then at least you know the themostat will open.

[clhorton]

Hey guy's I'm having trouble with my '87 325I with the m20. I have replaced my thermostat with a new unit, I have completely verified that the thermostat is in the housing with the gasket placed correctly, but no matter how many times I have used the methods for bleeding my M20 the thermostat never opens and the car continues to go up in temp. There appears to be no loss of coolant in the system, but and the engine runs fine when cranked. If this post is repetitive I apologize, but I've searched and used most of the methods I have found, including hooking up with my bmw through the reservoir tank. Do you guys have any idea why my thermostat does not like to open?

[clhorton]

Just placed the thermostat in a pan and it opens fullly. So my next guess would be that it is indeed locking due to air in the system. Any other ideas?



have you verified that the thermo stat is good?.Even though new it can be faulty.Place in a pan of water and heat.At some point(and if you have a thermometer you can verify that temperature)it will begin to open,but the main thing as the water heats up the thrmostat should open fully.Then at least you know the themostat will open.

[whiskychaser]

Just placed the thermostat in a pan and it opens fullly. So my next guess would be that it is indeed locking due to air in the system. Any other ideas?
If it wasnt overheating before you replaced the stat, its either the stat, air or a blockage somewhere. You tested the stat so its odds on its air. Might help if you leave the rad cap loose and let it cool overnight

[Ross]

If there is no circulation the stat won't see any hot coolant. Verify the pump is doing it's job.

[clhorton]

This may sound like a dumb question, but where is the best place for me to look to verify that coolant is circulating?




If there is no circulation the stat won't see any hot coolant. Verify the pump is doing it's job.

[whiskychaser]

This may sound like a dumb question, but where is the best place for me to look to verify that coolant is circulating?
If your rad has a seperate expansion tank, you should see coolant coming out of the end of the small hose from the rad where it enters the tank. The simplest way to test if you have circulation is if the top hose gets hot. But be careful - if your cooling system is making steam instead of circulating coolant that hose may get VERY hot

[clhorton]

OK, I went and bought a new water pump and am in the process of installing it (damn tensioner). Hopefully the new water pump will make a difference. The pump that came out had the metal splines also, so I guess I'll just wait and find out. With a little luck, I hope this works :(




If your rad has a seperate expansion tank, you should see coolant coming out of the end of the small hose from the rad where it enters the tank. The simplest way to test if you have circulation is if the top hose gets hot. But be careful - if your cooling system is making steam instead of circulating coolant that hose may get VERY hot

[clhorton]

OK, I am waiting for the gasket to come in for the water pump later on today. If my old waterpump was metal, does that pretty much mean the water pump was not the problem in the first place. I am praying it is not the head gasket, but am still worried this water pump may not fix the problem. Is there any such problem with a water pump, besides having a plastic impeller, that could cause air in the system resulting in a non-functioning thermostat. The car runs great otherwise. Somebody reassure me or let me have it :D

[632 Regal]

I think it's an air blockage.

heres what i remember winfred mentioning on the M-20's

drill 1/8 hole in stat and place with hole up

raise front of the car in the air

add water from the top hose

make sure pisser hose isn't blocked

other than that the heat is supposed to be on too.

[clhorton]

UPDATE: Ok guys, I have a new pump installed on the car. I have flushed the system today and have continued to bleed it. The bottom hose is still ICE cold so I am left to believe the thermostat is still not opening. I have drilled the 1/8 hole and 12 o'clock, nothing different. I have given the cooling system mouth to mouth many times with bleeder screw open and closed the screw while still blowing in, nothing. I am running short on new idea. I have seen it discussed that possible radiator problems could exhibit the same symptoms. Passenger side of radiator is much much warmer than the driver side, but is that just due to the fact that the thermostat is not opening? Thank in advance!:(

[whiskychaser]

If you think its the rad you could try back-flushing it with a hose. But is your heater working? If so at least you know you have SOME circulation going on.
Does the top hose feel empty? If you narrow it down to air you can always try snatching it if all else fails. But if you havent done it before I would give it a miss. You dont need scalding on top of your woes:(

[clhorton]

UPDATE: I just changed the thermostat again and nothing has changed on the car. At idle, the temp went to 3/4 and continued to climb so I killed the engine. Immediately after killing the engine I felt the radiator. The radiator is completely cold all the way around. Is the radiator being cold suggestive of a bad radiator. The bottom hose is still completely cold also. Could the radiator just be cold due a possibility that there is a head gasket leak and the thermostat is continuously becoming air-locked and therefore no coolant is circulating through the radiator or is the radiator supposed to have some amount of warmth even if the thermostat is not opening? At the return tank the coolant does not smell of gas, nor do I see any extra amount of air bubbles. I have tried bleeding it many times using the various techniques found on here.

[whiskychaser]

1. Is the radiator being cold suggestive of a bad radiator. The bottom hose is still completely cold also. 2. is the radiator supposed to have some amount of warmth even if the thermostat is not opening?
1. Not clear if you had a problem with the rad before. But I would say that for it to be completely blocked is rare
2. Hot water rises so it will be trying to get out of the top of the block, not the bottom. If it cant, you wont get circulation so your rad will remain cold.
If you are convinced its the stat, run it without one. It will take longer to warm up but my guess is it will still overheat. I'd be checking the heater return to see if thats getting hot. If not I'd be disconnecting the return to bleed it. Then I'd move on to the top hose etc. But as I said before this is damn dangerous so see if anyone comes up with a better idea first