Hi all, need some advice. I bough a 2009 R55 clubman with a bad thermostat (blew a hole in it) a little over a year ago. I replaced the thermostat with a Dorman aftermarket part. Along with this, i replaced the water pump and connecting pipe. Worked fine until this fall. Got a check engine light operating temp too low. Monitored the temp and had no heat intermittently. No coolant leak or loss. Temp running around 75 celsius.

I determined that the thermostat was stuck open. Also, the reading from the temp sensor got flakey. Lifetime warranty so i got a new one.

Installed the new one after pulling the engine and replacing the clutch.

The new one will not heat up above 70 deg celsius at idle and no heat idling for 30+minutes. When i take it down the road, temp moves all over the place. I keep reading swings going up and down from 78 to 110 deg celsius. Only seem to have heat when temp exceeds 85 degrees. You can feel the air temp change as the engine temp rises and falls.

I keep purging air from the bleed valve. No water in oil and compression fine and running is good. Occasionally it will rise to 120, then drop back down. Under accelleration, temp rises 5-10 degrees.

Antifreeze has been pushed out the overflow but not constantly and not overheating. Still runs great. There are times of hard accelleration with little temp change.

I am assuming the new thermostat is bad since I start it up and the car never gets warm enough to defrost the windshield. If it works right, the engine should reach about 100 , then the thermostat should open. Even cold days, the thermostat should regulate and prevent flow until operating temp.

I am concerned about the o-ring below the reservoir. Noticed some slight leaking ariund it, but not constant. Also system is pressurized. If you release the cap, there is pressure and always has had that. This makes me think the o-ring is ok since it holds pressure.

Anyone else experiencing similar problems? Am I overlooking anything? I’m ordering a new different brand of thermostat, but dont want to keep replacing them.

Any insight would be greatly appreciated.

Tim

 

bleed the system properly.
check if your water pump is physically running.
check the pipes going to the proper inlets. realoem.com
feel the pipes if they are actually hot, cold or in between.

 

Hello,

Did you check the other common leak locations other than the thermostat? I would double check to make sure you bleed is several times, i had to do this. Check that expansion tank on the bottom for hairlines cracks. Also, make sure the plugs on the harness are all the way in and are not cracked, the top sensor harness plug likes to crack and break.

https://www.northamericanmotoring.co...8-no-heat.html

Also, make sure there is no blockage to the heater core, this can also be done by feeling the pipes going to the firewall once the car is warmed up.

 

While you are in there, replace that plastic expansion tank with a stainless steel one available on ebay (or will ECS carry them?)

 

We have the Forge one for the expansion tank. Its in that main link under the expansion tank link and the kits on sale.

 

See, there ya go. Besides, they look a heck of a lot better under the bonnet than that ugly plastic blob.

 

Does a leak at the expansion tank cause air pockets to develop? I am thinking that I have two problems. First, I replaced a faulty thermostat with another defective one. Next, i had to remove the expansion tank and when I reinstalled the quick connect, it leaked a little at the o-ring. I am thinking the fluid is leaking and causing the air pockets to develop.

No leaks anywhere else, pump is running and hoses are correct.

Is there any electronic valves in the assembly that electricslly opens and closes?
Tim

 

The leak at the expansion tank can create a lower level of coolant in the thermostat as it drains the tank when you cool down and have the car setting, mine did this. The O ring leaks also at the bottom from oil changes and constant movement. This can drain a tank if it continues to leak and then do the same thing if you have cracks. 11537600674

https://www.northamericanmotoring.co...ant-leaks.html





There is an electric pump (aux pump) in my link above that kicks on after you shut off you engine, it runs for a short couple minutes and then shuts off.

 

Tim, I have been experiencing the same thing with my 2011 MCS Convertible, got the code, changes the thermostat multiple times, bleed the system and its not reaching over 170 degrees unless I am running the car for an hour! Did you figure out the culprit yet?

 

I have moved to AZ and unable to work on the car.


I have come to the conclusion that there is a crack in the exhaust runner to water jacket somewhere in the cylinder head. I come to this conclusion because the antifreeze is not being blown out quickly from compression gas at cylinder pressures of 175psi.


Since there is compression gas in the antifreeze (tested positive), and the cap is holding pressure (10-15psi cap I think), the gas has got to be coming from a low pressure source. The only low pressure source would be the exhaust runners since that pressure would most likely be whatever the exhaust back pressure is.


I suspect that if you were to remove the exhaust manifold and run the engine (NOT RECOMMENDED), the car would operate fine since the exhaust back pressure would not be high enough to push through the crack.


I have not removed the cylinder head to check, but suspect the cylinder head is fine. I did not do a compression check since the car ran "fine" and had plenty of power otherwise.


Tim