So, I finally get the car running and she runs great!!! with the exception that she over heats. I bought the car a month ago with a broken timing belt. I replaced the head, head gasket, water pump, fan clutch, and a whole bunch of other stuff not related to cooling. I thought it was the thermostat so I removed it to check, it made a little difference but only in the length of time required for the car to heat up. I can drive the car all day long (with no thermostat) and the gauge never leaves the blue and I don’t loose a drop of coolant. However, if I stop for more than a few minutes it begins to creep up and boil the water. I can start the car from dead cold and allow it to idle till it “heats” up and the radiator hoses never seem to warm up. I am at a loss. I have removed every hose I can think of and flushed everything with a garden hose and nothing appears blocked. Here is a short video. Any ideas would be greatly appreciated!! I should also note I did a leak down test and the only thing I found were leaky intake valves.
overheating 91 325i
Put the tstat back in and doublecheck all your symptoms again because replacing the tstat could well change symptoms. The coolant flow path dorks up when you remove the tstat because when it is gone coolant doesn’t have to go thru the radiator.
If the engine temp is fine when you drive but a problem when you are stationary then the issue is likely related to the fan.
Be wary of the coolant temp sensor. Once you lose a bit of coolant the sensor won’t be touching water anymore because it’s at the top of the system.
Bleeding the system is easy to screw up. The coolant has to be hot enough that the tstat opens. Once everything is nice and hot, then you can bleed.
If your return hose isn’t heating up then there is a problem with the tstat.
Thank you, I replaced the t-stat and drilled an 1/8th hole at the top, bypassed the heater core, and spent an hour bleeding the system. That, so far, has seemed to work! I am so relieved I knew was going to have to re-do the head gasket but I am definitely thankful I do not! I have put about 500 miles on it and so far so good. Not bad for $1000 total. 