Overheating problem series 2 1.3 coupe

[Owen_lassa]

Hi

I have a series 2 that I bought about 6 months ago and have been going through it - the trouble that I’m having is the entire time I’ve had it there has been an overheating issue.

I first noticed that running the car with the radiator cap off the coolant would churn in the radiator and if I gave it throttle it would blow right out of the radiator which signaled head gasket to me so I gave it a compression test and a leak down test both of which is passed with flying colors strangely enough… it was also shooting coolant out with the cap on once the car was warm

I then realized what I thought to be the problem which was that the thermostat had been punched out by the previous owner and there wasn’t one, so that as I revved up the engine it sped up the water pump and shot coolant right out the path of least resistance. I ordered an 83 degree C thermostat and installed that along with a new electric fan which looked like it had solved the problem, but I found that on a longer drive and once up to operating temperature the gauge would keep climbing and there would be coolant loss under the hood that had come from the overflow on the radiator

I’m not sure where to go from here - I’ve flushed the system many times and when flushed the water runs through relatively clear - I’m still thinking it could be a head gasket but unsure why it wouldn’t show up on either the compression test or the leak down test.

Any suggestions would be much appreciated
Thanks
Owen

[viiking]

I've seen big coolant movements in the radiators on other marques of cars when the engine is revved.If the radiator is full then the coolant WILL spill over. If there is an air space in the radiator then you normally wouldn't lose any coolant.

Before going too far in your engine diagnosis, I would disconnect the water pump drive belt and repeat the exercise. If the coolant stops its expulsion then you can pretty much say that it is the water pump causing it. You would I think want to do this with the thermostat either open or missing to reproduce what you initially reported on.

[Huib]

I agree that head gasket is most likely. What is a leak down test?

Did you check the radiator temperature if it is equally hot everywhere? If it is the original radiator it may have blocked channels.

[Owen_lassa]

I agree that head gasket is most likely. What is a leak down test?

Did you check the radiator temperature if it is equally hot everywhere? If it is the original radiator it may have blocked channels.

Leak down test is sort of the opposite of a compression test - you pull a spark plug and apply compressed air to each cylinder individually with valves closed and see if the air is escaping through the intake, exhaust, or into the radiator (ie. Head gasket). I did this test with the engine cold, but I am going to repeat it tomorrow with the engine hot and see if that changes the results. It is not the original radiator, newer aluminum one but I suppose it could still be an issue.

[Owen_lassa]

I've seen big coolant movements in the radiators on other marques of cars when the engine is revved.If the radiator is full then the coolant WILL spill over. If there is an air space in the radiator then you normally wouldn't lose any coolant.

Before going too far in your engine diagnosis, I would disconnect the water pump drive belt and repeat the exercise. If the coolant stops its expulsion then you can pretty much say that it is the water pump causing it. You would I think want to do this with the thermostat either open or missing to reproduce what you initially reported on.

I like this idea, but the water pump is gear driven so unfortunately I cannot perform the test.

[Huib]

Why not use the Midlock tester with the blue liquid? Hold the thing over the radiator. Squeeze the rubber ball several times. If the liquid turns yellow there is exhaust gas in the coolant.