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MG MGF Technical - Cause for MGF overheat/HGF....

My 97 MGF has just is just about to have it's 3rd HGF. I've had HG replaced in January but the cause never clear. Three weeks later I suffered the 'hit the red' on the temperature gauge again. When I checked the coolant, it was full of oil - the HG hadn't gone as I had abandoned the car once I noticed the temperature. The garage diagnosed a probable crack in head and replaced the head. Two weeks later I start to notice the temp is increasing very quickly on short journeys (but has not hit red) so ... I take it on a longer spin and eh voila, it hit's red, and the coolant is again full of oil.
The one thing that seems different to other HGF cases (I've spent all day reading)is that there is no water in the oil - when i check the dipstick it doen't have this 'mayo/honey' so no water has leaked into the oil - but I do have a coolant tank with a lot of oil in it and it's bubbling like mad. The mechanic thinks there may be a crack in either the head or the block and when it is running the oil leaks out as it's at higher pressure????? Any thoughts from anyone??

Good grief! I hope you are not paying for what seems to be major incompetence by the garage mechanics. You must be really peeved!


Could be that the HG has failed around the oil channel that directs oil to the camshafts. That's what happened to my '96 18i.
If you drop me your correct mail adress i can mail you a picture of what it looks like.

Just an idea...

Did they peform an oil change and engine flush after they fitted the new gasket. The mechanics should have done this approx. 200-500 miles after they changed the gasket as it takes some time for the coolant to be removed from the engine. How would they know, otherwise, when the oil/coolant contamination occurred? The oil in the coolant they found could have been from the original HGF just 3 weeks prior (if the flush was not done).


David Mason

Yep, I'm peeved - and getting more so every day ... I'm not even sure that there was a crack in the head when it was replaced - does oil in coolant usually indicate a crack somewhere or can there be another reason?

HGF was in December, fixed in January, did about 400 miles, oil in coolant Feb( just overheated - HG didn't fail), new head Feb, did about 250 miles, even more oil in coolant March (same again - HG hasn't failed). It was flushed in Jan and in Feb - I reckon the quantity is too much to be residual. I'm relectant to let the mechanic replace head/block until I know what the cause is!!!

Chech ou t the MX5 and the new MR2 Claudia.They will cure your problem.
john ruddock

This thread was discussed between 25/04/2001 and 27/04/2001

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