Cylinder Head or not cylinder head ?

[bongomonkey]

Recently has a overheating problem where water was gushing from the expansion tank when engine was hot. Changed the thermostat and bled the system (exactly as the service manual said!). Bongo fine for approx. one and a half months. Then all of a sudden the rubber hose from the thermostat to the steel pipe burst, split and dropped the coolant. Replaced the hose which was the original and all fine again for about two weeks. Then, the hose further along between the bottom of the radiator and the steel pipe burst and dropped the coolant. Have now repalced this today and done the necessary bleeding. Within half an hour OK, then temp rose very quickly in a bit of traffic (blowing water out of ecpansion tank).

Took centre of thermostat out (as it was when I bought it), bled it again (for a long time !). All OK stationary. As soon as I took it out within half a mile, temp right up again.

Opionions, if you please - Am I looking at a cylinder head problem where the coolant system is being pressurised by an influx of air via the head ????

Thanks for any posts in advance ....

[mikeonb4c]

You should be able to get coolant tested for traces of exhaust gases, which would confirm if it is a head problem or not. Otherwise, is your radiator crudded up maybe? Does the coolant look clear or not, and is the expansion tank looking stained.

Some thoughts to start with anyway

[Simon Jones]

Sorry to hear of your troubles. I had similar symptoms: excess pressure, overflowing expansion tank & failure to get all air out the system. I had no problems with hoses bursting, but if yours fail before the cap blows, then either the hoses are perished or the cap is faulty. This will need addressing regardless.

To cut a v. long story short, this was basically what I went thru:

1) Removed head, had skimmed & pressure tested (no fault found)
2) Re-assembled: same problem, but if anything slightly worse
3) Removed head, had pressure tested again at a higher temp (no fault found)
4) Followed excellent advice from Bellhill Garage & 'decked the block' to ensure flat mating surface
5) Used Wellseal head gasket sealant when re-assembling
6) Bled system & took for a very nervous test run - all fine
7) Took it to Bellhill Garage for a re-bleed.

Since then, we've done about 4000 miles with only one incident in Poland when we had an airlock caused by a minor cut in the bleed pipe.

Mike's suggestion is a good 'non-invasive' starting point. I've not tried it myself but I believe others on the forum have.

If you want to discuss further, let me know & I'll pm you my phone number.

Good luck - I know how you feel.

Simon