Hi All,
Hoping some of you techies can throw light on this prob. The Head gasket went on my 1994 Ford Granada (2 Litre DOHC) last week. One of the things I nothiced was the coolant system was pressurising. I just finished replacing the head gasket (after many hours of swearing at the thing) and the coolant system is still pressurising, (even when cold). The head gasket had gone between the water jacket, a piston and the outside of the block. I've had the head pressure tested and skimmed, and the block was OK. Any ideas???? My own thoughts are a possible blockage in the radiator, but I'm not too familiar with the cooling system.
Many thanks for any help given...
Nick
PS No water in oil, no oil in water, runs sweet and doesn't misfire at all.
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Hairline crack that only opens up when engine has been running for a while maybe?
Did you get the head X-rayed?
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Keith,
Thanks for the reply, I had the head pressure tested and skimmed and everything came back ok.
Not had it x-rayed though. The problem seems to happen from the moment the key is turned, although I haven't run the car for very long as I don't want to damage the head gasket again.
Cheers
Nick
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Nick
This is a curious one. How was it pressure tested may I ask, because the head off the engine will have more holes in it than you can shake a stick at and all of them would need to be blanked. Perhaps the exhaust manifold is cooled? and exhaust is pressurising the water jacket?. I'd spend an hour studying the diagrams and photos in the manual for all alternative pressure sources. If there is nothing it does come back to a cracked head or block or a duff gasket. Did you use the right tightening sequence when you pulled the head down?.
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Nick,
What happened to tell you the head gasket had gone in the first place and what is the sequence of events from the first moment it starts up now?
MM
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What do you mean when you say the coolant is pressurising? Is coolant being forced from the breather in the expansion tank when the engine is running? Are you using the correct procedure to refill the coolant system, you need to top it up until full and allow the engine to warm up with the cap off the expansion tank to allow all air-locks to escape, while keeping an eye on the coolant level and keeping it topped up accordingly.
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you replaced the thermostat of course?
madf
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Thanks to all for your replys.
I think I may have found the problem. I replaced the thermostat about one month ago, as it had stuck shut. Obviously this involved replacing the coolant. It now seems as if there was an airlock in the system, causing it to pressurise and the heater to blow cold, and this caused the head gasket to blow between the water jacket and the outside of the block. The current problem with the system seems to be the same. I ran the engine last night with the pressure cap off and at high revs for about a mile, and the coolant level had dropped. After filling it and doing the same thing again I put the pressure cap back on. The system now seems to be OK with no loss of coolant and pressure only when the system is hot, as you'd expect.
Many thanks to all again for your replies, a great site for us home mechanics trying to save a few bob.
Nick
PS If anyone needs any advice on doing a Ford DOHC head gasket, feel free to email me at nickcolebourn@hotmail.com and I'll offer any advice that I can, as i've got the bruised knuckles and cuts to prove it can be done at home ;-)
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Yoy often have to run engines over 4000rpm.to get trapped air out of the system.
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