Head Gasket Failure

I am experiencing problems with rapid head gasket failure on my ZB Magnette. It has a standard 1500 B series which was rebuilt prior to my ownership. The head has been pressure tested, converted for Lead free, re-faced. The block has been checked for distortion and is level and true. When running the temp has been showing a little high, but oil pressure has been consistently good.  I have replaced the 'stat, checked the water pump. My last resort is to draw all of the cylinder head studs, check, clear /clean threads, and seatings to make sure they are well and truly home etc. I have adhered to tightening sequence torqueing up in 10ft./pd. increments up to specified torque figure. What am I missing or what else could it be?


#1 Malcolm Eades 2015-01-27 17:53
Can you give us a bit more information on the nature of the failure. Is it "catastrophic"? i.e. does the gasket suddenly fail with much steam. Or does it just start slowly with partial leaks that get worse?

What kind of gasket are you using?

Has anything you've done to the engine increased the compression ratio significantly? Some cylinder heads have smaller combustion chambers.

Have you countersunk the tops of the stud holes to make sure the threads have not been pulled up during tightening?

#2 Trevor Jones 2015-01-27 18:00
The cheap head gasket sets are a complete waste of time, they appear to be similar to cardboard, a multi layer Payen or original copper gasket NOS is the only answer, £35 seems the going price.
#3 Malcolm Eades 2015-01-27 18:01
Trevor, I agree. I always try to get Payen if I can.


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