Best way to detach a head gasket from a block and head?

[chris-p]

Plastic putty knife should do it with ease.

Just tape a piece of sandpaper down to a piece of glass, or very straight surface, and do figure 8s with the head until you see the head is now straight. Usually low between the cylinders.

[outboardnut]

I am not familiar with this motor but-
are there any pins?
For example-number 90 on this parts list
http://www.marineengine.com/parts/johns … head+Group

[mr-asa]

quote outboardnut:

I am not familiar with this motor but-
are there any pins?
For example-number 90 on this parts list
http://www.marineengine.com/parts/johns … head+Group

There are pins, but only on either side of the crankcase, not head and block

[fleetwin]

I’m not sure I understand what you are describing. Are there broken head bolt shanks still stuck in the head? If so, is there more than one broken head bolt stud? If there is only one broken stud, you can smack on the other side of the head with a heavy plastic mallet which will cause the whole head to rotate, hopefully loosening the one broken stud as well.
You must be very careful trying to wedge something between the head and block, the head is unlikely to give way if broken studs are holding it in place, damage to the cylinder deck is inevitable.
I just can’t imagine anything holding that head in place if there are no broken studs, unless someone used JB weld or something else like that to glue the head down. You may want to consider finding a used head, then you can sacrifice the head in order to be sure you do no damage to the cylinder deck. Simply take an air chisel to the head outside the broken/seized stud(s) which will split the head open and loosen the salty grip.

[mr-asa]

The head of every bolt twisted off, leaving the body of the bolt in the head as if it were a stud.

[lloyd]

Worked this problem a number of times. Corrosion between the steel bolt shafts and the aluminum head is locking the head in place. Wedge between the head and block will usually damage both. Best bet is to clamp the head only in a large vise and using a 1/4" drift/punch hammer on the ends of the broken bolts/studs. Work around the head tapping/beating on all the broken bolts equally. The force and vibration will work it free.

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