How do I Remove Very stuck on Exhaust Manifold Gaskets?

KM7

Petty Officer 1st Class
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Aug 14, 2013
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337
I'm changing the exhaust manifolds. They came off easily, but the gaskets are really stuck on the engine block. They may be the original and 35 years old ! I've tried a hard plastic scraper and gasket removal spray. I have a one-sided razor, but I'm concerned about cutting into the metal. So far, I'm not making much progress. These original gaskets seem Very tough!!

Any suggestions? Heat? A drill with a (soft) wire wheel? Keep soaking with gasket remover? What else?

Thanks
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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52,947
Soak with penetrating oil

Then use a metal paint scraper or a gasket scraper.

I have use wood chisels in the past
 

Mc Tool

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Aug 7, 2024
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Soak with penetrating oil

Then use a metal paint scraper or a gasket scraper.

I have use wood chisels in the past
Paint scraper ....not to wide , maybe 1 inch and cut half the blade off to stiffen it up a bit and grind a bevel on one side ....like a wood chisel . Ideally you dont want to shave any metal off but as long as its not a chunk the odd nick isnt going to ruin the gasket surface . Exhaust gaskets are fairly thick and when fitted with a bit of exhaust sealant not a problem . Cast iron is pretty hard compared to aluminium . 🙂
 

IslandExplorer

Chief Petty Officer
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Oct 21, 2019
Messages
596
Oscillating multi-tool with nice sharp straight flat scraper blade for the win. Usually that gets right under it and will do a good clean job, and it's easy on your hands.

Can ping it with light ball peen hammer taps directly on it to get cooperative fractures started if extra resilient gasket. Go easy with hammer. One ping only.
 

KM7

Petty Officer 1st Class
Joined
Aug 14, 2013
Messages
337
Just to be clear, I'm trying to get very old gasket material of the cylinder head not the exhaust manifolds. I plan on replacing the manifolds.

Thanks for all the suggestions above. I will try a combination of all of them,

I have PB Blaster Penetrating rust remover and I also have CRC Gasket remover. I have been spraying with the CRC and letting it soak but the gaskets are Very hard after 35 years!! I'm not sure that the CRC is doing much. I can keep spraying and letting it soak. I also have a drill and wire wheels. That seemed to work at least partially, but it takes a long time. I'm taking it slowly to be sure not to wear down the mounting surface.

Is there a chance that the gasket material contains asbestos? I'll use a mask !!
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
14,247
Maybe heat it with a heat gun carefully…I had a heck of a time getting the old gasket material off. Took quite a while!
 
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