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Head Gasket Sealer

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I've installed a lot of head gaskets over the years but read an article recently that advised putting gasket cement on both sides of the gasket. I've never used any kind of sealer in the past and not had any problems. What do you guys do?
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It depends on the type of gasket. Any composite gasket like the FEL-PRO blue, then No. However when using the old style steel shim head gasket (like chevrolet used in the 50's and 60's), I hang the steel shim gasket in the sun and then coat both sides with a silver spray paint. A very light coat and allow it to dry. The silver paint is a clear with metallic in it. I have done this for years and never had a head gasket sealing issue, again only on the steel shim head gaskets. I learned this from an old machinist. It seems to work good as a sealing agent.
 

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Way back several decades when I was going to college, before the days of house size loans to attend, one had rich parents, scholarships or worked your way through. I had some of the first two and a lot of the latter.

So on and off I twisted wrenches and drove truck to augment my income. One afternoon when I came to the shop there is a Chevy in my stall for a valve job. I pull the heads which are warped as is the block. The pistons have about as much side to side movement as the crankshaft has stroke. I stopped and called the boss told him what I found and that a valve job would only serve to make this exhausted engine into a massive oil burner. He said wait till he called the customer. He calls back a bit later and says the customer insists on the valve job only. You know how mechanics always pad the job to make more money? So I clean the castings, check the shot guides another call “no” the customer doesn’t want the guides fixed. So I shoot the seats and grind the valves. Dress the seats so the valves set at the same height except for the guides a primo job. Not wanting a come back do to gasket leaks I libarlly coated the gaskets with 3M door gasket adhesive and put it together. Gone for several nights this damn thing shows up in my bay a few days later the customer now understands the Root Problem isn’t going to be solved with a valve job and has bought a major rebuild. So I got to tear the heads I so excessively glued to the block off again. By now the 3M was baked to everything which took hours to get the heads separated from the block without adding more surface damage than what was already there. Sometimes you can’t win for losing.

Bogie
 

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Hello, there. I am in my 60s, been building cars and engines a long time. Not a professional mechanic, I am a lawyer who restores cars for a hobby. I have been using this product since the late 1970s on head gasket installations. Works great every time. Spray on copper adhesive. They also make it in a can with a dauber, have used that as well but I prefer using the spray for head gaskets so I get an even coating. I also agree with the post saying it depends on the head gasket construction and composition. However. I prefer to make sure there are zero leaks due to possible imperfections in the surfaces of the head gasket, thus this product is used. Call it cheap insurance on the stuff where you don't think it is needed. Never had a problem even when a head cracked.

K&W Copper Coat Gasket Compound. Product number 401612


Permatex sells their version of this product as "Copper Spray A Gasket Hi Temp Sealant" but the products are similar in composition. Adhesive with copper particle suspension.
 

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As other said, good clean machined surface nada but if not so great then extra insurance.

Still I took some rusty heads and cleaned then up with the no-no disc and block, used Flepro blue headgaskets with no sealer and they held fine for years of light use But had several small leaks when pulled years later. I plan to slap some new heads(3rd set it'll see) back on that same shortblock cause it still good and if I take it apart might as well rebuild. This time I will deff use copper spray on the block side but since heads are new I will only coat the one side.
 

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Way back several decades when I was going to college, before the days of house size loans to attend, one had rich parents, scholarships or worked your way through. I had some of the first two and a lot of the latter.

So on and off I twisted wrenches and drove truck to augment my income. One afternoon when I came to the shop there is a Chevy in my stall for a valve job. I pull the heads which are warped as is the block. The pistons have about as much side to side movement as the crankshaft has stroke. I stopped and called the boss told him what I found and that a valve job would only serve to make this exhausted engine into a massive oil burner. He said wait till he called the customer. He calls back a bit later and says the customer insists on the valve job only. You know how mechanics always pad the job to make more money? So I clean the castings, check the shot guides another call “no” the customer doesn’t want the guides fixed. So I shoot the seats and grind the valves. Dress the seats so the valves set at the same height except for the guides a primo job. Not wanting a come back do to gasket leaks I libarlly coated the gaskets with 3M door gasket adhesive and put it together. Gone for several nights this damn thing shows up in my bay a few days later the customer now understands the Root Problem isn’t going to be solved with a valve job and has bought a major rebuild. So I got to tear the heads I so excessively glued to the block off again. By now the 3M was baked to everything which took hours to get the heads separated from the block without adding more surface damage than what was already there. Sometimes you can’t win for losing.

Bogie
Never considered using that 3m weather stripping for headgaskets. Might have to try it on a certain junky high mileage engine, if I ever slap it back together.
 
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