Hemi head gasket leaks

[Smokin' Joe]

I had a '66 Hemi rebuilt by a guy that has built at least 15 engines for me over the past 20 years. He admitted that this was his first Hemi, but as he is such a perfectionist, I didn't think there'd be a problem.

It's the original engine to a car we restored and after we installed it and fired it up, there are 4 oil leaks, one at the outside corner of each head. It's right at the point where the oil returns are.

The rebuilder offered to come and fix it, but I'm wondering what was done wrong the first time and what can be done to be sure it doesn't happen again.

Is there a particular "method" other than the standard torque sequence that needs to be followed to be sure there's no leak?
Is there a particular brand of head gasket that's better than the others?
Is there a particular sealant that's better than the others?

Thanks for the help, guys!

 

[68 HEMI GTS]

could be the surface on the heads or the block is to rough of a RA for the head gasket, has it been milled, is it deck/heads flat? gonna be kind of hard for anyone to know for sure without knowing all the variables. being all four corners are leaking im guessing the gasket just insn't sealing on the surface finish for some reason. nothing trick to the torque sequence. best fix would be a new set of quality head gaskets and to smear a little high temp RTV around the return holes on each side, that will solve the oil leak issue. thats all i would do if it were mine.

 

[Meep-Meep]

May also be not enough gasket compression at the oil return holes. This is not under pressure so the best case would be capillary action or something in that area isn't completely flat. Or as said above, wrong surface for the type of gasket. I wonder if one could clean that area out with a solvent until it's completely dry then use Loctite 272 to fix it (green wicking grade). If oil can get through there then acetone should be able to as well. If this is the only leak then that's what I'd try.

 

[Smokin' Joe]

Thanks, guys! I know that the heads were cleaned up a few thousandths, but I'm not sure about the block. I'll check on that tomorrow.

 

[snakeoil24]

What is leaking? Oil or Water?

1. You need to use Cometic gaskets, with copper spray on gaskets. Around the two outer Coolant holes you also need a small amount of RTV inside the cut out for the Cometic Gaskets. The heads need a bit of a cross hatch. also remeber you need to use a dog bone on valley studs. Never reuse head bolts and only use ARP. When you install head bolts use extra sealant on bolts. Do not use RTV on Head bolt threads use "sealant Dope". The heads need to be re torqued first time within 20 mins of first start up. Then do a second after 2 hours. Make sure your rocker shaft supports are properly seated on stands and have washers on bolts. Also remember these heads are nothing like doing a Wedge, Torque sequence is really finicky around water jackets. Also you can take a center punch with brass hammer and dimple around coolant ports. Make sure all air is gone before re torque. If this did not solve your problem then look for cracks around coolant ports on heads.

Also when you cleaned up the heads did they clean up the intake meeting joint in corners? These motors have no coolant running thru intakes. Remember these motors are not street motors , just de tuned finicky race motors.

 

[68 HEMI GTS]

What is leaking? Oil or Water?

1. You need to use Cometic gaskets, with copper spray on gaskets. Around the two outer Coolant holes you also need a small amount of RTV inside the cut out for the Cometic Gaskets. The heads need a bit of a cross hatch. also remeber you need to use a dog bone on valley studs. Never reuse head bolts and only use ARP. When you install head bolts use extra sealant on bolts. Do not use RTV on Head bolt threads use "sealant Dope". The heads need to be re torqued first time within 20 mins of first start up. Then do a second after 2 hours. Make sure your rocker shaft supports are properly seated on stands and have washers on bolts. Also remember these heads are nothing like doing a Wedge, Torque sequence is really finicky around water jackets. Also you can take a center punch with brass hammer and dimple around coolant ports. Make sure all air is gone before re torque. If this did not solve your problem then look for cracks around coolant ports on heads.

Also when you cleaned up the heads did they clean up the intake meeting joint in corners? These motors have no coolant running thru intakes. Remember these motors are not street motors , just de tuned finicky race motors.

what the hell are you talking about.. its not a chevy, the head bolts dont go through to coolant. cross hatch on the heads? dimpling the coolant ports? special torque sequence thats finikey? typical internet bullshit... and im quite qualified to say that

oh and read the post, OIL leaking from the OIL return holes.....

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and now i remember why i stay away from engine tech threads.

 

[snakeoil24]

what the hell are you talking about.. its not a chevy, the head bolts dont go through to coolant. cross hatch on the heads? dimpling the coolant ports? special torque sequence thats finikey? typical internet bullshit... and im quite qualified to say that

oh and read the post, OIL leaking from the OIL return holes.....

Just like I said, stop drinkin cool aid. I been doing hemi long before you where born do exactly like it says and no issues. The Heads need a good ruff surface for grip by cometic, whats so hard for you to understand. Yes sealant on bolts then no oiling threads nothing travels along bolts to soak cometics. and again dimple around water outlets and use RTV around openings.


- - - Updated - - -

and now i remember why i stay away from engine tech threads.

Just like I said, stop drinkin cool aid. I been doing hemi long before you where born do exactly like it says and no issues. The Heads need a good ruff surface for grip by cometic, whats so hard for you to understand. Yes sealant on bolts then nothing travels along bolts. Just lay off the cool aid

 

[IQ52]

could be the surface on the heads or the block is to rough of a RA for the head gasket, has it been milled, is it deck/heads flat? gonna be kind of hard for anyone to know for sure without knowing all the variables. being all four corners are leaking im guessing the gasket just insn't sealing on the surface finish for some reason. nothing trick to the torque sequence. best fix would be a new set of quality head gaskets and to smear a little high temp RTV around the return holes on each side, that will solve the oil leak issue. thats all i would do if it were mine.

Really good advice. It's common practice to use some RTV around the oil return holes. And with the MLS head gaskets a very smooth finish is required on the block and head surfaces. When we used the aluminum block and aluminum heads and had to correct the return hole mismatch to get the oil back to the pan, we found the gasket and block had enough surface, but the head barely covered the hole in the gasket. We had to weld additional material to the head to cover the hole. Pain in the pah-toot!