I've read the posts about coolant seepage, and followed the posts for quite awhile, so I'm aware of the prep requirements, etc.

Has anyone had OIL seepage due to Cometics? I've been trying to track down an annoying oil leak and I've come to the conclusion that it's the head to block mating surface. It's worst over on the front drivers side of the motor (#1 cylinder of course).

I also just read a post saying that the head bolts don't need to be retorqued, UNLESS the hardware has never been heat-cycled, so that implies to me that they DO need to be retorqued since everything was new in my case. Opinions/experiences?

TIA,

Brian

 

Was the block and heads surfaced to a maximum of 40ra?

 

Unfortunately I can't answer that question with any certainty at this point, but for the sake of discussion, let's assume no. As I said, I'm already aware of the prep requirements, but thanks for the thought.

I guess what I'm really wondering is are there any passages on the head to block surface that transport OIL? If the head to block surface didn't mate fully (regardless of the reason), would it be likely to leak OIL, or just coolant?

 

Only oil drain back is passed through the head gasket, pressurized oil is feed through the pushrods.

 

I always retorque them. Havent ever seen oil leak from that area but coolant yes from the pressure. The one trick I had learned was to put a very small dab of RTV on the upper corner of the head gaskets as its possible for a leak there. But thats just my 2 cents

 

When I've used cometics in the past, I liked to run the engine for 5 minutes, then re-torque.

My reasoning was that whatever amount the force of combustion was going to force the head up, and obviously I'm talking about very tiny amounts of movement; it would occur in the first few minutes of running.

I also suspect that by bringing the engine up to temperature, which should happen in that time period, you get an annealing process going on. A slight one.

When I retorque I believe that I am taking up whatever few hundred thousandths of slack that the first combustion events produced.


All these beliefs may be totally groundless, but I've never had a leaking problem.

 

Ahh, that's exactly what I was wondering. I was under the impression that the oil from the valve cover gets passed directly back to the lifter valley and doesn't pass through the head gasket. It's been too long since I looked at the head/gasket.

Does anyone have a picture of a head gasket and might be able to identify which holes handle what? I know the 4 big ones are the cylinders... ...but I assumed the rest were for coolant. Sounds like that is incorrect though?

I guess I'll try to re-torque them first. I'm 99% sure the upper areas where the block, heads, and intake all meet together are sealed well with RTV, but I'll know more once I tear into it. Thanks everybody!!!

 

that is correct, the only place the head gasket seals oil is where it sits near the intake/over the lifter valley, I think your oil leak is the valve cover/intake ends seals leaking and running/wicking down the head gasket ends and dripping there

 

Just to add to this discussion a little. I know Cometic's instructions recommend dry installation, but I have talked to a couple of guys who coat both sides with a thin layer of import grade RTV, (Permatex Grey), on both sides of the cometics. FWIW I also don't see a head gasket leaking oil happening very often, coolant yes, oil no. Before I tore my engine down I had a similar oil leak, never did find the cause, (I wasn't running Cometics at the time, standard Felpro's). It looked like it was coming from in between the head and block, even using dye and a UV light source. New gaskets and head bolts didn't cure the problem. I honestly believe that it was actually coming from the crank seal and being sprayed up onto the motor, just couldn't ever prove it.

 

Hmmm...I have a friend with a similar problem (much less though) and he's NOT using Cometics (neither car was re-torqued), but the wicking thing is a strong possibility and we've been trying to identify all the possible sources for that. That's why I'm trying to find out for certain whether or not oil is passed directly from the head to the block...

I believe mine to be very well sealed along the intake/block/head intersection and I'm fairly certain none of my front seals are leaking, but will check that again also. Thanks, all good info guys!

 

Sound like my car indeed, what is weird if I keep it at the full mark on the stick oil leaks everywhere but at 1/2 or add i never see a drop or wet spot and im not using any oil or it burning away.... I wonder too cause its wet all the way back close to the input on the rear

 

I used .057" Cometic head gaskets on our 386 (destroked 400). During the build, they were torqued and removed twice, and finally torqued a third time. Once to check piston to vale, once because of a leaking valve, and then during the final build (all while still on the stand). These gaskets have performed flawlessly on a 10 second race motor...for well over 100 runs. They've also never been retorqued. The machine shop that does all my machine work swears by Cometic gaskets.

Frank

 

Frank,

What value did you torque your heads bolts to?

 

I've got an oil leak between the #2 & #4 cylinders that looks like it is coming from the head gasket. Could the oil be leaking through the head bolt inside the valve cover directly above that spot? The car runs fine otherwise...I use the felpro 1071, afr-220 head, and studs. Perhaps a retorque is in order?