parish8

iTrader: (6)

i noticed awhile back i had a tiny head gasket leak, i was loosing a little coolant. i decided i didn't want any problems with the turbo i have planed so i pulled the heads tonight so i can surface them and put in some new head gaskets.

i found more than i expected, there is a tiny scratch in the head in the cylinder where i had a coolant leak, that is kind of what i expected but on 3 other cylinders there is evidence of the head gasket leaking from the chamber right out the side , what the heck did i do wrong?

i used cometic gaskets and arp head studs, i used the arp lube on and under the nuts and tightened them to 65-70ft/lbs. the studs called for 70ft/lbs with the arp lube and 65ft/lbs with aluminum heads. then all the way up to 85ft/lb's if you use motor oil for lube. i am geting the heads surfaced and using factory mls gaskets this time, what might i have done wrong?

BigTex

iTrader: (16)

Any pics of the head scratch you are talking about?

-Joseph-

iTrader: (12)

I'd use graphite gaskets from the '99 cast iron headed 6.0L if they still are available. Graphite style gaskets tend to seal better IMO. I don't like using MLS gaskets other than the ease of cleanup next time. Did you happen to use any of that copper spray sealant on the Cometic gaskets?

parish8

iTrader: (6)

i have a set of felpro composite gaskets and a set of factory mls gaskets, i plan on pushing it prety hard. the heads will be geting cleaned up tomorrow. what set should i use?

here are 2 pic's, one of the scratch and one of the blown out head gasket.

parish8

iTrader: (6)

i have some of that copper stuff too, i have never used it, should i? this little experience of not even being able to bolt on a set of heads has convinced me when i am ready to put together a good motor i will just pay for a pro to put it together, there seems to be more to it than i thought.

-Joseph-

iTrader: (12)

Which Fel-Pro, the 4.155" bore/.041" thick ones or stock style? If they are stock bore/thickness, make sure they are at least 4.0"+ bore so that the piston does not smack them at TDC. Since your going FI, I would stick with a stock thickness (.055-.060") gasket which would be about 9.4-1 compression I think on the 6.0L engine. I use something similiar to copper spray on Cometic gaskets, its red though and very tacky...forgot the name. I let the gaskets sit for 10 minutes before assembly when I use the adhesive.

For an iron block I would go about 72lbft final torque. Start off and do 30lbft first in the factory torque sequence, then do 50lbft, then do the final pass of 72lbft. IIRC I did about 30lbs on the small bolts close to the intake ports using the ARP stud kit.

That scratch don't actually look too bad in the picture.

Bowtieman4life

iTrader: (1)

Did you torque the bolts down, lossen them and retorque them. I know it sounds wrong and they don't come with good directions but a guy here in Sac didn't torque, loosen and retorque and he had a similar problem. Call ARP and ask them the sequence and the steps. Its a pain.

parish8

iTrader: (6)

no i didn't, i did do that on the rod bolts but not on the head bolts, at what point are you suppose to loosen them? after full tq and then right back to full tq? what are the exact steps?

the felpro's i have are stock style(old stock that is) for a 6.0, they were cheap too, like $26 for the pair.

i am still not sure wich set of gaskets to use, i could see trying as much as 12+psi some day.

thanks for everyones help.

badboy4life

When i did mine ARP told me to tight them in the torque sequence to 23lbs and then do it again in the same order at 70lbs.

Ryan23silverado

iTrader: (1)

Parish are you talking about that thing that looks like a hair layed on between the chambers? I don't thin that would do what you are seeing. I bet torque sequence/gasket is to blame...
I use ARP studs with a GM MLS gasket. I used mobile 1 oil as a torquing lube (use ARP lube if possible) and did a torque of 30, 60, 85ft/lbs using the factory torque sequence. **I did not torque them down, loosen them, and then retorque them again as mentioned above. I would think you would want to "crush" the gasket only once IMO
Don't get down man head swaps are easy. Maybe there was just something wrong with the gasket.

Steve - Race Eng

iTrader: (1)

I see a few problems here. First, looking at the photos of your gaskets it appears your block deck and or head are not machined smooth enough for the Cometic MLS gasket. Both block and head surfaces need to be very smooth and flat.

I do a lot of blocks of all makes and models. Some of the Honda engines run well over thirty pounds of boost with the Cometic gaskets. You need to follow directions for these gaskets to work. Use no sealer of any kind on the Cometic gaskets. They have a nitrile coating applied at the factory. The coating will not do it's job if you apply sealers to the gasket face. You must retorque the nuts on the head studs after running. Get the engine hot, (take it for a ride) let it cool down, then loosen the nuts one at a time and retorque to spec. Do this in the correct sequence, center out. If you do not retorque, failure is guaranteed.

Fel Pro does not recommend their 1041 gasket for more than ten pounds of boost. If you plan on running anywhere near ten pounds of boost do not run the Fel Pro gasket, it will fail.

One of the best features of the Cometic gasket is the spring steel face. This face will help seal the head block interface during hard running when the head is bound to lift a bit off the block. The weak area of the LS1 - LS6 engines is the design using only ten bolts per head. The small block engine has seventeen providing much better and more even clamping.

Steve Demirjian
Race Engine Development

SAM98WS6

Steve thanks for the input. The cometic head gaskets I got 3.910" bore did not come with any instructions or paperwork at all so there were no instructions to follow. Typical of all these companies. We found that after the final torque sequence, the nuts loosened up after a few minutes. We kept going back over them in the proper sequence until they did not tighten anymore. Probably 1/2 turn more over half an hour. thats with ARP moly. Maybe that will help keep them tight and flat. Never heard of loosening and retorquing after a heat cycle but I trust your expertise. I will call cometic today.

parish8

iTrader: (6)

the cometic's are toast now, sounds like the felpro's wont hold what i want. that leaves me with the factory mls gaskets that i have.

what are the spacifics for using the factory mls gaskets? do i need to retorqe after a heat cycle? copper sealant or not?

SAM98WS6

I called Cometic tech line and spoke to Brandon. He says they only recommend the ARP torque information and nothing else. I asked if I should go back over the nuts after one heat cycle and he says not if ARP doesnt recommend it. There is nothing special about installation of their head gaskets. I will let well enough alone and see what happens. like I said they kept taking torque a few times after they sat...maybe that was the issue...spring back. hope this helps.

There is nothing like experience like steve has...if I run into problems i will know what to do.