How to seal Cometics

[turbojimmy]

I thought the first 2 GM pills I put in my radiator sealed the Cometics. They definitely slowed it down, but they're still leaking.

So I put 3 more tabs in. The additional 3 tabs sealed up the right side but the left side is still leaking. They only leak externally - water and oil are not mixing.

So now what? I haven't tried retorquing them yet. I guess that's next. What's involved in retorquing the heads? I assume header removal, definitely valve cover removal. Can you even do the passenger side with the engine in the car?

If that doesn't do it I guess the heads will have to come back off. I talked to the engine guy today and he said he put a very smooth surface on the heads and block and that both were decked/planed. He's offered to make good on it, but if it's something I can do myself I can go ahead and do it. I knew I was taking the risk when I asked for Cometics.

Thanks,
Jim

 

[DailyDrifter]

had the same exact problem, i put alumiseal in the rad. Have'nt drove the car that much to see wheather its still leaking or not.

 

[Bent6]

You can try Moroso Alumaseal or what I have used on several occasions is sodium silicate. Go to any pharmacy and ask for sodium silicate - it will come in a 32oz glass jar and looks like corn syrup. Pour it directly in your radiator being careful not to spill. It will seal up any fine scratches and/or cracks on the sealing surfaces. It can also be used to seal concrete! I know it may sound unorthodox but I got this trick from a very well respected Buick guru and have used this on many occasions after a rebuild on my S2 race engine to take care of minor water leaks.

 

[BEATAV8]

I just installed a fresh set of cometics too (I always use them). I've always had this same seepage issue in the past with these gaskets after installing them dry. This time I used liberal quantities of permatex copper spray. Will report back how it works out.

 

[JayC]

I dont see any reason you couldnt use GE1200 on them. Ive used it for years.. it will seal anything.

Wear gloves.. dont get it in your cuticles.

 

[Russ Merritt]

Cometics are an awesome gasket, and I hate to see them get a bad rap. We never used a super smooth surface like they recommend and never had a coolant leak. I always torque the heads several times during assembly and NEVER retorque after running. 85-90 ft/lbs and I do spray them with the copper coat, wipe both the heads and block with brakleen before assembly, and drop in 3 crushed GM seal tabs into the radiator. They are reuseable several times with just a clean up of brakleen as long as the gasket wasn't hurt, I won't use any other gasket. Above method has worked flawless for several years.

I would def retorque very carefully and post how much more you get on the bolts/studs. I know it sucks but do it and you'll know for sure where they are......

 

[forcedfedv6]

Indian Gasket zinch, will seal it right up, make sure you put a light coating inside of them between the layers as well as on the outside and do some around where the oil drains back around the heads torque in increments of 15 starting at 60 until you reach 90 pnds and call it a day .

 

[turbojimmy]

I would def retorque very carefully and post how much more you get on the bolts/studs. I know it sucks but do it and you'll know for sure where they are......

Since the RH side appears to have sealed up I'll just do the LH side. The LH side won't be too tough to get at with a torque wrench.

Jim

 

[Russ Merritt]

Since the RH side appears to have sealed up I'll just do the LH side. The LH side won't be too tough to get at with a torque wrench.

Jim

Good start but if you get a good 1/8-1/4 turn, you gotta do the other side too. If it's tight, surfaces might not be flat. Good luck, keep us posted.

 

[turbojimmy]

Good start but if you get a good 1/8-1/4 turn, you gotta do the other side too. If it's tight, surfaces might not be flat. Good luck, keep us posted.

I was afraid of that. So what do you think I should shoot for? They're ARP bolts. 85-90 ft. lbs.?

Thanks,
Jim

 

[Russ Merritt]

Id start low say 65/70 ft/lbs and see where they actually are. Then 75, 80, 85. Nice and slow in the stock sequence.

 

[turbojimmy]

Id start low say 65/70 ft/lbs and see where they actually are. Then 75, 80, 85. Nice and slow in the stock sequence.

Will do - thanks for the advice. I'm going to wait probably until next week to try it, though. It's not even leaking enough for the coolant to hit the ground. It evaporates before it even drips on the header. I have a lot of parts coming in during the week and only want to disable the car once. Plus, it's going to be too nice tomorrow to not get some cruising time in.

Your plug wires are awesome, by the way. You are a master of the tiny wire tie, kind of like the way one trims a Bonsai tree.

Jim

 

[Russ Merritt]

LOL!!! That was a good one..... Bonsai tree

 

[cork]

Cometics are an awesome gasket, and I hate to see them get a bad rap. We never used a super smooth surface like they recommend and never had a coolant leak. I always torque the heads several times during assembly and NEVER retorque after running. 85-90 ft/lbs and I do spray them with the copper coat, wipe both the heads and block with brakleen before assembly, and drop in 3 crushed GM seal tabs into the radiator. They are reuseable several times with just a clean up of brakleen as long as the gasket wasn't hurt, I won't use any other gasket. Above method has worked flawless for several years.

I would def retorque very carefully and post how much more you get on the bolts/studs. I know it sucks but do it and you'll know for sure where they are......

Coppercoat between layers or just top and bottom ?

 

[Russ Merritt]

Coppercoat between layers or just top and bottom ?

Some does get in between while spraying. I don't concentrate on getting it in there.

 

[BEATAV8]

I just sarted my engine tonight. This is the first time I've used the copper coat and it's the first time starting it up with no HG leaks! Will see what happens after a few more heat cycles but I expect it'll be fine.

No extra sealers in the cooling system right now. I used nearly a full can of copper spray to do both gaskets. It oozed out a little when I torqued the heads down.

I have studs with liberal application of ARP moly lube and I went 20-40-60 and ended with a solid 80 ft*lbs on a firm sweeping pull.

Cometics really are a great gasket. Extremely strong. I just went through the motor because I lifted the head running 30psi of boost. Even so, the old cometic gasket didn't blow and I could still drive the car without issues. The only symptom was burning coolant after coming down off of high boost, but it would clear up after a few seconds and go away. Ran a 10.60 like that and drove it home!

 

[cchilly]

Another option when using cometics is to use GM silicone around the coolant passages. We used this on some recent boat engines that have screw blowers on them. No problems at all.

 

[jpwalt1987]

I removed the rivet that holds the gasket together and spray the thin outside pieces with copper coat on both sides. I also torqued down the ARP studs to 70 ft/lbs as recommended by a DLS. No leaks to speak of so far!!! I love it.:biggrin:

 

[Scott Atk]

I removed the rivet that holds the gasket together and spray the thin outside pieces with copper coat on both sides. I also torqued down the ARP studs to 70 ft/lbs as recommended by a DLS. No leaks to speak of so far!!! I love it.:biggrin:

Jeremy, What lube does DLS reccommend on the threads. That number seems low compared to others?

 

[TAPerf]

Remove the rivets. Install one shim at a time. Put a "very light" film of RTV/Silicon Adhesive around all the water passages and up to the intake end seal area. Place the next shim on and do the same. No need for any RTV on the outside as this gasket, it has a black viton rubber layer applied. Torque your heads. Yes, you should re-torque. I will let the engine sit as long as I can. If I know it will be a week before we ship, I will let it sit for two days and then re-torque. This will be done by breaking the bolt or stud loose 1/8"-1/4" turn, then pulling to full torque without stopping, you must not stop. Do this in the normal sequence. In two more days I will re-torque again the same way. If the engine happened to end up sitting here for a couple weeks longer, I would repeat it one more time before it leaves. This allows the gaskets and heads to crush, the studs or bolts to stretch and after time the gasket will loose clamping pressure. So as the fasteners relax, the gasket and head crushes you expose them again to full torque, then again and again. This procedure will increase your head gasket success. Use this procedure when installing any type of head gasket on any type of engine.

Mike Tomaszewski
TA Performance Products Inc.
480-922-6807