Cometic HG leaked water then stopped leaking?

[BEATAV8]

Odd problem with my cometic head gaskets...
109 block with iron heads, heads and block were decked for flatness. ARP studs @85-90 ft*lbs with loctite to seal the threads in the block. Cometics were installed clean and dry. On initial startup the gaskets did drip a bit of coolant externally, which was treated with cooling system sealer (bars-leak) and promptly stopped. Engine has about 800 miles on it now and hasn't been pushed hard yet.

Anyways it was warming up at idle when it starting steaming out the tailpipe. Shut it down and found some milky engine oil and coolant level down about 1 qt. Changed the oil. Drained the coolant. Removed the plugs and pressurized the cooling system with 40PSI air, no leaks found anywhere. Checked torque on the heads studs and everything was tight. Filled it up with water, started it back up and allowed the cooling system to pressurize itself and this time nothing funny happened.

Anyways at this point I just treated it with some ceramic cooling system block sealer and will see what happens.

I'd appreciate any comments!

 

[441120]

I'd keep a close eye on the coolant level and change your oil again. :frown:

 

[d0n_3d]

I just started and ran my car last week with a fresh set of Cometics and GN1 heads and had the same problem...I also have head studs and used the blue loctite (paste style) on ALL the threads of all studs...i was only leaking water on the driver side...ran some K & W block sealer through the coolant system and it helped SOME but still had some water seeping through the studs...it's getting better everytime I run the car...I'll throw some GM sealant tabs in there to see if it clears up for good....I've heard you just have to run the car and let it heat cycle many times before everything seals....My powermaster unit and ac compressor went out just a few days ago and the car has been down since then....I'll have her back and running this week again....it never ends!

 

[bison]

Just started mine last week with cometics. No sealant on gaskets and zero leaks. Just used some loc-tite thread sealant on the studs. Both head and deck need to be very smooth and perfectly flat or they will leak. I have not added any sealant tabs yet. I probably wont if the coolant level doesnt drop in the overflow tank.

 

[d0n_3d]

I'll admit my block has never been touched...so that's probably why mine leak. I've blown 4 sets of Felpro head gaskets before this set of Cometics. I'm sure my deck surface is not perfect.

 

[gnmaster2004]

I spray the gaskets with copper coat before install, never had a problem

 

[1FASTV6]

I sprayed with Permatex Hylomar.

 

[BEATAV8]

Next time it comes apart I will probably again go with cometics but I will definitely use the spray on copper sealant. I heard you are supposed to really lay the copper coat stuff on heavy? Almost one whole can of spray per pair of gaskets?

Despite the water leak issues I think these gaskets are the "hot" setup, just need to get it right.

 

[BEATAV8]

I'd keep a close eye on the coolant level and change your oil again. :frown:

You bet.

My wife's 87T looks a lot like the one in your pic. Same color but with chrome trim.

 

[BEATAV8]

I've heard you just have to run the car and let it heat cycle many times before everything seals....

I think that's right Don, especially after seeing mine leak during a warm up cycle at idle, then not leak later on. Even at 90 ft*lbs fastener torque, the joint still moves during thermals.

 

[Razor]

I spray the gaskets with copper coat before install, never had a problem

+1.. and a pack of GM seal tabs for good measure.. Not 1 drop

 

[breiter]

SCE Titan Head Gaskets

I run SCE Titan head gaskets with the O-ring in the gasket instead of having to O-ring the block and heads. I used an ARP stud kit and run Champion irons. The engine is stil new and only has 240 miles on it now. I noticed a little coolant (few drips) initially on the bottom of the heads after the initial break in of 20 minutes. I checked the oil and water and everything was ok so I wiped the heads off and drove the car for a few miles and checked again. I have not had any signs of further leaks.

 

[my1stgn]

Sorry but I hate these Cometic Gaskets and have had nothing but bad luck with them! I used them on my GTP and they never stopped leaking. If the ones for the GN are the same style (multi-layer steel gaskets) they are designed to go on DRY so using Hylomar or Copper Spray is just a band aid. I contacted Cometic about my $300 leaking junk gaskets and they told me to send it to them and they will send back an "update" version. I guess they wanted to see where they "failed"........ well freakin 3 years later Im still waiting for the "updated" gaskets..... but even then I still wouldnt install that junk!

 

[buickboy]

I installed the first ever production set of Cometic MLS HG's on a buick V-6. Still on there and run 25 lb boost, no problems. ARP bolts 85 lbs, iron heads, 109 block. Like others seaid, block and head prep are the key. Keep those junk seal tabs out of the motor. It junks the cooling system.

Mitch

 

[GN SBS]

Are you guys following their suggested surface prep? Cometic calls for a very smooth surface (50 RA, I believe-- see a post from me about 2 years ago for complete details) on the heads and block.

Edit: this thread has details.

-Scott

 

[my1stgn]

Are you guys following their suggested surface prep? Cometic calls for a very smooth surface (50 RA, I believe-- see a post from me about 2 years ago for complete details) on the heads and block.

Edit: this thread has details.

-Scott

I would assume they call for a good surface prep in order to reduce liability once the gaskets leak. But thats just me. My engine block had ject got back from the machine shop and the heads too so there wasnt any issue with surface prep, yet they still leaked on start up. Went back to stock head gaskets and running 13PSI (is a S/C GTP not a GN so thats as high as it gets ) and a 90 shot of NOS and the stock head gaskets still holding on..... 112K miles later!