How to seal Cometics

[blue-t]

i use permitex aviation gasket sealent no leak so far

 

[chris mccord]

I've used copper spray on my last two L67's with Cometics and studs. They don't seem to be leaking so far. Not running as much boost as the GN's though.

I'm debating on running them on my GN when I build it. I hope they work, I don't want to have screw with a nagging leak.

 

[KWIKR 1]

Guys check out a product by Permetex called "Super 300" . It blows everything out of the water when it comes to sealing . I have used it on steel shims and head studs and it works GREAT , and I would suggest you use it on those Cometics shims . This product is used in the Diesel industry on steel head gaskets . says right on the bottle for use on high compression milled heads . Give this product a try you will not be sorry .


http://www.akd-tools.gr/xmsAssets/File/TDS/PERMATEX/80058.pdf

Comp Cams Custom Roller Camshaft - Hot Rod Magazine

 

[turbojimmy]

Guys check out a product by Permetex called "Super 300" . It blows everything out of the water when it comes to sealing . I have used it on steel shims and head studs and it works GREAT , and I would suggest you use it on those Cometics shims . This product is used in the Diesel industry on steel head gaskets . says right on the bottle for use on high compression milled heads . Give this product a try you will not be sorry .


http://www.akd-tools.gr/xmsAssets/File/TDS/PERMATEX/80058.pdf

Comp Cams Custom Roller Camshaft - Hot Rod Magazine

I'll have to give that whirl. Thanks for the info.

Jim

 

[KWIKR 1]

I'll have to give that whirl. Thanks for the info.

Jim

it also is very inexpensive at $4-$5 for a 4 oz bottle . it is "super-nasty" as mentioned in the article . Good idea to wear some sort of disposable latex protective gloves . If this stuff gets of your fingers or hands you'll be wearing it for the next 2 years . ending up with some sort of dark brown stain on your fingers does not look real cool .

 

[turbojimmy]

it also is very inexpensive at $4-$5 for a 4 oz bottle . it is "super-nasty" as mentioned in the article . Good idea to wear some sort of disposable latex protective gloves . If this stuff gets of your fingers or hands you'll be wearing it for the next 2 years . ending up with some sort of dark brown stain on your fingers does not look real cool .

Good advice. My only hesitation with that stuff is that you brush it on. It would seem like you'd get a more even (level) coat with a spray like the copper stuff. Plus, I have an entire case of Permatex spray copper stuff on the shelf. How I got it is a funny story.....

A few years ago I was on the Permatex site looking for the part number for the BRUSH-on copper coat stuff. I noticed that their site only showed two different sizes of spray-on stuff. I knew the brush-on stuff existed at the time (it doesn't anymore) so I e-mailed them and told them that their website was incorrect. I pointed out that they'd probably get a lot more sales of the brush-on stuff if their catalog was corrected to state that the 4-oz. size was actually a brush-in-can deal. I went on to say how much I preferred the brush-on so that I could get a nice, thick coating of it. They were so appreciative that they said they'd send me a case of brush-on copper coat for free. What came in the mail? A case of SPRAY on stuff. So I still have a lot of it on the shelf.

Jim

 

[KWIKR 1]

Good advice. My only hesitation with that stuff is that you brush it on. It would seem like you'd get a more even (level) coat with a spray like the copper stuff. Plus, I have an entire case of Permatex spray copper stuff on the shelf. How I got it is a funny story.....

A few years ago I was on the Permatex site looking for the part number for the BRUSH-on copper coat stuff. I noticed that their site only showed two different sizes of spray-on stuff. I knew the brush-on stuff existed at the time (it doesn't anymore) so I e-mailed them and told them that their website was incorrect. I pointed out that they'd probably get a lot more sales of the brush-on stuff if their catalog was corrected to state that the 4-oz. size was actually a brush-in-can deal. I went on to say how much I preferred the brush-on so that I could get a nice, thick coating of it. They were so appreciative that they said they'd send me a case of brush-on copper coat for free. What came in the mail? A case of SPRAY on stuff. So I still have a lot of it on the shelf.

Jim

you could use a small foam roller to spread it out , to get a more even coat result if need be .

 

[turbojimmy]

Well, here's an update.

Right around Thanksgiving last year, I took the car to Atco. It's about a 100-mile trip and the car began losing oil pressure on the way down. It was a fresh rebuild, and I thought I heard a subtle knock from it since the day I fired it up. When I got to Atco, the oil pressure seeemed decent as long as I didn't lock the converter (evidently a tell-tale sign of a thrust bearing problem, but I didn't know it at the time). I got 3 runs in before the oil pressure got really bad. I drove it 100-miles home with very little oil pressure. Predictably, it needed a new crank, bearings and thrust bearing. I had it completely rebuilt again.

The cometics were reused, this time sprayed with copper spray-a-gasket. The f$&!@ng things still leak. This time it's just the right side. I had ARP studs installed this time. I'm going to try to re-torque them before I add more pills to the antifreeze. It doesn't leak nearly as bad as before, but you can see that the block is wet around the cylinders at the gasket. Looks like oil, tho, not water?

Jim

 

[blue-t]

leak

could be leaking oil, if the leak is at the end of the head via the oil drain backs

 

[turbojimmy]

could be leaking oil, if the leak is at the end of the head via the oil drain backs

Good point. I know oil is getting out that breather. Might be all it is. I got under there because I smelled antifreeze, though. Couldn't find any - just a little oil.

The good news is that the thing, even after the last rebuild, was puking oil everywhere. The engine guy replaced my fance FelPro silicone valve cover gaskets with cork and installed a new timing chain cover and oil pump that I got from TA performance. I dare say that, except for the little bit I see between the head and block, it's dry as a bone under there. I've never seen it that way the entire time I've owned the car.

Jim

 

[wickedtt]

Well, here's an update.

Right around Thanksgiving last year, I took the car to Atco. It's about a 100-mile trip and the car began losing oil pressure on the way down. It was a fresh rebuild, and I thought I heard a subtle knock from it since the day I fired it up. When I got to Atco, the oil pressure seeemed decent as long as I didn't lock the converter (evidently a tell-tale sign of a thrust bearing problem, but I didn't know it at the time). I got 3 runs in before the oil pressure got really bad. I drove it 100-miles home with very little oil pressure. Predictably, it needed a new crank, bearings and thrust bearing. I had it completely rebuilt again.

The cometics were reused, this time sprayed with copper spray-a-gasket. The f$&!@ng things still leak. This time it's just the right side. I had ARP studs installed this time. I'm going to try to re-torque them before I add more pills to the antifreeze. It doesn't leak nearly as bad as before, but you can see that the block is wet around the cylinders at the gasket. Looks like oil, tho, not water?

Jim

So what cause the first build to go bad was it antifreeze in the oil or ?

 

[turbojimmy]

So what cause the first build to go bad was it antifreeze in the oil or ?

I don't know. The antifreeze and oil never mixed. One theory is that once the crank started moving around, the oil journals were blocked and the bearings weren't getting lubricated. I drove it 100 miles, sometimes at highway speeds, with very low oil pressure and knocking pretty loudly. I knew it needed rebuilt again anyway, and I had to get it home. The original source of the knock was the thrust bearing, and it went downhill pretty quick from there.

This "new" engine doesn't have that subtle knock that I heard from the get-go on the previous engine.

Jim

 

[darkred87T]

The crank would have had to walk far enough to miss the journals. Then you would have lost oil pressure (which you did). I forgot you drove it home with low oil pressure. It might be why it looked so bad when he tore it apart. The tune is proabably fine.

 

[84gnct]

Cometics can be a real pain to seal. I used them in a Pro Stock application and the following tips might help.

Deck and head finish. There is a specific R/A for Cometic..I don't have it handy but I will look through my notes. As the engine is already assembled it is too late for that particular fix. The Cometics like a little surface roughness.

You have to use a light even coating of gasket sealer, get some between the layers around the water feed holes.

Figure out which lube ARP is specifying for torquing down your heads. Believe it or not this make a huge difference. I use a grease from Chicago Pneumatic supplies.

Retorque after 12 hours from initial assembly.

We found that the gaskets held up better after they sat over night and then were retorqued.

We then gave up and went to the Fel-Pro MLS gasket:

 

[HP Man]

I've never used cometic HG before but had others leak. Mine leaked up through the studs, tried everything before lock-titing them, squeaky clean threads both on the studs and block threads. I believing in using ARP threaders to condition the block threads, as their studs are rolled on threads not done by standard methods. Results were awesome, no leaks, very little movement after a heat cycle run. I like the factory gaskets on a 109 block, used aluminum paint on the surfaces and had no leaks. Again with stock gaskets. I also used water only for the first several hundred miles and it gives the best cooling of any other coolant in my opinion and tests. Yes use the clay tablets in any HG job. I put mine under the thermostat before running the engine, block off the heater lines so as not to plug the heater core. My .02$ Gene PS. Mike T. listed as being a Junior Member is funny as he is one of the most experienced Buick Engine Builders left in the Country. Thanks Mike!

 

[turbotwister]

could be leaking oil, if the leak is at the end of the head via the oil drain backs

BINGO!

Nick,

 

[vacuum 6]

...The cometics were reused, this time sprayed with copper spray-a-gasket. The f$&!@ng things still leak. This time it's just the right side. I had ARP studs installed this time. I'm going to try to re-torque them before I add more pills to the antifreeze. It doesn't leak nearly as bad as before, but you can see that the block is wet around the cylinders at the gasket. Looks like oil, tho, not water?

Jim

Put the pellets in, use all six.

 

[8urV8]

Well still having a issue with mine as well.Proably need to use the cooper spray gasket as well.

 

[asloan5]

I had my heads milled per cometic instructions something like ra-52 or better surface .I made sure both block and head gasket surfaces were lacquer thinner clean then gave the gaskets outer sides a light coat of hylomar as per the instructions that bill anderson gave out in one of the threads on here. I re-torqued the head studs 3-4 times before putting motor in car per instructions from TA performance also a thread on here. I did not need any cadillac pills and have not had any leak. Just did alot of research and reading before hand and no issues what so ever.

http://www.turbobuick.com/forums/stage-ii-tech/195599-head-gaskets-cometics-1007s.html
post #3 and #5

the post from TA peformance may be on turbobuicks.com