Cometic mls failed!

The gasket failures are not just restricted cummins, turbo buicks also blow these things if anything is not perfect. There are a lot of different things that are done wrong, first block and head are not perfectly matched to each other (the head must sit perfectly flat on the block just like you wouldn't even need a gasket), there is no retorque done after warming up, halfway through torqing you have to let it sit and seat for a few hours, the wrong torque sequence is followed, also people are rushing and not tightening the head in 5 pound increments, instead choosing to go with 20 pound increments. Also the gasket will continue to seat itself up to a month after installation. So you have to check the studs consantly for the first 3000 miles or so. I got this info from turbo buick guy that has gone thru a couple sets of cometic gaskets already, but he was drag racing before his gasket had seated properly.
 
Well, I work on Caterpillar truck engines for a living and the reason I went with the mls was because of the success Cat was having with them on the C13's. However, when I recieved the Cometic, the first thing I noticed was the lack of a true fire ring. The gasket just sort of "ends" when it gets to the cylinder. This leaves 5 or 6 thin layers of metal exposed to extreme heat and pressure. There has to be some kind of "rolled" edge facing the cyl. But, I assumed Cometic knew what they were doing and I put it in anyway.:badidea: As far as block goes, I would like to surface it as well, but I'm not willing to pull the engine and completely strip it down to do so.(Even more $$$$$$).
 
Then fire ring it or oring it and be done. 3 years on my oring job been truck pulling it for 3 years and zero issues.
 
mhuggler said:
However, when I recieved the Cometic, the first thing I noticed was the lack of a true fire ring. The gasket just sort of "ends" when it gets to the cylinder. This leaves 5 or 6 thin layers of metal exposed to extreme heat and pressure. There has to be some kind of "rolled" edge facing the cyl. But, I assumed Cometic knew what they were doing and I put it in anyway.:badidea:
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Actually the factory cummins MLS is shaped that way with all the layers exposed to the cylinder also
 
CanadianCarGuy said:
The gasket failures are not just restricted cummins, turbo buicks also blow these things if anything is not perfect. There are a lot of different things that are done wrong, first block and head are not perfectly matched to each other (the head must sit perfectly flat on the block just like you wouldn't even need a gasket), there is no retorque done after warming up, halfway through torqing you have to let it sit and seat for a few hours, the wrong torque sequence is followed, also people are rushing and not tightening the head in 5 pound increments, instead choosing to go with 20 pound increments. Also the gasket will continue to seat itself up to a month after installation. So you have to check the studs consantly for the first 3000 miles or so. I got this info from turbo buick guy that has gone thru a couple sets of cometic gaskets already, but he was drag racing before his gasket had seated properly.
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Also similar issues with Turbo DSM (Mitsu Eclipse/Eagle Talon). Again with main reason being that most folks just throw them in with little prepwork to replace a recently blown headgastket. Regardless, there are a lot of guys having great success with them. Not saying this is exactly the reason for problems in the Cummins engines, but possibility.
 
Maybe I'll give the Phuzion a try. Might as well take another for the team!:kick: LOL
 
CanadianCarGuy said:
The gasket failures are not just restricted cummins, turbo buicks also blow these things if anything is not perfect. There are a lot of different things that are done wrong, first block and head are not perfectly matched to each other (the head must sit perfectly flat on the block just like you wouldn't even need a gasket), there is no retorque done after warming up, halfway through torqing you have to let it sit and seat for a few hours, the wrong torque sequence is followed, also people are rushing and not tightening the head in 5 pound increments, instead choosing to go with 20 pound increments. Also the gasket will continue to seat itself up to a month after installation. So you have to check the studs consantly for the first 3000 miles or so. I got this info from turbo buick guy that has gone thru a couple sets of cometic gaskets already, but he was drag racing before his gasket had seated properly.
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wow, what a PITA! I think I'll stick with the ol' "O-ring + marine gasket + one re-torque = hold 80+psi boost"
 
Forrest Nearing said:
wow, what a PITA! I think I'll stick with the ol' "O-ring + marine gasket + one re-torque = hold 80+psi boost"
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Thats whay I did. I had the Cometic MLS sitting in the garage.
I called Garrett from Pure Diesel Power and said the hell with it cut the head for o-rings, because Im only doing this once.
Stay with the tried and true stuff. Orings have been tested time and time again.
 
mhuggler said:
Maybe I'll give the Phuzion a try. Might as well take another for the team!:kick: LOL
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I'll save ya the guessing, they dont work either on a Dmax.... I dont expect results to be much better on a Cummins
 
I would have probably done o-rings in the first place, but I don't have the tooling to do it. I also don't work in a machine shop anymore(I gave up alot of perks when I burned that bridge!). I can still surface heads,blocks, etc. where I work now, but that's about it. I'm very untrusting of other people's machine work and o-rings, in my past experience, are pretty touchy. You have to know how much protrusion and thickness wire each type of gasket/engine likes. They also have to be very even, i.e not much variation in protrusion cyl. to cyl. I'm sure you guys could help me on the specs., but I don't know of any local machine shops that could do a good job for me. Their prices also went through the roof not long ago.:mad:
 
Mhuggler,

UCF machine in Carlisle does excellent work. They have a lot of experience with o-rings and fire-rings. Give Mike a call @ 717-249-8517.

Doug
 
I'm gonna be getting fire rings done instead the cometic piece as well, they keep sending me the MLS gasket instead the phuzion that I pay for! Not to mention the first gasket had a slight crease in it between the middle cylinders (I'm sure that wouldn't seal worth crap!). It's not that I don't trust cometic gaskets, it's just I don't trust any machine shops! Especially ones that have never o-ringed before!
 
Jetpilot said:
Mhuggler,

UCF machine in Carlisle does excellent work. They have a lot of experience with o-rings and fire-rings. Give Mike a call @ 717-249-8517.

Doug
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Never tried UCF come to think of it. Thanks for the tip.:Cheer:
 
For the Pennsylvania guys, anyone hear about Rutts in harrisburg?? I am in same boat, i dont want a machine shop messing up my head. The cometic looks likes a good deal, but all the failures i am not liking. I assume ones are ck'ing the block and head surfaces. What price does UCF want to oring a head.
 
I am local to the Harrisburg area and I have gone by and spoken with Rutts. Problem I had was there were not very reassuring and pricing. UCF has done over 50 heads for me alone (when I owned PDW). They are very familiar with o-rings and fire-rings. They can also do anything else you want/need done, balance, rebuild, cam bushings, rollers, etc.
 
Jet Pilot, I work in Harrisburg. You prob were at our shop a time or 2. All of our engine work goes to Rutts. Very rare occasions something is not right but 90% of the time they do excellent work. Have you personally done any of the cometic installs w/12mm studs. Or would you stick w/ 0.20 marine and o-rings. I will be running a 64/71 - 14 turbo, 435's at 18-20 degrees timing - 12v motor
 
I have not used any of the cometic gaskets for the diesels..... I wanted to give it some time to see what the success rate was. Since they have come out I have had numerous guys contact me about their failures, and most were done correct.

For me going with a good o-ring job and the .020 marine gasket is about the best option for a street driven vehicle.

Doug
 
Jetpilot said:
I am local to the Harrisburg area and I have gone by and spoken with Rutts. Problem I had was there were not very reassuring and pricing. UCF has done over 50 heads for me alone (when I owned PDW). They are very familiar with o-rings and fire-rings. They can also do anything else you want/need done, balance, rebuild, cam bushings, rollers, etc.
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I've seen some really botched work from Rutts. I was an engine machinist myself so I know what to look for. In their defense, this was out of a pile of jobs sent their way from where I work. Anyone have a general idea what UCF might want to o-ring the head? I'll surface it myself before I give it to them.
 
Mhuggler, As with you, I'd like to find one that specializes in dodges. I prob am going to order a head from Pure Diesel Power and have it cut for rings. The prices is decent and I can port and do the valve springs myself. Anyone get a cut cylinder head from Pure Diesel or know anyone who has??
 
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