Hammer

First thing I would like to offer about this and I have said this before in a different thread on these gaskets is this....

While Cometic makes some of the absolute best gaskets out there for other applications,the problems you are experiencing may not be the headgaskets fault at all.IF you went to the Cometic gasket in hopes of NOT needing to O-Ring or Fire-Ring then you may have made a mistake.See,just because Cometic makes a great product does not equal these gaskets being the end all fix for your high cylinder pressures and even higher boost levels.

It would not matter what gasket your running when you combine big boost pressure,loads of fuel volume,timing advances and/or nitrous no normal non-ringed head will stay sealed.Yep,it may take it for a while for it to fail,as did all the stockers from way back when the diesel performance began,but,it will fail,pressure always gets its gasket.

When you combine the amount of our motors compression,timing advance and big boost no normal,non-ringed head has much of a chance to stay sealed.Ever wonder why when we build nitrous gasser motors they have much lower compression ratios?.Plus every performance application where cylinder pressures are going to be extreme most seal the cylinders off with a ringed head and/or block to prevent headgasket failures.

Its a simple thing,Cometic is and has a great product,but,they are just a band-aid for those who desire a short way to performance gains.The only way to ensure a chance at not loosing your head gaskets when your goal is performance oriented is to o-ring or fire-ring.........Andy

Silver Slug

Well I spoke to cometic today and they are willing to work with my and anyone else who has a problem with the gasket, if you were running a cometic gasket and it failed they want it back to see what the problem is so they can correct it, so give them a call and start there, and my motor is killed because I never saw a temp problem and most of the coolent was pushed out and the sensor never saw hot coolent and cyl #5+6 have bad scuffing.

ratsun

Part of what you say is true however a stock Cummins gasket would have held longer/more in my application I'm sure. Block and head surfaces were milled to Cometics spec of RA, timing was moderate @17*, fuel was limited with the stock injectors and drive pressures were 1-1 or less. (FWIW the stock 200k HG lasted almost a year at this power and more) The third gens come stock with a MLS gasket and generally they are able to hold quite a bit more than the reg 24v with the conventional gasket so.....? Is it that Cummins builds a better gasket or is there some inherent difference between the 12/24v verses the common rail engines that make them harder on HGs? As I said in my earlier post I think that Cometic deserves credit for jumping on board for us and I'm sure they will come up with the solution however at this point I think the stock gasket will work better.

ratsun

I lost a 24v block when the rear frost plug fell out on cold slushy morning Think you can hone it out?


I will give Kevin a call next week and send mine back to him.
My gut is it leaked between the layers since I could find no evidence on the block or head? It's nice to know they want to keep working on it.

Crimedog

It is nice to know that Cometic is willing to stand behind their product and actually wants the gaskets back to try and figure out the failure point. That's a top notch company to me, I'm sure with that kind of a drive they will get this figured out soon

HOHN

Is anyone doing an O-ringed head in conjunction with the Cometic gasket?

ratsun

Hohn
Cometic was very specific about NOT combining their MLS gaskets with O-rings.

74dart

You can bore the block out and add sleves. When I melted down the #1 and #2 pistons I had mine bored + 0.75mm.

https://www.dieseltruckresource.com/...6&ppuser=39037

Silver Slug

Well I spoke to cometic after they received the headgasket, they told me that it failed because of head lift, the gasket has misc carbon tracking marks between the layers. I am not running super high boost levels to have this problem and I am using arp studs + they said that I might have bad head studs but why are other peoples gaskets leaking? They will not refund any $$. I bought new A1 technologies studs and honed the block but how much boost will a stock hg hold with studs- some shops say it will be ok- I need the truck for work so it is going back together next week ( no time to fire ring)

HOHN

I'd like to try the Custom Age 625 studs-- those things look mighty impressive.

Tq them to 150 and see how the head holds.

JMO

Mike D

Scheid has a fire ring system that won't require you to cut the block or head and will lower your compression ratio, which is needed with your setup IMO. I've been running it since the summer with great results so far. 50lbs of boost and nitrous.

I refer back to my previous post with regards to what may have caused the issue in the first place. Look on the bright side, at least it was the HG and not a new inspection port on the side of the block.