New, Improved Cometic MLX Head Gasket

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cut7

New member
Has anyone used the new version of their MLX head gasket? I know they had a bunch of failures about 8-10 years ago; so no need to chime in about that. Apparently Cometic changed the design, rolling the layers back over on themselves around the cylinder; effectively creating a fire ring. Anyone have experience with the new design?
 
I held a cummins mls and a cometic mlx right next to each other, visually looks the same basically. only difference is mlx has a different coating
 
cut7 said:
What mods were done to your 12v?
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They make a MLX (MLS style) 12V head gasket that still keeps everything separated, but they have proven to not be very good in the past.

Leuthen said:
I ran the new mlx on my 12v never had any problem what so ever.
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Any info on how long you've had it in, and what you've put it through? There's really no reason we shouldn't have a good aftermarket 12V MLS head gasket in 2017!!
 
Sorry for the late reply but anyway, I've had it on there for about a year. I'm not easy on it by any means either and it has never gave me a problem. Mods are sxe69, 5x16s, ported head, 188/220, 215 pump, 7mm dvs, rac plug, 05 cr pistons, 30* timing, and supporting mods
 
Leuthen said:
Sorry for the late reply but anyway, I've had it on there for about a year. I'm not easy on it by any means either and it has never gave me a problem. Mods are sxe69, 5x16s, ported head, 188/220, 215 pump, 7mm dvs, rac plug, 05 cr pistons, 30* timing, and supporting mods
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That sounds pretty healthy! I might have to give it a go next time I need one. Are there call outs for block and head surface roughness you tried to meet, or did you just put it on smooth?
Also, studs or just head bolts?
 
Poulina said:
I held a cummins mls and a cometic mlx right next to each other, visually looks the same basically. only difference is mlx has a different coating
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Look around the bores, are they the same? Pictures please, if possible.
 
I'd be curious to know how the new version is working out, but the first one was so bad I don't think I'd be bold enough to try their mls again. I think I got 300 miles out of mine before one of the layers got spit out.
 
So I just looked at a 6.7 mls gasket, it's just 4-layer steel with no fire ring around the bore. I've seen plenty of mls gaskets & this doesn't look any different than anything else I've seen. Is no one having problems blowing 6.7 head gaskets? I wonder if the people who had problems with the original Cometics started with truly flat surfaces on both the head & block.
 
cut7 said:
I wonder if the people who had problems with the original Cometics started with truly flat surfaces on both the head & block.
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As a former machinist, I can rightfully say that the block was perfect and I surfaced the head myself. I also used studs to clamp it down tight. Those gaskets were 100% garbage.
 
After spending some time talking with Cometic about their new MLX gasket, I pulled the trigger and ordered one. I planned to put it on my Junker thinking it could solve my head gasket woes, but Cometic recommended I don't run an oring with the gasket, even a softer copper oring was a no-no, so I put it on the shelf. Luckily a few weeks later the head gasket blew on our other 1995 test mule. We didn't machine the block (it was within 002" but we wanted to test this as a viable option for guys not pulling the entire engine. If an engine is going to the machine shop, it's going to get fire rings or orings, but for the average customer with a blown head gasket, this might be a fix. We started with a fresh machined head and new ARP 2000 head studs torqued up to 125 ft lbs, drivin cautiously for a couple days, then warm re-torqued to 130 ft lbs. We gave the gasket a fair chance to hold power since the previous setup was the original 280k headgasket with simple re-torqued head bolts (old gasket blew first dyno run with compound turbos when torque surpassed 1200 ft lbs). The MLX gasket immediately spewed fluid the first hard pull on the dyno. We checked the studs and all were good and tight at 130 ft lbs, but we cranked them up to 135 ft lbs to really get some additional bite on the new MLX gasket. The next dyno pull, it mixed fluids and pushed lots of soot into the coolant.

We made a couple more dyno pulls to finish our numbers testing and then quit before we hurt the engine. Removed the head and fire had traveled between the layers of the MLX gasket, punched through the pinch weld that holds the layers together around each cylinder, and then allowed all kinds of mixing and problems between the gasket layers. There were no signs of leakage on the top or bottom of the gasket, no flame trails through the viton coating, so the gasket did flare out nicely and seal well to the head and block, it simply was too weak and allowed the fire and combustion to travel through and between the layers.

In short, new MLX Cometic Gasket is ABSOLUTE JUNK!!!!

We went back with an in-frame Isky Groovomatic 041" oring and aftermarket head gasket, did our usual retorques, using same head, same studs, same everything other than new gasket with orings, and the head gasket held up to several hundred more test sessions ranging from 1000 ft lbs to 1400 ft lbs. It held up to several abusive burnouts, track outings, employee parts runs, a couple sets of tires, etc. The in-frame block oring setup isn't reliable for big HP, but it held great on this truck in the 500 to 650HP range and proved to be much better than the new MLX trash gasket. Maybe the MLX will hold with perfectly flat micro polished bllock deck and cylinder head, but why waste money on the gasket when OEM gaskets with orings are so much better or firerings for big HP setups.
 
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