Mike94ZLT1

iTrader: (3)

I put a new engine in my car several months ago, and used GM MLS gaskets and new GM headbolts when I installed my heads. It was a brand new block, and the heads were brand new from PRC. I've got about 3500 miles on the car, and last night I noticed a small puddle under where I was parked. It was kinda late, so I parked the car and called it a night. Today the car was bone dry and there was no puddle under the car. I started it, and let it warm up to operating temperature, and after a little while I noticed some liquid dripping down the passenger side onto the ground. I let it run for a few more minutes, and then turned the car off. I took my little bendy mirror thing and a flashlight, and looked around. I checked all the lines back there, and I checked the freeze plug in the back of the head, which all were fine. I then looked at the little bit of exposed gasket between the head and the block in the very back corner, and it was damp and I could see where coolant was slowly seeping down. So I obviously need to change my head gasket, has anyone else had a similar problem in so few miles? Thanks! -Mike

DaddySS

Before you tear it down, clean up the area and be doubly sure. Could be the steam vent in the back, or in my case I had the heater hose leak and drip onto the cross member making look just like the head gasket was leaking.

Mike94ZLT1

iTrader: (3)

It's on a Vette, there are no heater hoses there. Maybe its that coolant plug on the top of the head in the back, I have reused it several times, I got it used and its been on 3 different engines of mine so this is at LEAST its 4th engine. Perhaps that is leaking and it is running down the back?

allngn_c5

iTrader: (3)

Funny you ask about failed head gaskets. I had the same problem with gm MLS. Mine failed at about the 4000 mile mark. Replace with cometic .040 if you have the clearance. You'll pick up some more hp/tq and a bump in compression. Good luck, been waiting to run you. Now I know why you have been MIA. Hope you get it fixed soon.

Out of curiosity what were your final numbers after she came off the dyno ??

DaddySS

That's a good bet. You really have to do a poor job of prepping and torquing for the GM gaskets to leak or fail.

santiago

iTrader: (28)

i did a head swap to stock ls6 heads and mine never leaked. stock hb/gaskets.

Mike94ZLT1

iTrader: (3)

There wasn't a whole lot of prepping, both the engine and the heads were brand new and never ran. I had no bolt holes to clean, but I blew them out with air anyways. I wiped the head and the block surface down with mineral spirits, and since there had never been a gasket or anything else there before that should have been sufficient.. I printed out the instructions from LS1howto.com and had them laying on my windshield so I could follow them exactly.

studderin

iTrader: (28)

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mr. Jones

I have not heard any problems with these gaskets.
25000 miles on my setup (ls6 heads new and 8000 mi. on the block). I was also told they held up well to boost.
verify every possibility before you take it apart.
hope it turns out to be a simple fix.

Juiced2000SS

iTrader: (1)

LPE told me they use GM gaskets on most of their turbo stuff without issues. They must be decent.

allngn_c5

iTrader: (3)

Have you checked everything over yet ?? Any possibilities other then the head gaskets ??

If it does end up being the head gaskets then make sure you have room to go to the thinner .040 cometics before you do. Cometics are a much better gasket. One thing to remember you may have just gotten a bad set of gm mls's. The first set of Cometics I put on didn't seal up at all. Had coolant coming from around the #2 cylinder. Very pissed. No more Cometics in stock and had to settle for gm Mls due to being on a time schedule that was a day behind already. They failed in about 4000 miles. Another set of cometics were added this year and the car hasn't missed a beat. Try another set of gm mls, you may have had the one set that was weak. Or go with the top dollar cometics. Either way you'll be back on the road and ready to race I hope.

So what numbers did you put down, or did she start leaking before you got it strapped on the dyno ??

LS1curious

Did you use head studs ? Are the dowell pins in the block ? did you make sevral pass's on the gaskets and the studs to ensure they were properly strectched before final Tq'ing them ? Did you replace the o-rings in the steam vent fittings ?

I have seen GM MLS gaskets take some serious hits that would have vaporized a standard cometic and be completely fine.