[camaroman7d]

I have never coated my MLS head gaskets, they come with as coting on them and both styles Cosmetic and Fel Pro said to install dry.

I would be interested in knowing what type of sealer was used on the head bolts/studs. There is a certain brand that I had issues with before.

[ss27]

I agree with all of the above for the most part. You might wan,t to check the head bolt holes at the top of the block. I have seen them crack on a 400 . The head bolt sealer i use is the brown genuine G/M sealer wich is none other than Permatex Aviation 3 D in a G/M can or the liquid teflon. Alex

[sixd8rs]

Another place to look is at the caps on the crank bolts. I've had a block that leaked at these bolts. Just can't remember if it was at the bolts that were splayed or not. But they went right into the water jacket.

[97Z4C]

to me = i am wondering if you decked the block and made sure surface was true, especially with steam holes- for me . i use the indian head sealer no matter what gaskets and havent had any issues on my 400s even hundreds of nitrous passes--many may disagree -its just me

[MickyT]

Thx for all advice, dont see any signs of cracking however will get magnifier and really look close. Never any overheating. Had a tech tell me that many short run periods can create water in oil situation as it never heats to op temp and that has certainly been case over past several months as it is moved around the body shop.

[Eleanor's Nemesis]

Originally Posted by MickyT

Thx for all advice, dont see any signs of cracking however will get magnifier and really look close. Never any overheating. Had a tech tell me that many short run periods can create water in oil situation as it never heats to op temp and that has certainly been case over past several months as it is moved around the body shop.

Out of curiousity, do you use any fuel that contains alcohol....like E-85 or something similar?

Lots of my drag racing friends that use alky as a fuel have told me if they don't get the engine up to temp it will 'milk the oil'. Full synthetic seems to be worse than conventional or semi-syn for this phenomenon.

[ace's68]

You need to re-torque the heads after a few heat cycles. Aluminum and iron expand at different rates... Also, I've noticed I have to go over ALOT of my intake and especially valve cover bolts because the engine shakes and vibrates so much... Another problem area is main bolts that go into the water jacket. 400's usually crack at the main webbings, especially on 4 bolts, and the mains as well.
FWIW my stock truck vortec L-31 leaked water like a siv because all of the intake bolts were hand tight, it just goes to show the cam doesn't have to be radical engine to back bolts out.

[DOUG G]

Originally Posted by camaroman7d

I have never coated my MLS head gaskets, they come with as coting on them and both styles Cosmetic and Fel Pro said to install dry.

IF the heads have any imperfections or the wrong RMS for MLS gaskets they could leak...and it's an extra measure to help prevent a leak.

[camaroman7d]

Originally Posted by DOUG G

IF the heads have any imperfections or the wrong RMS for MLS gaskets they could leak...and it's an extra measure to help prevent a leak.

I understand your point and I have heard of others using baby powder, etc.. I've just never had a problem. Probably jinxing myself now.

I also don't re-torque my heads and never had a problem with that either. Same thing regular fel pro and Cometic says no re-torque needed. Won't hurt to do it, but the few times I have checked the bolts were still tight. Intake manifolds and headers are a different story.

[68rs406]

Originally Posted by camaroman7d

I understand your point and I have heard of others using baby powder, etc.. I've just never had a problem. Probably jinxing myself now.

I also don't re-torque my heads and never had a problem with that either. Same thing regular fel pro and Cometic says no re-torque needed. Won't hurt to do it, but the few times I have checked the bolts were still tight. Intake manifolds and headers are a different story.

This is my experience as well, I have never retorqued my heads. I would suspect the bolts that were loose got missed in the torque sequence possibly.

The short run/ moisture deal is possible, but it depends on how much moisture you are seeing? And as Michael points out anything with alcohol in it really draws in the moisture. Or there is a bolt leaking etc.
But the fact the bolts were loose was likely the problem, I would wonder why they were like that, retorque and change the oil a few times and run it.The only time I have seen loose head bolts other than from not properly tightening is after a nasty nitrous meltdown and a smoked head gasket.

[6D9]

Mikey I had the same problem with my 408 and AFR 195's. Turned out to be the ARP thread sealant was garbage. I removed 1 bolt at a time and used a different sealant. Never had another issue!

[68rs406]

Originally Posted by 6D9

Mikey I had the same problem with my 408 and AFR 195's. Turned out to be the ARP thread sealant was garbage. I removed 1 bolt at a time and used a different sealant. Never had another issue!

Not the first time I have heard this, I used it on my previous motor and it worked fine, I might have just gotten lucky. It's messy and has a strange consistency though, so I quit using it. I picked up some good teflon paste and have had great luck with it.

That said, it wasn't sealant that caused the bolts to come loose I don't think, but almost certainly the loose bolts caused the leak. I would have to guess the root of the problem is the loose bolts from possibly torquing? And it was not leaking at first I don't believe?

[grampstoyz]

Are you using washers on the head bolts?

[MickyT]

It was ARP sealant. Also using ARP bolts. Weird that all lower bolts both sides (neaerst exhaust ports) were quite loose. I did use a torque wrench to c how tight they were for removing them. Something tells me that is a no no?

[Everett#2390]

Not really. In reality, a cylinder head gets torqued in place in three steps, it should be un-torqued in the same three steps in reverse pattern. Keeps the head straight.

But then, I've always unscrewed the head(s) in one step and haven't had any problem either.

Only sealants I have ever used are Indianhead Shellac and Permatex A200, on the bolt threads. Never leaked.