5.3 unknown mileage, I've been pushing 3-7psi through it via a VS racing billet 70/70 for a few years now. Motor has been mostly gone through (oil pump, cam, valvetrain, heads refinished and rebuilt) stock untouched short block deck with Speedmaster studs. I put cleaned up stock heads 862s I believe no knotch on them. I developed a head gasket leak or something causing oil/combustion to get into the cooling system. I pulled the heads and found that the driver side #5 and maybe #7 had some a few small areas where I could get a .0015 feeler between the deck and straight edge, same on the head side around #5. I was running cheapo 3 layer MLS gaskets no spray. I figured given the small spaces maybe some new MLS with copper coat would seal it up. That was last year and thought I had fixed it. Well I popped the cap and found some $hit on the bottom of the cap again. Chemical test shows very slow bubbles (maybe 1 tiny one every 3-5s) just enough to move the fluid in the tester which is almost nothing. Fluid didn't change yellow after 10 min or so but lightened slightly. So now I'm in the hard place, the motor is not worth getting it decked. Previously I pushed 100psi through each cylinder to try to get bubbles out of the coolant to narrow it down and got nothing. It seems that it needs to be good and hot and maybe get boost to push through.

I pressure tested the cooling system 20psi no leaks, Not getting any external leaks, no smoke out of the exhaust. This is what happened last time except the leak was alot worse and I got more green/red foam in the coolant that floated on top of the coolant as it dropped. I'm kinda at the point where I want to just pull the motor and replace it but I'm willing to maybe do some stuff thats easier in the meantime. What are the thoughts on the below.

1. First would be to add Kseal headgasket fix to see if that works.
2. Pull the driver head and swap the MLS to a Graphite gasket, I hear they seal better and given my low boost a stock felpro or something would be fine no?
3. Has anyone scraped JB weld or something onto the deck to fill the gap?

Whats annoying is that I thought it was fixed and it sat all winter not being worked on and then this.

 

While the heads are off given any thought to having the heads decked?

 

Heads were decked/cleaned before I put them on, that was like 4 years ago, they maybe have 2k miles on them. I know they are slightly warped according to my straight edge and feeler gauges but at max .0015" which makes me think maybe a graphite gasket will seal it? I was also just thinking of pulling the driver head as thats the one I think it is.

 

Composite gaskets would seal worse. Get the typical 7 layer MLS BTR sells for the small bore Install dry, no silly copper coat gimmicks, thats nonsense... and prevents proper heat transfer from head to block. Also prevents movement. The HG is upposed to move! Thats one of the main reasons they went to a MLS gasket. Coatings prevent this.

When the heads off do a DIY surface on it or even better take them into be surfaced.

You can DIY block sand the deck too. I use a machinests block and 400 grit. Brush on some Dykem Steel Blue and sand it. Any low spots are very easy to see. Doesn't need to be perfect.

Old thread I did. This surface held 25+ with no issues.

https://ls1tech.com/forums/generatio...k-surface.html

 

So, I don't know if this would be worth trying but I saw a video where a guy took a large piece of tempered glass, glued some 220 or 330 grit iirc to it and used it to deck his heads and cylinder block.
He set the glass with paper glued to it on his block with the deck facing up and flat, set the cylinder head on the glass for weight and just worked it back and forth.
Looked like it worked very well.
Yes, you'd have to yard the engine out and completely disassemble it, but it wouldn't cost much to get these supplies, and the engine may have to come out anyways unfortunately.

 

Beat me by just a few minutes lol.

 

You think the 7 layer seals better?
I would need to purchase all the things to do it myself.

 

Ive seen that too, For the heads that makes sense. the block is where I get turned off. Engine is in the car, not alot of room to sand it down. If I'm pulling the motor I'm likely changing it out. Sanding the heads likely isn't going to fix the issue given that the block is also out .0015 in that same area.

 

yes more layers make for a better seal and allow more leeway in terms of deck surface. Purchasing those things is a drop in the bucket compared to machine work and paying someone else labor.

 

got a part number for these for the 5.3? I don’t see 7 layer for a 5.3 on summits website (just standard 3 layer) which is what I have now.