So I used the 3 layer ls1 head gaskets on my 4.8 and iv heard the 862 heads may have a ridge that dont work with certin gaskets??
So I got everything put together and filled it up with water and yesterday when I went back i noticed it was dripping with water from the rear of the engine, i looked and looked and all I can tell is that its coming from the head gasket, I fired it up and it leaks a little faster, idk what to think. Its not coming from the cross over tubes, its dry everywere above the head gasket and it drips onto the started sheld and off the rear of the block were the trans bolts on. Theres just to much stuff in the way with the turbo system to pin point it. How on earth can the head gasket be leaking? bran new ls1 gasket with arp head studs and it was a running engine never been apart.
I guess the head or the block has to be cracked, unless the gasket has a defect, but it had a steady drip with no pressure in the water system. Theres no reason the ls1 gasket wouldnt work on a 4.8 would there?

 

your head have that notch? if so that is why your metal ls1 gasket is leaking
For heads with the notch it requires the graphite gaskets
Early model 706/862 heads had the notch 99-01

 

Yeah they have the notch, but i have a set of 98 ls1 heads in the shop and the have the notch as well, but they may have had a different style of gasket as well im not sure I didnt pull those off. I just wanna make 100 percent sure before I go throw the work of pulling the heads back off. But I think your right, that is where it looks like it could be coming from, right around cylender #6.

 

What he said! You need the 97-01 Gaskets, P/N 12498543. We keep them in stock for $39.95 + the FedEx truck ride.

 

He's building a boost setup, planning on going to 18+ psi, will the graphite gaskets hold that with the ARP studs?

 

Alright I found an old layered steel gasket and a non steel gasket in my shop, also have the heads that came off my bros 98 vett witch have the notch like mine, and this is the problem for sure, the layered steel gasket has one rubber seal that runs all the way along the bottem of the head were the others are sealed around each water jacket. So the layered steel gasket thats in there now runs right under the notch leaving in open for water to just run right out. Damm! I should of caught this when putting it together!
Now like ls1freek said, this thing will see 18psi and maybe a small 50 shot one day, will that gasket hold that? Like said I have arp studs so heads will not lift but will the gasket still hold?

 

If you are concerned with running the factory composition style gaskets in conjunction with boost, Victor Reinz has a set of retrofit MLS head gaskets available for the earlier engines that originally came with composite gaskets.
Part number 54441 - GM 4.8L VIN V, 5.3L VIN P, T & Z 1999-2007

I have never used these nor know anyone that actually has used them, however they are out there.

 

Ok thanks, Ill look into then.

 

I've got a set of those gaskets ready to go on with my 706's on an LQ4. They look nice, not like that's anything to go by with gaskets...I was supposed to do the head swap this week while I was off work, but I never found my motivation.

 

Do those gaskets have a 4" bore? Cuz you need that with your LQ4