91yj

I just got my motor put together, I used 803 heads on a lq4 with mls gaskets part# 12589227. I had these same exact heads on a 5.3 with felpro mls head gaskets and they worked fine. Now with the gm gaskets there is coolant leaking. I read about this having to do with the notches on the bottom of the heads and that graphite gaskets will work, however I don't think graphite gaskets were made for a 4" bore.

Can I have the heads milled down far enough to remove the "notch" ? Will this solve the coolant leak?

Burken01

iTrader: (88)

You can try copper permatex spray on the gaskets and then reinstall.

where exactly do you notice the leaking, check your coolant crossover as well because those gaskets get worn out and get flat easily..

91yj

It was right where the notches are in the heads. There was a good size puddle under the motor in just a few mins of sitting after I turned it off, so it was dripping pretty fast. Where and how do I apply the spray?

Marc 85Z28

iTrader: (8)

You cannot use a MLS head gasket with the old notched heads. I would not attempt to mill the heads to remove the notch. I don't remember how deep they are off hand, but IIRC you would have to remove A LOT of material that would dramatically increase the compression ratio and possibly ruin the chamber design.

Mr. Gasket makes a 4" bore graphite gasket.

Copper spray is applied to MLS gasket surfaces to help with minor imperfections with sealing surfaces. It will not help in this case.

91yj

thanks for the input, I found the gaskets you mentioned, do you know if they have exactly a 4.00" bore? Would this cause problems if I used it? The reason I ask is most gaskets are oversized a little. My engine has not been over bored.

Burken01

iTrader: (88)

It won't hurt, lots of people are running 4.100 ls9 head gaskets on ls1 3.905 bores...

91yj

right, but this would be a 4.0" head gasket on a 4.0" bore. I know oversized head gaskets are fine, but what about exactly equal?

Marc 85Z28

iTrader: (8)

Typically running a gasket around ~0.010" larger is preferred. However, ff you've got a virgin block with a 4.000" bore, then the 4" head gasket will work with those heads. In this the case the cylinder head chamber dictates the gasket size, and since the chamber is designed around a much smaller bore, the gasket should still seal without interfering.

91yj

alright thanks guys, I ordered the gaskets yesterday they should be here tomorrow. Just to make sure ill measure them to check that they have at least a 4" bore.