1slow01Z71

iTrader: (36)

Like I said you're fine with MLS headgaskets, just make sure you clean the deck of the block really well and you are good to go.

budhayes3

iTrader: (19)

I'm building an 03 LQ9, but I have no idea what year the heads are? I should be OK to use the MLS's right? I mean, isn't that what they came with stock?

terravast4

iTrader: (25)

if you check the head on the comustion chamber side there is a little recess like half a quarter at either the #3 or #6 cylinder, if you have these heads the MLS gasket will not work. GM made a steel shim design that has teflon sealing material at the surface that specifically seals around these recessed areas. Th MLS gaskets do not have a sealing surface at this spot and that is why they have a tendency to leak.

1FastBrick

iTrader: (17)

This is the only valid information in this post. Thank you!

FWIW The 99 and 2000 model year 5.3/4.8L have the graphite head gasket. In 2001 They started using MLS gaskets. I believe it was the early 1999-2000 862 heads that either had the recess or not depending on either when or were they were cast. I havent been able to get exact info on that.

As far as coolant leaks go, if you use the wrong gasket in the wrong application then yes you will end up with a leak. I am not 100% sure why but occasionally some of the newer MLS equipped blocks do leak between the head and block matting surface.

I personally did an 05 avalanche 5.3L with flex fuel option that was leaking between the head and block. It was repaired some were else and withen a week showed signs of leaking again. They heads were checked and reconditioned and the block showed no signs of warpage or other damage. When I reassembled it, I used a Glue between each layer of the MLS gasket and on the top and bottom of the gasket near the front of the block were it was leaking. The vehical has since been shipped to Dubai and has hasn't had a problem since.

dlt76028

iTrader: (13)

did you get those heads done at that place i told you about?

A Low Dime

iTrader: (13)

Sure did. They are doing Scott's heads are machining my block as we speak..

dlt76028

iTrader: (13)

WHAT???

TVI

Where are you all getting your machine work done?

dlt76028

iTrader: (13)

Wes Automotive Machine Shop in Haltom City

TVI

Excellent, thanks. I actually live in Haltom City, too.