Another broken LBZ piston

LBZ

Super Moderator
Staff member
Jul 2, 2007
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B.C.
How are the lmm holding up with piston falures.

Hit or miss as well. Sikdmax cracked one over a year ago or so in his LMM. Same piston as the LBZ, just bad luck it seems.

I've been lucky so far but am building an engine on the side in prep for the worst-which I expect anytime now.:(
 

Devolont

New member
Jun 27, 2010
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There is a kit, the dealer calls it an overhaul kit. I asked him if it had the head gaskets, bearings, and piston rings and he said yes. Sure enough, none of those items listed were included but I was supplied with just about every gasket besides injector seals. Valve cover gaskets to the intake T, both T-Stat gaskets and a huge pile of others. The kit also includes the front and rear main seal. Real quick, I am in the middle of tearing my 04.5 LLY from a broken valve head with less than 1000 miles, whats the best way to remove the front main seal. I got the rear but I cannot seem to get the front seal. There is a specialty tool but I do not want to spend that much on a tool for one use. Also, I am only 19 so if there are any little tricks that you might think I already know, do not think I know the trick.
 
Oct 16, 2008
948
12
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Idaho
EGT's are a direct representation of how hot the piston is getting , it can def lead to the piston failing even if from heat cold extreme cycles it can make the casting waeker , i personally belive the LBZ piston failures are falt out bad casting / crummy pistons , some get good ones other get the crummy ones , luck of the draw really .

I agree to a point, but lots of timing can disguise high cylinder temps by not showing as much EGT as a lower timing tune would. I would think that would show the driver a much safer number than what is really happening in the cylinder. Which might explain why some see a "low" EGT number with a cracked piston and others might see a "high" number. Just my thoughts.

On another note, did anyone notice how far the spray pattern is out of the bowl, isn't that a big indicator of too much timing?
 

ripmf666

Active member
Sep 20, 2006
15,123
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Wentzville Mo
There is a kit, the dealer calls it an overhaul kit. I asked him if it had the head gaskets, bearings, and piston rings and he said yes. Sure enough, none of those items listed were included but I was supplied with just about every gasket besides injector seals. Valve cover gaskets to the intake T, both T-Stat gaskets and a huge pile of others. The kit also includes the front and rear main seal. Real quick, I am in the middle of tearing my 04.5 LLY from a broken valve head with less than 1000 miles, whats the best way to remove the front main seal. I got the rear but I cannot seem to get the front seal. There is a specialty tool but I do not want to spend that much on a tool for one use. Also, I am only 19 so if there are any little tricks that you might think I already know, do not think I know the trick.

I wish your first post was of what you needed and not that you got the overhaul kit. Most of the time you fo not need everything in the kit and also it does not have the head gaskets so you end up spending more money on it. With getting the front seal out go to the dealer you got the kit from and see if they will rent or loan you there removal tool and the intaller for the front and rear main seals. If I was not loaning mine out right now inwould offer mine to you and refund a hold cost. I usually loan them to anyone buying seal kits and other parts from me. Good luck if you need any help start a thread of your own and also check out the Gm spec area I have almost all the info and specs you will need to do anything to your motorbif not I will post it for you or Kyle aka Dmaxfireman will also help you.