Lost the motor?

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
13,886
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Mid Michigan
IMO, you wrecked the engine. Sorry. Might be able to salvage something from it, but expect the worst.....
 
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danzick

playing with fire
Feb 20, 2014
435
1
18
Livingston, MT
IMO, you wrecked the engine. Sorry. Might be able to salvage something from it, but expect the worst.....
yeah I am. im basically just hoping the drivers side head is good, and the crank. Now ive got to decide if i want to piece together a motor from a new block and rods, pistons ect. or if i get a reman. This engine has 83K on it, so If the crank is ok Id like to use it.
 

MAXX IT OUT

<<<IT WORKS
Mar 1, 2013
1,719
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Des Moines, Iowa
Ouch!

yup, like zerogravity said. over-revving it floats the valves. you can either pop the keepers off doing that and drop a valve or if its bad enough, the piston hits the valve, bends the stem, breaks the head off and the valve head kills the piston, head, etc.

compression test aint worth it now lol
Agreed, I bet you floated a valve which took out the head and piston. When I lost my piston I just had a rough idle and was burning oil. Sadly valvetrain upgrade are over looked on most stock bottom ends.
 
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danzick

playing with fire
Feb 20, 2014
435
1
18
Livingston, MT
A question for you piston experts in the mean time. Does anyone have a good sxs picture of a stock vs delipped piston? I'm starting to wonder if the main difference between mahle factory and performance piston is just that. I have 2 lathes I use for my welding/ machine repair business. I'm sure I could manage to delip them myself.
 

bimmer95

Member
Mar 15, 2019
48
5
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Morgantown Pennsylvania
No there's more to the performance cast pistons then delipped. It's a different piston. I have delipped a few sets of oem an mahle oem replacements on my lathe, it's easy enough just takes some time. Open the bowl to around 2.5 inches and smooth out the sharp edges.

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danzick

playing with fire
Feb 20, 2014
435
1
18
Livingston, MT
Yeah after I posted that I watched mahles video comparing the two. I'll probably go with a factory set and delip them. I don't need a high horsepower capable engine. Just a good towing one, and one that can handle 600-700hp of short street sprints. I'll probably start a thread in the engine building section next.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
Yeah after I posted that I watched mahles video comparing the two. I'll probably go with a factory set and delip them. I don't need a high horsepower capable engine. Just a good towing one, and one that can handle 600-700hp of short street sprints. I'll probably start a thread in the engine building section next.
do not buy the mahle OE replacement pistons. they are known to be weaker than a set of GM lb7 pistons. if you are going the stock route, buy LB7 pistons from GM and delip them. otherwise id pony up and buy a set of mahle race cast. if you are staying on stock injectors, you are still going to run the risk of cracking them. only fingers pistons would be trustworthy enough to handle high pulse width, high timing stock injectors. if you keep your pulse width down under the 1500uS area, race cast will be fine for the hp you want. beyond 1500uS is deminishing returns anyhow in relation to engine health
 

danzick

playing with fire
Feb 20, 2014
435
1
18
Livingston, MT
Gotcha. I'm actually looking into a local engine with 113k. If the motor is in good shape when I tear it down, I'd probably use those pistons and delip them. I'll probably dig into this deeper with you guys once I tear my engine down and start a build thread to ask you guys different directions to go. I'm not really in a hurry. This truck gets about 1500-2000 per year put in it. I have the time to build an engine.
 

danzick

playing with fire
Feb 20, 2014
435
1
18
Livingston, MT
thoughts on a 2002 fully dressed engine with 170k for 2500? what would be the chances the block wouldnt need any attention? even if it would need attention, is it a good way to go to start a new foundation for another engine? there is one on market place about 2 hours away.
 

danzick

playing with fire
Feb 20, 2014
435
1
18
Livingston, MT
So actually, not as bad as I thought. Block and head is totally destroyed. But, drivers head is fine, along with I'm pretty sure the crank and cam. The piston exploded. I did not drop a valve. The stems are still in the head. Far as I'm guessing, the piston was weak or cracked and the high rpms from forgetting to put it in drive finished it off. A shame. The engine was in great shape. Good crosshatch in all cylinders.
 

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ZeroGravity58

Active member
Mar 23, 2008
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Maryland
What do the valves look like in the #5 bore where the piston let go? I'm not saying it can't happen but I've never seen a piston explode for no reason. I still suspect valve to piston contact. I also wouldn't reuse anything out of the bottom end of that motor. It's not worth it at this point.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
13,886
250
83
Mid Michigan
Why wouldn't you use the crank and the cam if they look good?
Because according to that head, those piston pieces went all thru the engine. I wouldnt use any internal parts from that engine.

.....and it looks like you dropped two valves which killed that piston, not the other way around.
 

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