Engine knock and don’t know what it could be

[jonawhie61989]

Damm! You cracked a piston! Did you run this truck hard? Was the motor maintained? Just curious how a piston cracks.

I just bought the truck and I was in the hospital after having a minor stroke and we only had it for a week. It broke down had to be towed home and I have just been able to tackle this and that’s what I found m. It doesn’t look like the motor was ever maintained properly from the looks of the inside. I have an opportunity to put a 5.3 in from a 08 tahoe till I can rebuild the 6.2. But I don’t know if it’s plug and play or if there is things I will need to change any onsite would help. Thank you in advance

 

[solli5pack]

I just bought the truck and I was in the hospital after having a minor stroke and we only had it for a week. It broke down had to be towed home and I have just been able to tackle this and that’s what I found m. It doesn’t look like the motor was ever maintained properly from the looks of the inside. I have an opportunity to put a 5.3 in from a 08 tahoe till I can rebuild the 6.2. But I don’t know if it’s plug and play or if there is things I will need to change any onsite would help. Thank you in advance

Not sure 100% if it's plug and play. I think you might have some tuning issues with the computer so maybe grab that as well from the Tahoe. Im sure others with more knowledge will chime in. I would definitely swap in new motor mounts when you have the motor out!

 

[jonawhie61989]

Not sure 100% if it's plug and play. I think you might have some tuning issues with the computer so maybe grab that as well from the Tahoe. Im sure others with more knowledge will chime in. I would definitely swap in new motor mounts when you have the motor out!

Ok thanks I will be sure to ask for those when I go pick up the motor

 

[OR VietVet]

Damm! You cracked a piston! Did you run this truck hard? Was the motor maintained? Just curious how a piston cracks.

Severe or long enough detonation can crack a piston. I have seen cracks, that were just that, a crack. I have never taken a piston out and had it come apart in pieces.

 

[strutaeng]

WOW. Sorry to hear about your issues, both healthwise and truckwise.

Take care of your health first priority. Please. I pray you make a speedy recovery.

As far the engine, there appears to be some valve marks on the piston. What does the head look like? Most likely that matching valve is bent.

You could swap a 5.3 temporarily, but will need a computer reflash to run good. Otherwise everything else should be plug and play assuming it's from the same generation of vehicle. Is there someone helping you on this work?

 

[petethepug]

Meh, I’m not really sure your issue is with the top end. I think that’s the DOD / displacement on demand option some 6.2 had


Someone else just lost the L9H in their newly acquired 09 Denali. They went through the motions to resurrect it for the next 250k in a thread.

If you have a lead on finding a 6.0L gas motor from a 3/4 or 1 ton pick up you’d have a direct drop in motor with no need for tuning. They run Reg fuel, the later version are e85 too.

Turning some wrenches is gonna be good for getting you back on track, but don’t back sass your Dr’s orders and overdue it or not take those 10,000 pills they give you. Seriously though, enjoy and

 

[jonawhie61989]

Meh, I’m not really sure your issue is with the top end. I think that’s the DOD / displacement on demand option some 6.2 had
View attachment 426730

Someone else just lost the L9H in their newly acquired 09 Denali. They went through the motions to resurrect it for the next 250k in a thread.

If you have a lead on finding a 6.0L gas motor from a 3/4 or 1 ton pick up you’d have a direct drop in motor with no need for tuning. They run Reg fuel, the later version are e85 too.

Turning some wrenches is gonna be good for getting you back on track, but don’t back sass your Dr’s orders and overdue it or not take those 10,000 pills they give you. Seriously though, enjoy and

Thanks and this 6.2 was non afm/dod and now that I have it out of the truck I am going to break it down and have a machine shop work some magic on it. But do you think the 6.0 would be a better option?

 

[j91z28d1]

that's an impressive level of damage. I have a feeling your machine shop is going to say it needs sleaves. at that point I don't know that cost wise there's going to be much to rebuild. 6.2 are getting expensive thou, so maybe if you're dead set on having a 6.2. I'm thinking the heads are hurt pretty badly too.


my only guess is dropped valve seat, which is fairly common. piston hit the valve hard enough with the seat holding it open that it broke the piston.

heck of a thing thou.

 

[jonawhie61989]

that's an impressive level of damage. I have a feeling your machine shop is going to say it needs sleaves. at that point I don't know that cost wise there's going to be much to rebuild. 6.2 are getting expensive thou, so maybe if you're dead set on having a 6.2. I'm thinking the heads are hurt pretty badly too.


my only guess is dropped valve seat, which is fairly common. piston hit the valve hard enough with the seat holding it open that it broke the piston.

heck of a thing thou.

The heads are not damaged surprisingly but I am set on rebuild no matter the costs. Just had the cylinders checked and they are not severely damaged the shop said they can go .20 on the bore to clean them up.

 

[Fless]

The heads are not damaged surprisingly but I am set on rebuild no matter the costs. Just had the cylinders checked and they are not severely damaged the shop said they can go .20 on the bore to clean them up.

Better rein 'em in to only 0.020. Unless you're getting some much bigger pistons....