6.2L Winter Refresh

[SpareParts]

Yeah.

 

[j91z28d1]

Talked to 3 machine shops and the cheapest i can get it bored 0.010 over and honed is $900 bucks and i supply the pistons.
They all will clean the block, deck it then torque plate hone it or they will not touch it.

So tempting to just say fk it and just pretend i don't see the scratches. There are 2 scratches i can catch with my finger nail the rest i can barely feel.
Younger days i would just slap it back together and not give it another thought.

what were you tyring to do with it again? Just quick build to swap it out later with a full build in another truck?

honestly, did you notice any blow by when running before? if not and this isn't your forever built. I'd toss it together and forget what you saw haha. if you're tyring to make. max power and last a 100k miles, maybe have it cleaned up.

 

[j91z28d1]

and can you even go 10 over with these thin sleaves? I feel like 5 over is the standard next size up?

would 2.5 even clean those up?

 

[SpareParts]

It's just a refresh. Was not planing on any machine work but now?
It did not use any oil after i fixed the oil leaks. As you can see looking at the heads there is no indication of oil burning. Plugs were all burning clean.
I don't know about blow by but at 136K it had to have some. There was a little less than 1/4 cup of thick goo that ran out of the intake when i removed it.
I had the wife start it when cold so i could watch the exhaust. No smoke on start up.

I don't know if 5 thou would clean it up. That's 0.0025 deep cut + hone, so probably another half thou. That would probably clean it up. I just said 0.010 without knowing.
If i take it to a machine shop, i would probably have them order the pistons also.

I only drive between 5 and 10K a year so no matter what im never gonna ware it out i suppose. Maybe a catch can would be warranted in this case if i just put it back together.

 

[donjetman]

To eliminate the oil in the intake problem the new improved driverside valve cover is a must: https://static.nhtsa.gov/odi/tsbs/2014/MC-10114272-9999.pdf

Here's my ole ds vc and the new improved:

 

[Joseph Garcia]

To eliminate the oil in the intake problem the new improved driverside valve cover is a must: https://static.nhtsa.gov/odi/tsbs/2014/MC-10114272-9999.pdf

Here's my ole ds vc and the new improved:
View attachment 472441

Can you tell if you have the original valve cover without taking it off? Is there something on the outside of the valve cover that could identify if it is the original valve cover?

 

[SpareParts]

Mine is the old style and i do plan on getting the new style.
I do not think there is anyway to tell without removing one.

 

[donjetman]

No, you can't tell

 

[SpareParts]

I mentioned the oil in the intake as a reference to blow-by but some is normal with high miles and the old style valve cover.

Im thinking if i was only dealing with a little cylinder taper or a couple scratches it would be no big deal.
Having the scratching and excessive taper combined would be a problem.
I have never felt the need to have a bore gauge but today i ordered one.
Here is what GM says
* Piston - Piston Diameter - Measured Over Skirt Coating
4.0653-4.0665 in
* Piston - Piston to Bore Clearance - Production
-0.0019 to +0.000 in
* Piston - Piston to Bore Clearance - Service Limit with Skirt Coating Worn Off
0.0022 in

I do not know what the size of new pistons are but i have read new pistons usually measure under 4.065 for clearance.
I also have no idea how to bring the info into an understandable form for me so ill have to figure it out.
Looks like only 0.002 is allowed or two thousands? Seems tight but what do i know im an idiot sometimes.

Anyway, what im trying to get at is, If the bore is already too big ill send it to the machine shop. If not i'll just put it back together.

 

[swathdiver]

Aluminum 6.2 block is only allowed to be bored .020" over max.

 

[SpareParts]

Yeah .020 seems to be the standard weather it needs that much or not because of core shift during production.
The cylinders are fit in a jig. The block is then pored around the cylinders.

Piston to wall clearance is .0025 to .0033

Cleaned and polished the crank. No scratches or nicks. Nice shiny and smooth!
Rod journals should be 2.100, Mine measure 2.995 and seem to be round on 1 journal the other 3 are 2.100
Mains should measure 2.559, Mine measure 2.559
Crank is fine to use as is.

Too many little details or keep going?

 

[j91z28d1]

details are always interesting

 

[strutaeng]

How did you polish the crank journals? Mechanically or by hand?

 

[SpareParts]

By hand.
It really needed nothing and measured out fine before i started. I used 1500 wet/dry, WD40 and a shoe string. After measured the same.
Grandfather taught me that about 50 years ago. Now it's all over YouTube university.

Here is something i wish i had done.
I should have measured all the clearances with the old parts before i tossed em all so i would have a reference between old and new.

 

[donjetman]

I mentioned the oil in the intake as a reference to blow-by but some is normal with high miles and the old style valve cover.

Installing the "improved" valve cover is critical for reducing oil consumption.

Bought our 07 Denali w/L92 in 2013 w/130k miles it was burning at least 1 qt of oil per 100 miles (see spark plug pics). I completed the TSB TSB 10-06-01-008M and all these yrs and 71k more miles later it never needs oil any makeup oil.

 

[SpareParts]

The plugs are pretty bad for sure.
The plugs I removed from my engine were at least a couple of years old and were tan colored with no deposits. Guess i did not take a pic though. They were NGK.
I'm not even gonna try to deny the valve cover fix but i my self have never seen the problem on a non afm engine that im aware of anyway.
My engine had almost 240K on it and im sure had blow-by so finding less than a 1/4 cup of goo i would think is normal blow-by residue junk.

I do not mind experimenting a little.
On the current installed engine, i did enlarge the holes on the baffle part to allow the oil to drain out better. I also bought a catch can but have not installed it yet so i could monitor what is going into the intake.

On the engine i removed looking at the piston rings showed the oil rings were barely expanding and were gooey feeling when moving them. The top ring had a gap of .020 at the top and a tight .019 at the bottom. Service shows .0173 max. Rings were shot also contributing to goo in the intake.
I should look at the intake valves and see what they look like.

 

[SpareParts]

Here is a question for ya'all
My stock pistons had valve relief cuts facing each other.
When looking at pistons i see 2 other styles.
True flat top's and the 3rd style with 2 valve reliefs side by side.

What determines what piston you can or should use?
I would think the style with 2 reliefs side by side would be best?

 

[strutaeng]

Here is a question for ya'all
My stock pistons had valve relief cuts facing each other.
When looking at pistons i see 2 other styles.
True flat top's and the 3rd style with 2 valve reliefs side by side.

What determines what piston you can or should use?
I would think the style with 2 reliefs side by side would be best?

What camshaft are you thinking of running? Piston-to-valve (PTV) clearance and compression ratio is what determines the valve relief (if you need them), which is also affected by lift.

I thought the valve reliefs were due to VVT, no? Your engine has that, right? Are you keeping that?

 

[SpareParts]

Im actually debating on the cam. Was going to go with the one Geotrash has, but VVT is not a bad thing either, so a VVT performance cam would also be good.
Something like this one.

GPI - High Lift LS Camshaft (4.8L / 5.3L / 6.0L / 6.2L) - Gwatney Performance

Our camshafts are our most popular product, and for good reason - they are pound for pound - the best on the market. These high lift performance truck cams are specifically designed and engineered to take your Silverado, Sierra, Tahoe, Yukon, Avalanche, Suburban, hot rod, or street rod to the...

gwatneyperformance.com

 

[West 1]

To avoid morning start up piston rattle the piston to wall clearance should be .001 to ,0015.