Can I put the longer skirt pistons in a 2002?

[c good]

The piston slap isn't real bad when cold. Mostly goes away when warmed up. If I decide to rebuild my engine, can I get the new longer skirted pistons and install with no problems?

Or am I better just getting a lower mileage engine from one with the longer skirts? What year did the longer skirt pistons start? Thanks for any info.

 

[mrrsm]

NO... With the Caveat that if you tried doing this ...say on a Turbo-Charged LL8 Motor ...You would have to go to SHORTER Connecting Rods...which would naturally DROP THE COMPRESSION RATIO down substantially below the Stock 10+/1 Ratio.

If You tried doing this...the Longer Piston Skirts would dive below the bottom of the Cylinders many times during their 4 -Cycle 720 Degrees of Rotation ...and the Skirts might make direct interference contact with the Rotating Crankshaft Counter-Balance Throws (...usually coincidental in their positions whenever the Con-Rods are fully withdrawn on the Descending Crankshaft Journals) ...and that would imply... Bye Bye Motor.

THESE are the Only Pistons to install... perhaps also only after replacing the ovalled out Ancient Cylinders with the Cast Iron 1.5 mm Thick Walled Cylinder Sleeves available via the GM OEM Replacements... a Non-Trivial Job for most Mechanics ...best left to the Tender Mercies and Clemency of a Qualified Machine Shop:



The Attached PDF shows a comprehensive collection of Vortec LL8 Engine Specs that may prove useful in your future Engine Re-Building Efforts.

Please... Remember THIS Engine Builder's Caveat Emptor:

"If You are NEARLY Correct ...Then You are PRECISELY Wrong..."

 

[c good]

Thank You MrRsm!

I would definitely have a local, reputable machine shop do the sleeve inserts. I've seen your posts on what it takes to press the old ones out and install the new liners.

By the time I bought all the special tools it would be more than having a shop do the work.

My plan is too keep driving it as is. It only slaps when cold, and quiets down when warmed up. The lap is still there, but it's significantly quieter.

It burns very little oil since I did the BG oil treatment and switched to Valvoline Restore and Protect. About 1/2 to 3/4 qt in 4500 miles.

It runs strong and is now a vehicle I trust since solving the PCM ground problem

My other option is to buy an engine with lower miles and install it. The problem with that is I would not know it's history and if it was maintained.

I would probably tear it apart and go through it first. The Envoy is a weekend vehicle I use mostly during the winter months for the desert.

I might just have to plan a summer project. Go through the original engine. That way I know what I have.

 

[mrrsm]

The positive thing about finding and obtaining a relatively Low Mileage LL8 compatible within the 2002-2004 PCM-Harness Wheel House is that you can Stand Mount it and do Exploratory Component Replacements on the motor that might include GM Timing Cover and Cloyes Timing Chain Set R&R which is quite critical and damned near impossible to perform on an already installed Engine... Remembering that a goodly number of those eBay GM 4.2L Engines will have wound up in the Salvage Yards BECAUSE of the insolvent P0016, P0017 and P0345 Trouble Code issues,

Think of the ease of performing an R&R and Clean Out of the Crankcase and then doing a Bench-Top Soak of the Oil Pick Up Tube in Berryman's Chem-Dip as well as perhaps doing the alternative upgrade of the GM OEM Updated Front Cover - Gerotor Oil Pump Combo right along with the Melling Oil Pick Up Tube (Orange Silicone Grommet vs. the OEM "Blue" Teflon O-Ring Version) Upgrade ...again,,, with Equal Ease and Aplomb.

All Other Gasket and Cleanup such as with the R&R of the Timing Cover and Intake Manifold is likewise a breeze by comparison to having the dreadful duty of working on a Drop & Swap Motor... once it has been installed without remembering to R&R the Front & Rear PTFE Oil Seals and a finding a Cracked Flex-Plate after the fact... as these also fit within this "Take A Stand" category and make these Jobs both accessible, instructive and truly ...a pure pleasure to perform.

 

[efi-diy]

Only with forged custom made pistons and the increase in skirt length is about 1.5mm.

GM fixed the piston slap issue with the 06 up connecting rods that have a oil squirter hole in them. But to ensure proper oiling the crank needs to be cross drilled.

 

[c good]

Would an '05 engine drop in my 2002? If I'm reading everything correctly the '05 has the upgraded oil pump and front timing cover? Does it have a different PCM?

I don't need an engine yet, but I'm planning ahead. Or would I be better off to stay with the 02-04 as MrRsm mentioned and buy the upgraded oil pump, timing cover, etc.

IIRC my 02 has an oil level sensor but I would think I could just swap over my oil pan whatever engine I go with if not my 2002 correct?

Thanks for all the great info everyone.

 

[Mooseman]

The 05 is a direct drop in, minus the oil pan for the oil level sensor. One minor difference is that 05 went to returnless fuel system but the fuel rail can also be swapped from your 02.

The oil pump mechanically is the same. It's the oil pump pickup and seal that changed, which required a change in the pump's mating surface for the pickup. May have to confirm what year this change happened.

 

[c good]

Thank you Mooseman. Definitely appreciate the info. This will help me make a decision. Any add'l info is great.