Any GM Techs on board here?

broncosbybart

broncosbybart

Is it 5 YET?
Joined
May 15, 2008
Location
Charlotte, NC
Kind of a tech question but not really pertinent to 4x4's.

Got an 05 Colorado 2.8L truck w/103k on it. I was told that it had the head done once already for the valve seat issue. Truck was using a quart of oil every 200 miles. No idea where it was going. It didn't smoke like a crop duster and it didn't leak out. Any ideas where it was going? It just lost compression on the 3rd cylinder (probably a valve issue- 0 psi compression) and I'm thinking of tearing the motor down to have it rebuilt. I have no thoughts as to why it used that much oil and if it is even worth it. Can't seem to find a good used engine anywhere.
 
You could always put a 5.3 in it :D
 
Well...a 4.8 would still get damn good mileage in that little truck!

I'd pull the head and see what you can tell from what. You may be able to see something just from pulling the valve cover too. Maybe a rocker arm let go.
 
the 2.8 4cyl, 3.5 5cyl in the Canyon/Colorado and the 4.2 6cyl ( in Trail Blazer/Envoy/Isuzu Ascender ) have history of valve issues, seats, stems, and weak springs add to this that tearing down in the vehicle is a frustrating endeavor. head bolts breaking off in the block during disassembly ( also on reassembly ) timing chain HELL, which requires puling timing cover off ( as well as oil pan to pull cover )

Head bolts, torque to yield ( NOT reusable ) very brittle, be damn sure the threads are very clean when reassembling, use lube on the threads ( lightly ), they might still break when torquing ( angle torque, a real PITA under the cowl for the rear cyls )

4.8/5.3 with 4L60 and 3.42/3.27 gears would fly AND get good mileage in one of these trucks, a Trail Blazer SS drive train swap ( 5.3, 4L60 AWD ) would be fun too
 
Thanks guys. I am hesitant to tear her down but right now I think it is the best option. It only took a few hours to get the valve cover off... Everything looks good from the top of the cylinder head. Nothing obvious yet.

I had another one of these that had the valve seat issue but GM did the warranty on it. This one was supposed to have been done but I have my doubts.
 
The new heads should have the updated seats unless they had them replaced at a mom and pop shop there is a possibility the head bolts were over torqued causing the head bolts to break resulting in loss of comp id pull the valve cover and take a 3/8 ratchet and socket and see if any of the head bolts are loose id also recommend using arp head studs and not the aftermarket head bolts
 
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