[Swampperman]

2007 NNBS 1500 5.3 LY5 has 64K miles, I bought it with 59K miles and no warranty in November. It started misfiring and then lost power. Had mechanic at work put it on the scanner, pulled codes po300, po171 and po174. I pulled the intake and replaced intake gaskets, Replaced plugs with ac delco iridiums even though old plugs looked alright and truck still didn't run right but cleared po171 and po174 codes. Coils, plug wires and injectors are good. I dropped the truck off at the local dealership. They called yesterday and said plug #1 and #7 were oil soaked. I got a print out a week after I bought the truck from another dealership with a history report and two pistons had been replaced under warranty at 30K miles. I am going to pick the truck up today and go from there. Could the rings be stuck? Should I pull the motor and rebuild it?

 

[04crewcabz71]

Was a compression check done? Such low mileage and two cylinders are leaking oil? Was a cylinder leak test done? Might want to get another diagnosis done from another place. If the motor has 2 cylinders with bad rings then it's time for a rebuild or another engine.

 

[04crewcabz71]

Wait a minute, the motor had 2 pistons replaced verified by history? Could have been a motor with a bad replacement or improperly installed rings.

 

[Swampperman]

I had the mechanic for the city I work for do a compression check and he said it was good. I asked the parts manager yesterday if he could bring the history of it up and was told it was blocked. I am going to go back to the dealership that gave me the print out and see if they can tell me which pistons were replaced. I pulled the plugs for #1 and #7 and put some marvel mystery oil in the block to see if the rings are stuck.

 

[Swampperman]

Marvel didn't help anything. I am going to do a leak down test and go from there.