chevellepst

Ok so here's the rundown, 98 tans am 5.7 ls installed a new oil pump and pickup oring as well as an ls2 chain. Car will make 40psi cold idle and a little over that at 2k cold and hot it's at 20 psi idle and will jump to 40 psi by 2k rpm but will not go over 40 even at 6k rpm. This is the same problem I had before the new pump which is a 10296 . If it was a bearing problem I would not think it would go from 20 psi hot almost instantly to 40psi off idle . I'm out of ideas guys please give me some things to trym

Dimeomboost

Both of mine did exactly what your saying but because it never went below twenty I kept driving thinking I would be able to figure it out and then eventually it would only go to twenty psi I tore it down and voila bad bearings the other motor went from 60Psi to 15-20 immediately like within minutes no knocking either time. I know its not what u want to hear but because I drove the first motor so long between 20 and 30 psi crank was bent 40 thou. new rods pistons bearings everything was 500 miles old. Rods are dark blue and purple save yourself the grief of u can tear down I would but maybe someone else has some magical idea and I'm totally wrong bmi hope so for your sake

crainholio

iTrader: (2)

There have been cases where people were sold the wrong o-ring, or installed it on the wrong pickup tube ridge, or didn't lubricate the o-ring during assembly and pinched it. Any of these will cause what you're describing.

chevellepst

Crainholio, I got the part # for the blue pickup oring off of here and have it to the parts person at the dealer. I oiled it and triple checked it when installed . It didn't get pinched or anything like that to my knowledge, I was very careful with it as I know they are easy to screw up lol

Taxman20

iTrader: (11)

my 6.0 did the same exact thing. 40 cold, 20 hot but would run up to 40 a highway speeds. Had near 200k on it. Bearings. Its tired.

lsfalcon

If you tap into the oil system and use a clear tubing you can see if there is air in the oil while it is being pumped through the system.