poundsofjane

I have a 08 Sierra with 165,000 on the ticker. Lately, when engine is cold, it takes a while to build oil pressure. At idle, it won't build enough to keep the top end of the motor from making noise. If I rev it up, it will build pressure and the lifter noise goes away although it never reaches the pressure it did when newer. I have replace everything on the outside of the motor(sensor, new filter, and now, new oil pump). Even with a new oil pump, the pressure is just as it was before I changed it. At every stoplight, I have to power brake to keep the revs up so pressure will stay up. If I dont, the lifters start to make noise. Well, it sounds like one lifter only. It diffenately isn't getting oil to the top end when pressure drops. Where could I be getting blockage. And one more note, when I turn left hard, it tends to help build pressure. Turning right makes it lose pressure almost like it is low on oil and sloshing around but that is not the case. Please help before I destroy this motor. It is a LMG rpo 5.3 with afm disabled. Thanks

Robert91RS

iTrader: (2)

Sounds like a bad lifter and you will need to inspect the cam too. Have you monitored oil pressure with a scan tool yet or just the dash gauge?

poundsofjane

Do you mean a manual gauge or the kind that you plug into under the dash? The mechanic who replaced the oil pump plugged onto under dash and said it was running identical pressure to what was on the gauge. But didn't check with a manual gauge as far as I know. It definitely isn't getting oil to at least one area of engine on top end when gauge goes low. Still runs strong, doesn't smoke or burn oil, and no leaks. It's never been hot and I always changed the oil when dic said to. When I get it out on the open road and keep it at highway way speeds, you wouldn't know anything is wrong with it. I have noticed my fuel mileage has gone to crap lately. Not sure if thats related. I have opened my filter on about every other oil change and have never found anything that would sUggest that the motor is wore out. Gotta do something quickly cause this is my only ride. If anyone near Houston has ideas and can advise me of somewhere that could straighten this out for me, holla back

Robert91RS

iTrader: (2)

Are you getting any misfire codes?

poundsofjane

Yes, I got p0300. Random misfire. That obviously means something and I bet you know what. C'mon, spill the beans man.

Robert91RS

iTrader: (2)

Already told ya, its cam and lifters. Maybe a slim chance you broke some valve springs but i'll bet you lunch its the lifters. Seen it plenty of times.

poundsofjane

Can you explain to me why it causes my oil pressure to drop? And is that worth fixin in a motor with 165k miles or should i look for another engine? Thanks for the help

Robert91RS

iTrader: (2)

Your lifters are hydraulic, when they fail they have the potential to puke oil. Because your effectively runing on 7 or fever cylinders, your idle is dropping and further compounding the issue.

This is a good excuse for a cam swap for most guys around here.

00ecsb6.0

iTrader: (2)

A guy came into my work with the same problem. Dropped the oil pan and the pickup tube mesh/filter was clogged with old, hard oil. Replaced it AND the o-ring on the end of the pickup tube and all is normal now. The o-ring on the tube can also cause you to lose oil pressure.

00ecsb6.0

iTrader: (2)

165k is nothing to a ls motor. Agreed with robert91rs