lower oil pressure 05 tahoe

[lilflip]

i have an 05 tahoe and odometer reads around 350k, i was told the engine had been swapped by previous owner when i bought the truck. had some lifters fail and spun a main bearing with low oil pressure. had a mechanic do a full rebuild. still lower oil pressure after. 5-10at idle and read 12 when i hooked it up at the shop. would only increase to 15-20 when at 2500rpm+. no change whatsoever in higher rpm’s. changed pressure switch before getting a solid reading, no change. i did a flush and dropped the pan and found a mixture of sludge and metal shavings. i asked the mechanic and he said that it was probably some metal from the rebuild and what was leftover in oil galleys. the pickup tube was clogged. the mechanic had changed the oil pump but not the pickup tube. i decided to switch to a high volume oil pump and put a new pickup tube on when i replaced it myself. made sure the correct o ring was on and torqued everything to spec. i did a flush, and then changed it out with mobil 1 5w-30 full synthetic with an stp filter. at first crank it reads 50-60psi but once it’s warmed up i am still reading on the dash around 10-15 at idle but oil pressure increases with rpm this time. i’m at a loss.

 

[Sam Harris]

i have an 05 tahoe and odometer reads around 350k, i was told the engine had been swapped by previous owner when i bought the truck. had some lifters fail and spun a main bearing with low oil pressure. had a mechanic do a full rebuild. still lower oil pressure after. 5-10at idle and read 12 when i hooked it up at the shop. would only increase to 15-20 when at 2500rpm+. no change whatsoever in higher rpm’s. changed pressure switch before getting a solid reading, no change. i did a flush and dropped the pan and found a mixture of sludge and metal shavings. i asked the mechanic and he said that it was probably some metal from the rebuild and what was leftover in oil galleys. the pickup tube was clogged. the mechanic had changed the oil pump but not the pickup tube. i decided to switch to a high volume oil pump and put a new pickup tube on when i replaced it myself. made sure the correct o ring was on and torqued everything to spec. i did a flush, and then changed it out with mobil 1 5w-30 full synthetic with an stp filter. at first crank it reads 50-60psi but once it’s warmed up i am still reading on the dash around 10-15 at idle but oil pressure increases with rpm this time. i’m at a loss.

Based on what you discovered after the mechanic “rebuilt” it, I’m suspicious there isn’t an internal issue, such as cam bearings, or something else.

 

[strutaeng]

Spun main bearing usually damages the block to where it's junk. At the minimum, the rebuild requires an align bore/hone of the crank housing bores.

Do you know what exactly the mechanic did on the rebuild job? Did he send it off to a machine shop?

You most likely will have to tear it down again or look for another engine.

 

[lilflip]

Spun main bearing usually damages the block to where it's junk. At the minimum, the rebuild requires an align bore/hone of the crank housing bores.

Do you know what exactly the mechanic did on the rebuild job? Did he send it off to a machine shop?

You most likely will have to tear it down again or look for another engine.

sorry for such the late reply. as far as i know it only went to the machine shop for a broke off bolt. after speaking with him, he said the only thing he didn’t replace is the cam bearings and said they looked fine. he also said he honed the cylinders. outside of that, i have no idea. i’ve found a good running engine that i’m going to swap out a few parts with and do the job myself. thank you for the information, once i get the other engine in i’ll do a full disassemble and see what went wrong.

 

[lilflip]

Based on what you discovered after the mechanic “rebuilt” it, I’m suspicious there isn’t an internal issue, such as cam bearings, or something else.

i’ve been betting on cam bearings since i found out he didn’t replace them. i found a running engine, i’ll be swapping some parts over, add a btr cam with new springs and such and hopefully have it back on the road soon.

 

[Matthew Jeschke]

Sorry but did I see that right???? Debris in gallies after rebuild. He didn't clean the block and it's passages????

After hearing that I'd not be able to take a mechanic seriously. Rebuilt engine should be clean enough to eat off of... Heck to set in an operating room, it should be SUPER clean.

And why tear down a block to leave old cam bearings. They are cheap. I'd replace them regardless... Best to do a. Full rebuild as it is out. Skipping parts like that doesn't really save much money or time.biggest investment is pulling the engine and machine shop.

Sorry to hear. Probably you have issue in oil passages. If you want run lots of detergent through crankcase. Likely cannot make it much worse as I suspect maybe a bad rebuild.

Another thought, is your pickup tube oring correctly seated?