when i bought my 2005 yukon the oil pressure gauge was pegged out at 80 after startup. no big deal i thought, replace the switch and itll work again. ive done this before. replaced the switch today, and its reading about 15/20 on the gauge and getting a low oil pressure warning light. although the truck has 213,000 miles it was serviced at proper intervals, i saw a carfax and po took to dealer for all work. truck is super clean, motor is whisper quiet when its running, no tapping at a cold start or anything. read that there could be a screen below the oil pressure sending unit gunked up, but doesnt appear to be one on my model. i havent tried to check oil pressure with a mechanical gauge as of yet. any thoughts? put old sending unit back in so i wouldnt have to look at low oil pressure warning till i get it fixed.
replaced oil pressure switch, now low oil pressure warning
- Thread starter johnm
- Start date
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Sasquatch
Full Access Member
I just had to change my sensor on friday, My gauge was pinned to 80 as well and now it works fine.
Do you know if your gauge cluster has ever been repaired or replaced? I ask because if you don`t know that the stepper motors in the cluster are known to fail and i`m wondering if you could have a bad stepper on top of the bad oil pressure sender.
When my oil pressure stepper went bad it would read all over the place, Sometimes high and sometimes low. I would try to check your oil pressure with an external gauge first to rule out the stepper and save your bearings by not driving with no oil pressure. If your pressure is good it`s probably the stepper.
Do you know if your gauge cluster has ever been repaired or replaced? I ask because if you don`t know that the stepper motors in the cluster are known to fail and i`m wondering if you could have a bad stepper on top of the bad oil pressure sender.
When my oil pressure stepper went bad it would read all over the place, Sometimes high and sometimes low. I would try to check your oil pressure with an external gauge first to rule out the stepper and save your bearings by not driving with no oil pressure. If your pressure is good it`s probably the stepper.
I had a similar problem with my 20005 Denali XL 6.0L. I changed the o-ring on the oil sump pickup tube, which fixed my oil pressure problems. Take a look at this link. Good luck
http://www.tahoeyukonforum.com/forum/showthread.php?t=67664
http://www.tahoeyukonforum.com/forum/showthread.php?t=67664
SLCHOE
ASE Master Certified + (L1)
Put a mechanical gauge on it to verify oil pressure first. Otherwise you are just taking stabs in the dark.
verified that i did indeed have a low oil pressure situation. have replaced the oil pump, although when i removed it, it appeared to be in good order. nice and tight, and the relief valve was functioning, also replaced the o-ring on pickup tube. ill finish tomorrow putting the crank pulley on and the water pump, then fill with fluids and fire it up and see what we get. hopefully this solves the problem. motor had developed what sounded like a lifter ticking, but maybe a little worse sounding. hopefully no damage was done. did look at camshaft through bottom of motor while pan was off and had some wear but nothing excessive looking, but havent measured anything. dont really want to do a cam job, but if that is what is needed that is what will be done! oil pan on 4x4 is a PITA! took at least an hour after i got all the bolts off of it to wiggle it out. didnt remove the front drive, just loosened it up and dropped it. pan slid back in in about 5 seconds, just knew i was gonna fight with it. anyone else pulling the pan has trouble with it, reach in and guide the pickup tube over the shield it sits down into, thats how i finally got it to come out.
SLCHOE
ASE Master Certified + (L1)
Well it's good that you verified the low oil pressure condition. Hopefully what you have done will fix it but excessive crank bearing clearances are usually what cause low oil pressure. I hope it's not that.
pretty sure the noise is a rod knocking. after replacing oil pump and o-ring on pick up tube, oil pressure is still really low. looking to find a crate motor to do a swap with. may try throwing some bearings in the bottom end, but not hopeful about the outcome. itll be a few paychecks to save up for a crate motor, and i will be doing the swap myself. in the meantime ill just ride the motorcycle back and forth to work. looks like the bearing swap would run about 150 or so in parts so havent decided if ill throw that money away yet or not. may just pull the pan and remove the bearings for visual inspection, dont have a micrometer but i could see scoring and such. i have replaced bearing on bottom end with some success in the past, some not successful. tried pulling plug on each cylinder while running and listened for a change in the knock, but the sound never changes, so it could be cam bearings, or a list of other things. id scrap it if i hadnt just bought it, and it is in awesome shape.
afpj
Full Access Member
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I'm trying to follow but I missed something. When you got the car, no knocking but oil pressure gauge pegged. After changing oil sending unit started knocking and confirmed low pressure with a separate guage? Compression cylinder check? Coolant in oil or visa versa?
no coolant in oil, compression good all the way around. and yes. ran good. nice and quiet motor. confirmed low pressure with seperate gauge. was pulling a trailer, cruise on, hard downshift, revs up to about 5 g knocked cruise off pretty quickly after it revved up that high, sounded more like a tick at first progressed into a knock sound fairly quickly. was out of town and had no choice but to drive back home.
