Oil pressure gauge low at idle

GMCsierra06 · November 3, 2018

I’ve been recently experiencing low oil pressure at idle on my 2006 GMC Sierra 1500 5.3. It currently has just over 185,000 miles. I’ve been hearing a lifter/valve ticking that has gotten louder, especially when cold. In some cases the lifter noise is very loud, but only temporarily, then subsides. I’m not sure if they are related, just thought I’d mention it.
The oil pressure gauge reads around 30 psi when first starting and sometimes drops as low as 20psi. Until the engine get to operating temperature, it hovers around 30 at idle, but once up to temp. It will increase slowly according to RPMs. 1500-2000RPM increases pressure to 35-40. 2500-3000 increases oil pressure to 45-50. 3000-4000 increases it to close to 60psi. Any thoughts on this?

First pic is at idle, when fully up to operating temperature, second is at about 2000RPM

Doug_Scott · November 4, 2018

That's not low oil pressure. Cars with oil lights used to have oil pressure switches that would trigger the light at 7 to 10 psi. Used to be a good oil pressure on a race engine was typically 10 psi per 1,000 rpm.

GMCsierra06 · November 4, 2018

I agree it’s not dangerously low, but lower than normal. It usually stays at 40 psi all the the time and only increases maybe 5-10 psi at most. Also noticing a slight vibration coming from the engine. I feeling it in the accelerator pedal and floor when accelerating.

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Doug_Scott · November 4, 2018

Something I noticed over the past 40 to 45 years is that once you notice something that only happens occasionally under very specific conditions, it will start to happen more often until it happens all the time, but only when you are driving. Anyone else driving can not make it happen. For whatever reason, your driving habits will alter themselves so whatever noise, vibration, roughness in engine etc will happen all the time. The human brain can work against you sometimes.

Could that vibration you are feeling be something like a bad u-joint instead of a engine vibration?

GMCsierra06 · November 4, 2018

I don’t think it’s a U-joint, because it vibrates even in park when I rev the engine. It seems like there’s a loss of power as well. I’ve had the transmission replaced 15,000 miles ago with a Jasper transmission and I regret it. The things shifts hard and hesitated and is starting to slip.

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Doug_Scott · November 4, 2018

I know this will appear to be heading off topic, but I think it may be connected. When you say the transmission is starting to slip, what are you doing when it appears to be slipping. Does your truck have the 4L60E?

Are you seeing any random misfires codes set in the ECM?

GMCsierra06 · November 4, 2018

Yes, it’s a 4L60E.It shifts hard from 1-2, feels soft and sometimes slips from 2-3-4. No I haven’t had any misfire codes, but I did have a knock sensor code come up when I gave it full throttle to 5300RPM. I cleared it and it never came back. The transmission doesn’t seem to be able to handle full throttle attempts, so I don’t give it full throttle anymore.

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Doug_Scott · November 4, 2018

10 minutes ago, GMCsierra06 said:

Yes, it’s a 4L60E.It shifts hard from 1-2, feels soft and sometimes slips from 2-3-4. No I haven’t had any misfire codes, but I did have a knock sensor code come up when I gave it full throttle to 5300RPM. I cleared it and it never came back. The transmission doesn’t seem to be able to handle full throttle attempts, so I don’t give it full throttle anymore.

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Did they program your TCM or did you get a tune put on it? I have a Blackbear tune on mine, it was done at one of their in person appearances where Jason would get in the truck with you and do the TCM tune. It's been just over 8 years, and my 4.8 will get rubber on a WOT 1-2 up shift more times than not and Jason recommended not altering the line pressure as much for the 2-3 and. 3-4 upshift.

Are you getting a flare up berween gears? By that I mean does it feel like it hits neutral for a millisecond or two before it completes the shift? Is this situation more when cold, and a lot better when fully warmed up?

GMCsierra06 · November 4, 2018

No, my truck is completely stock apart from a leveling kit and larger 285/70R17 tires. The transmission is a stock remanufactured transmission and I believe it has a shift kit. 1-2 shifts do feel like there is a pause before the shift happens and it usually jerks into 2nd. When I first started driving it after the transmission was installed, 2-3 shift was clunky and made a grinding noise and now it’s just barely a shift at all, meaning it’s very light. Seems like the slipping happens when it hot outside. The colder weather seems to improve the shift quality.

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GMCsierra06 · November 13, 2018

Well I’m fairly certain I have an oil pump going bad and I believe the vibration could be coming from a damaged cam lobe/ lifter. I’ll be planning a to do a oil pump swap soon, but won’t be a small task, considering the front differential has to be removed to access the pan. Also have a bad steering idler arm and inner and outer tie rods will be changed as well.

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