Tahoe idle oil pressure

[JPVortex]

Hi so my 05 tahoe with the 5.3 seems to have lowish oil pressure while idling. At idle it has around 25-27psi of oil pressure, compared to a few months ago where it was a steady 35-40psi. Oil was low the other day and I topped it off, but the oil pressure stayed the same.

 

[CLSVT]

I'm curious to hear the comments you receive. On a related subject, I've never been very comfortable with the accuracy of these dashboard oil pressure gauges in our Chevys. If I'm going to diagnose an issue, I want to be sure my data is accurate. Has anyone verified the accuracy of these dashboard oil pressure gauges? What method did you use to verify? Sorry, I don't mean to hijack your question, just feel better knowing we are looking at real readings.

 

[OR VietVet]

Two things, quick PITA to change possible fix is the oil pressure sensor and use a Genuine GM replacement part when you do. If you do change it, attach an oil pressure gauge and check it. My 05 does idle at close to 40 PSI.

 

[Sam Harris]

What kind of oil filter do you use?

 

[JPVortex]

I'm curious to hear the comments you receive. On a related subject, I've never been very comfortable with the accuracy of these dashboard oil pressure gauges in our Chevys. If I'm going to diagnose an issue, I want to be sure my data is accurate. Has anyone verified the accuracy of these dashboard oil pressure gauges? What method did you use to verify? Sorry, I don't mean to hijack your question, just feel better knowing we are looking at real readings.

I haven't verified with hooking a gauge up yet, just going off of the one on the dash, and yeah I'm not sure I believe it either.

 

[JPVortex]

Two things, quick PITA to change possible fix is the oil pressure sensor and use a Genuine GM replacement part when you do. If you do change it, attach an oil pressure gauge and check it. My 05 does idle at close to 40 PSI.

Will def do this soon, thanks!

 

[JPVortex]

What kind of oil filter do you use?

I think it may have a Supertech right now, not sure why I cheaped out on it a few months ago. I plan on changing it soon, 3500 miles into a full synethetic change, but the oil looks pretty dark brown so I'll change sooner than later with probably a Mobil 1 or ACDelco filter.

 

[Fless]

If the tach gauge is correct the idle seems a bit low, FWIW. You might want to get a scanner on it to see what the desired (commanded) idle speed is and compare it to the actual per the scanner PID. Not sure if the gauge is off or not.

 

[iamdub]

Hi so my 05 tahoe with the 5.3 seems to have lowish oil pressure while idling. At idle it has around 25-27psi of oil pressure, compared to a few months ago where it was a steady 35-40psi. Oil was low the other day and I topped it off, but the oil pressure stayed the same.View attachment 389361

Don't take this lightly. Treat it as a serious matter, diagnose it THEN determine from that if it's not so serious.

First off- verify the condition. As the others mentioned, the gauges and sensor can be faulty. Use a mechanical gauge to verify the pressures. You can connect the gauge to the sensor port. If you do, you might as well have a new sensor on hand to replace it while you're at it.

If the pressure is indeed low, and it onset rather abruptly, dive in to the common cause(s). Low quality oil breaks down and has wilder viscosity swings and a low quality filter can cause a drop in pressure. Or, if the filter clogged up and you're now bypassing it. The Supertech should be okay since it's synthetic, but you still have to start with the easy stuff first. Change the oil and filter with good stuff and observe.

If no change, do the O-ring test. Add two extra quarts to the crankcase and drive somewhere, preferably close and not requiring high RPM, you can put the front into a nosedive, like a shallow ditch or back it up a hill. If the pressure suddenly jumps up to its previously normal range, then you've diagnosed a leaky O-ring. Drain the extra two quarts and plan your repair.

Another possibility with this generation is a cracked head allowing the coolant to mix with the oil in amounts so small that it goes undetected. It sludges up the inside of the engine. Eventually, the pickup screen gets choked off, reducing oil pressure. Do you have to add coolant ever so often, like once a month?

 

[JPVortex]

Don't take this lightly. Treat it as a serious matter, diagnose it THEN determine from that if it's not so serious.

First off- verify the condition. As the others mentioned, the gauges and sensor can be faulty. Use a mechanical gauge to verify the pressures. You can connect the gauge to the sensor port. If you do, you might as well have a new sensor on hand to replace it while you're at it.

If the pressure is indeed low, and it onset rather abruptly, dive in to the common cause(s). Low quality oil breaks down and has wilder viscosity swings and a low quality filter can cause a drop in pressure. Or, if the filter clogged up and you're now bypassing it. The Supertech should be okay since it's synthetic, but you still have to start with the easy stuff first. Change the oil and filter with good stuff and observe.

If no change, do the O-ring test. Add two extra quarts to the crankcase and drive somewhere, preferably close and not requiring high RPM, you can put the front into a nosedive, like a shallow ditch or back it up a hill. If the pressure suddenly jumps up to its previously normal range, then you've diagnosed a leaky O-ring. Drain the extra two quarts and plan your repair.

Another possibility with this generation is a cracked head allowing the coolant to mix with the oil in amounts so small that it goes undetected. It sludges up the inside of the engine. Eventually, the pickup screen gets choked off, reducing oil pressure. Do you have to add coolant ever so often, like once a month?

I'll check with a mechanical gauge ASAP. I will also change the oil and filter with high quality stuff if it actually has low oil pressure. From there I'll test the o ring if needed.

As for the cracked head theory this truck has never used any coolant whatsoever, I've never had to even top off the coolant at all. Only time I've lost a bit was when removing the lines at the throttle body lol.

One thing I'm worried about is oil consumption. My oil was very low the other day, and this truck has never consumed oil, I checked it about a month and a half ago and it was nearly full, yesterday I had to add a quart. Underneath is slightly wet around the pan, but no more than it was before. So I'm not sure if its burning it or what.