Low Oil Pressure at Idle

[Joseph Garcia]

20-25 at warm idle and 40+ at warm cruising speed would be considered normal working oil pressure parameters, IMO.

 

[Nicolai8775]

20-25 at warm idle and 40+ at warm cruising speed would be considered normal working oil pressure parameters, IMO.

Just so odd that my Tahoe, for the 5 years I had it, had steady 40psi at idle and 55-60 with throttle.

 

[OR VietVet]

Just so odd that my Tahoe, for the 5 years I had it, had steady 40psi at idle and 55-60 with throttle.

My current 05 does this. With 136k miles on it. Only oil pressure related work done is the sender and changed the oil pickup tube and o-ring.

 

[badtothe bone]

So when I bought this truck, a 2004 z71 Suburban, I noticed the pressure was just a little bit lower than the "normal" pressure than on my old Tahoe.

I changed the oil and filter with Royal Purp 5w-30 and a WIX. It raised the pressure back up to where it should be. 40 at idle and 45-50 when I press the throttle.

I've driven 3,000 miles already cause I road tripped to Idaho. I'm assuming the oil is less viscous now, but the oil life counter on the dash says it's at 50%. At idle I get 25psi, at throttle I get maybe 40psi. I had read somewhere that it should be 10psi per 1000 rpm. If this is true I'm still in the acceptable range. But I don't like it cause it's not normal.

2 questions. Is this the O-ring issue on the pickup tube? Or could it be the rear main seal, I have some seepage on the backside of the pan where it meets the trans and some drips on the driveway. Does the rear main seal being broke affect oil pressure to the degree that I'm seeing? Maybe I have both issues.

I don't hear knocks, on a cold start I sometimes hear what I'm guessing is a lifter tick. It goes away within minutes of startup. I hope it's not a bearing lol

The damn thing is 18 years old and wore out, either change the engine or rebuild it or just accept it the way it is!
Have you done a leak down test on each cylinder, how is the compression? How much oil does it consume?
If oil pressure bothers you, run 20W50 in it and change it often. I changed my oil in mine every 3k, and had no problems.
My question is - with a jalopy that old, how long do you think its going to last? Where I live, a 10 year old vehicle is OLD, and a 20 yr old vehicle is JUNK!

 

[Nicolai8775]

The damn thing is 18 years old and wore out, either change the engine or rebuild it or just accept it the way it is!
Have you done a leak down test on each cylinder, how is the compression? How much oil does it consume?
If oil pressure bothers you, run 20W50 in it and change it often. I changed my oil in mine every 3k, and had no problems.
My question is - with a jalopy that old, how long do you think its going to last? Where I live, a 10 year old vehicle is OLD, and a 20 yr old vehicle is JUNK!

Well, this is a tech forum, specifically in the 2000-2007 part of the forum. So why are you browsing it and commenting on people's posts if you don't like JUNK trucks. Must have woke up with sand in your *** this morning.

 

[Nicolai8775]

Well, this is a tech forum, specifically in the 2000-2007 part of the forum. So why are you browsing it and commenting on people's posts if you don't like JUNK trucks. Must have woke up with sand in your *** this morning.

With that said. I was considering running a bit thicker oil, but I just changed it after I replaced the oil sending unit with more 5w-30 royal purple. Tried some switches I found from the salvage yard. No change. But the fresh oil brought the pressure up a quite bit. Replacing the oil sender unit did not stop that leak. Haven't had a chance to rip off the intake and look at the valley cover gasket yet.

 

[Mudsport96]

Havent reread the whole thread, but check the side block off/oil cooler adapter for the leak. And after i fixed the oring on my 400k mile 5.3 she idles 20ish psi and highways around 40ish. If i foot it and wind it out to 5500 it will climb to 65-70 psi. Just do the oring, at this age, if it isn't the issue today...it will be in the near future.

 

[Walchit]

Good luck, I changed my o-ring and it only fixed it for about 30 seconds. Which may have just been the new oil or something I guess. Had 40psi when I started it.

 

[NardDog]

For internal oil pressures there are more than one component inside the engine that work together to give you the oil pressure, the o ring on the pick up tube is one, but you also the oil barbell, the cam retainer plate, and few other places. In my experience with the oil pressure units they work for a while and then crap out. The one i have on my 5.3 now works intermittently. As far as your ticking noice you should rule out a broken head bolt which is very common.

 

[GreenTahoe2004]

Minor note regarding the 2004 Tahoe/ Suburban 5.3 liter engine and oil.
At about 190,000 miles on my 2004 Tahoe (VIN engine code Z) I switched from the Mobil 1 M-107 filter to the larger M-206/ M-206A because I was sometimes tripping the bypass valve on the filter (I think) and spiking the oil pressure at about 3000-3500 miles. I've used the longer M-206 / M-206A filters for the past 265,000 miles without triggering that sort of pressure spike before changing the oil every 4,500-7,500 miles