Intermittent Low Oil Pressure when Warm

[StuckinMN]

2008 Suburban 5.3 with 225K.

Recently several issues started all at once.

1. Oil pressure would drop when driving. It would go all over the place. Sometimes would stay low and engine light come on. If I stopped for a bit, it goes away.

2. Gas smell. Couldn't see any leaks. Seems to have gone away after changing Oil Sender (or gas tank is not full). We will see when I get more gas.

3. Traction control not working message on occasion - goes away quickly though. These seems to come on it my kids fart too loud, so who knows.

4. Have a slow oil leak. Probably pan, not sure.

The battery was old and iffy so I changed it out. I don't think it was putting out the correct voltage. I was hoping this was the issue - emphasis on hope.

Yesterday drove 20 miles and at 19 miles it started acting up. Arrived at destination and had meeting for 10 minutes. On trip home took hiway instead - no issues.

Bought oil sender. Had neighbor mechanic put it in. He is amazing as he climbed on the engine and changed it is 3 minutes tops - and he normally works on European cars (he is from Europe). It took him 10 minutes to remember IF he had such a socket and where it was - but 3 to change : )

I had a few 10 mile trips and all seemed fine. Today took a 20 mile or so trip and it oil pressure dropped again so stopped to check oil. All good. Started it back up and oil pressure fine.

So I am guessing something is blocking the oil. Probably in the pan or maybe the filter. Any ideas?

I bought this truck in Nov 2019 as a winter beater when I returned from overseas. The Covid came so didn't bother getting anything newer. Other than rust, it was a well maintained vehicle and I put 30K on it without issue. The engine is quiet and rides very smoothly - so hate to get something else. But wife drives it in winter and the car can be on fire and she will keep driving.

 

[StuckinMN]

2008 Suburban 5.3 with 225K.

BYW - this engine has always had solid oil pressure - gauge always right of 40 psi. Even now, if it is running normally it is at 50+ PSI.

 

[Geotrash]

2008 Suburban 5.3 with 225K.

Recently several issues started all at once.

1. Oil pressure would drop when driving. It would go all over the place. Sometimes would stay low and engine light come on. If I stopped for a bit, it goes away.

2. Gas smell. Couldn't see any leaks. Seems to have gone away after changing Oil Sender (or gas tank is not full). We will see when I get more gas.

3. Traction control not working message on occasion - goes away quickly though. These seems to come on it my kids fart too loud, so who knows.

4. Have a slow oil leak. Probably pan, not sure.

The battery was old and iffy so I changed it out. I don't think it was putting out the correct voltage. I was hoping this was the issue - emphasis on hope.

Yesterday drove 20 miles and at 19 miles it started acting up. Arrived at destination and had meeting for 10 minutes. On trip home took hiway instead - no issues.

Bought oil sender. Had neighbor mechanic put it in. He is amazing as he climbed on the engine and changed it is 3 minutes tops - and he normally works on European cars (he is from Europe). It took him 10 minutes to remember IF he had such a socket and where it was - but 3 to change : )

I had a few 10 mile trips and all seemed fine. Today took a 20 mile or so trip and it oil pressure dropped again so stopped to check oil. All good. Started it back up and oil pressure fine.

So I am guessing something is blocking the oil. Probably in the pan or maybe the filter. Any ideas?

I bought this truck in Nov 2019 as a winter beater when I returned from overseas. The Covid came so didn't bother getting anything newer. Other than rust, it was a well maintained vehicle and I put 30K on it without issue. The engine is quiet and rides very smoothly - so hate to get something else. But wife drives it in winter and the car can be on fire and she will keep driving.

Welcome to TYF! Did your mechanic friend change out the screen that's under the oil sender? Gotta pull it out with a pick and replace with the sender and lots of folks miss it if they're not familiar with the GMT900 series trucks.

TC not working messages can have a few causes. Only way to know for sure is to put a good scanner on it that can read all modules (a Tech2 is best) and see what codes are getting stored when it happens. Most common causes are either a failing fuel pump (an engine not running 100% right will trigger the TC system to shut off), or the steering position sensor on the steering shaft. On my 2007 it was the fuel pump and I knew this because I was getting a high fuel pressure error that would trigger the check engine light at the same time.

Oil leak is probably the oil cooler block off plate above the oil filter. Easy repair.

Gas smell could be the fuel tank vent valve on the fuel rail, but again a Tech2 would reveal any stored codes that would give you clues.

 

[StuckinMN]

Well, it seemed to me that there was a clog of some type preventing the oil from circulating - hence low pressure starting after the vehicle ran for 20 minutes or so. I thought it could be the oil filter or the screen in the oil pan. If I stopped the engine for a few minutes it was fine - probably giving time for the sludge to back up. Who knows : )

So I had the oil changed at a fancy shop. And the oil pressure is now back to normal - above 50. I only drove it home from the shop so only time will tell if it holds.

The shop wanted $89 to clean the oil off to see where the leak is coming from. I will put some dye in it and see if I can see anything.

Geotrach - "Oil leak is probably the oil cooler block off plate above the oil filter. Easy repair." --> Thanks, I will take a look with the dye.

Other oil leaks seem hard to repair. Oil pan is a b*&^h.

Gas smell is gone but I am less than half a tank now. I will deal with the oil leak first and then fill it up and see what happens.

 

[StuckinMN]

So after 3 weeks oil pressure is still great. So just an oil changed fixed it. I took a 2 hour road trip during the blizzard and all was fine.

In fact, this vehicle's oil has been 50+ PSI when driving (40 at idle). I wonder if the previous owner put in a higher performance oil pump.

It was too cold to deal with the oil leak. I will once it warms up.

 

[Dustin Jackson]

@StuckinMN How many miles do you typically drive between oil changes?

 

[Fubar0715]

FWIW, I had some issues with low oil pressure which helped with an oil change and sensor/screen change. However, was never really comfortable with cruising pressure after warm-up that hovered around 20-22lbs...Knowing I had an leak underneath, decided to bite the bullet and put in the work. I pulled the oil pan, replaced the pickup tube O-ring, new pan gasket, and new oil cooler gasket. Pressure now sits solidly nearly 28lbs at idle, about 40lbs cruising, and gets above 55lb if I mash the loud pedal.

 

[StuckinMN]

@StuckinMN How many miles do you typically drive between oil changes?

I change oil whenever the dash tells me. We mostly drive short local trips so changes are more less than 5K.

But I had just had the oil changed when I had a new lifter put in - so less than 1K. But that guy used a different oil filter - and who know what other changes there were.