No oil pressure at start up, 2001 Tahoe

[clandr1]

Ok, so I can't get a GM puller, so the Chrysler one will have to do. Since I am removing the starter, thoughts on replacing it? It's the original, do these usually last forever and very reliable?

This is only a sample size of one so take it for what it's worth, but I've had my original starter since I bought my truck (2005) and I now have 175,000 miles on it without any issues.

 

[Searay45db]

And here are the pics from inside the engine...no idea if they are any good...

This is only a sample size of one so take it for what it's worth, but I've had my original starter since I bought my truck (2005) and I now have 175,000 miles on it without any issues.

yeah....I'm at 150 on my 2005...it's the age....I guesss

 

[JonnyTahoe]

This is only a sample size of one so take it for what it's worth, but I've had my original starter since I bought my truck (2005) and I now have 175,000 miles on it without any issues.

 

[JonnyTahoe]

For the past 45k miles my truck has had its oil pressure drop to zero, within 20-30 seconds after start up. It was not the result of a bad sensor as I tried replacing that first, besides, the loud ticking that would almost always follow was a pretty good sign of the problem. If I immediately took off driving, the pressure would stay up, but I had to keep the rpm's up. Once the vehicle warmed up everything functioned normally until the engine got cool again.

I bought an oil pump with the intention of changing it out but a friend told me to just change out the oil sump O-ring instead as usually that is the issue with no oil pressure in a 5.3.

On a 2x4 Tahoe it is very straight forward to drop the oil pan to access the sump and access the O ring. You have to remove the cross brace under the oil pan which is 4 bolts. You also need to remove the two oil pan/bell housing cover bolts (they hold a small plastic shield in place that keeps road grime out the bell housing. You also need to remove two bolts that hold the wiring harness in place. A simple electrical connector on the low oil sensor then you can drop the pan by removing all of the pan bolts.

Once the pan is down there are two nuts that hold the oil sump to the main bearing caps, as well as the small bolt that actually bolts the sump tube to the bottom of the oil pump. I removed the O ring and it was flattened out like a wedding ring, but not cracked or deteriorated. It was very loose when pulling out the tube as well. I put the new O ring on, which was $2 and shaped more like a fat doughnut. It was harder to press the oil sump tube back into place but it was fairly easy.

Scotch bright pad was used to clean the grime from the block where the oil pan gasket seats. I had a bad oil leak forever and the pan gasket was the culprit as it had long since flattened out as well. Once the oil pan was cleaned up and both surfaces cleaned for a new gasket I had the truck back together and running in less than 3 hours.

High oil pressure once again. With 526k miles this is the most extensive "tearing" into the drive train I have had to do, other than a 2-3 shift solenoid going back in the transmission a while back.

Hopefully this thread will help anyone with similar oil pressure issues who thinks they need a new engine, when in reality you can fix it for $60 in parts and an oil change.

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Your original O-ring still looked ok compared to the others on here.

 

[Yoslick]

Mine was literally cracked and very flat on the outside as well as the inside, someone asked if I went with a High Pressure pump, I did not, only Hi Volume. 60# is pretty sweet with an engine with 220k on it now !! The hard part was the Harmonic Balancer, luckily I found a Chryster 3 jaw and got it off, putting it back on was another matter, eventually welded a big socket on a air chisel and a few bumbs of the trigger she walked right on like it was greased! Whole job took me 9 hours, included a new Water Pump/Thermostat, Idlers, belts and 2 tensioners.

 

[JonnyTahoe]

Mine was literally cracked and very flat on the outside as well as the inside, someone asked if I went with a High Pressure pump, I did not, only Hi Volume. 60# is pretty sweet with an engine with 220k on it now !! The hard part was the Harmonic Balancer, luckily I found a Chryster 3 jaw and got it off, putting it back on was another matter, eventually welded a big socket on a air chisel and a few bumbs of the trigger she walked right on like it was greased! Whole job took me 9 hours, included a new Water Pump/Thermostat, Idlers, belts and 2 tensioners.

Good choice you need Volume with a high mileage engine.

 

[JonnyTahoe]

These projects seem to take on a life of their own. Starts with a simple O-ring and you end up replacing everything you had to remove to get to it. How did the Timing Chain look ?

 

[JonnyTahoe]

After reading your thread a few times over the last few months I decided to finally tear into my oil pump O-ring. My Tahoe is a 4X4 which has the front Differential directly underneath the oil pan and has to be dropped down to remove the pan. My O-ring was exactly like yours flat and green in color. I loosened the two nuts that hold the Oil Tube first then the pump bolt last and the whole tube fell out onto the garage floor it was that loose. I too have had a bad oil leak for awhile so I'm hoping the new pan gasket takes care of that. I wish I would of blasted the underneath of the pan better as the oil and grease make it a messy job which would of saved time because I have to clean it by hand now. This is the most work I have ever done to the truck which has 290k mi. working on your back doing this O-ring change is something I never would of even attempted had it not been for your thread. Much Thanks.

 

[SnowDrifter]

After reading your thread a few times over the last few months I decided to finally tear into my oil pump O-ring. My Tahoe is a 4X4 which has the front Differential directly underneath the oil pan and has to be dropped down to remove the pan. My O-ring was exactly like yours flat and green in color. I loosened the two nuts that hold the Oil Tube first then the pump bolt last and the whole tube fell out onto the garage floor it was that loose. I too have had a bad oil leak for awhile so I'm hoping the new pan gasket takes care of that. I wish I would of blasted the underneath of the pan better as the oil and grease make it a messy job which would of saved time because I have to clean it by hand now. This is the most work I have ever done to the truck which has 290k mi. working on your back doing this O-ring change is something I never would of even attempted had it not been for your thread explaining what your oil pressure was doing at start up and then how it would be ok when the engine warmed up which was exactly what mine was doing. I decided to do the project which for me has taken a few days and just getting it back together today.

Shit dude... If you're pushing 300k and the most you've had to do is drop the oil pan, you're in good shape!!!!

 

[clandr1]

Shit dude... If you're pushing 300k and the most you've had to do is drop the oil pan, you're in good shape!!!!

No kidding!