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 If you drive a Chevy/GM w/the 5.3 V-8, watch out for 0 oil pressure... ETA: Tentatively fixed...
Adventurer96  [Team Member]
4/21/2009 3:02:20 PM
The wife just lost oil pressure in our 2001 Yukon out of nowhere - from healty to zero PSI - last week. She saw the gauge, then the light, and parked immediately. Good job wife, says I.

Since then, my buddy and I have tested the pressure w/a gauge to make sure it's not a faulty sensor, and there is no pressure. After a bunch of research on the interweb and some phone calls to savvy GM mechanics, the smart money is on the oil pressure relief valve being broken, or else the oil pickup fell off into the oil pan. Either of these options would make sense because a bad bearing or similar would have had a gradual decrease in oil pressure, and oil levels were still good with no leaks anywhere.

We're going to check out both over the next couple of days, and I'll post back here in case anyone else on arfcom runs into this. Let's hope it's the right answer, because the guys that towed it wanted to immediately put in a new engine without telling me what's wrong with this one for $4400.

More to follow...
k12lts  [Team Member]
4/21/2009 7:11:30 PM
Something that sudden has to be a mechanical failure like a broken oil pump drive shaft or pump, drop the oil pan and take a look. How many miles on the engine? If it's an otherwise good engine it should be an easy fix.

Good on her for knowing to stop right away.

Let us know what you find.
bill3508  [Team Member]
4/21/2009 10:11:34 PM
The oil pressure relief value getting stuck open has happened to many of the LS2 guys. First one I've heard of on the 5.3 though.
Adventurer96  [Team Member]
4/21/2009 11:15:22 PM
Just turned 100k about two months ago. I've used Mobil 1 synthetic in it since I got the truck, around 35k miles. This last oil change I used Pennzoil Platinum. Never again, by the way - the valve is unrelated but to me it's always going to be associated w/Pennzoil.

I will keep you guys posted, and yes - she's the most car-savvy woman I've ever met. Hmm, coincidence she's my wife? Maybe...

Thanks...
bill3508  [Team Member]
4/21/2009 11:41:37 PM
Originally Posted By Adventurer96:
Just turned 100k about two months ago. I've used Mobil 1 synthetic in it since I got the truck, around 35k miles. This last oil change I used Pennzoil Platinum. Never again, by the way - the valve is unrelated but to me it's always going to be associated w/Pennzoil.

I will keep you guys posted, and yes - she's the most car-savvy woman I've ever met. Hmm, coincidence she's my wife? Maybe...

Thanks...


Pennzoil Platinum is some of the best oil you can buy, well tested. Shit happens sometimes.
Adventurer96  [Team Member]
4/21/2009 11:53:57 PM
Originally Posted By bill3508:
Originally Posted By Adventurer96:
Just turned 100k about two months ago. I've used Mobil 1 synthetic in it since I got the truck, around 35k miles. This last oil change I used Pennzoil Platinum. Never again, by the way - the valve is unrelated but to me it's always going to be associated w/Pennzoil.

I will keep you guys posted, and yes - she's the most car-savvy woman I've ever met. Hmm, coincidence she's my wife? Maybe...

Thanks...


Pennzoil Platinum is some of the best oil you can buy, well tested. Shit happens sometimes.


Yeah, I know, but unfortunately since I had an oil system problem the one time I try a new oil I'll always associate it w/PP. I think you're right, shit just happens sometimes and this is an unusual one but all signs point towards those two problems.

I'll post more as it comes along.
flynhiraptor  [Member]
4/21/2009 11:59:48 PM
Drop the pan, remove the water pump and front cover. remove pickup tube and oil pump. Look for any broken gears in the Geroter? oil pump.
Remove the pressure relief valve from the front, you should find galling on the relief valve and relief valve passage, or broken spring. Fairly common on the early 4.8/5.3 . Even seen a few on the '08's.
Adventurer96  [Team Member]
4/22/2009 12:09:24 AM
Originally Posted By flynhiraptor:
Drop the pan, remove the water pump and front cover. remove pickup tube and oil pump. Look for any broken gears in the Geroter? oil pump.
Remove the pressure relief valve from the front, you should find galling on the relief valve and relief valve passage, or broken spring. Fairly common on the early 4.8/5.3 . Even seen a few on the '08's.


Tremendous, thanks. Sounds like a few hours and more than a few beers at my buddy's shop.
flynhiraptor  [Member]
4/22/2009 10:55:42 AM
I forgot, you will need water pump gaskets, Dexcool(special tool to remove/hold water pump pulley to remove fan clutch), Front cover gasket and new seal(there is a special tool if I remember for installing the front seal), (special tool to remove crank pulley it is not keyed and use old crank pulley bolt to install) new crank pulley bolt, oil pump pickup tube o ring, oil pan gasket(drill out rivets on old gasket) a bit of sealant on oil pan gasket where front/rear covers meet and oil and oil filter and misc cleaners(brakekleen)
MillerSHO  [Member]
4/22/2009 12:51:17 PM
Originally Posted By flynhiraptor:
I forgot, you will need water pump gaskets, Dexcool(special tool to remove/hold water pump pulley to remove fan clutch), Front cover gasket and new seal(there is a special tool if I remember for installing the front seal), (special tool to remove crank pulley it is not keyed and use old crank pulley bolt to install) new crank pulley bolt, oil pump pickup tube o ring, oil pan gasket(drill out rivets on old gasket) a bit of sealant on oil pan gasket where front/rear covers meet and oil and oil filter and misc cleaners(brakekleen)


What's the deal with that tool to install the front main seal?

Is it truly needed?

I've heard some people getting away without it and I've heard others horrors stories for not using it.
Adventurer96  [Team Member]
4/22/2009 6:15:22 PM
Here's an update - the bolt that retains the oil pickup line on the oil pump had backed out. So, the pickup was loose and wasn't doing its job. However, the guy working on it said that he couldn't get the oil pickup to line up with that bolt hole. We'll take a closer look today, but that might be the culprit.

We're debating just re-installing the pickup with a new o-ring, or replacing the o-ring and pickup, or replacing pickup, o-ring and oil pump.
jeep450  [Team Member]
4/22/2009 7:36:24 PM
If you replace the oil pump the front cover will have to come off as it is driven off the front of the crankshaft. It is not driven by a drive shaft. I would just replace the oil pump pick up tube seal and put a little blue locktite on the bolt.
Adventurer96  [Team Member]
4/22/2009 11:11:56 PM
Originally Posted By jeep450:
If you replace the oil pump the front cover will have to come off as it is driven off the front of the crankshaft. It is not driven by a drive shaft. I would just replace the oil pump pick up tube seal and put a little blue locktite on the bolt.


I hope that's the case, as long as the tube isn't bent in any way.
Adventurer96  [Team Member]
5/3/2009 2:49:14 AM
OK, it turns out the pickup was fine, but we replaced the O-ring and the oil pump. My buddy started the truck and it runs well, no leaks and good oil pressure. We replaced the belts as well.

Unfortunately, I'm away for another week and a half or I'd be home driving it myself, watching it like a hawk. I think the fact my wife noticed it in the first place means she's more than capable of keeping an eye on it.

We replaced the transmission fluid as well, last replaced about 30k miles ago, thereabouts, and I used Mobil 1 synthetic. I mainly did this because the truck pulled a small trailer last summer and this was its first winter in Duluth. I figured it wouldn't hurt. My wife said there was a little slipping in the transmission tonight from 1st to 2nd gear when she drove it to the grocery store, but it got better on the way home.

I hope this is it, but man I love these vehicles. I hope I can keep it another 100k miles.
Adventurer96  [Team Member]
5/23/2009 12:23:31 AM
Almost a month and this seems to have fixed it.

No more Pennzoil for me - period.