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Oil Pressure

FleshEater

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2010 Chevy Tahoe, 131,000 miles, 5.3l, bone stock...

Oil pressure at idle is 20 psi when up to running temp. This weekend while towing in the mountains it dropped to about 18 psi momentarily.

Is this normal pressure for a 5.3l? My Silverado idles around 35 psi.

Wife wants to tow out to Utah next year for vacation. Tahoe will be the vehicle we use. If I need to start tearing into this now would be better than later. However, it has ran at 20 psi at idle since we bought it...only things I can think to check is the screen on the oil pressure sensor, oil pump and pick up tube, or the valve body gasket in the DOD system.
 

Rttoys

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Any tapping noises?

You can put a sending unit and screen in for shits and giggles, but I have had more problems with oil pump pickup tube o rings. If it’s not one of those, you’ll have to go deeper and hope it’s not something worse. Dod engines have a knack for chewing cams and such.
 

FleshEater

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Any tapping noises?

You can put a sending unit and screen in for shits and giggles, but I have had more problems with oil pump pickup tube o rings. If it’s not one of those, you’ll have to go deeper and hope it’s not something worse. Dod engines have a knack for chewing cams and such.

Motor sounds good.

I forgot about that o-ring...that's what I read most people replace for better pressure.

This is going to suck dropping the oil pan on a 4WD.
 

Elwenil

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Bad sensor? Random pressure fluctuations are usually a bad sensor, low oil or a blockage, like a spun bearing.
 

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I have an 07 Chevy Silverado K3500 4wd with 242K a 6.0L that also has a oil pressure gauge that bounces around.

No codes for that from what ive read.

If it goes beyond just a sensor thats it for this motor, I'm not dropping the pan just to realize my other issue with its PO300 code is a flat cam on one or more lobes.

Non °DOD engine that I know of (but then I wouldn't know how to tell)
 
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Rttoys

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I have an 07 Chevy Silverado K3500 4wd with a 6.0L that also has a oil pressure gauge that bounces around.

No codes for that from what ive read.

If it goes beyond just a sensor thats it for this motor, I'm not dropping the pan just to realize my other issue with its PO300 code is a flat cam on one or more lobes.

If it’s bouncing around, I’d toss a oil pressure sensor in.

The P0300 could easily be intake gaskets, which is fairly common. Cam lobe problems are not common on 6.0. That’s more of a DOD thing.
 

Rttoys

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Motor sounds good.

I forgot about that o-ring...that's what I read most people replace for better pressure.

This is going to suck dropping the oil pan on a 4WD.

Everyone overlooks that oring. If it dry rots and flattens, it’ll suck air instead of oil.

There are “tricks” to get that oring out without pulling the whole pan. I have seen YouTube videos on it, but have never tried it. I feel there’s a secondary failure with the oil pan gasket, that everyone overlooks. It’s overlooked because it’s replaced when doing the oring, so you are inadvertently fixing 2 problem areas.
 

FleshEater

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Guess I should clarify my oil pressure doesn't usually fluctuate at idle at all. It's basically right at 20 psi at idle constantly. When it dropped to 18 momentarily that was after 7 hours towing, 85 degrees, and going slow in the mountains.

What I was curious was if this is an okay oil pressure for the 5.3l. I just find it odd that my truck idles around 30-35 psi. Same motor, but 30,000 less miles.
 

Rttoys

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Guess I should clarify my oil pressure doesn't usually fluctuate at idle at all. It's basically right at 20 psi at idle constantly. When it dropped to 18 momentarily that was after 7 hours towing, 85 degrees, and going slow in the mountains.

What I was curious was if this is an okay oil pressure for the 5.3l. I just find it odd that my truck idles around 30-35 psi. Same motor, but 30,000 less miles.

“Ok” yes (according to GM). Acceptable, no. Normal, no.

all of these truck ls engines should be just a tick under the 40 mark at idle, and over the 40 mark off idle.

I have 30 ls based trucks and vans at work (I’m a fleet mechanic) and have had 20-30 more since they have been out. All of them have oil pressure like I just stated (except some of these new ones with dual stage oil pumps 🤨) . Anytime one of mine would be at the 30 mark or under at idle, I pull the pan and do the o ring. It instantly bring the pressure back up to 40. We get 300k miles of hard use on our vehicles before we sell them.

Losing oil pressure in DOD engines are a little different than our non-DOD 6.0L, because of them chewing up camshafts. All else is the same.
 

FleshEater

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“Ok” yes (according to GM). Acceptable, no. Normal, no.

all of these truck ls engines should be just a tick under the 40 mark at idle, and over the 40 mark off idle.

I have 30 ls based trucks and vans at work (I’m a fleet mechanic) and have had 20-30 more since they have been out. All of them have oil pressure like I just stated (except some of these new ones with dual stage oil pumps 🤨) . Anytime one of mine would be at the 30 mark or under at idle, I pull the pan and do the o ring. It instantly bring the pressure back up to 40. We get 300k miles of hard use on our vehicles before we sell them.

Losing oil pressure in DOD engines are a little different than our non-DOD 6.0L, because of them chewing up camshafts. All else is the same.

Thank you! That's what I wanted to know.

I'll drop the pan.
 

Rockbuggy84

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I recently went through this on a 2005 5.3 with 200,000 miles on it. Started dropping enough that it began to tick at idle after towing or going through the hills.

I wasn’t sure if it was a pickup issue such as an o ring, or simply a plugged screen from sludge and abuse.

Delo seems to have enough detergent in it to keep all my Cummins engines clean for hundreds of thousands of miles, so that’s where I came up with my plan.

Drained the oil and pulled the filter. New wix filter and delo was added. Ran it for a couple days with weight behind it and noticed the pressure wouldn’t drop as low and no tick.

So I went and drained the oil and pulled the filter again. Oil was significantly dirty for being in there for a couple of days, so obviously it picked up and is grabbing a bunch of shit out of the engine.

I did this 3 times total in apx a week and a half and the oil pressure has come up close to 10 psi at idle and no more ticking. I’m guessing that the screen and engine is loaded with sludge and I’ve gotten enough off the pickup screen to lube the engine better.
 

FleshEater

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I recently went through this on a 2005 5.3 with 200,000 miles on it. Started dropping enough that it began to tick at idle after towing or going through the hills.

I wasn’t sure if it was a pickup issue such as an o ring, or simply a plugged screen from sludge and abuse.

Delo seems to have enough detergent in it to keep all my Cummins engines clean for hundreds of thousands of miles, so that’s where I came up with my plan.

Drained the oil and pulled the filter. New wix filter and delo was added. Ran it for a couple days with weight behind it and noticed the pressure wouldn’t drop as low and no tick.

So I went and drained the oil and pulled the filter again. Oil was significantly dirty for being in there for a couple of days, so obviously it picked up and is grabbing a bunch of shit out of the engine.

I did this 3 times total in apx a week and a half and the oil pressure has come up close to 10 psi at idle and no more ticking. I’m guessing that the screen and engine is loaded with sludge and I’ve gotten enough off the pickup screen to lube the engine better.

I bought this with 107,000 miles on it, so I'm kind of interested in seeing how much sludge is in the pan.

Damn Haynes manual says a shitload of unnecessary stuff needs to come off. Watched some YouTube videos and it doesn't seem too bad. If it isn't too bad dropping the front diff I might re-gear it, too.
 

Rockbuggy84

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I bought this with 107,000 miles on it, so I'm kind of interested in seeing how much sludge is in the pan.

Damn Haynes manual says a shitload of unnecessary stuff needs to come off. Watched some YouTube videos and it doesn't seem too bad. If it isn't too bad dropping the front diff I might re-gear it, too.

If you have a car lift, or access to one, it’s quick and easy.
I just swapped an engine in a 2011 4wd pickup with a 5.3. I was worried about clearance at the oil pan to front diff for removal, so I yanked the front diff.

Took about 30 minutes to drop the entire front diff and skid plate assembly on my lift. tons of access to the oil pan after that.
 

FleshEater

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If you have a car lift, or access to one, it’s quick and easy.
I just swapped an engine in a 2011 4wd pickup with a 5.3. I was worried about clearance at the oil pan to front diff for removal, so I yanked the front diff.

Took about 30 minutes to drop the entire front diff and skid plate assembly on my lift. tons of access to the oil pan after that.

This will all be while laying on the floor...no lift.

I don't need it up and running immediately so I can take my time.
 

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Dropping the ft diff is the best plan of attack.

Get the correct o ring too. Don’t try to match it up from a universal o ring kit. Felpro makes good ones, and believe it or not, getting one from the dealer is not that expensive and probably your best bet. It will be the exact one you need.

the oil pan gasket is riveted on. No biggie, just drill out the heads of the rivets and clean everything like normal.

Now the important part, the pan is part of the engine structure or backbone and must be aligned properly. Not a big deal. Put all your bolts in loosely. Snug 2 up front (balancer side) where the pan just starts to make contact with the engine. Now on the rear (transmission side), tighten the back 2 bolts going up to the engine. Then tighten the bolts going sideways from the trans to the pan. Now, loosen the 2 bolts to the engine. Tighten the 2 trans bolts more. Back to tighten the 2 engine bolts again then loosen the trans bolts. and repeat.

do this until the pan has worked it’s way up and back flush with the engine and trans, then tighten all the pan bolts.
 

FleshEater

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Dropping the ft diff is the best plan of attack.

Get the correct o ring too. Don’t try to match it up from a universal o ring kit. Felpro makes good ones, and believe it or not, getting one from the dealer is not that expensive and probably your best bet. It will be the exact one you need.

the oil pan gasket is riveted on. No biggie, just drill out the heads of the rivets and clean everything like normal.

Now the important part, the pan is part of the engine structure or backbone and must be aligned properly. Not a big deal. Put all your bolts in loosely. Snug 2 up front (balancer side) where the pan just starts to make contact with the engine. Now on the rear (transmission side), tighten the back 2 bolts going up to the engine. Then tighten the bolts going sideways from the trans to the pan. Now, loosen the 2 bolts to the engine. Tighten the 2 trans bolts more. Back to tighten the 2 engine bolts again then loosen the trans bolts. and repeat.

do this until the pan has worked it’s way up and back flush with the engine and trans, then tighten all the pan bolts.

I just ordered an o ring from Summit Racing. It was a red Felpro, but I like the idea of going to the dealer. I’ll call and make sure they got it.

Yeah, I read a YouTube comment about reinstalling the pan and making sure it’s close to the trans. Guy quoted like .010 gap between the two.
 

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I just ordered an o ring from Summit Racing. It was a red Felpro, but I like the idea of going to the dealer. I’ll call and make sure they got it.

Yeah, I read a YouTube comment about reinstalling the pan and making sure it’s close to the trans. Guy quoted like .010 gap between the two.

You need to match the o-ring to the pickup tube style your engine has. If you are replacing the oil pump at the same time it will come with multiple o-rings
 
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06 6.0 260k, oil pressure was running high when warm 60+. then on 2 occasions dropped to zero, ding ding ding then returned to normal. Replaced sensor and screen, works like it should.
Buy the sensor socket.
 

Rennat_2006

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On the 06 and older engines you can replace the oil pickup tube oring without dropping the pan, not the case in the 07 and newer. I cant remember what exactly was different but with the pump and oil pickup tube but I tried it on my wife's 08 Burban after doing it that way to multiple older ls engines and it's a no go on these. Like mentioned above about a half hr or so job to drop the front diff out on these trucks even working on the ground.

I would recommend starting with replacing the oil pressure sensor. GM part only and cleaning out or even replacing the sensor underneath of it. Have the engine tuned to turn the afm/DOD off also now before it starts to show issues.
 

FleshEater

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On the 06 and older engines you can replace the oil pickup tube oring without dropping the pan, not the case in the 07 and newer. I cant remember what exactly was different but with the pump and oil pickup tube but I tried it on my wife's 08 Burban after doing it that way to multiple older ls engines and it's a no go on these. Like mentioned above about a half hr or so job to drop the front diff out on these trucks even working on the ground.

I would recommend starting with replacing the oil pressure sensor. GM part only and cleaning out or even replacing the sensor underneath of it. Have the engine tuned to turn the afm/DOD off also now before it starts to show issues.

Because I’m not having a dip in pressure and just overall lower than normal pressure I think it’s the o ring. This has never dropped to zero.

DOD has been shut off for two or more years.
 

FleshEater

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Dropping the ft diff is the best plan of attack.

Get the correct o ring too. Don’t try to match it up from a universal o ring kit. Felpro makes good ones, and believe it or not, getting one from the dealer is not that expensive and probably your best bet. It will be the exact one you need.

the oil pan gasket is riveted on. No biggie, just drill out the heads of the rivets and clean everything like normal.

Now the important part, the pan is part of the engine structure or backbone and must be aligned properly. Not a big deal. Put all your bolts in loosely. Snug 2 up front (balancer side) where the pan just starts to make contact with the engine. Now on the rear (transmission side), tighten the back 2 bolts going up to the engine. Then tighten the bolts going sideways from the trans to the pan. Now, loosen the 2 bolts to the engine. Tighten the 2 trans bolts more. Back to tighten the 2 engine bolts again then loosen the trans bolts. and repeat.

do this until the pan has worked it’s way up and back flush with the engine and trans, then tighten all the pan bolts.

Thanks for all the information, man. Seriously appreciate it.

I did the job today. 15 year plan on this land is a big shop with a damn lift.

When I pulled the o-ring, it was torn and flat. I think oil pressure is back up now, but won't know until I drive it. I tried three times to get the front diff back in by myself, No dice. Definitely need a hand. I let the truck warm up to 210 and it stayed right around 38 psi. I also slowly revved it up, and the pressure actually went over 60! It would rarely do that before.

My truck has a lifter tick at start up after sitting for two days or so. That will be the next project.
 

Rennat_2006

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I would highly recommend living with the lifter tick if it is only at startup and goes away. Lifters seem to be super hit or miss for these damn things, factory ls7 which everyone recommends have been hard to get ahold of lately, even at that there is plenty of shit garbage ones out there. I bought a set from the local dealership that I have an account with when i did the wife's burban engine and I've got at least 1 bad one on cylinder 5 from the set I bought. It knocks until the engine gets up to running temperature, pisses me off but not bad enough to RIP the heads back off of it with no guarantee of not having the same issue.
 

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Thanks for all the information, man. Seriously appreciate it.

I did the job today. 15 year plan on this land is a big shop with a damn lift.

When I pulled the o-ring, it was torn and flat. I think oil pressure is back up now, but won't know until I drive it. I tried three times to get the front diff back in by myself, No dice. Definitely need a hand. I let the truck warm up to 210 and it stayed right around 38 psi. I also slowly revved it up, and the pressure actually went over 60! It would rarely do that before.

My truck has a lifter tick at start up after sitting for two days or so. That will be the next project.

Good deal. The pressure sounds like it should be now. I’m glad I could help. If it’s not the end all fix, you know it was damn sure a problem. It’s amazing how a $5 o ring can destroy an engine.

I only really hear lifter tic for about 1 second after startup and that’s about it. Using an AC Delco filter helps with all that too. Don’t forget on first startup after the repair, everything is dry, so noises for a second or so would be normal.
 

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Good deal. The pressure sounds like it should be now. I’m glad I could help. If it’s not the end all fix, you know it was damn sure a problem. It’s amazing how a $5 o ring can destroy an engine.

I only really hear lifter tic for about 1 second after startup and that’s about it. Using an AC Delco filter helps with all that too. Don’t forget on first startup after the repair, everything is dry, so noises for a second or so would be normal.

Actually the Tahoe purrs like a kitten. My Silverado tapa for a minute before it stops. I’ve owned it since it had 40,000 miles on it. Bought it six years ago and change oil religiously.
 

FleshEater

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Good deal. The pressure sounds like it should be now. I’m glad I could help. If it’s not the end all fix, you know it was damn sure a problem. It’s amazing how a $5 o ring can destroy an engine.

I only really hear lifter tic for about 1 second after startup and that’s about it. Using an AC Delco filter helps with all that too. Don’t forget on first startup after the repair, everything is dry, so noises for a second or so would be normal.

OH, I do have one more question. Those back two motor bolts, the long ones at the rear, they're 10.9's and torque specs are 18 ft. lbs. Man, I was wrenching on them, and I was worried about breaking them. I started them by hand, everything feels fine, but should I back them out and re-torque them? I am so nervous to snap those long bastards off in the block. They're not going anywhere, and are probably close to 18 ft. lbs. Is this normal for those two odd bolts?
 

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Yeah I've snapped one of those before, if I remember right they are a different torque than the rest and I learned that the hard way.

If their snug leave it be.
 

FleshEater

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Well, fuckall...that only increased my idle pressure by 1 psi. Now hot idle is at 21.

Going to pull the sending unit and check the screen. If all is good there, it has to be the gasket in the valve body. Fuck these DOD engines.

This motor sounds excellent. I took a video but can’t upload it. It’s paid for so might as well keep tearing into things. Haha!
 

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OH, I do have one more question. Those back two motor bolts, the long ones at the rear, they're 10.9's and torque specs are 18 ft. lbs. Man, I was wrenching on them, and I was worried about breaking them. I started them by hand, everything feels fine, but should I back them out and re-torque them? I am so nervous to snap those long bastards off in the block. They're not going anywhere, and are probably close to 18 ft. lbs. Is this normal for those two odd bolts?

Ya, I do all those by “feel”. I use a 1/4” drive ratchet and palm it at the base, so I can’t over torque any of those bolts.
 

Rttoys

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Well, fuckall...that only increased my idle pressure by 1 psi. Now hot idle is at 21.

Going to pull the sending unit and check the screen. If all is good there, it has to be the gasket in the valve body. Fuck these DOD engines.

This motor sounds excellent. I took a video but can’t upload it. It’s paid for so might as well keep tearing into things. Haha!

Are we talking about truck 1 or 2? The one you just did that pressure came up to 40?

and yes, dod sucks.
 

FleshEater

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Are we talking about truck 1 or 2? The one you just did that pressure came up to 40?

and yes, dod sucks.

Well, the pressure held good while idling on the jack stands. After driving it tonight after putting the front diff back in the pressure dropped back down to 21 psi.

My truck (Silverado) with the lifter tick has GREAT oil pressure, and the Tahoe has 21psi but purrs like a kitten ALL the time.

In the bottom of the pan on the Tahoe there was a decent amount of black crud built up at the bottom. There were tiny contaminants in the pick up tube screen. I’m hoping the screen at the sending unit is clogged. I really don’t want to pull that valve body and replace it.

I own two GMT900’s. Next vehicle will be a GMT800 or 400.
 
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