2005 gmc sierra 1500 question

[Fish along]

I just purchased this 05 GMC SIERRA 1500,AND IM SEEING THAT ITS SAYING THAT I HAVE LOW OIL PRESSURE, A FRIEND OF MINE SAID IT WAS PROBABLY THE OIL PRESSURE SENSOR SWITCH NOT WORKING PROPERLY, ANY ONE ELSE ON HERE DEALT WITH THIS PROBLEM, IS IT SOMETHING THAT I SHOULD BE WORRIED ABOUT? IVE ONLY DRIVEN A FEW HUNDRED KLMS,SINCE I GOT IT. THANKS FOR ANY REPLIES 9

[Buckhead]

It could be the oil pressure sensor.

It could also be the oil pickup tube. They have a tiny o-ring that gets hard - cracks or fails and causes low oil pressure. It is a lot of work to change that.

[Fish along]

It could be the oil pressure sensor.

It could also be the oil pickup tube. They have a tiny o-ring that gets hard - cracks or fails and causes low oil pressure. It is a lot of work to change that.

How common is this o ring cracking?

[Arty]

I have a 5.4 triton engine of the same vintage, with a pretend pressure gauge in the instrument cluster. It has a simple pressure switch behind it which feeds the engine computer, which then generates a fake meter signal. (cost saving design, obviously)

But every time it's used now (i.e. engine starts and pump powers up) the needle advances about 10 to 60 degrees of rotation and never goes back. Can't just swap it out with a real pressure transmitter because lots of computer logic in the computer checks for the switch signal. The pressure switch itself is probably OK for now, but you'd never know.

Some day I will just tee off of the switch to put a transmitter sensor input onto it, then put a real meter onto the dash for it. Maybe doing that would be reasonably easy in your engine, to at least be able to see what the frig is really going on.

[1GH]

It’s much more likely its just the stepper motors behind the gauge cluster. It is a known problem for 2003 to 2007 chev and gm products. Google is your friend.

[TBark]

My ‘04 Sierra did that too.
I had to pull the screen beneath the pressure sensor.
It took a small hooked nail to pull that screen, not the easiest to get to, back of the top of the block, near the firewall.
Some solved the issue with just an oil and filter change, but I did the screen.
It did have some stuff on it.

On yours did the PS just show a little off? Like in alarm at Idle?
If it’s low and doesn’t move at all at different RPM, I’d agree with dash stepper motor.

TBark

[Stinky Buffalo]

If you can get a hold of an OBD reader, you should be able to pull the oil pressure sensor value, that way you can determine whether it's the gauge or the sensor - at least you'll have a starting point.

[Peace Meal Farm]

Agreed on the pressure sender and the filter screen underneath it. I take the intake off to do them ...

[sako1]

Definitely the sender and screen. Did 3 this week already. Literally a 5 minute job.

[Fish along]

My ‘04 Sierra did that too.
I had to pull the screen beneath the pressure sensor.
It took a small hooked nail to pull that screen, not the easiest to get to, back of the top of the block, near the firewall.
Some solved the issue with just an oil and filter change, but I did the screen.
It did have some stuff on it.

On yours did the PS just show a little off? Like in alarm at Idle?
If it’s low and doesn’t move at all at different RPM, I’d agree with dash stepper motor.

TBark

When I start it up the beeping will sound and the dash shows low oil pressure then I put it in gear and drive it and it stops the guage hand goes to nearly half and stays when driving .sometimes when I stop the the hand will start to go down again, it always happens when I start it.

[Fish along]

Definitely the sender and screen. Did 3 this week already. Literally a 5 minute job.

Well that's a bit of good news.

[Fish along]

Agreed on the pressure sender and the filter screen underneath it. I take the intake off to do them ...

So how long would it take you to change it?Thanks.

[Johnny G1]

It could be the oil pressure sensor.

It could also be the oil pickup tube. They have a tiny o-ring that gets hard - cracks or fails and causes low oil pressure. It is a lot of work to change that. I know of 2 engines here in Clearwater that have the same untill the lifter's went out, new lifter's one side and the other side went out, they didn't check o ring as it is 4x4 and means pulling motor 4.8 & 5.3 motor's same problem, expensive fix if you have to pull oil pan on 4x4, o ring @ front of the motor behind oil pump, my self would not own either motor. Forgot to say low mile motors in both, like 130k.

[sako1]

I know of 2 engines here in Clearwater that have the same untill the lifter's went out, new lifter's one side and the other side went out, they didn't check o ring as it is 4x4 and means pulling motor 4.8 & 5.3 motor's same problem, expensive fix if you have to pull oil pan on 4x4, o ring @ front of the motor behind oil pump, my self would not own either motor. Forgot to say low mile motors in both, like 130k.

Definitely don't need to pull the engine to pop off the oil pan. The front diff drops out in 20 mins.

[esher]

My 2005 4.8 has 320000 k on it, body will fall off before the engine dies.

[overhere]

When I start it up the beeping will sound and the dash shows low oil pressure then I put it in gear and drive it and it stops the guage hand goes to nearly half and stays when driving .sometimes when I stop the the hand will start to go down again, it always happens when I start it.

^^^ this is the indication of the oil pickup tube seal . At low rpm when cold , you must fix it or the motor will pack it in . Seen it lots

[Johnny G1]

Definitely don't need to pull the engine to pop off the oil pan. The front diff drops out in 20 mins. Yes we know but @ 77 yrs old it is easier to work on the motor on a engine stand if you got to pull the heads to get the stinking lifter's out of that breed of an engine, and don't lay on my back any more looking up into an engine, not your normal small block like your 283-350 and it is much easier to pull the engine if you have to do extra work on it to make everything right, been into a couple small blocks the last 60 yrs.

[Flatland]

Have a 2005 gmc with the 6.0 that had 300000 on it and was acting the same. No oil pressure when cold. Changed the pickup o ring and replaced the oil pump at the same time. It's been a couple years but I think it was 250$ for parts and the truck has 360000 on it now. I'm no mechanic but it took a day in the shop to do it.

[Fish along]

My 2005 4.8 has 320000 k on it, body will fall off before the engine dies.

Did your dash show low pressure at any time? thanks

[esher]

Did your dash show low pressure at any time? thanks

Never, step motors in dash were done around 220000.

[Fish along]

^^^ this is the indication of the oil pickup tube seal . At low rpm when cold , you must fix it or the motor will pack it in . Seen it lots

How long can i drive it like this? It seems to have lots of power. Can a mehanic tell me if its the tube or not?

[amosfella]

How long can i drive it like this? It seems to have lots of power. Can a mehanic tell me if its the tube or not?

If you got a smoking deal on the truck, it's quite likely that the previous owner knew about it.

With improper oil pressure, it doesn't take long to screw up an engine.

As was said, most OBD2 readers can read the actual oil pressure.

[JBE]

If you got a smoking deal on the truck, it's quite likely that the previous owner knew about it.

With improper oil pressure, it doesn't take long to screw up an engine.

As was said, most OBD2 readers can read the actual oil pressure.

How can the OBD2 reader give you actual oil pressure if lets say the sending unit is bad? Is there another sending unit on the engine?

[Stinky Buffalo]

How can the OBD2 reader give you actual oil pressure if lets say the sending unit is bad? Is there another sending unit on the engine?

The one that feeds the gauge likely won't; but the OBD reader will at least show you what the sensor is "seeing" - if the reading is within specification, then it's likely you have a gauge issue.

[Fish along]

If you got a smoking deal on the truck, it's quite likely that the previous owner knew about it.

With improper oil pressure, it doesn't take long to screw up an engine.

As was said, most OBD2 readers can read the actual oil pressure.

There’s no smoke that I can see,stopped or driving

[amosfella]

How can the OBD2 reader give you actual oil pressure if lets say the sending unit is bad? Is there another sending unit on the engine?

Then you thread out the pressure sensor, and thread in a manual gauge to double check. The code reader will tell you if the gauge is reading properly from the sender. Baby steps to find problems like these unless the failure is catastrophic and obvious.

Maybe I should have been clearer in the way I wrote it.

[amosfella]

There’s no smoke that I can see,stopped or driving

Probably wouldn't smoke much until actual failure.

[Johnny G1]

Another way to find if the oil O ring is the problem is to face the truck down hill and add an extra quart or 2 of oil and if the oil pressure comes up you will know it is the O ring that is leaking as it will be submerged in the oil and not drawing air, one of the dumbest motor's that gm has built and the 6 ltr is the same design, the next problem is noisy lifters not getting enough oil. Good Luck.

[Kurt505]

^^^ this is the indication of the oil pickup tube seal . At low rpm when cold , you must fix it or the motor will pack it in . Seen it lots

This would be my guess.

One thing you can do to test it is use thicker oil with bars leaks or something like that. If that stops the alarm then it’s your o ring. The o ring is only $1.20 but igg to takes about 7 hours to change out.

[amosfella]

The o ring is only $1.20 but igg to takes about 7 hours to change out.

That's almost as bad as the Mercedes 275 6L V12 twin turbo engine. It has a $2 oring that gets brittle, and if you don't change it it looks like a rear main seal leak. It's a $15k job to fix it. You have to remove the engine and tear the top end down to the block to get to it. On the plus side, it's unlikely that your engine will self destruct if you don't fix it. Your car will just mark its territory everywhere you park it.

[overhere]

How to tell if it's a pick up tube issue jack back tires up 18 inches and over fill engine oil by 2.5 liters .

Leave til motor is cold . ( morning).
By doing this oil will be covering the oring in pickup tube , if oil pressure reads normal and symptoms are gone you need to fix the oring , if it's the same then drain oil to proper level and continue diag.

[Johnny G1]

What was the outcome with this truck????