Oil Pressure

mrgrim · April 28, 2008

I just picked up an 04 Silverado 1500 4x4 with 5.3 and 50,000 miles.The

question I have is about oil pressure,I know the guage on the dash is not

a true guage but in this truck it sits at 20psi and never moves while the

truck is running.I think it should read more but then what do I know.Is

it normal for it to sit at 20psi?

hubbycap · April 28, 2008

I just picked up an 04 Silverado 1500 4x4 with 5.3 and 50,000 miles.The
question I have is about oil pressure,I know the guage on the dash is not

a true guage but in this truck it sits at 20psi and never moves while the

truck is running.I think it should read more but then what do I know.Is

it normal for it to sit at 20psi?

A I've not had a Chevy that kept a constant oil pressure throughout the RPM range. My well-worn '95 C1500 varies from 20psi at hot idle to 60psi at cold running. Runs around 50psi hot on the highway.

My '07 5.3 runs 20-50psi. 20psi is enough though, if in-fact that is accurate.

You may want to put an ohm meter on the oil pressure sender and see if there is an RPM-influenced fluctuation.

pennzoil29 · April 28, 2008

I had asked a mechanic at a gm garage, and he told me 20# at idle is normal, and 40# while driving is normal. My '99 5.7 with 159k usually idles at 30# ,and varies around 50# when driving at normal temps. I don't think you have anything to worry about.

mrgrim · April 28, 2008

It just seems strange to me that it jumps to 20psi at startup and just sits there

the whole time the truck is running.I was under the impression it would move

or vari some based on rpm.

can a scan tool read "real" oil pressure?

How would I go about testing the psi on my own?

I just want to make sure that its ok as this truck is new to me so I dont have

any idea what is normal with this truck.

Zembonez · April 28, 2008

You are correct in assuming that this isn't normal operation. The gage should fluctuate with engine speed and give different readings when hot vs. cold, etc.

Sounds like a sending unit issue but it is technically possible that the gage is funky.

pennzoil29 · April 28, 2008

It just seems strange to me that it jumps to 20psi at startup and just sits there
the whole time the truck is running.I was under the impression it would move

or vari some based on rpm.

can a scan tool read "real" oil pressure?

How would I go about testing the psi on my own?

I just want to make sure that its ok as this truck is new to me so I dont have

any idea what is normal with this truck.

I must've misunderstood your question. On cold start up, are you telling us that the gauge only goes to 20# and sits there? If so, I think I would look into it a little deeper. That doesn't sound good.

mrgrim · April 28, 2008

Ok this is what I just did....The truck is cold and its 50F outside if it matters.

Turn on key all gauges move to starting position

Start truck,all gauges move to normal spots but oil pressure stays at 20Psi

I also noticed that of 8 times of turning key on and starting

3 times the oil pressure gauge did not move at all.It was at 20psi

with key off and when key was turned on it did not move.

I think the gauge is busted in some way. Is the sending unit a common cause of this type of issue?

Can any one tell me where is the sending unit located? I would guess that if I unplug it that the

gauge should hit 0psi and stay there and may throw a light on as well.This would show me the

gauge can move and is not stuck or broke?

After some looking around here on the site I found what looks to be

a warranty ext on the clusters in 03-04 Trucks due to failure.It lists

that gauges may stick as one of the failures covered.They will replace

the cluster at no cost to says the posting.I would like to narrow down

the problem so I am not hit with the $93 per hour the GM dealer charges

for diag and repair work just to find it was a $30 sender.

pennzoil29 · April 28, 2008

Ok this is what I just did....The truck is cold and its 50F outside if it matters.

Turn on key all gauges move to starting position

Start truck,all gauges move to normal spots but oil pressure stays at 20Psi

I also noticed that of 8 times of turning key on and starting

3 times the oil pressure gauge did not move at all.It was at 20psi

with key off and when key was turned on it did not move.

I think the gauge is busted in some way. Is the sending unit a common cause of this type of issue?

Can any one tell me where is the sending unit located? I would guess that if I unplug it that the

gauge should hit 0psi and stay there and may throw a light on as well.This would show me the

gauge can move and is not stuck or broke?

It should be located around the oil filter. It is above the filter on a 5.7. You can get an oil pressure gauge and check it yourself. When you remove the sending unit, you will have to install a fitting for the gauge to connect to. Use some teflon tape on the threads. Good luck, and I hope this helps you.

bossier62guy · April 28, 2008

Ok this is what I just did....The truck is cold and its 50F outside if it matters.

Turn on key all gauges move to starting position

Start truck,all gauges move to normal spots but oil pressure stays at 20Psi

I also noticed that of 8 times of turning key on and starting

3 times the oil pressure gauge did not move at all.It was at 20psi

with key off and when key was turned on it did not move.

I think the gauge is busted in some way. Is the sending unit a common cause of this type of issue?

Can any one tell me where is the sending unit located? I would guess that if I unplug it that the

gauge should hit 0psi and stay there and may throw a light on as well.This would show me the

gauge can move and is not stuck or broke?

After some looking around here on the site I found what looks to be

a warranty ext on the clusters in 03-04 Trucks due to failure.It lists

that gauges may stick as one of the failures covered.They will replace

the cluster at no cost to says the posting.I would like to narrow down

the problem so I am not hit with the $93 per hour the GM dealer charges

for diag and repair work just to find it was a $30 sender.

Contact M. Cueva and I bet he can tell you what the service bulletin concerning the instrument panel is. If your truck is indeed affected take that service bulletin # with you when you go to the dealer and it shouldn't cost you a dime to get it replaced.

bossier62guy · April 28, 2008

Try this thread, I think it's what you need.

http://www.gm-trucks.com/forums/index.php?...0134&hl=ipc

ZZ327 · April 28, 2008

my 05 5.3L usually runs 45 at startup running and idling, and 35-40 when hot. Never really under 35.

bossier62guy · April 28, 2008

After some looking around here on the site I found what looks to be

a warranty ext on the clusters in 03-04 Trucks due to failure.It lists

that gauges may stick as one of the failures covered.They will replace

the cluster at no cost to says the posting.I would like to narrow down

the problem so I am not hit with the $93 per hour the GM dealer charges

for diag and repair work just to find it was a $30 sender.

BTW, the oil pressure sensor is on top of the engine on my 02 5.3L....I'm sure it's in a similiar location on your 04. You may have to remove the plastic shield on top of the engine to access it.

mxdirtrider56 · May 10, 2008

He is correct. More likely than not it is the cluster, however, I believe your vehicle exceeds the mileage that GM will cover the cluster replacement. I work at a GM dealership and replacing faulty clusters is probably the most common type of repair we see. Ususally it is due to faulty speedometer or fuel gauges though. But it is likely that your gauge issue is due to one of these faulty clusters. There has been a warranty extension but I think it acutally stops at 40,000 miles. Don't take my word to be exact though as I work in parts and not the service department!!