2003 chevy 1500 5.3L Oil Pressure Problem

[LD1]

This one has me racking my brain so I thought I'd consult the collective wisdom of the board.

My tow vehichle:
2003 Chevy silverado 1500 4x4 5.3L engine and 99000 miles on the clock which Isn't my daily driver. I use it ocassionally to haul stuff, tow tractor, and plow snow in the winter.

Last winter when plowing, I was driving down the freeway and glanced down at the Oil Press guage and it was pegged well beyond 80. I immeniatly pulled over, popped the hood, looked around, pulled the dipstik, etc. Couldnt find anything. I got back in the truck, started it, and guage shows the normal 40 or so. It did this many times since and I just put her in N, turn the key off, and the restart, put back in D and everything is fine.

Now it is going the other way. After about 15-20min driving, it shows 0. If I shut if off for ust a inute, it bounces back to the 40 but another 15min later back at 0.

I have replaced the sending unit and that wasnt it. I really dont think it is actually at 0 because an engine with Hydraulic lifters and 0 oil press would not have any power and be making all kinds of noise. I have driven with the guage on 0 for 30min before and if it were really 0, it would probabally be overheating and locking up.

I have a mac scantool bu I dont have the right card. Just usingthe generic OBD II wont let be see anything related to the oil pressure. Obviously the simplest would be to put a guage on it but I don't have one, and its a PITA to get to any ports.

So I was wondering if anyone has any ideas?? I know the guage clusters on these truck tends to be a problem, but it doesn't act like it is sticking. A google search didn't turn up much other than the cluster is warrentied to 100,000miles. Can anyone verify this if it is indeed the problem?? Everything else in the cluster work fine except the backlight for the oil press guage doesnt work.

Any help would be greatly appreciated.

 

[Soundguy]

you said one thing right.. the gauge cluster is a POS.. I have a 2000 yukon 4x4.. probably similar chassie.. and same 5.3

oil and fuel gauge do their own thing...

luckilly I got a good deal on the thing.. should have known better buying a government motors.. certaintly won't ever do so again.. dodge and ford have been too good to me to ever consider a gm unless it was practically free.

If I was you.. I'd get a mechanical gauge and see what was going on by compairing cluster to real gauge... sure.. some PITA work.. BUT.. cheaper than a 5.3 rebuild..

good luck

( ps.. I had my yukon in the shop 2x in warranty and 1x out of warranty to correct the POS gauges and sender and she still has odd readings sometimes... )

soundguy

 

[timswi]

Can't verify, but it sure seems like a guage issue to me. Can you hook up an external oil pressure guage to the sending unit to verify?

You're right that the truck would be screaming bloody murder with no oil pressure, in fact the fail safes would probably kick in as well.

 

[lostcause]

i'd have it plugged into a tool that can read it. if you have had a gauge go to zero or peg at max, then i'd guess it must have thrown a few codes.

i have a 01 duramax that had an empty reading fuel gauge and idiot light on. plug in a tool and it reads the information correctly and reports the correct level to the tool. use the tool to reset the fuel level and the gauge returns to working order for a while. that all resolved itself with an injector job. my guess is that they were returning excessive amounts of fuel and that one of the tank levels did not read right and it would throw a code & dump the level reading to empty.

totally different issue, but same sort of situation. i'd guess a sending unit/computer before the gauge.

 

[Hawghauler]

We have a fleet of GMs here in the middle east and they are by far the most reliable of all our vehicles, Ford, Mopar, and foriegn. We have many at 350K plus miles and they operate tip top. Two things in general dictate oil pressure. Main bearing clearance and your oil pump. I have never seen oil pressure mechanically go up, so your issue is probably a module controling the guages. We do have issues with that here. The 5.3 is a stout performer. No doubt the module is in some god awful place to reach. The sender is easy to replace. There is a reason guages replaced idiot lights, but the advent of the micro chip is a PITA for routine things a sending unit or solonoid could control. I don't like electronic controls where you don't need them.

 

[LD1]

i'd have it plugged into a tool that can read it. if you have had a gauge go to zero or peg at max, then i'd guess it must have thrown a few codes.



totally different issue, but same sort of situation. i'd guess a sending unit/computer before the gauge.

No codes. The only code it has is and EVAP purge solenoid.

I replaced to sending unit. Maybe the computer, but the computer controls many many other things that all seem to be fine. But I guess it is possible??

I'm not sure if I am going to get a mech. guage, or the correct chip for the scanner.

 

[Diamondpilot]

I would go buy a cheap mechanical gauge an install it with a T where the sending unit goes.

That being said my friend is a GM guy and had the same issue with his truck about the same era and miles. His ended up being a cam bearing and a new motor cost what the truck was worth. He sold the truck with a bad motor to a high school kid who had a wrecked truck with a good motor.

My guess is its a cam bearing like his. The main reason is his mechanic told him they were usually the culprit.

Chris

 

[RickB]

The instrument cluster in early 2000's GM trucks are garbage. GM had an extended warranty and a well documented fix-as-fail program on them. I have the paperwork in my glove box. Mine is apparently going to work until I have to fix it on my dime.

 

[Ryan03]

My vote also goes for the cluster. Remans with vin and vehicle odometer programing and can be had on ebay for between $200 and $300 dollars. It is normaly handled on an exchange basis, Your credit card is charged the cluster price and core price, you fill out a online page with vehicle info vin mileage etc, print out a mileage disclamer, fill it out, then mail it. When the company receives your mileage disclaimer in the mail, your reman cluster is flashed to your truck using your vin, then shipped to you. Once received, swap your cluster, put the old one in the box and ship it back. Your card is credited for the core when it is received. Price of remans will vary based upon whether or not you have a driver info center in your cluster.

Verify the oil pressure using a scan tool or mechanical test gauge. The scanner is the preferred method, as this also verifies the wiring is not damaged, which the mechanical gauge does not. Not a bad idea to wiggle the connector on the sender and harness around a little while somebody wathes the gauge, especialy around connectors and junctions.

 

[Hawghauler]

They can also be had at a lot of auto parts stores. I thought that all these new advanced technological vehicles were supposed to be more reliable! Did somebody give me wrong info?

Actually they are, old idiot lights never worked right. Guages weren't too reliable either. The comuterized are just harder to fix and cost more.