02 Silverado 5.3L, LT, Low Oil Pressure

Messages
835
Location
CA
Own a 2002 Chevy Silverado with 380k miles on the original engine. For a few months now I've been noticing the oil pressure gauge needle bouncing around. This morning the dash light "Check Engine Oil Pressure" came on and noticed that the oil pressure gauge needle was at Zero while at a Stop sign. As soon as I drove off from the complete stop the gauge needle moved back up to the normal range and started to bounce around again. The light did not come back on again but the gauge needle continues to peg down to Zero when coming to a Stop. Not sure if I should be driving the truck around Any advice is greatly appreciated
 
Messages
13,247
Location
North Carolina
I had my gauge pegging all the way to the right at times, and times, usually when warm zero. I replaced the oil pressure sending unit. Fixed the issue. Its on the back of the engine on the drivers side. Helps to have small hands, slim forearms as its tough to get to. Might be easier on a lift from underneath , but i don't know.
 
Last edited:
Messages
138
Location
Alberta
Could be the stepper motor at the gauge cluster or even the cluster itself. I've had the oring issue that i fixed with a new oring. In that situation the oil pressure was low on a cold start up but would go to normal once warm. Then I had the situation you currently have. My gauge was all over the map for a few day then nothing. I replaced the sending unit behind the intake manifold. It worked for a day or two so i replaced it again but this time nothing at all. So my next thing will be to get the cluster rebuilt.
 
Originally Posted by Gito
Not sure if I should be driving the truck around Any advice is greatly appreciated
No advice but if you even suspect there might be a chance it's mechanical and not the gauge or sender you probably shouldn't be driving it with pressure going to zero at idle. 380k is impressive, all your miles?
 
Messages
5,676
Location
Fort Worth, Texas
'99-'02 GMT800 trucks use a "Analog Resistive" oil pressure sensor......Unlike the '03-'07 GMT800 EOP sensors, They don't go bad very often! The Oil Pressure Gauge stepper motors are also not nearly as failure prone as the '03-'07 either. With that many miles.....I would expect some NOISE to go along with no oil pressure? With the EOP being a 1-wire resistive sensor......The signal circuit grounding out (Shorting) can cause your symptoms. I agree with checking the oil pressure with a mechanical gauge.....The EOP sensor is a little tough to access on this platform, I would check it at the Bypass Plate above the oil filter. *Remove the Bypass Plate. *Drill out the boss with the correct drill for a 1/8" NPT tap......21/64" or a Q letter bit works great. *Tap the boss deep enough for good thread engagement. You will need a 1/8" pipe plug when your done. [Linked Image]
 

Gito

Thread starter
Messages
835
Location
CA
Originally Posted by AZjeff
Originally Posted by Gito
Not sure if I should be driving the truck around Any advice is greatly appreciated
No advice but if you even suspect there might be a chance it's mechanical and not the gauge or sender you probably shouldn't be driving it with pressure going to zero at idle. 380k is impressive, all your miles?
Original owners. Yes, all miles by us.
 

Gito

Thread starter
Messages
835
Location
CA
Originally Posted by clinebarger
'99-'02 GMT800 trucks use a "Analog Resistive" oil pressure sensor......Unlike the '03-'07 GMT800 EOP sensors, They don't go bad very often! The Oil Pressure Gauge stepper motors are also not nearly as failure prone as the '03-'07 either. With that many miles.....I would expect some NOISE to go along with no oil pressure? With the EOP being a 1-wire resistive sensor......The signal circuit grounding out (Shorting) can cause your symptoms. I agree with checking the oil pressure with a mechanical gauge.....The EOP sensor is a little tough to access on this platform, I would check it at the Bypass Plate above the oil filter. *Remove the Bypass Plate. *Drill out the boss with the correct drill for a 1/8" NPT tap......21/64" or a Q letter bit works great. *Tap the boss deep enough for good thread engagement. You will need a 1/8" pipe plug when your done.
No noise, no rough idle, no noticeable symptoms other than the visual symptoms described (gauge needle). Oil gauge needle has been dancing around for approximately 2 months and today was the first day that the dash light came on and it was then that I noticed the oil pressure needle at zero. As soon as I stepped on the gas, the needle moved up. I'm going to first try swapping the sending unit from my father in laws 2000 Silverado to our 2002 Silverado. Will report back
 

Gito

Thread starter
Messages
835
Location
CA
Drove the truck around the block this morning to check on the oil pressure gauge needle. It's back to doing what it has been doing for a few months. The needle on my gauge dances or fluctuates between 20 and 40 psi. Does not move higher than 40 psi. Even before the needle started to dance, it had always been steady at 40 psi.
 
Messages
4,161
Location
Texas
Can not remember the model year , but I have seen a youtube video of the " screen " on the oil pressure sending unit stopping up and giving bad / misleading info . On a Cghevy or GMC truck . From what I hear of the difficult of changing this sensor , if I pulled the original one out , I would replace it with a new one .
 
Messages
5,676
Location
Fort Worth, Texas
Originally Posted by WyrTwister
Can not remember the model year , but I have seen a youtube video of the " screen " on the oil pressure sending unit stopping up and giving bad / misleading info . On a Cghevy or GMC truck . From what I hear of the difficult of changing this sensor , if I pulled the original one out , I would replace it with a new one .
2007 & up Gen IV engines equipped with AFM had the screen to protect the lifter deactivation solenoids from debris.
 
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