Oil gauge pegged, acting crazy, low pressure? Some advise for ya'

[Grocery Getter]

Oil gauge pegged, acting crazy, low pressure? Some advice for ya'

Ok..... so like many of you my oil pressure pegged all the way to 80 a few months ago and I know it was the cluster or the sending unit but since it was high pressure I wasn't in a rush to fix it.

On monday my gauge came back to life but was reading about 20 and would fluxuate with the RPMs up to about 40@3500rpm's. Now I'm thinking, great......pressure gauge works again.....kind of

Well..........as the day goes on the pressure keeeps dropping and dropping until the gauge reads zero and the "low pressure" warning and chime comes on and will not go off EVER(three days of constant chiming HELL)!!!

Clearly it's either the gauge or the cluster so I go to the shop I use sometimes and they think it is the cluster right away, he calls hoe brother a GM tech at a dealership.....cluster, I talk to about five shops on the phone......CLUSTER. So, I go get the steppers replaced $180 for 15min worth of work and $30 worth of stepper motors........NOPE!NOT IT!

My gut told me it was the sending unit since the needle has movement but I went with the experts. No I start calling for quotes, $450, $300, $240...... I get quoted 1.3-4hrs labor. I was told the intake manifold had to come off and all kind of crazy shit.


So, since I was out $180 bucks already I decided to take a look at Chiltons and see if it was as hard as they said......

What a load of crap, I went to Autozone bought a $40 sending unit and $10 socket(it uses a special socket). The little bugger is on the back of the block on the driver's side. It was a REAL ***** to reach but BY NO MEANS hard. The hardest part was getting a clip off to remove the harness. Once you get the clip off it's just throw on the socket, a universal joint, and a 6'' extension and the little bugger comes right out. Getting the new one threaded was a tiny challenge but not a problem. I have really big hand and arms and I found a way to get in there by reaching around the block from the passenger's side with one hand and through all the wires on the driver's with the other so I could get two hands on the sucker'. All and all it took me less than an hour and I'd say the first 20-25min were spent trying to get the clip off without breaking the harness.

So, if you are having gauge issues here is what I suggest:

If the gauge is stuck somewhere EVEN WHEN THE TRUCK TURNS ON/OFF then it is probably the stepper 9/10 times out of 10. When the stepper goes it will not move at all

If the gauge is pegged at 80 but it moves to zero when the truck is off then I'd say it's the sending unit. Or if the gauge is all over the place

If you ate not sure I'd go this route:

Replace sending unit- $50
if that is not it
Have stepper motors replaced at spedometer shop-$180+/-
if that is not it
It is probably your oil pump but that is very rare on these engines unless you take crap care of your vehicle

Disclaimer: Just my observations and conclusions from the past week of dealing with this issue, of course each case may vary and I may not be 100% correct but this is the conclusion I came to after my oil pressure extravaganza---good luck

 

[Eagle]

nice> except I wish you had done the steppers yourself. Steppers plus soldering iron plus desoldering iron is about $50... and it takes about an hour tops.

 

[Grocery Getter]

nice> except I wish you had done the steppers yourself. Steppers plus soldering iron plus desoldering iron is about $50... and it takes about an hour tops.

I know, I know but I am shit at soldering and I was afraid I'd REALLY **** up the cluster trying and have to get a new one. Also, it was during the week and I did not have time to order steppers and give it a whirl and I was bugging out about the possibility of the oil pressure really being low and the engine getting fried.....kind of a combo of no time and panic....that ******* chime can really instill some fear into ya'.....for real, it makes everything seem so urgent and every whiff of exhaust smells like your engine burning up....... live and learn.

 

[Eagle]

yeah N/P if you get the chime it's the sensor or a real problem.
Glad you were able to resolve it and give us the skinny.

 

[Grocery Getter]

For sure, I looked all over for info on this and found bits and pieces here and there.... a lot of threads saying cluster/sending unit but no real sold answer.....

I would have done a white up but you can't see anything, you are pretty much working blind and going by feel so there is nothing to take pics of. I got my camera back there just to locate it but the pics are *****.......

so if someone tells you they need to remove the intake manifold to swap out the sending unit chuckle and NEVER go back there again because they are full of crap.........highway robbers......banditos

 

[ChazMan]

Hey Grocery Getter,
I have my oil guage is pegged all the way to 80 psi when engine is running and it comes back to zero when engine is shut off. So, I knew it was the sender unit and I just got a new one in my hand.

I think I can feel the sender unit at the rear top of the engine with my hand but not 100% sure if it is the right one because I can't see it. Is it screwed "vertically" into the rear top of the engine little bit toward the driver side? What's the trick to disconnect the harness from the sender unit?

 

[BOSS]

I'm always amazed at how easy something is when someone says it's hard when they're charging you $$ to do it, great info GG

B

 

[Grocery Getter]

Hey Grocery Getter,
I have my oil guage is pegged all the way to 80 psi when engine is running and it comes back to zero when engine is shut off. So, I knew it was the sender unit and I just got a new one in my hand.

I think I can feel the sender unit at the rear top of the engine with my hand but not 100% sure if it is the right one because I can't see it. Is it screwed "vertically" into the rear top of the engine little bit toward the driver side? What's the trick to disconnect the harness from the sender unit?

Yes, that's it. It is on the driver's side vertically inserted. Bro, I wish I had a trick, it took me 25min to get the harness off. I reached one had around on the pass side and one through all the wires on the driver's side hugging the motor, I had a tiny flat head in my hand and tried to get it under the clip but since I couldn't see it it was sketch. I just wiggled and pulled until it popped off, I ended up breaking the sender side of the clip to get it off by pulling on it, I am lucky I didn't break the clip on the harness. I stuck my camera back there and snapped a few pics to try and get a feel for what I was working with.

 

[trebor8820]

Sorry for digging up an old thread; I'm having a very similar issue, so hopefully you can chime in and confirm that it sounds like the sending unit.

When we crank the truck up, the oil pressure gauge shoots to 80, but then when it gets up to 2000 RPM, it drops straight to 0 and gives the Low Oil Pressure warning... then back at idle it goes back up to 80 again. We're afraid to drive the truck too much in case there is something wrong with the oil pump; does this sound like the sending unit to you? If so, I'll pick one up tomorrow and throw it in there; but if it sounds like it could be anything different, I'd appreciate some advice.

Thanks

 

[04denali]

I have a similar problem and took my yukon to the dealer for various other problems and they said it was the oil pressure sensor.. But im skeptical of that because they said my cluster was bad cuz my rpm doesnt work. My oil pressure gauge goes up and down and is now pegged out further than the 80, pointing down