No Oil Pressure ...

[bastenblood]

When the truck is warmed up , at a stop or slowing down near a stop , the oil pressure gauge drop to 0 , with the check gage light .
If it stays at idle , it will indicate 0 until I stop the truck wondering what the hell is going on ..

[video=youtube_share;71IgGw7OT3w]http://youtu.be/71IgGw7OT3w[/video]

I have a 2002 Envoy SLE 4,2 4X4 with 162 000 km with :

- Synthetic oil change every 5000 km
- Cleaned throttle body
- New Delco CPAS
- New Delco plugs a year ago
- New water pump a year ago this

I search on the site and the only posts i found was about a bad sensor or sending unit .

 

[Mike534x]

Have you tried replacing the Oil Pressure sensor/sending unit?

I run into the same issue on mine as well, though it happens intermittently after an hour or so of driving. I've tried replacing the sensor twice (the second one was replaced by the dealer) and I still run into the issue. As long as there's no knocking of any sort then you should be just fine, the only way to really tell is if you hook up a guage where the sensor screws into and test to see what your pressure is (it should be a little over 10 PSI?) It could be a chafed wire or a short or something of that nature causing the warning to appear.

And have you tried cleaning the throttle body too?

 

[bastenblood]

Yup , I clean the throttle and change the air filter every year . The engine was ticking before this problem
and when the pressure drop there is no sound or vibration change in any way . My cluster makes a grinding noise too ( did anyone hear it? )

Where is the sensor located ?

 

[Mike534x]

The sensor sits right above the oil filter.

Could be a stepper motor but from what I've read when they go bad they usually just point downward.

What kind of ticking was the truck making before this? If possible could you make a video of what it sounds like?

 

[bastenblood]

The sensor sits right above the oil filter.

Could be a stepper motor but from what I've read when they go bad they usually just point downward.

What kind of ticking was the truck making before this? If possible could you make a video of what it sounds like?

Just made this , just a little bit cooler than an hour ago when i made the first video . No oil pressure drop , just is usual tick .

[video=youtube_share;LdHrYspnAXA]http://youtu.be/LdHrYspnAXA[/video]

 

[bastenblood]

Anyone else have any insight ?

 

[TangoBravo]

I know my stepper motor is bad on my oil guage and it will get stuck on the high end. Anytime the key is cycled it will climb and stay high with no movement while driving. As far as the ticking I am not sure enough to speak on it. But your certainly on the right forum so Im sure someone will chime in and help.

 

[CaptainXL]

Really a simple way to test the wiring is to bypass the switch by removing the connector and jump both pins together.

If the dash gauge stays up then replace the switch and go from there. If after replacing the switch the problem reappears then its time to connect a handheld oil pressure gauge.

 

[gmcman]

Just poking fun, but that motor sounds like my dad's Jetta TDI.

Seriously though, pull the serpentine belt and run the motor for a few seconds and see if the noise persists, no longer than 1 minute.

What oil filter are you using? Definitely check the oil pressure yourself with a separate gauge before you start replacing sending units just to be certain you have adequate pressure.

Could be valvetrain related or possibly an exhaust leak.

 

[CaptainXL]

pull the serpentine belt...

Could be valvetrain related or possibly an exhaust leak.

Let's stay focused here and not get sidetracked. The problem is that the gauge goes to 0 when the engine is warmed up. None of that stuff would have anything to do with it.

However changing the oil and filter as gmcman suggested would be a good starting point. Use an ACDelco PF-61e filter if you can.

 

[bastenblood]

The oil and filter are new from thursday , I do not know wich brand
of filter the shop I go to put in usually , the oil level is good , no leak
and no rpm drop when the pressure goes to 0

 

[gmcman]

Cap't I agree, and it's most likely an electrical issue, but....THAT motor, sounds like a diesel. Way too much racket and could be the recording device...dunno.

Something to consider and could be overkill....is to take it to the shop where you had the oil changed, and show them the pressure gauge. This is only to document the problem and tell them that after the oil change, my pressure is "0" at idle. Could be something they did, who knows what oil they put in there, this is only to cover your tail. Of course, they could say "Well, you need to leave it here so we can diagnose if you want us to cover any damages" Tough call and just wanted to toss that out to you.

Roadie has stated these pressure gauges are not true pressure gauges in the sense they don't read incrementally, more of a "you have pressure" and you don't really know how much. Hope I'm not putting words in his mouth.

I would think in the event of a low oil pressure situation the warning light would be red and not amber like yours so to me that may be a good sign.

The reason I suggested removing the belt is to hopefully quiet the motor due to a probable water pump failure. If it still makes all that racket with the belt removed it could be internal and possibly from a low oil pressure situation.

I had a low pressure issue like this in an old Pontiac V8 and the bearings were standard and the crank had been turned down .010, yielding .012 clearance. When cold it had pressure but warm idle it would fall off, driving was OK.

 

[bastenblood]

So I have the shop check the oil pressure when the gauge indicates 0 , and it was good . Installed the new
sensor , everything is back to normal .