Community Forums

Full-Timers · 12-07-2022, 08:12 PM

2005 W22 8.1L Oil pressure gauge is jittery. I don’t use the motorhome much but I start it once a month and let it idle for 15 minutes then bring it up to 1500 RPMS before shutting it down. This time I took it down for a little gas. On the way down I didn’t notice, but on the way back I observed the oil pressure gauge jittering. I noticed that if I start it cold oil pressure is steady at around 60. As it warms up it slowly, but steadily, drops to about 35 and is steady at 35 at idle. As I raise the RPMS to 2000 it rises up to around 60 but is jittery all the way up. Once at 2000 RPMS it is steady. When I let off the accelerator it jitters its way back to a steady 35. I was going to try installing a new sending unit until I saw the price.
So I ask, have you seen this issue?

Arch Hoagland · 12-07-2022, 08:25 PM

You stated you have a 2005 8.1 but your signature shows a 2003 Rexhall.

I'm curious what you have.

TandW · 12-08-2022, 08:05 AM

Part is <$20.00 on-line.
On edit, it will eventually fail high.

1972VWbus · 12-08-2022, 05:34 PM

Unless you plan on driving the RV it's best to not start it once per month. Idling alone isn't enough to burn off condensation. Condensation is a by product of combustion.

Just disconnect batteries. And prior to storage add an appropriate amount of Sta-Bil fuel stabilizer then top off fuel tank. Then run the generator for ~20 min or so at ~50 percent load. Shut off.

Done until spring.

Full-Timers · 12-08-2022, 05:50 PM

Quote:

Originally Posted by Arch Hoagland

You stated you have a 2005 8.1 but your signature shows a 2003 Rexhall.

I'm curious what you have.

Good catch...

My car is a 2005

The motorhome is a 2003 Rexhall on the Workhorse chassis with the 8.1L

Full-Timers · 12-08-2022, 05:57 PM

Quote:

Originally Posted by TandW

Part is <$20.00 on-line.
On edit, it will eventually fail high.

Yeah, I might be able to find one at $20 but I like to use genuine AC Delco parts or OE when possible.
Workhorseparts.com wants $148.38! OUCH!!

donr103 · 12-08-2022, 10:02 PM

Many times. Just corroded.. just go down to oil pressure sensor somewhere around oil filter.. pull off connection and use electric contact cleaner on both ends.. re attach and check.. Many times it works..
Good luck and keep us posted

LETMGROW · 12-09-2022, 09:53 AM

The oil pressure switch is available from NAPA part # OP6732 at just over $80.00. The wiring harness is also available from NAPA part # EC89 at a cost of around $42.00. These are Echlin parts which are well respected in the repair industry.

yeloduster · 12-09-2022, 10:10 AM

The drive train for the Workhorse chassis is a GM truck. If you search for an Oil Pressure Sensor on Workhorse Parts you will find the part number is 12677839. This is a GM part number. It is also the Oil Pressure Sensor for a 2003 Chevy Silverado 3500 with 8.1L engine.

Do an online search for "GM 12677839". That search will return multiple hits for ≈$50. Pick a vendor.

It could be the gauge in the dash!

Full-Timers · 12-09-2022, 07:40 PM

When I get off my lazy B**t I plan to do as donr103 said and first check the connection. Next I will probably remove inspect and reinstall. Next step will be to replace with an inexpensive unit.

nvs4602 · 12-09-2022, 07:55 PM

Another common problem with chevy was the stepper motors in the instrument cluster go bad. They either stick or jitter like you described. Had to replace all of mine on my 2003 Avalanche.

Here's a video on how to fix.

https://youtu.be/QGtALzf4XCw

Full-Timers · 12-09-2022, 08:05 PM

Quote:

Originally Posted by nvs4602

Another common problem with chevy was the stepper motors in the instrument cluster go bad. They either stick or jitter like you described. Had to replace all of mine on my 2003 Avalanche.

Here's a video on how to fix.

https://youtu.be/QGtALzf4XCw

Yeah I gave that a thought to. I should have added to my list of troubleshooting, temporary install a pressure gauge. That should tell me if it is really jittering or a bad stepper motor.

Full-Timers · 12-30-2022, 07:58 PM

I got to thinking that oil pressure shouldn’t fluctuate as quickly as my gauge indicates. It has a very distinct random jitter only when moving. At idle it is steady and if I raise the RPM to 2000 it is steady there however on the way up and back down it is erratic. So, I may be wrong but I believe it is not an engine or even a sending unit problem and more of a gauge problem. This is a 2002 chassis and is pre stepper motor gauges. I saw a video showing they are oiled gauges and can go dry causing an erotic movement.