Community Forums

tim fm ct · 06-10-2015, 03:18 PM

2005 GM Vortec 8.1
While traveling, the low oil pressure and warning alert comes on from time to time and returns to normal. It's been in the shop and the sending unit has been changed. After awhile the same problem returned.
With the help of Dale from Oemy's, I'm pursuing having the cluster and computer checked to be sure the ScanGuage will get reliable data.
I'm still waiting to hear from a Workhorse/GM facility.
Here is what I'd like to do:
Disconnect and remove the oil pressure sending unit and replace it with an old fashion oil pressure gauge with the dial within my view. Even though the actual oil pressure is good and the warnings are an electrical malfunction - - I'd like to actually see that the pressure is good.
Because the sending unit activates the warnings etc electrically, I'd have to disable that function since it's no longer there..
Will this work?

vettenuts · 06-10-2015, 04:59 PM

Curious who is working on your coach in CT?

tim fm ct · 06-10-2015, 05:02 PM

Quote:

Originally Posted by vettenuts

Curious who is worki

ng on your coach in CT?

Scranton Motors in Vernon - - - next thursday.
Actually the process was started with an urgent stop in Farmsville NC They changed the sending unit...

garyspang · 06-10-2015, 07:01 PM

Leave the electronics alone. These computer driven devices have a tendency to go into an occasional short reset mode. All gauges go to zero and alarms may activate.
Instead wire a digital oil pressure readout only in parallel on the existing sensor.
This will give you your peace of mind and will not upset the computer.
If the pressure still drops, then you may be sucking air into the lubrication system.

jacwjames · 06-10-2015, 07:14 PM

I agree with garyspang, I'd put in a new oil pressure gauge and confirm you have a problem. Should be easy to do.

I had the same problem with my 460 engine, the oil pressure would fluctuate and at time go to zero. I got concerned so I installed a separate oil pressure gauge. Unfortunately it did confirm I had a problem. I talked to a mechanic I trust and he said try putting in new oil pump, I said OK and he ordered the parts. I took it to his shop and was an active observer. We had to remove to air intake off the top and jack the engine up to have enough room to drop the oil pan enough to change oil pump. He knew what he was doing as he was working blind under the engine. He took the 2 bolts out holding the pickup tube to the oil pump. He then pulled the oil pump and handed it to me. I told him that he might as well remove the pick up tube which he left it partially bolted to the engine >>>> the weld on flange on the pick up tube had cracked and separated. The oil pump was sucking air causing the fluctuation and would loose prime at idle. Bought a new pickup tube and installed with the pump and all was good.

~3 years later I bought our current coach and told him I was selling the old one, he brought his dad over and he bought it with cash. He was confident that I had taken care of it. He still has it 6 years later

tim fm ct · 06-10-2015, 08:05 PM

Quote:

Originally Posted by garyspang

Leave the electronics alone. These computer driven devices have a tendency to go into an occasional short reset mode. All gauges go to zero and alarms may activate.
Instead wire a digital oil pressure readout only in parallel on the existing sensor.
This will give you your peace of mind and will not upset the computer.
If the pressure still drops, then you may be sucking air into the lubrication system.

Thanks Gary,
Not sure on your suggestion. Are you saying to leave the sending unit there and wire a digital oil readout in parallel with the sending unit?
The engine oil pressure does not actually drop. The digital readout on the dash fluctuates and the numbers vary and then the alarm goes off. Then in a few seconds to minutes (seems like forever) everything goes back to normal where the pressure gauge in the dash reads correctly for awhile. Could be for an hour or so.
How does the added digital readout prevent the low pressure alarm from going off?
I understand the peace of mind with the new readout but what about the alarm?

mgscott4 · 06-10-2015, 08:18 PM

Just mount a T where the sensor screws into the block. Sensor on one fitting and oil line on the other. Figure out what size, probably 1/8 NPT maybe 1/4 NPT thread into the block then figure out what your oil line fitting needs. It shouldn,t be that hard to find all the parts you will need.

Samflhomes · 06-10-2015, 09:27 PM

Would a larger filter help

Brazel's RV Performance · 06-11-2015, 12:08 AM

Do you use a Fram oil filter by chance?

thedjjack · 06-11-2015, 12:28 AM

I would t-fitting manual gauge good quality...

Next I would confirm issue with low warning alarm... Keep the system but get it working or fix the low pressure issue...

I would also change oil now and cut filter(s) apart

x2 on filters....

garyspang · 06-11-2015, 09:56 AM

ti fm tc
Since you have a new sensor, the new readout can be wired in parallel with your existing wiring. This is very easy.
Then you can definitely determine if the fluctuations are for real, or are caused by something else. The prior suggested purely mechanical gauge addition is also very good if you feel uncomfortable with electronics, but a bit more work. I have installed a T fitting at the sensor location, but for a Bypass filter and a Pre-oiler. It was no big deal, just a bit tedious.

Arch Hoagland · 06-11-2015, 10:28 AM

Quote:

Originally Posted by Ultra RV Tech

Do you use a Fram oil filter by chance?

Hmmm. What would make you ask that question?

Myself I always go to the Chevrolet dealer and buy a PF454 oil filter after having problems with an aftermarket oil filter many years ago.

tim fm ct · 06-11-2015, 03:40 PM

Quote:

Originally Posted by garyspang

ti fm tc
Since you have a new sensor, the new readout can be wired in parallel with your existing wiring. This is very easy.
Then you can definitely determine if the fluctuations are for real, or are caused by something else. The prior suggested purely mechanical gauge addition is also very good if you feel uncomfortable with electronics, but a bit more work. I have installed a T fitting at the sensor location, but for a Bypass filter and a Pre-oiler. It was no big deal, just a bit tedious.

Gary etal,
I get the procedure of adding a "T" and the mechanical gauge but I'm not so confident about connecting an electronic gauge in parallel with the existing sender. I think there are three wires going into the sender. I've got to tap the electronic gauge wires into into one of them and the other to ground - - right? Which one of the three sender wires am I tapping into?
However, with either method here's my question. It the false data is sent to the RV computer and it is determined that the oil pressure is good via the added mechanical gauge or the added electronic gauge what's going to prevent the low pressure alarm from sounding?

Brazel's RV Performance · 06-11-2015, 09:07 PM

Quote:

Originally Posted by Arch Hoagland

Hmmm. What would make you ask that question?

Myself I always go to the Chevrolet dealer and buy a PF454 oil filter after having problems with an aftermarket oil filter many years ago.

It's a known issue that Fram oil filters can cause a low oil pressure condition on the 8.1L. We were even sent a tech bulletin back in the day from our Workhorse rep about not using them.