Low oil pressure warning again...only when pulling my small trailer.

[c good]

I thought I had the problem solved. Berrymans crankcase soak, new pressure switch, Valvoline R&P. Etc.....I hadn't towed my 2000 lb trailer in two years.

With all of my driving to the desert, four wheeling, driving around town, pulling long grades I haven't had the low oil pressure warning come on.

Yesterday after pulling the trailer about 7 miles, come to a stop light, the low oil pressure warning popped up.

I put it in neutral, raised the rpm up about 50 rpm more and the warning goes away.

It only did it twice over the numerous stops and over the 40 mile round trip.

I wonder if the extra electrical load brings the RPM down just enough to drop the rpm down and cause the problem.

For some reason I was thinking Mooseman had a similar problem? If so how did you end up dealing with the problem?

I'm going to finally install my true oil pressure gauge and see what is actually going on.

Im currently using 5w-30. I'm wondering if 10w-30 might help? Or if it's just something I have to live with when towing.

Thanks all for any input.

 

[Mooseman]

Did you actually check your oil pressure with a mechanical gauge? What brand pressure switch did you use? Just because it's new doesn't mean it's good.

How long have you been on this oil? There is a possibility that the R&P has cleaned it out so well that the oil filter is plugged. Switching to 10w30 is also a viable option and not a bad idea while towing or summer months.

For some reason I was thinking Mooseman had a similar problem? If so how did you end up dealing with the problem?

Not with my 4.2L. I did with my Avalanche and my Saab 9-7x, which were caused by wrong oil pumps being used when deleting the DOD.

On that same thought, I should preemptively replace my switch and keep the old one as a spare. I should also install the oil pressure gauge I've been meaning to install for the past couple of years

 

[c good]

Hi Mooseman,
I did put an oil pressure gauge on it a few years ago when I first had the problem. It was a temporary hand held type that I ran the hose up to the windshield and could watch while driving. I think I posted the results on here somewhere.

The numbers were good. I put an AC Delco pressure switch on it and haven't had the problem since until yesterday.

I just need to add the physical oil pressure gauge and know for sure what's going on. In the meantime I may just swap out for some 10w-30 and see how that works.

 

[junkcar65]

I had a similar problem, but mine was happing at full operating temp at idle. My engine is just old and there is enough wear that I was getting ~4.5psi oil pressure at idle. I swapped to 5w-40 European blend and a 180F thermostat. I get about 12psi at hot idle now.

 

[mrrsm]

There may be another internal engine phenomena involved on a High Mileage GM 4.2L LL8 I-6 Motor affected by the demands of Towing:

A Worn Thrust Bearing at the #5 Crankshaft Bearing - Journal position.

Under the greater demand for Torque when Towing, if the Thrust Absorption dimension has been thinned down by the normal bearing surface Wear Cycle of engine operation over 20+ years, the gaps on all of the leading edges between the Connecting Rods to Mains areas might be able to open up -=just enough=- to allow some of the expected Oil Film Pressure thought to be constant in between the Mains Caps Bearings and the Crankshaft Mains Journal surfaces to allow for a greater amount of "Bleed Off"... even if the Gerotor Oil Pump is able to crank out 60+ PSI at Higher RPM.

Just My -->