[ftwmlp]

Don't have much experience with high mileage engines so bear with me. A few years back my brothers and I bought a 1998 Chevy C3500 Dually with 163K miles on a 5.7 L31 gas engine that we hoped to use for several more years as a reliable tow truck for hauling small cattle loads to market. Truck had been auctioned from the public works dept of a local municipality so we felt good about maintenance record & price. Fast forward to last year, we've only added 5K miles and oil pressure gauge starts to read very low pressure at idle. Older brother takes to local small town Chevy house, they keep for almost a week, report they checked bottom end and oil pump, suspect cam bearings need to replaced.

Not familiar at all with SBC from that vintage, but internet seems to agree cam bearings can be an issue at that mileage level. Any opinions on whether it's worth a rebuild, or reman engine swap, or cut and run now?

Additional detail, 4L80e trans, 4.10 rear end, six new tires (less than 2k miles on all six).

Appreciate any and all advice.
Mike Pearson

[72projectbird]

I'd double check the pressure with a mechanical gauge. GM sending units from that era like to act up.

[Half-Inch Stud]

Any engine thst is presently driving a 4L80 might be a good engine to maintain,

[newmexguy]

I have a '90 silverado with the 5.7L TBI engine, it had a new oil pump installed before I bought it at around 200K. It has 295K now. Engine never opened, aside from that oil pump job, to best of my knowledge. Still runs, tired, but am hoping to get it into the 315k range before engine comes out. Running thinner oil (0W, 5W) could also give low oil pressure readings.
Would have figured a 3500 chassis would have had either a 7.4L or a Diesel.

[sdbob]

As 72 said I'd ck with 'known' good mechanical gauge. Even 2nd gauge just to be sure. This day and age 'junk' from overseas just isn't what products use to be.

[geeteeohguy]

As stated, verify the pressure with another gauge. If faulty, how low is the pressure? All you need is 10psi for every 1000 rpm. Consider running 15/40 oil.
You can get a GM crate engine with a warranty for under 5k for your rig, and it would be money well spent if you don't want the hassle of a rebuild.

[ftwmlp]

Originally Posted by geeteeohguy

As stated, verify the pressure with another gauge. If faulty, how low is the pressure? All you need is 10psi for every 1000 rpm. Consider running 15/40 oil.
You can get a GM crate engine with a warranty for under 5k for your rig, and it would be money well spent if you don't want the hassle of a rebuild.

I agree with the need to verify the pressure with another gauge, but I watched some videos about the location of the oil pressure sender on this particular engine and lost some of my enthusiasm, getting lazier in my old age.

Also looking hard at the "crate engine" option. Seems there are some attractive options, but several say they are only "calibrated" for up to the C2500 powertrain, don't really understand what that means.

Thanks for all the input so far, really appreciate the responses.