High Miles, Low Oil psi

[oldschool]

I just purchased an 1989 1500 with 198,000 miles on the 5.0L engine. After it warms up, the oil pressure drops to near nothing at idle. At highway speeds the oil pressure runs about 35 psi. It doesn't use any oil. I was told that if I replace the oil pump, the engine will start using oil. Do you agree? Thanks.

 

oldschool

[redvett]

Bad cam bearings with that kind of mileage.

[MustGoFaster]

how's the oil leaks while standing/sitting overnight?

could also be a bad main seal, once it warms up, it's dripping enough to loose oil pressure.

 

that's one possibility. if that's not the case I would look into worn bearings/journals, and perhaps the pump, most of the time I would think that a bad pump would be bad. cold or hot. but I could be wrong, there's seals in the pump too that probably get soft as the engine heats up.

[snoman]

Bad cam bearings with that kind of mileage.

 

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Not cam bearings as they rarely wear out before the main and rod bearing do. If you are using 5w30, STOP and try atleast 10w30 even in winter and maybe 15w40 (not 10w40) in summer and it will help pressure a noticable amount. the 305 has a fairly sturdy bottom end and as long as it is not knocking it can run with low oil pressure for some time. if you get about 10 PSI or more at a idle and 30 or more at cruise, you have a lot of miles left in it. Just change oil often too.

[95Sierra2500]

I don't know who told you that changing an oil pump will cause you to use oil...but I've NEVER heard of that, and I've changed my share of them.

[snoman]

I don't know who told you that changing an oil pump will cause you to use oil...but I've NEVER heard of that, and I've changed my share of them.

 

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I agree, it was bad advise but if I went to the trouble to drop the pan to change pump, I would check and cahnge bearing in there while it is apart. Rod bearings are usually the first thing to go on a SB when pressure get low. THe rod and even main bearing are not hard to change once the pan is off.