Low Oil Pressure

[Tom - SS2]

After sitting for the winter, my '77 Scout II has problems keeping oil pressure. Engine is 304, cold oil pressure reads 40 psi, after warming up 15 - 20 psi on the road, 0 - 5 psi at idle. I swapped out the stock oil pressure gauge for a mechanical one - no change, still low oil pressure. Last night I ran some engine flush in the oil, and then drained the oil out and did an oil and filter change. The oil had less than 100 miles on it, and it came out black. With new oil and filter, I started it up ----- 45 psi cold. After warming up and driving for 20 miles, pressure dropped again to 15 - 20 psi on the road, 0 - 5 psi at idle. Now, even when cold, 25 psi is the best it will get up to. Checking the oil, it still has good color, unlike the previous 2 - 3 oil changes, where within 100 miles the oil starts to get black. My question - what should I do next? I was thinking of dropping the oil pan to see if I have sludge in the pan or if the oil pump is getting plugged up. Or is that just a waste of my time? I know that sometime in the future the engine will have to come out, for rings, bearings, or whatever - I'm just hoping I'm not at that point now.

[Bill Bennett]

What brand oil? What weight oil? What filter?

[Tom - SS2]

I've tried all different kinds of oil - right now 10-40 Castrol GTX. Same results with straight 30 wt. Same results with oil additives like Lucas. Same results with good or cheap oil filters.

[RobertC]

Not that it will help your problem, but you should run SL rated oil -- not the newer SM rated oil (not enough zinc / additives)...

Based on what you say, drop the oil pan and I am pretty sure you will find pieces of cam bearigs...

There are many threads here on the subject...

[Jeff Jamison]

I know this wont help,I have been running my scout like that for 4 years now waiting for it to quit on me.Its still running fine 20,000 miles later.I have a spare engine.I would keep running it,find a spare engine to get ready for when it does go.
Jeff

[Will Marsh]

I agree with Jeff. Run it, and start collecting the replacement.

It will probably run another 5-10K without a major issue. At some point you'll see the oil pressure go to zero and it will just quit when the cam bearings are completely gone. At that point you can run it about 30 min on a cold start, and if you let it sit for an hour it will run for a couple miles before the lifters stop working again. BTDT.

I probably wouldn't do that if I intended to rebuild the motor, but if it's just marking time until the replacement is ready you should be fine.

HTH,

Will Marsh

[Mark Pietz]

Will,
Why cam bearings? Wouldn't worn main/rod bearings do likewise? I once had one of these that had low pressure and put in rod bearings. Wow, went from a hopeful 10 psi to 15-20.

??

[Tom - SS2]

I think someone in the past has put in a different cam. At idle it has a distinctive lope to it. I suppose if I want a rebuildable engine I should at least drop the oil pan and take a look. I'll post back any results of my inspection.
Thanks all.

[ScoutFam]

Originally Posted by Mark Pietz

Will,
Why cam bearings? Wouldn't worn main/rod bearings do likewise? I once had one of these that had low pressure and put in rod bearings. Wow, went from a hopeful 10 psi to 15-20.

??

Scout SVs are notorious for cam bearing failure after sitting for extended periods....usually the front end of the cam. the bearings adhere to the cam and when you start it up the bearing material will shed off... check the oil pan for kibble and you will have the answer.

[Will Marsh]

Originally Posted by Mark Pietz

Will,
Why cam bearings? Wouldn't worn main/rod bearings do likewise? I once had one of these that had low pressure and put in rod bearings. Wow, went from a hopeful 10 psi to 15-20.

??

Probably, but if the rods or mains have that much clearance there's usually a knocking noise there as well. IME, the cam bearings in these motors are the usual culprit for low oil pressure.

FWIW, the '93 Buick I drive daily has that knock (mains) in the 3800. It's run 40K in 3 years since I decided I wasn't putting any more $$ in the motor it has, just drive it until it gives up. Not bad for a car I have $700 in.

My $.02, YMMV.

Will Marsh