1979 351w oil pressure and oil weight

[dominickbuff]

I have a 1979 351w engine and have low oil pressure at temp(good oil pressure when cold) I am currently running 10-40 will going to 20-50 help?

Engine has 250k miles and has never been rebuilt

I have confirmed the oil pressure with a mechanical gauge

 

[ka9mnx]

I ordered the pump it will be in later in the week…

Like said above, order a set of rod and main bearings along with the oil pump.

Are you checking the oil pressure with a mechanical gauge?

 

[D60]

Do you have an interest in keeping this original? A 351 from that era might be pretty low performing.

The 351Ms were rated at something like 152hp when new

OP, did the vans get a Windsor in '79? I didn't think so.....?

 

[AdmiralYoda]

Hold on a sec, lets not just throw good parts at it. If it was 3-4 psi while running and driving I'd expect it to come apart. What gauge are you using to measure the oil pressure? Is it the one on the dash?

I'd install a mechanical gauge on the engine somewhere to verify the oil pressure and perhaps change the gauge sending unit (or gauge) if it is off

If the oil pressure actually is that low and it hasn't self destructed a high volume oil pump and the thickest oil you can find will help out for a little while. But with the mileage that high....it might be time to start thinking of a rebuild or replacement.

 

[dominickbuff]

You cant drive with only 4 psi. You will damage the engine quickly. Time to pull the pan and roll in bearings and a pump,then hope the cam bearings are good enough.

Pump has been ordered

Like said above, order a set of rod and main bearings along with the oil pump.

Are you checking the oil pressure with a mechanical gauge?

yes

 

[Bladecutter]

It has 3-4 psi when warm

When was the last time you changed the oil filter?
Let's make sure there isn't a restriction there, first.

 

[DuckRyder]

if it really has 3-4 lbs at speed im surprised it hasn't self disassembled.

Sure put an oil pump in it if it isn't too bad of job, but unless the refill spring is stuck i suspect you're engine shopping, unfortunately.

 

[dominickbuff]

The 351Ms were rated at something like 152hp when new

OP, did the vans get a Windsor in '79? I didn't think so.....?

Yup 5.8 Windsor

 

[dominickbuff]

When was the last time you changed the oil filter?
Let's make sure there isn't a restriction there, first.

Filter and oil change was done less than 10 miles ago … can’t hurt to check tho

 

[D60]

Yeah 3-4 at hot idle for a Windsor is actually fine (not ideal, but not a problem). But if you're seeing that when driving above idle, that's not good.

Many, many years ago a buddy with a fullsize Ford '80-86 swore the old Fram orange can of death had let go of some paper element and clogged an oil passage destroying his engine. I'm not sure exactly how that was verified and I know Frams are no longer this bad, but I guess looking for a restriction first is not a foolish step.

 

[RedSpider]

Wouldnt surprise me if it does turn out being the oil pump. I was victimized twice (302's, not 351's) by bad oil pumps from that era.

 

[OVERKILL]

Throwing a pump in it won't solve the problem, I'd be checking the bearings. Our '95 351W GT40 Pro Boss has ~40psi hot at idle with 5W-40 in it for reference.

 

[ripcord]

If the oil pressure doesn't increase to 20 it so psi with the engine reved up to cruising RPMs, then you need to fix whatever the problem is before the insides of the engine show up on the outsides.

When you pull the pan, at least remove a main bearing cap and a rod cap to see how the bearings look. I bet you see the bearing surface worn through to the copper. If you do find really worn bearings, then a new oil pump will probably only increase pressure a small amount and new bearings are in order. Also, if you drag your finger nail on the crank surface and can feel it catching, then the crank needs to be polished at a minimum.