REALLY Low Oil Pressure

[grant_71]

Ok, if you read my last post about the first cruise i took and the problems i started having, this might be part of it. Looking back i never had much oil pressure, but i thought it was just a faulty gauge, well i am idling with about 0-1psi of oil pressure, and if i rev up i might hit 4-6 psi. I have tried 4 gauges, (2 stock, 2 mechanical) they all say the same. I had a brand new pump in so i switched that out, didnt help any. Changed the oil filter, Didnt help. Any other ideas? is there a bypass valve like on a Che^y? this is a rebuilt 302 to pretty much stock specs. What would a spun bearing do? I am pretty much lost on this one, i can prime the pump with a drill so i know its working......]

Grant

 

[bigmuddy]

Grant, just thinking out loud but did you get the correct pickup for the pan you are using?

Ben

 

[grant_71]

Yep, both stock pickup and pan, and i replaced the gaskets in it to make sure it wasn't sucking air.

 

[76Broncofromhell]

It sounds like it could be a few things:

1) Oil galley plugs left out
2) Too much main or rod bearing clearance (over .004 and it's going to blow oil all over the place)


My guess is the "stock rebuild" was a job of putting in new bearings. Not machining down the crank .010 or .020 under and running .010 or .020" oversized bearings, leaving you with excessive clearance and thus low oil pressure.

 

[irwin]

you can run a motor on one pound of oil pressure seems to me you with instantly would melt down if that was the correct oil pressure.

 

[Bronco Brian]

Run it mine has been that way for a few years still keeps on going

 

[COBlu77]

Have you tried a new oil pressure switch (sender)? It's located just above the oil filter. Those are notorious for plugging up and then showing little or no oil pressure to the gauge. They're only around $7 or so.

 

[66Bronco]

Sending unit interference?

I've seen where someone has been a little to liberal with Teflon tape and it blocked the oil pressure sending unit passage. Might be something to check.

I also had a similar problem and it turned out that the oil galley plugs had not been installed by the machine shop


-Terry

 

[Broncobowsher]

There are 4 press in oil galley plugs. 1 under the intake at the back of the valley and 3 under the timing chain gear. Leaving one of those out will vent your oil pressure. The one under the intake is a common one for rebuilders who are not familer with fords.

That low of oil pressure isn't good. I'll say you probably didn't hurt anything, but I wouldn't keep running it like that. and don't put it under a load.

Most small engines (Briggs and Stratton) are splash lubed only. Model T was splash lubed. Even as late as the '50 the old Chevy blue flame 6 had pressure to the mains but the rods were splash lubed. 2 strokes are lubed off of oil fumes mixed with the fuel. It is surprising how little lube it takes to keep things moving.

 

[Pa PITT]

I sure wouldn't drive it or put it under a load ...BUT hopefully it something stupid
didn't you say you can prime it with a drill ...this means you've had the dist out ..correct ...that little shaft that goes between the oil pump and the dist. I think is 5/16 hex..It is supposed to be straight flat not twisted....I saw this once at my parts house that shaft had twisted which shorten it just enough to pull out of the dist ....hince no oil pressure due to the oil pump no longer being hooked to the drive gear ...also it's possible to drop that rod into the pan when installing the dist.
How thin is your oil not thinned out with gas is it ...
Does it knock as it's idling ...I'm kind of a redneck on something like this I'd pull the oil pressure sending unit out of the hole it in and plumb in a line and run it into a jar ..Crank it and see if it pumps any oil into my jar...
What do the lifters sound like ..

 

[grant_71]

I am thinking of checking the oil galley plugs, that would make sense why when i shut it off i can hear oil draining back into the pan. I did replace the sender and tried two mechanical gauges. There is no teflon tape blocking the holes, i can pull the sender extension out of the block and fire it up and oil just barely leaks out. I was the one who did the rebuild and i did have the mains ground and used oversize bearings. So anyhow looks like i am checking the galley plugs....which i am 99% sure i remembr installing, but i have been wrong before. I will let you know how it goes.

Grant

 

[Broncobowsher]

If the plugs are there, put the pan on (if it is off) and spin up the oil pump with the drill. That oil is flowing somewhere, you can here it. With the intake and timing cover off you should be able to see enough of the engine to figure where it is flowing to.

 

[Pa PITT]

Hey I just remembered one that whipped me for a couple of months ..years ago ..I built a 440 cid dodge had a lot of toys around it well it started up great no problem ...But after I drove it for about 5 mile I'm like you I had no oil pressure ...After changing the oil pump twice and taking it apart seveal times I had the intake off and spun up the oil pump all of a sudden you could see the oil blow by the sides of some of the lifters !!...WTF ..how can that be .so I pulled the lifters out I had 3 different lifter in it ...Now how did this happen I owned the parts house then and I had called the warehouse supplier and ask for bulk lifters .their the same just cheaper the warehouse buy them in batches if 100 or 250 in one tray ....I had ordered 16 the kid just grabbed 16 put them in a sack and shipped them to me ...
I got them and I checked 2 of them to make sure they were the same I really did but I did not check all 16 ...Now I put my lifter in a plastic milk jug full of oil over night so they will bleed out all the air ..So when you pull them out to install their driping of oil and you slide them in the lifter hole thinking alls well ...Lubed up like that you can't feel the difference they were 3 size in my batch ..Lession learned look at every thing ..
I called the warehouse, told them, they went back and that tray of about 60 had about 15 wrong in it ...I'm sure the kids $6.00 help didn't care but they heard about it ....

 

[grant_71]

We have a winner...

Before i even tore into the engine i looked at my spare parts kit, sure enough, there were the oil galley plugs....i got the one under the intake, but i missed the three on the front...not sure how, but i did (probably because this was my first SB Ford i ever built when i was 15...). so i got all those put on last night, i just need to pick up a gasket set today. The worst thing is i have built a 302 and a 289 since this one and obviously put those together right. It is probably a good thing if i screw up a rebuild it is my motor and not a customers.... Thanks for all the help, hopefully tonite i will have some real pressure when i fire it back up

Grant

 

[wildbill]

It sounds like it could be a few things:

1) Oil galley plugs left out
2) Too much main or rod bearing clearance (over .004 and it's going to blow oil all over the place)


My guess is the "stock rebuild" was a job of putting in new bearings. Not machining down the crank .010 or .020 under and running .010 or .020" oversized bearings, leaving you with excessive clearance and thus low oil pressure.

#1 would be one of my looks also there are a couple under the timming case cover screw in typ that could be lose ect. Good luck. Bill %) ;D

 

[grant_71]

Finally

Well after my Dumb@$$ 16 year old self screwed up the rebuild 7 years ago, i got it all back together and fired up, 65-70 psi.....runs a lot better now, just hope i didn't screw anything up when i ran it before Thanks for the help

Grant