Hey all,

I've slowly been losing oil pressure on my '83 F350 with a 460. When I got the truck the pressure seemed fine according to the factory dash gauge (needle in normal range). I changed the oil and filter a few months ago and used a Fram filter with Mobil 1 10w30 synthetic. Now I know the 10w30 is not the right weight so I'll be changing it soon again. But I've noticed that the oil pressure's been slowly going down. At cruise the needle would be about 1/2 way up in the normal range. Now it's barely into the normal range and at idle it drops all the way to 'L'. I did have an issue a few weeks ago where the gauge just quit for a day. So I'm not terrribly worried as I don't hear any knocking or weird noises coming from the engine.

How accurate is the factory gauge? Would an aftermarket one be a better choice? I'd prefer not to grenade my engine after all the work I've done to the truck.

 

Also, how hard is it to check the oil pump pickup screen? Can you see it through the oil pan drain hole?

 

here is a thread that may help. Just the 1st one that came up through search.

https://www.ford-trucks.com/forums/1...-question.html

I wouldn't trust the stock oil gauge one way or the other. The sending unit works through grounding, so any wiring issues/sender issues etc will give a false reading. I've also read on here that there is inconsistency between members trucks on what means what as far as the gauge. There trucks may run noticeably different pressures or it could be inconsistent gauges. I'd guess the gauges have a lot to do with it.

I would personally put in a good mechanical gauge. Something that important I wouldn't leave to a subjective gauge. You should be able to ground the sending unit and see if it moves the needle the whole way. But that really doesn't nail down any issues. At least with a mechanical gauge you will know if you have an engine issue.

Hope this helps a little or atleast points you in the right direction (or a direction,lol).

Charlie

 

I do not know the answer to this. Hopefully someone else does.


BTW my local advance is running half off sunco gauges. Maybe yours is, if money is an issue.

 

I had not considered a ground issue. My engine harness was pretty bad when I bought the truck. The battery ground cable's attached directly to the block right now though I don't think grounding would be the problem.

 

Your block could be very well grounded but as I've learned not everything connected to is very well grounded lol. With the rust mud and gunk on mine it's shocking anything electrical works.

Either way checking/replacing your sending unit or going to mechanical gauge, to me, seems like the place to start. It could keep you from running down issues that might not be there.

 

The block has to be grounded to the frame and the cab. Most V8's have a ground from either the intake manifold or the driver's side valve cover to the firewall. If that's not there the cab isn't properly grounded.

But I agree with Charlie - don't trust the factory gauges. Install aftermarket. I like the mechanical ones as they have a 270 degree sweep vs the 90 degree sweep on electrical ones.

 

From my experience, the factory gauge ain't very accurate. Mine reads on L from 60 PSI and reads on the A at 20 PSI hot idle. All the rest of the gauges work fine. So, not sure whats up with my oil pressure gauge, but I've noticed lots of other people have the same deal as me. Put 15W40 in the engine.

 

Did an oil and filter change, went with conventional 10w40 this time. Still seems low but did come up some on the dash gauge. So I'll go with it for a bit and see what happens. What gets me is that the pressure was fine before I did the first oil change to synthetic and seemed to be fine afterwards for a bit too.

 

A synthetic will have a top-of-the-line detergent package. My guess is that it removed sludge that was restricting some passages, thereby increasing the flow of oil and, therefore, reducing the pressure. If it isn't using oil then everything should be fine, although you may want to use a higher viscosity oil.

 

One time, I substituted 10W30 Mobil 1 in what is now my son's truck. As soon as I started the truck, the lifters made noise. The synthetic oil is thinner. Try this experiment: take a quart of conventional 10W30 in one hand and a quart of synthetic 10W30 in the other hand. Rock them back and forth and feel the difference!

 

You may want to ditch that 'Orange Can of Death' too!
Cardboard headers, fewer pleats and a crappy bypass make for poor filtration in my book.

I run 5 or 15-w-40 Rotella without problems.
Think I may try Delvac for my fall oil change.

 

And to add to the votes, get a mechanical gauge on there. That way you will know for sure.

 

I've never tried.
Maybe a borescope would help?
Trying to keep drips out of your eye and a flashlight in there at the same time is going to be a challenge.

My cab has a braided strap on either side of the cab. From the pinch weld to the footwell cab support of the frame.

No doubt a gauge that gives an *actual reading* is good peace of mind (or a nightmare staring you in the face)

 

About the ground....

I wasnt trying to suggest that his block wasnt properly grounded. If the sending unit isn't making good clean contact with the block then I would assume that it could throw off the gauge. When I removed my sending unit, to install the mech, it was black with gunk all through the threads. I can only assume in at one point leaked and sludge eventually filled in, I don't know why it was dirt and black but it would shock me if mine had an adequate path to ground.

The larger point I was failing to make is that a lot of things could be ruled out by spending an hour and $20-$30 installing a mech gauge.

Imo it would be like trying to fix an electrical problem with out a multimeter. You got to be sure of where you are if you want to figure out how to get where you're going.

I do wish you the very best if luck. I'm still trying to figure out the whole volume/pressure aspect of oil. Lubrication vs cooling etc etc. It's too much for my feeble mind to take in at once lol