Zero Oil Pressure

[Mongo]

My deuce usually runs about 15lbs at an idle and 25 while driving. It was hot yesterday (90 + degrees) and at one point while idling the oil pressure dropped to zero. The oil is full and was changed by the previous owner just before I bought it. The motor has about 43K miles on it. I have no idea what oil he used but he seemed knowledgeable.

Now the question is if I should change the oil again just to be sure of the grade, change the oil and filters, or just buy a crate motor a local guy has. Any opinions?

 

[WarrenD]

The first thing I'd check is to see if the oil pressure gauge is functioning. Not sure if they are mechanical or electrical. Electrical gauges have a sender and I've seen many of them go bad. Hate to change an engine for a bad sender or gauge.

 

[kastein]

Verify with a mechanical gauge before doing anything. I haven't done this yet but it is on my list of things to do.

Mine runs around 20 idling hot, 40 or 50 idling and running cold, 30 to 40 running hot. And my motor hasn't seen the best of treatment. But if there is anything I know it is that electrical gauges lie when something is broken or worn (which can be invisible) so I want to put a mechanical gauge on it before I do anything else.

At least on a 5 ton with a 465, the sender is in the block at the rear on the passenger side (below the manifolds.)

 

[hndrsonj]

Yep, verify with mechanical gauge.

 

[nk14zp]

First check to see if you have fuel in your oil!

 

[LowTech]

My deuce usually runs about 15lbs at an idle and 25 while driving.

That makes me think that your sending unit and gauge are not made for each other. It's half what most read.

Def check what others have suggested first.

 

[91W350]

That has to be a sick feeling. I have one that stays 45 to 50 pounds and the other indicates 25 to 30 all the time, 15 on a hot idle....sweating over that a little, think a mechanical gauge is coming to a shop near me..... Glen

 

[319]

Don't drive it until you check it out. Minimum oil pressure at idle is 10psi. Hopefully it's just a bad sender or gauge.
Could also be a 60 psi sender and a 120 psi gauge. Be sure you have the correct sender.

 

[A/C Cages]

Might be just the gauge, mine works when I smack the dash or hit a bump. I will change it out when I get it back from being bobbed.

 

[tie6044]

Don't drive it until you check it out. Minimum oil pressure at idle is 10psi. Hopefully it's just a bad sender or gauge.
Could also be a 60 psi sender and a 120 psi gauge. Be sure you have the correct sender.

How do you know what sender you have?

 

[davey8943]

How do you know what sender you have?

It is stamped on the sender. You will likely have to pull it and sand a few years worth of grime and paint.

Just for completeness sake, if you had a 60 psi sender and a 120 psi gauge, the gauge would read high. The sender would send 50% of 60 psi (30 psi) and the reader would show 50% of 120 psi (60 psi).

My vote is either fuel dilution or bad sender all together!

Good luck!

Dave

 

[Jimma]

One of mine sometimes goes to zero, if I tap on the glass, it will return to where it should be.

 

[Mongo]

Hmm.... when I checked the oil the other day it did seem far too thin and I was thinking to myself that it was diluted with something. How would I be getting fuel into the oil?

 

[m16ty]

Hmm.... when I checked the oil the other day it did seem far too thin and I was thinking to myself that it was diluted with something. How would I be getting fuel into the oil?

More than likely it would be coming from the FDC. Do a search on how to bypass it.

The flame heaters have also been known to dump fuel. It could also be a leaking IP but this doesn't seem very common.

 

[Mongo]

I am fairly certain my sender and gauge are a matched set.

I am equally certain that my fuel is becoming contaminated.

I will check out the FDC before I do anything else.

Thanks for everyone's help on giving me a quick (and hopefully accurate) diagnosis.

And just as an FYI, the reasoning behind me jumping straight to the idea of a motor swap:

I have a lot of miles and hours on my motor compared to most of the Deuces out there.

I need to change the clutch so I will be separating the engine and tranny anyway soon.

A complete crate motor is $1000 or less. It is built with a C-Turbo, Fresh IP, Fresh Generator, Fresh Compressor, and so on. The IP and turbo alone would be worth the money.

I like to have spare parts for anything I own.

Didn't want you guys to think I was rich, stupid, or crazy for jumping straight to an engine swap for a seemingly simple problem.

 

[davey8943]

...
A complete crate motor is $1000 or less. It is built with a C-Turbo, Fresh IP, Fresh Generator, Fresh Compressor, and so on. The IP and turbo alone would be worth the money.

I like to have spare parts for anything I own.

Didn't want you guys to think I was rich, stupid, or crazy ...

Mongo,

If I had a less than 1K fresh engine nearby, I would seriously consider buying it, if even just to sit on!

Oh, and don't worry, no one here thinks your stupid or crazy... Mainly because we are all CRAZY!!!

Welcome to the club!

Dave

 

[Mongo]

Well.... I had a REALLY bad time getting the FDC bypassed and the oil changed. Several incredibly stupid decisions and self-inflicted delays later as well as a week of "black ball" days, I got it done.

The work done:

Bypassed the FDC due to a perceived leak (it was not leaking).
Replaced plastic fuel line with steel line and new brass fittings.
New Rotella 15w 40 oil and filters.
Fuel settings not changed.

The result:

Still getting only 15 lbs oil pressure at idle and 25 while driving (at least it is consistent).
Truck now has a TON more power.... so much that it worries me.
My clutch now slips "on demand" when in 5th and I hit the gas.

I am reluctant to change the clutch until I get the oil pressure problem sorted out as it may cause me to pull the engine.....

 

[davey8943]

Mongo,

How soon after changing oil did the pressure run at 15 and 25?

Clutch slippage is one of three things:
1) mis-adjusted clutch
2) "lubricant" on the clutch disks
3) entirely too much power.... as in "the multi shouldn't be able to make this much power" too much power....

How much free play is there in the pedal? Where is the friction point? Should be about 2-3 inches and 3-5 inches...

If your clutch is adjusted right, pull the inspection cover on the clutch and see if you're leaking gear / engine oil on it!

Good luck!
Dave

 

[greg2560]

mine runs around 60 psi hot or cold fresh motor the temp would go on the fritz some times bad ground on the gauge mount. Just tap and looks norm on the temp guage. Check your grounds

 

[SEAFIRE]

Our Mechanic swapped out our electrical guages for mechanical ones he got at NAPA, fit in the dash, and works a whole lot better.

I don't know about your increased power issue, when we bypassed the FDC on our original motors, the power was the same.

How do you know your FDC was not leaking before you bypassed it? just curious