Air in the oil line--from WHERE?

[Michael Fowler]

I tried to piggy-back this onto another thread, but maybe it needs its own place, so here it is.
After arriving at the IDI ralley, I noticed that oil pressure had dropped from its customary 40 psi hot, at speed, to about 15, with the hot idle reading under 5psi. I removed the (new) copper tubing from the rear of the gauge to see if there might be air in the line like there was a few weeks ago when I replaced the original plastic tubing with the copper. Well, there was air, plenty of it. In fact, a continuous stream of air bubbles.
This puzzles me.
I cannot think of how air can get into a pressurized oil system. Therefore I am inclined to think it must be coming in before the oil pump. That means, the pick up. in the oil pan.
I WIL NOT drop the oil pan with the engine in the truck (ever again). So it looks like I will be pulling the engine to investigate.

Is my reasoning sound? Is there another possible source for air in the oil stream?
Thinking a little out the box.....Has anyone cut a hole in the bottom of the oil pan to access the pickup? Some of you might remember air-cooled Volks Wagens had a large plate on the bottom of the oil pan. Would something like that work?

 

[towcat]

if you cut the hole, how are you going to weld it back up? all that oil dripping down isn't going to stop anytime soon. if you have taken apart the lower end before, you know that there's two possible air intrusion points, one is the pickup tube to the pump and the second is the pump to the block.
that being said, oil gets beaten to a foam in the pan. one of the additives is designed to break down the foaming as quickly as possible.
how old is your oil change?

 

[MARQ2277]

Huh, you say, you are getting air, in your pressure line. It would seem to be somewhere from where you attached the tubing, to the gauge itself. Try attaching the gauge directly to the oil plug in the block, either in the back where the original sensor is, or in one of the access plugs in the oil cooler. Try a different tubing set up, etc., before tearing the engine apart. And, if after all that you still believe the air is still coming from the engine, start with the oil cooler, oil filter flange, etc.

Marq

_________________________________________________________

1990 Ford F-250 4X4:
7.3 IDI with 120K on the clock:
ATS Turbo with waste gate:
Stage One Injectors (Oregon Injector Service):
Complete Return Fuel Kit (Oregon Injector Service):
DB2 Pump, cranked up with Cold Advance wired permanently on:
4” down pipe, 4” straight through exhaust stopping between cab and bed (no fuff on my stuff):
Torque Converter Lock Up Switch (On/Off/Lock-Up):
E4OD Line Pressure Controller (adjusted to fast/firm shifts):
4” lift w/Rancho shocks:
Big Fat Tires on custom rims:

Tows 1985 fully loaded heavy 28 foot RV (my house) everywhere:

 

[Michael Fowler]

Oil had 200 ( hundred) miles on it.
I even changed it again to verify that the oil was not the problem.

MARQ227---I fail to see how any leakage in the tubing, or plumbing associated with the gauge would draw air INTO a pressurized oil system. Am I missing something?

Engine is N/A--no turbo--so there is no source of pressurized air from that source.

 

[GenLightening]

How long did you run it without the gauge attached? After shut off, the oil will drain back into the block, how much depends on how long it sits. That's one flaw in the mechanical design for oil gauges. Have a pan ready and leave it running for a minute or 2 and see what happens. You may be able to keep it from happening by having a loop or 2 in the line to keep the oil from draining straight back into the block. Might be worth a try.

 

[Michael Fowler]

The copper line has several loops. I put them there for strain relief as i never thought of drain back being a problem. I guess I did something right in ignorance.
cool!

 

[Joe Mc]

I was reading about it somewhere and now I can't find it.
About the nut that supports the oil-pump pick-up tube coming loose and causing the tube to crack and start sucking air.

 

[MARQ2277]

No, I was just trying to be helpful and making sure nothing was overlooked before taking the engine apart. Let us know what happens.

Marq

 

[icanfixall]

I'm guessing you are using 1/8th inch copper tube. If so when I changed my old copper tube of 11 years my oil pressure was very slow going up or down. I tried several differant locations but all the same. It turned out to be the cut ends of the copper tube. When they are cut with a tubing cutter they really need to be "cleaned out" at the cut. I had less than a 30 thousands hole for the oil to push thru. This delayed the pressure going up or down. What tipped me off was when I shut down the motor the pressure would stay up for about 6 seconds, then very slowly drop to nothing. This is why I changed to an electric Isspro EV gage. Plus I never did like oil in the passenger compartment. That could really make a hot dirty mess requiring a new interior... Maybe some skin too. I've seen my oil at nearly 300 degrees pulling some grades here in So Ca...

 

[Michael Fowler]

No, I was just trying to be helpful and making sure nothing was overlooked before taking the engine apart. Let us know what happens.

Marq

I really do appreciate any input. Please do not be offended--but I am trying to understand how air can get into a pressurized oil system. I do not think it can--so I am leaning to pulling the engine. believe, I would prefer am easier fix.

 

[Fordsandguns]

Why not try an electric gauge like ICFA and see if you are stil getting the low reading? Then if you are, go ahead and pull it to check the pump and pickup tube.

 

[MARQ2277]

Oh, no problem, trust me, when I found oil in my rediator I wished for days for an easy fix. But, I had to suck it up and pull the oil cooler to fix my little oil issue. At any rate, keep us in the loop.

Marq
_______________________________
1990 Ford F-250 4X4:
7.3 IDI with 120K on the clock:
ATS Turbo with waste gate:
Stage One Injectors (Oregon Injector Service):
Complete Return Fuel Kit (Oregon Injector Service):
DB2 Pump, cranked up with Cold Advance wired permanently on:
4” down pipe, 4” straight through exhaust stopping between cab and bed (no fuff on my stuff):
Torque Converter Lock Up Switch (On/Off/Lock-Up):
E4OD Line Pressure Controller (adjusted to fast/firm shifts):
4” lift w/Rancho shocks:
Big Fat Tires on custom rims:

Tows 1985 fully loaded heavy 28 foot RV (my house) everywhere:

 

[Michael Fowler]

Why not try an electric gauge like ICFA and see if you are stil getting the low reading? Then if you are, go ahead and pull it to check the pump and pickup tube.

IFCA's problem was not the same as mine, therefore I do not believe his solution will help in my case. He had a gauge with severely dampened readings. The reduction in diamewter at the ends of the tubing makes sense for that observation.
My issue is not a slow-reacting gauge, but low oil pressure --observed on both the factory, and my extra mechanical gauges-- accompanied with air in the tubing for the mechanical gauge. If someone has observed where a loose fitting, or something else allowed air to enter into the pressurized line, I would like to know about it.

 

[icanfixall]

Before you pull the motor why not try running the motor after its warmed up and flush out the line into anything safely in the passenger compartment. Maybe a large plastic bag?? The hook it back up and see what the pressure is.... I just hate to see you pull the motor and find nothing. Thats plenty of work... I know..

 

[Michael Fowler]

Good idea! I have run it long enough to allow maybe 4 ounces flow, but, I'll try a larger amount.

I would not want to be like (person un-named) who installed a nicely painted rear axle only to discover it was the same ratio as the orignal axle.....