>image from the 1993 Ford Shop manuals - Lubrication system for the 7.3L removed for my reply<

Good image from the 93 shop manuals, Devin. I think it's relevant

I was looking at that same image from the 1987 shop manuals for the 6.9L a few weeks ago, relating to a problem someone had with an Oil Cooler. I remember following every little arrow indicating the oil flow and also looking to confirm where the back-pressure to the oil pressure sender is coming from (if it's the same as gas engines) but I couldn't confirm that from the images.

Later tonight after a needed break I hope I have the convenience to look that image up again and compare it with the 7.3L image. I will note any differences compared to the 87 6.9L and if justified I'll post the 1987 6.9L diagram. Much of the 87 manuals, even though it was a design change year (7th to 8th generation) are identical to 1985 and 86 manuals and then probably much still the same for the 84-83-82?

I'll be sure to look for additional information that is relevant to this topic thread but those manuals are huge and difficult to search through. Information can be spread out through several manuals so I might not have the energy to search for much.

I may have read the 'idi oil cooler thread' recently so I might give it a quick look or have to skip it.

I saw yesterday from your build thread, (after reading the tires thread) that you have gone crazy working on your F350. The term "obsessed" comes to mind because I know what that is like. I became obsessed with my truck and fixing it up to be a really nice truck but I can't do the amount of physical work that you have accomplished in the time frame that you have done it. It takes me a lot longer due to some physical limitations - mainly chronic pain 24/7 and it's not nice to me. (plus the chronic fatigue that it causes) So I have to spread work out over considerably longer periods.

This is the last restoration work I will ever be doing and I had always envisioned that it would be a classic high performance street car 50s-60s or old hot-rod of some kind but it turns out to be this big ol' diesel supercab pickup. That's fine with me as I don't want to live in a city and far prefer to live out in a remote area where the truck will be much more practical than a hot-rod. That's what I bought the truck for- to get me there with whatever I take with me. So, I will get just as much enjoyment out of restoring this truck as I would building a performance car or hot-rod.

I have an important tip for you on your rebuild (something you already finished awhile back so it's not urgent but it is important) and I'll try to send that to you in a private email. I am mentioning it here so I'll be less likely to forget it again. Just not in any condition to do it now, I need a break.

 

my 91 factory oil pressure gauge, moves when the engine is hot, go's down at idle, just as it should.. the IDI has a very robust oil system, with a built in oil pressure regulator, it samples filtered oil pressure, thru a small passage, this oil works on a small valve, that sends excess oil directly back to the pan. as oil heats up, and viscosity drops, less is returned. that way the pistons are cooled consistently, and bearings have the necessary oil pressure. One should use a quality filter such as a 7.3 power stroke mobile 1, 601 it has two stage filtering 18 and 5 micron. its a little bigger and flows more than the stock IDI filter. fits most IDI applications, may hit under carriage on some trucks....

 

I took a video today, though poor quality, it wil show that on a 1993 the gauge so long as it's above 4psi or so, will read NORMAL (its actually reading lower today despite having good oil pressure)

The turbo i replaced i believe had larger bearing clearences even though it was just rebuilt. My oil pressure sender and gauge are both on the turbo oil supply, which is fed from a 1/8" NPT fitting in the block. Even though i have a turbo block, it's tapped 1/8" NPT, my 94 block is tapped 1/4" NPT. I think the 1/8" NPT doesnt necessary supply adequate oil to read the pressure being it's atmospheric pressure on the other side of the turbo. Which is why when i switch the turbo the new turbo probably has tighter tollerances.

I think my mains are seeing plenty of pressure, in any case my 94 block is at the machine shop finishing up to go in this truck anyway. But the 93 IDI gauge does nothing other than say there is pressure, not how much or any varying. My 1996 Powerstroke is the same way.

 

Double check your sender for me. Is it a smaller module 1" in diameter that has a plastic top to it, or is it larger, about 1.5" in diameter and a solid metal can?
The first is a switch.

Remember that at idle, your alternator voltage will drop(one of the downsides to the 1st gen alternators on these trucks), usually down into the 13.5V range from the 14-14.5V range.
That may be what you are actually seeing on your gauge.

 

Hi Shawn, I was up all night again and too tired to write this but I will.

I confirmed the changeover to switches and the years it occurred for each truck and van model, after Rob posted about it. I'll mention that later after some sleep.

I was so stressed out and angry about what Ford did with these gauges that I actually got sick and puked! I was also really burnt out from lack of sleep and not feeling well. It's taken since then to recover!

This action by Ford has caused an incredible amount of confusion even in the parts industry! At least in the sales of parts!

I discovered something very interesting and I'll post the web page for this later. In trucks/vans that came with a switch there is a 20 OHM resistor in the circuit from the switch to the gauge. Without that resistor the ON_OFF type pressure switch will go to direct ground and peg the gauge to the right side and with the resistor in the circuit the gauge needle will go to the middle of 'NORMAL' = a position on the stock gauge (according to that web page), that would indicate approximately 40 PSI if the gauge was reading actual pressure. In the OFF state of the switch the needle will of course go to zero.

Now, if you install a real pressure sender in place of the switch, that resister in the circuit will cause the gauge needle to read a very low oil pressure! When I read that I wondered if this is actually what you were experiencing when the factory gauge was/is reading so LOW = 3-4 psi I think you wrote. That would explain it, if you have a real pressure sender installed but did not remove the resister in the circuit.

If anyone's truck is one that came with the ON_OFF style pressure switch (or later variation of it if there is a variation) then that 20 OHM resister is in the wire coming from the switch to the back of the instrument panel and it should be in the wire somewhere close to the switch. Otherwise, the person who wrote that web page thought that in some of the newer models the resistor may be on the instrument cluster circuit board and can be located by tracing the lines on the circuit board from the gauge location.

I can't focus enough right now to analyse what you wrote above about the turbo change and gauges - I'll do that later but I'm wondering if the change in pressure reading that you experienced after putting on the new turbo is due to a change in the wiring- or the change in the in the senders you just described or maybe both.

 

The top gauge in my pillar pod with the blue digits is a digital Autometer 6927 Pressure gauge, its a real sender in addition to the factory gauge, i installed both to ensure i had two methods of measuring oil pressure. I had a Glow Shift gauge with electric sender before this too with similar oil pressure readings, slightly lower though. The Ford factory gauge has alwasy read normal so long as the engine is running. If i twist the connector on it it will vary a little, with the key on engine off it reads no oil pressure. I'm just adding my experience because the ford gauge says everything is fine, which many rely on, and i have used two not so cheap, oil pressure gauges to verify it is low.

Here is a picture of my oil senders on top of the turbo. The larger being the Autometer, the smaller white the Ford factory

 

Here is the link to the webpage I mentioned in my previous post. Keep in mind that the switches, pressure senders and gauges we are talking about are used in a number of different models and years of Ford cars and trucks.

Ford Oil Pressure Gauge Fix

 

That was a very good post by speedwrench72.

and... I also had the same question (plus a bit). But I see now that he has an E350 Van which has a very different style of sender/switch than the trucks and they may work differently and at least some some have additional functions.

The 91 Trucks have the sender/switch that I think you are describing, also shown in the parts listing for 88 trucks at Rock Auto. Here is that list:

By the way, it appears from this list and some misc. searches that in 1988, F250 trucks were made with both systems. A couple of the Vans changed to the "switch" type in 1987 and other vans not until 1990-91

1988 FORD F-250 7.3L 445cid V8 DIESEL Oil Pressure Sender / Switch | RockAuto

Yesterday I discovered that the original can style (real) pressure sender on my truck was replaced with: STANDARD MOTOR PRODUCTS PS240T T-Series
- the one with the gray plastic top which I have also pretty well confirmed that this is a simple switch type, even though the design appearance is a bit misleading. It will be replaced soon with a proper replacement pressure sender like the one that is supposed to be in it!

ALL of the replacement senders for the 1987 trucks are the metal can type, real pressure senders and after cross referencing those and others with Ford OEM part numbers I have decided that the STANDARD MOTOR PRODUCTS PS60 is the safest bet to get the factory gauges working properly in any of these idi trucks and vans at least up through 91 and probably up to 1997 for all of the diesel trucks and vans.

In any of the Rock Auto listings if you click on the part number a pop-up screen will show you the makes, models and years of vehicles that the part is made for. The INFO button will also show the OEM part numbers that the part replaces.

Here is the 1987 list:

1987 FORD F-250 6.9L 420cid V8 DIESEL Oil Pressure Sender / Switch | RockAuto

Now I am going to get some sleep.

 

The smaller factory sender in this picture... is the oil pressure switch, not actually a "gauge sender"

 

My problem is the opposite, it pegs out @ 55mph & stays pegged until I shut her down. Got no weird noises...NOTHING. But it scares the **** outta me because this is my family's ONLY VEHICLE!!!! MY e350 4x4 Club Wagon with a 7.3L Powerstroke diesel in it..I I just replaced the serpentine belt when all this happened.