1973 Ford 4000 Oil Pump

[doublewide]

Hey yall,

I’m looking for some opinions on this. I have a 1973 Ford 4000 SU farm tractor with the 172 ci, 3 cylinder diesel. Over the summer I noticed that the oil pressure gauge was showing a decrease in pressure. Unfortunatly I cannot remember for sure what the pressure was prior but I think it was about 50psi but now was down to about 35 psi. I decided to replace the pump, pressure gauge, new oil and filter.

I installed a new pump #FDS3542 from Steiner Tractor
New filter, Motorcraft # FL1A
6 quarts Rotella 15w40 and 1 quart Lucas oil heavy duty diesel stabilizer.

The new Bosch pressure gauge read 70psi at start up and dropped off to 65 or so once warm. I used the tractor to mow several times since for about an hour each time. The ambient air temperature each time was in the high 40’s or low 50’s and the oil pressure remained the same as described ( 65 – 70).

Today was downright balmy. Mid 50’s and I started the tractor to move a boat. I was focused on the volt meter at start up and not the oil pressure but did notice when the oil pressure dropped off suddenly to about 35psi. I got off the tractor to look around and saw oil blowing out of the base of the filter. I shut the tractor down and upon inspection found the base of the filter so distorted that the o ring was blown out. It took 6 quarts to fill back up and a new filter. I started the tractor again and the gauge pegged to 100 psi then blew the filter again.

What the bleep!

 

[doublewide]

From my manual it looks like the relief valve assembly is an integral part of the pump. I would say that qualifies as a defective pump...

 

[Bumpsteer]

No oem pump available?

Ed

 

[doublewide]

You know, I never thought of oem... until this happened. I put aftermarket injection pump, injectors, water pump... never a problem. Thanks for the input Bumpsteer.

 

[doublewide]

This is the original pump that was putting out low pressure. The bolt and washer appear to retain the cap that holds the pressure relief valve in the pump housing.

 

[doublewide]

This is the pump that I installed that malfunctioned. On this pump. The cap is completely covered by this plate.

 

[doublewide]

How do you get the cap out? I want to inspect the spring and piston.

 

[Joe H]

Just a guess, it's stuck in there. Hence the 100PSI. Try pushing it in, see if it moves or pops out. Should be a pretty stiff spring somewhere in the works.

Joe H

 

[Truck Shop]

When you removed retaining bolt it should have released spring and valve at same time.
try inside snap-ring pliers in that hole.

 

[doublewide]

I can see the spring behind that cap. I can see a piston / plunger from the inside of the pump after I remove the impeller and the impeller housing. It looks like the over pressure port directs the excess pressure back into the pick up screen. I did try running a #14 sheet metal screw into the cap to try prying the cap out on the junk pump. I didn't pry to hard as I didn't want to bleep things up.

I will get back into it tomorrow when I get back to work.

Thanks guys

 

[Joe H]

You shouldn't be able to run a screw into it, it's stuck solid if you could actually get the threads to engage.

As Truck Shop said, there's a strong spring in there that should have launched itself.

Joe H

 

[doublewide]

…and drive in a new plug(cap).

 

[doublewide]

 

[doublewide]

That plug is sure has a tight fit. The threads on the sheet metal screw tore off and the plug did not move.

 

[doublewide]

I just finished installing the replacement pump that Steiner sent me along with another new oil pan gasket. 7 new quarts of Rotella 15w40 and a new Motorcraft FL1A filter. 85 psi at start up…. Slowly building to 100psi within a minute or two and I shut it down. It did not blow the filter but I didn’t give it a chance to. I did prime the pump prior to install.

 

[doublewide]

Maybe I should go to a straight 30 weight.

 

[Truck Shop]

It's not a oil weight issue.