Mike's 1993 Dodge Cummins Truck Blog

The local Cummins parts house, FJM Trucks, called a pump rebuilder and got me the answer. I described to the rebuilder on the phone what the parts looked like. He told me the tiny hole in the piston faces down into the bore where the control valve (pressure regulator) sits. The rebuilder says that guys that play with pump pressures have this happen more often. But it happens in stock pumps as well. The clip goes in only until it’s flush with the bottom of the control valve. The top of the control valve can be pounded down with a drift and hammer to increase the pressure he said. Also he mentioned that if I did that the pump would have to be calibrated again. Now worries here, this old girl is staying stock. The pic shows the correct way this valve goes back together.

I installed new orings as soon as I got the control valve apart. That way I didn’t mix up any orings with other assemblies.

This control valve head takes only a 10mm wrench. It was very tight. So I had to use some leverage to get it free.

Here are all 4 o-rings on the control valve. This also shows the orientation of the parts. The governor shaft seal is installed but is still waiting for it’s washer and jam nut.

Control valve with o-rings removed without adding any scratches.

The control valve had 3 parts loose when I took it out of the pump body. In this pic I installed the spring and piston into the control valve. The only thing remaining was this clip. It seems like it would be a press fit.

I hope this is how the control valve parts go back together. I used a magnet to pull them out of the bore the control valve screws into.

No place for the spring and piston to be held in the cavity that they came out of. It must mean that the parts are held in the control valve with the circular clip.

Under this governor shaft nut, is the leak that started this whole project. The o-ring was brittle. When I took it off of the governor shaft, it was stiff and then it cracked. I got the nut loose. The shaft itself was 2.6 turns out from being fully seated. One of the forums says that it should be bottomed.

Somewhere I found a post that showed a tool ground from a flat blade screw driver that will remove the front seal. I just wish I knew which site.

Here is another tool ground from a screwdriver. Here is the site that it came from.

The engine tag from Cummins. The engine number is required for ordering parts.