restoring the engine oil pump

[randiego]

Folks, A lot of times, when we are rebuilding our engines, no one wants to use a used oil pump in our rebuilt or reconditioned engine. Well, not because I am cheap, but I am dearth on throwing away a part just because it has been used. The following is a guide line for restoring a mildly used oil pump.

Start by cleaning the pump externally from all smudge or deposits that will easily come off. I take the pump to the solvent tank and give it a good scrubbing with a brush and a 3M scouring pad. After, I wash the pump with sudsy, warm water in the sink, removing the balance of the oil and solvent and rinse thoroughly. Initially, I resisted taking the housing into my media blast cabinet, not wanting to get any contaminants in the passages of the pump. Besides, it is for me and I am not interested in the external cosmetics as no one will see it.

Now is the important part. Over a clean towel, disassemble the pump. I start by prying off the pick up screen and inspecting the inside of the pick up, looking for telltale metal filings. IF there are particles present, the pump may be non serviceable. Especially on an engine that may have had a piston, valve or crank failure. If there are no (or few) particles, that is a good sign. A lot depends on how the previous owner took care of his (or her) motor. One who regularly changes oil and filter will result in a fairly clean engine. I then take the three bolts holding the housing together, taking care not to let it fly apart as there is a spring in the housing.

Once you have the pump apart, noting the location of the spring and the two special washers that go on the ends of the spring, take the plate that covers the two impellers and look at the surface of the plate, the two impellers (one is on the long drive shaft and look at the general condition of the parts. If the plate has deep circles (from the impellers wearing into the surface) or if the bottom of the housing has deep cuts in the aluminum housing, the pump may not be serviced and is a candidate for the recycle bin. If the inside surfaces on the aluminum housing have minimal wear and are not deeply grooved, you have a good candidate for restoration.

At this point, I scrub the screen pickup housing, pump body and top cover as clean as I can get them. Internally, they usually are really clean. The heat of combustion heats up the oil, burnishing the exterior of the pump with a brown patina. This is not an issue and do not be tempted to clean them in your blast cabinet. This leaves microscopic particles behind and no matter how much you clean and blow out, you can never be assured that you get all of the residue cleaned out of the passages in your pump.

I take the cover plate, that in most cases, has wear circles in the steel. If they are no more than 8 to 12 thousandths (approx.) deep, this is an easily serviced item. Look into the bottom of the housing on the other end of the impeller gears. As long as they are not grooved and have mild circles (wear), the housing should be o k. Essentially, there is no service work to the impeller gears. If you try to service them, all you accomplish is increasing clearances and losing oil pressure. Remember, this is for a pump with minor wear.

I use 3M 180 cut (wet or dry) sand paper (full 8X11 sheet). I have a steel topped work bench that is perfectly flat that is my surface that I work on. If you do not have a steel topped bench, you can use a sheet of glass to put on your bench (1/4 or more thickness), to use as a flat base.

Keep a small basin of water near and wet the paper, laying it on the flat surface. Using circular motions with a mild amount of pressure and start sanding. The paper will stick to the glass or metal topped bench from molecular adhesion, aiding in holding the paper secure for the sanding procedure. The paper will fill with material being removed from the plate, thus frequent rinsing of the paper and the plate.

After a good amount of sanding, wash the paper off to clear the material from the paper. Inspect the plate. You will notice a difference as the plate is smoothed. Continue with the circular sanding and rinsing till you have all the groves removed. It will take time but the results are easily attained. I finished the plate in less than 20 minutes. When you have the plate smooth, wash the plate thoroughly, removing all of the loose material. Thoroughly wash the pump and blow the parts out till dry.

Use liberal amounts of assembly lube, coating all the internal parts and re assemble the pump. Be sure to re-crimp the screen on to the pick up. I use a plastic mallet and tap the screen all the way around for a good, snug fit. The pump should be back to 95 to 98% of the original pressure that the pump put out at new. Remember, this procedure is for a mildly worn pump and not a really rough unit.


For additional assurance, I took my pump to my re-builder. He looked at what I did and agreed that it looked great. When I have the engine back together, I will do a pressure test on the oil system to see exactly how much pressure that the re-coned pump puts out.

This simple procedure will save you over $150.00 for a new pump. AND you can use the resources saved on other things that you will need for your FIAT.

Ciao,

Randiego

Coming soon; servicing an early fuel pump.

[RRoller123]

nice contribution!