This is the difference between the OEM front oil seal and aftermarket replacement.
The OEM is the one in back. see how much thicker it is?
This is the entire oil pump:
5 bolts and it's off. 2 bolts are long, 3 are short (one of which is just a little shorter than the other two) MAKE SURE you note which bolt comes from which hole. The o-ring will probably be stuck to the back of the pump when you remove it. Also, the inner oil pump gear will probably remain on the drive gear on the shaft. When you remove the large gear from the housing, DO NOT pull the gear out at an angle. It will jam. It must be pulled straight out. Check the housing for this kind of wear. This pump was still delivering good pressure, but I used a newer one.
get a 7/8" BOX end wrench and loosen the "nut" on the front of the housing. There is a copper washer that is suppose to be under this cap, but this one was missing. Finish unscrewing it by hand. There is a spring under it, so when the threads are loose, it will pop out. Keep some pressure on it when it releases. Pull out the spring, and use a small hook-shaped tool to pull the piston out. wrap a clean rag around an unsharpened pencil and clean out the bore. Check for gouges (bad ones). clean the oil off of the piston and inspect it also. lube the piston (oil or a light coating of grease will work) and slide it back into the bore. It should move freely with no hang-ups or rough feel. drop the spring back into the piston, and re-install the copper washer and cap (while pressing down, turn).
Hope this gives you a good idea of what to expect.
