oil pump rebuild. off the engine. you can put new gears,midplate in with it on the engine,but anything more like i'll be doing requires removal of the cover,and then removal of the fuel and water pumps.
here's the victim. 9 bolts hold the cover on. the big plug is the pressure relief valve assembly.
if off the engine,before dis-assembly,pull up and down on the pump drive shaft to feel the freeplay. this one had a lot.
that will be remedied in a bit. remove the pressure relief plug first,withdrawing rthe assembly,as shown. it is in correct order for re-assembly in pic as well.
remove the 7 bolts holding the pump cover to the housing. 7/16" bolt heads.cover may need a tap or so to dislodge. if on the vehicle the gears will spill out. note typical score marks on cover.
after cleaning,you can measure the end gap of the gears to housing. the gears should stand out of the housing a few thou or more.you slide feeler guages between straight edge and timing cover to find amount. but don't be surprised if they don't. some are even flush. this one was.
so,here's how we fix that. get a flat pane of automotive glass. pull the side window out of your GW if you need one,lol!
get a tub of valve grinding paste,smear it over the glass. i'll first get the score marks out of the cover. big circles,or even straight line is fine,but either way you want to keep central pressure on the piece,and turn it 1/4 turn every 25 laps or so. add compound as you go.
the finished cover. the fine scratches are from trial fitting the cover.
next we do the cover,and remedy those flush gears. but first. the typical gaskets for these pump kits are about .010" thick,compress a couple thou upon tightening. thinner are available from Bulltear.com,and are a viable way to tighten clearances. but the thinner the gasket,the greater the chance for leaks.
so,we do the same lapping treatment to the cover. it is a little cumbersome,but once you try it you'll see there are ways to hold it squarely on the glass. remember to rotate it now and then,checking often. it's a pain constantly cleaning for checking but has to be done.
this may take a while,especially if it's a flush cover like this. you want to go till you have about .004-.005" clearance. then trial fit the cover with gasket installed.the gears must turn freely.
now,the gears turn freely,yet end play is nearly nil. perfect.
also. all but the late engines came with a bypass in the cover. a little spring loaded piston next to the filter mounting stud. a real joke,it was eliminated on the very late engines. it can allow dirty oil to bypass the filter and go straight to the motor. the valve is seen on the upper cover. i highly recommend getting a plug for that valve,as shown on the lower cover, from Bulltear.com. they fit very nicely,easy to install.
also,if you have a very late model without the bypass valve,it'll likely take the later,smaller metric oil filter. the filter stud can be removed,and substituted with an earlier stud,to fit the earlier bigger filter. the cover threads were unchanged with the switch to the late filter.
the oil pump inlet necked down pretty small,i opened it up with the dremel.
i also enlarged the outlet hole in the pump,which is very small. i used a rasp.
here's the inlet and outlet together after the work was done.
here's a stock cover,same as what i started with.
that should move a little more oil.
i'll go into the final reassembly and pump prep for start-up later. it's the reverse of the take-apart process. also,MY engines don't get vaseline run through them.