Being on the process of changing my B21's oil pump with a high high volume Melling (30mm gears) i stumbled on a weird issue.
Having the intermediate shaft (which drives the pump and distributor) out of the engine and oil pump removed, only having the pump's drive shaft in place, i tried to rotate the shaft-gear by hand. No problems there.
Then i removed the geared drive shaft and bolted the pump on the block (only the upper part to have access to the internal driving gear). Rotated the gear no problems there also.
Last i installed the geared drive shaft of the pump which dropped in place (and assembled the pump with both gears and bottom part). I tried to rotate the drive gear by hand and noticed that the gear turns freely for 3/4 of the turn and has some weird drag for 1/4 of the turn.
I thought that the pump had something wrong and installed my old pump back on. Tried the same procedure with the old pump (volvo original) but same thing happened. I thought something was wrong with the drive shaft, so i took another one from a B230 donor engine i have. Same thing happened as well. Oiled and lubed everything, but nothing really changed. Tried a third pump (febi) nothing changed. Note that all pumps would turn when out of the engine perfectly.
I got both of the block drive gears in hand and started investigating them. And then a discovery ! On both engines on almost the same spot the shafts had some weird mark. It looks like they were having some interference with the block after being used.
The right one is from B21 the left is from B230. Don't mind the grinded mating part to the pump of the B21 shaft, it was a pump reinforcing ring clearance experiment. Just look at the circled part.
So any ideas ? Do these shafts bend after use ? Do they touch the block after being driven hard ? What is causing it ? Anyone that has a drive shaft in hand to check the marks ?
I assume this is the reason of the 1/4 circle drag of the test. Any inputs would be helpful.
Having the intermediate shaft (which drives the pump and distributor) out of the engine and oil pump removed, only having the pump's drive shaft in place, i tried to rotate the shaft-gear by hand. No problems there.
Then i removed the geared drive shaft and bolted the pump on the block (only the upper part to have access to the internal driving gear). Rotated the gear no problems there also.
Last i installed the geared drive shaft of the pump which dropped in place (and assembled the pump with both gears and bottom part). I tried to rotate the drive gear by hand and noticed that the gear turns freely for 3/4 of the turn and has some weird drag for 1/4 of the turn.
I thought that the pump had something wrong and installed my old pump back on. Tried the same procedure with the old pump (volvo original) but same thing happened. I thought something was wrong with the drive shaft, so i took another one from a B230 donor engine i have. Same thing happened as well. Oiled and lubed everything, but nothing really changed. Tried a third pump (febi) nothing changed. Note that all pumps would turn when out of the engine perfectly.
I got both of the block drive gears in hand and started investigating them. And then a discovery ! On both engines on almost the same spot the shafts had some weird mark. It looks like they were having some interference with the block after being used.
The right one is from B21 the left is from B230. Don't mind the grinded mating part to the pump of the B21 shaft, it was a pump reinforcing ring clearance experiment. Just look at the circled part.
So any ideas ? Do these shafts bend after use ? Do they touch the block after being driven hard ? What is causing it ? Anyone that has a drive shaft in hand to check the marks ?
I assume this is the reason of the 1/4 circle drag of the test. Any inputs would be helpful.
