my 69 thunderbolt has begun sumping a ridiculous amount of oil through the primary chain case breather... so much so that the crank case is full of oil(pissing out the timing plug when removed) and the oil bag is empty. I pulled the timing side cover, and the pump.. all seems to be in good order (although the pump gets a bit tight 3/4's through a full turn). anyone have any idea of what else i should look at/address? any thoughts are much appreciated.
Take the sump plate off and check the gauze, if its coated in crap it wont return much. Check the ball in the sump pipe is not stuck, it should be free at the end of the tube. Put a new o-ring in the pump. Put a new gasket (one that fits) on the pump. Tap the non return ball bearing into its seat LIGHTLY, then fit a new spring.
not at all.. nothing is coming back to the tank, surprised i haven't bent anything. I ordered new washers, o-rings, gaskets, springs and balls for the pump, and OPRV. the send/return lines are 2 weeks old and made sure they were clear of debris, and not over tightened on the tank or the union. I checked the ball in the scavenge pipe, and it seems to move freely.. im going to pound it with some carb cleanner and compressed air to make sure the return ports are clear, and reassemble when the rest of the bits come in on Friday.
Try priming the pump, fill the return line and the pressure side with plenty of oil when re-assembling.
I take it the lines are the right way around? Check the sump pipe is not loose in the cases too. It's a bugger if it is as you'll have to split them to correct it..
the scavenge is in there proper, ball is moving as it should. Lines are correct. I did notice today was when i took the spring from my donor pump(out of a 67 a65L), I matched it up with what came out of the 69.... aaaand the one from the 69 is about 1/4" shorter than the 67. Checked the parts book for 67 and 69, spring is exactly the same P#. I'm starting to think that whomever had this before me kinda cobbled some bits together to get it going.
That would explain the wet sumping but not the return issue. Make sure that the pump is sitting squarely on the case and the gasket is sealing all around it, when you put it back together. Any air drawn into that side will stop the return working properly.
With the lightning pump you can test it in situ as the tacho drive can have a small piece of plastic tube pushed over it and driven by a portable drill, the standard t'bolt pump has no tacho drive so that's not on. It's only a guide but it does help, it tells you the return is working and may sometimes show pump flange leaks up.
Thanks Nick, i got all the intake/return galleys flushed out and cleaned, pump and OPRV rebuilt(oprv was completely gunked up). When i spin the pump its is definitely pushing oil both ways. my last question is with the pump base and 4 bolts.. should the pump/tach spindle spin easily by hand when not installed? Because when i tighten down even slightly on the bolts the pump locks up/ wont spin by hand. I cant seem to find it listed in my work shop manual or articles.
Last edited by BSA-Jay; 07/07/1711:33 pm. Reason: missed a word or 2
When i spin the pump its is definitely pushing oil both ways. my last question is with the pump base and 4 bolts.. should the pump/tach spindle spin easily by hand when not installed? Because when i tighten down even slightly on the bolts the pump locks up/ wont spin by hand. I cant seem to find it listed in my work shop manual or articles.
I guess it "should" but almost none of them do. I have several pumps, one iron and the rest crap metal, and in every case if I tighten these bolts more than barely tight enough to hold the plate on they don't spin freely by hand. Is this normal? Maybe for BSA, You tell me.
The spring is only light so testing it is quite deceptive. With hot oil passing over it all the time, it looses its temper a lot faster than valve spings do, thus goes soft . Every A 65 owner should have a few in their parts stash so any and every time the pump comes off the spring gets replaced.
I,m not so sure about the non return of oil to the tank , sounds very much like crossed pipes , very easy to do. but , one problem I encountered was shitty made gaskets stopping the ball seating correctly. Most gaskets ive used , ive had to open up the hole for the bearing in the gasket , the bulk of em are pretty crap
1969 BSA A65 Lightning 1994 moto guzzi California Triumph sprint GT 1971 BSA B50 Victor special 1968 BSA B44 SS