BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: fenderman! on 13 Jul, 2020, 23:38

Title: 1955 A10 oil return to tank issue
Post by: fenderman! on 13 Jul, 2020, 23:38
I'm not seeing the oil stream coming out of the pipe in my oil holding tank..I'm afraid to run the engine..I recently had cylinder bored and installed new pistons and rings..
Title: Re: 1955 A10 oil return to tank issue
Post by: AWJDThumper on 14 Jul, 2020, 08:01
Sometimes it can take a few minutes for the oil to start circulating again. However, it's not worth the risk of running it longer than this and unfortunately it means checking the oil path from the oil tank to the oil pump back to the tank again to see what's going on. Could be anything causing the problem from blockage, to air lock, to incorrect reassembly, etc
Title: Re: 1955 A10 oil return to tank issue
Post by: fenderman! on 14 Jul, 2020, 23:09
I did confirm that the ball is not stuck on the pick up tube.isnt there supposed to be a certain amout of oil laying in there? when I dropped the plate/screen there really wasnt any  oil that that drained out. how does the  pump pick up the oil if there not a certain level all at start up? I did take out the oil pressure regulating valve body and made sure the ball and seat were clean  too..I also took of the line from the tank down to the crankcase and blow out to confirm free flow of oil from the tank to engine..gonna take of the side cover and look at the pump drive tomorrow..
Title: Re: 1955 A10 oil return to tank issue
Post by: fenderman! on 15 Jul, 2020, 00:22
I did take off the feed line and blow out.reconnected and watched oil flow out before I reconnected at the crankcase end..
Title: Re: 1955 A10 oil return to tank issue
Post by: AWJDThumper on 15 Jul, 2020, 13:20
If the problem is with the non-return valve under the oil pump, for example, then the pump would need to be removed. To check the NRV is working ok and the feed side of the pump is also working, I would be tempted to take off the pressure release valve and start the engine and check oil squirts out (very messy). Alternatively, you could try turning the engine over by hand but this is likely to be hard work!
Title: Re: 1955 A10 oil return to tank issue
Post by: fenderman! on 15 Jul, 2020, 21:32
I did take of the pressure relief valve and kicked over a little and didnt see any oil squirting out..would be afraid to start risk hurting engine.
Title: Re: 1955 A10 oil return to tank issue
Post by: fenderman! on 15 Jul, 2020, 23:57
Well I loosened the PRV and kicked over a few times and just got a little oil.but somehow I put all together and now I have coming out the pipe.had a few bubbles at first but went to stream.not sure what I did.so if it stops while riding I guess you just wont know till theres damage.makes me want to rig a flow switch with light..my new question..how does the oil fed up to rocker box get back to crankcase?
Title: Re: 1955 A10 oil return to tank issue
Post by: chaz on 16 Jul, 2020, 06:52
There are cast holes in the head that allow the oil to return down through the cylinder and the push rod tunnel acts as a return passage
Title: Re: 1955 A10 oil return to tank issue
Post by: AWJDThumper on 16 Jul, 2020, 12:07
Quote from: fenderman! on 15 Jul, 2020, 23:57
Well I loosened the PRV and kicked over a few times and just got a little oil.but somehow I put all together and now I have coming out the pipe.had a few bubbles at first but went to stream.not sure what I did.so if it stops while riding I guess you just wont know till theres damage.makes me want to rig a flow switch with light..my new question..how does the oil fed up to rocker box get back to crankcase?
This has happened to me on other bikes - once the oil starts flowing again it should be ok. It may be one of those air lock type issues which always seem to be difficult to understand. It may just have needed kicking over a few times with the PRV off to get thing working again!
Title: Re: 1955 A10 oil return to tank issue
Post by: bikerbob on 16 Jul, 2020, 16:38
Something I always do after an oil chage on start up is to hold my finger over the return feed pipe blocking the hole, this has the effect of pressurising the system and forceing oil up to the rockers thus eliminating any air locks. You only need to block the hole for a few seconds.
Title: Re: 1955 A10 oil return to tank issue
Post by: MickFarmer64 on 23 Jul, 2020, 20:04
Quote from: bikerbob on 16 Jul, 2020, 16:38
Something I always do after an oil chage on start up is to hold my finger over the return feed pipe blocking the hole, this has the effect of pressurising the system and forceing oil up to the rockers thus eliminating any air locks. You only need to block the hole for a few seconds.

Read on here about doing that when changing the oil. Definitely worked for me and it seems like a really good tip.