The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Bender on 18.01. 2010 09:13

Title: Primary chaincase drainplug?
Post by: Bender on 18.01. 2010 09:13

I hope the pictures work.....

Is this the chaincase drainplug, on the underside, on my "51 A7 Plunger?
If it is, there is a screw inside the bolt. Is this the drain and the larger one the fill level?

Looking in the inspection hole there seems to be plenty of oil in there, but oil constantly weeps from the next cover screw on the left, under the bulging bit. (It's been leaking for a year or more and should have emptied itself by now?)
Title: Re: Primary chaincase drainplug?
Post by: Rusty nuts on 18.01. 2010 09:26
No, that is the primary chain tension adjuster.
Oil is drained by removing one of the forward cover screws, varies depending on year & owners modifications.
Title: Re: Primary chaincase drainplug?
Post by: LJ. on 18.01. 2010 09:48
As Rusty says.... See my pic. This is the oil leveler hole, to drain the oil undo all the others with a big tray underneath. Note the oil seal on bolt.
Title: Re: Primary chaincase drainplug?
Post by: Bender on 18.01. 2010 10:49

Thanks for the picture A.J.
That would explain why mine leaks..... No "O"-ring on the screw!
Title: Re: Primary chaincase drainplug?
Post by: BSA_54A10 on 19.01. 2010 09:28
next time you pull the primary off have a look at the bolt holes.
Two of them will have groves or lands machined in them.
The lower is the drain bolt & the upper is the level bolt.
Over the years ( and particularly if cap headed bolts have been used ) the surface below the bolt head chews out so it is prudent to give them a light facing with an end mill or counter bore from time to time.
Also the largest steel washer that will fit in the hole will slow down the process no end.
From memory the brain & level screws had either a fiber or copper washer under them to make an oil tight seal.