Hitchcocks Forum

Hi I have a problem with the oil in primary Chaincase dropping and going into main engine causing level in engine to rise,I use ATF in Chaincase and it's started to contaminate engine oil So I drained both oils and refilled both with my normal 20/50 oil and been for an 80 mile ride and Chaincase oil and engine oil remained at correct levels and clutch is working fine and not dragging,so any ideas what's going on?

Are you overfilling the primary chaincase?

Simple answer - use 20/50 in the primary case. I always do and it causes no problems, either with the clutch or cross contamination either way, as I have the same in the engine as well.

Redditch or Indian Bullet?



Only place I can think of oil could get from the primary to the engine on an Indian bullet is via the left hand crank seal and into the crankcase.



I believe some Redditch models (maybe not the bullets though) have a breather on the primary case? Such a thing could also be responsible depending on how it's set up.

Hi,no I haven't overfilled Chaincase but someone told me it could be a pressure build up in Chaincase,is there an oil seal in the inner case at the front?

On Indian bullets (you haven't said which you have yet) there is a paper gasket between the inner chaincase and the crankcase but it is round the outside of the left hand crank seal. The only way I could see that pressure could build up in the primary chaincase is if it was blowing gas through the crank seal into the chaincase. However that is also the only way oil could get from the chaincase into the engine.



So yes, there could be pressurisation of the primary chaincase but this would be an effect rather than a cause. The cause would be the same cause as oil getting into the engine ie. a leaking crank seal



One thing I'd note on the Indian bullets. That crank seal is behind the engine sprocket and the thing that stops it moving out along the crankshaft are three metal tabs trapped under the nuts that hold the inner chaincase on. That suggests to me that there is a historic propensity for the seal to move itself out. So it might be worth having a look to visually check that seal is still in place and those tabs have been fitted in the correct place and the right way round. Also that the engine sprocket spacer piece is in good condition and where it should be. Here's a picture of the one I assembled a couple of weeks ago.

I'd also check the crankcase breather is clear and breathing freely because the primary case could only pressurise through that seal if the crankcase does first.

Thankyou kindly for your comments, it is an Indian bullet,I replaced the big end 18 months ago and fitted New crank seal along with New mains I'm pretty sure I fitted tabs ok,can I fit another New main seal without stripping motor and also where is crankcase breather situated? Thankyou

I reckon it should be possible to fit a new seal without stripping the engine although not necessarily straightforward. I'll stress I have never tried on a bullet though so take this as a guess rather than concrete advice. If I was going to try, I'd carefully screw a couple of self-tapping screws into the old seal and use these as an anchor to pull it out. Probably by wrapping a loop of wire round each screw head then using a hammer shaft inside that loop to pull/tap it out. I've done that with a gear change oil seal on a different bike before. Fitting a new one should be a case of driving it in with an appropriate size drift.



The breather location will depend on the year of bullet. It is usually either a cast stub on the left hand side of the crankcase, just below the base gasket or a screw in stub on the top of the oil tank just below the carburettor which is normally attached to a convoluted series of pipes and catch-cans. I'm surprised you don't know though, you'd have had to disconnect and reconnect the crankcase breather when you removed/refitted the engine when you did the crank rebuild. This does make me wonder if you have it all in the right place so is a good first port of call. On the ones with the breather in the oil tank, if you got the breather and return hoses mixed up, you'd pressurise the engine.

Thankyou again stinkwheel,yes I did know about engine breather, I have our host's modification that breathes back into engine and I fitted it correctly, I was asking where the Chaincase breather is situated as I was told it could be building up pressure in Chaincase.