SQ4 breather pipe

[Henning G]

Hi everyone, I just have a question on INTERNAL breather pipes on SQ4 from 1939. I have noticed that on later SQ4 there is an angled pipe inside, but can’t find it for my 1939 in the parts catalogue, so perhaps there should not be one. Regards Henning

[robjameson]

I’m not sure if it should have one or not, but my ‘48 has an internal breather pipe which is routed similarly to that on the later square fours.

[Henning G]

Hi Rob, THANKS a lot, I think mine should have one too. How is yours attached? Just pressed into the union and then screwed on with a single clip on the oil pump? Thanks for your reply..
Regards Henning

[Pete.Silson]

I don't think so. My 1946 engine, which was very original, didn't show any sign of anything ever been fitted.

Pete

[robjameson]

Hi Henning,

You describe it almost exactly as it is. The brass pipe is sitting just inside the banjo bolt that comes through the back of the timing case, and has a small bracket soldered to it to secure it to the oil pump bolt. The end at the banjo bolt is smeared with silicone sealant.

Since Pete’s bike doesn’t have this, we can assume that it is a modification, most likely done by Dad or David Jones in the mid 90s and must have been fitted for a reason.

Rob

[john.davies]

I don't think so. My 1946 engine, which was very original, didn't show any sign of anything ever been fitted.
1946 timing chest.jpg
Pete

I agree, my 46 did not have one and still doesn't.

[Henning G]

HI, THANK you so much for your answers. One thing is seitan, it doesn’t matter if the breather pipe is installed or not, was afraid it might lose a bit of oil if not installed.