H/W Single Oil Pumps

JBP650 · Post by **JBP650** » Tue Mar 14, 2006 1:53 pm

quote:
John, never ever use a thick gasket on these types of items, like carburettor bodies, they are made of crap metal, and they will just bow and you will be back where you started.

Hi Biscuit,
Thanks for your comment
The advise given to me was to use a 'thicker' gasket to overcome any small deflections that may be in the end plate or crankcase. The one supplied with the gasket set is paper thin and I have replaced it with one approx twice the thickness - ie very thin card thickness. I see your point but this thickness would not promote any deflection of the cover plate. However, next time around I will revert to an original gasket.

With thanks
John
Thanks

TommoT · Post by **TommoT** » Tue Mar 14, 2006 5:11 pm

Just a thought: since you have changed the oil pump plunger itself, would the wrong type, i.e. the early singe start plunger cause this? I believe I have seen up to 5 different types, with the main difference being the later ones cut with an extra thread (don't know the right words here!) making them so-called 2-starters, rotating at twice the speed. Pure guesswork here.

Another guess would be if the plunger index bolt does not engage with the groove in the plunger. This would render pump action negligible but still allow oil to seep into the crankcase. I actually experienced this once, with the primary chaincase slowly filling up with the overflow throught the main bearing. Maybe not likely with your multiple assembly/disassembly sessions!

Let's hear what you find out, when you do, caus' eventually you will!

JBP650 · Post by **JBP650** » Tue Mar 14, 2006 5:45 pm

quote:
Just a thought: since you have changed the oil pump plunger itself, would the wrong type, i.e. the early singe start plunger cause this? I believe I have seen up to 5 different types, with the main difference being the later ones cut with an extra thread (don't know the right words here!) making them so-called 2-starters, rotating at twice the speed. Pure guesswork here.

Another guess would be if the plunger index bolt does not engage with the groove in the plunger. This would render pump action negligible but still allow oil to seep into the crankcase. I actually experienced this once, with the primary chaincase slowly filling up with the overflow throught the main bearing. Maybe not likely with your multiple assembly/disassembly sessions!

Let's hear what you find out, when you do, caus' eventually you will!

Hi TommoT

I have tried 3 pumps in engine - all of them stamped (very small letters)'2S' on the thicker disharge end which I take as meaning 'Two Start'. There is a new plunger index bolt in use and the pump definitely goes round and round and also back and forth. This is witnessed with the end cover plate removed.

Thanks for your suggestion, and I will let you know when I discover the solution.
Best regards
John

itma · Post by **itma** » Tue Mar 14, 2006 6:32 pm

A really obscure thought; years ago, and memory is straining for exact recall here; I believe I once found a late 2s pump with the wider locating groove in a crankcase that only took the earlier thin pin, so the pump did`nt get its full travel

JBP650 · Post by **JBP650** » Tue Mar 14, 2006 8:04 pm

quote:
A really obscure thought; years ago, and memory is straining for exact recall here; I believe I once found a late 2s pump with the wider locating groove in a crankcase that only took the earlier thin pin, so the pump did`nt get its full travel

Thanks Itma,
I have checked that the pin fits into the groove exactly - they are both the wider type.
Best regards
John