Navigation

You are here: Home / Messages / Heavy Twins / 650ss oil leak from tank

650ss oil leak from tank

Up to Heavy Twins

650ss oil leak from tank

Posted by david_metcalf at June 22. 2017

I have recently restored a 1967 650ss and have only just got it running. I have found that after a few miles when the engine is warm, there is a steady trickle of oil coming out of the oil tank cap. Obviously first thoughts were too much oil in the tank but this is not the case. The breather from  the crank case is clear and to the chain guard is clear. I have checked the oil immediately after a run and it is quite frothy (not sure if this is normal) but is nowhere near the top of the tank. I have changed the oil tank cap but has made no difference. Any suggestions would be greatly appreciated.

Re: 650ss oil leak from tank

Posted by terence_rafter at June 22. 2017

I had a similar problem and found it was the lip that the cap twists onto. It seems to only be soldered on and the solder had cracked.  Silver solder and powder coating sorted mine out.

Re: 650ss oil leak from tank

Posted by david_metcalf at June 22. 2017

Previously terence_rafter wrote:

I had a similar problem and found it was the lip that the cap twists onto. It seems to only be soldered on and the solder had cracked.  Silver solder and powder coating sorted mine out.


Is the solder around the base of the lip ?

Re: 650ss oil leak from tank

Posted by Bob Matthews at June 22. 2017

The oil level doesn't have to be anywhere near the top of the tank to still get leaks from the oil tank cap.  When on the road, the oil slops about considerably inside the tank and will reach the oil cap on the slightest of bumps or hollows.

So the leak has to be either the cap seal or the joint around the top of the neck.  I got away with turning the rubber seal that's inside the cap up-side down to cure my leak, but you could also check for flatness across the top of the neck with a small block of flat wood (or something similar) and ultimately, do a pressure test with a bicycle/airbed pump and a bowl of water.

Re: 650ss oil leak from tank

Posted by Bob Matthews at June 22. 2017

Also, is the oil tank breather free?  Put a piece of clean rubber hose onto the breather and blow into it to see if it is actually able to breathe.

Re: 650ss oil leak from tank

Posted by Gordon Johnston at June 23. 2017

Oil tanks can crack where the top bracket attaches to the tank. Worth a careful check there.

Re: 650ss oil leak from tank

Posted by terence_rafter at June 23. 2017

Previously david_metcalf wrote:

Previously terence_rafter wrote:

I had a similar problem and found it was the lip that the cap twists onto. It seems to only be soldered on and the solder had cracked.  Silver solder and powder coating sorted mine out.


Is the solder around the base of the lip ?


"Neck" is probably a better description. At it's base, where it's joined to the tank, is where mine leaked.

Re: 650ss oil leak from tank

Posted by david_metcalf at June 23. 2017

Previously terence_rafter wrote:

Previously david_metcalf wrote:

Previously terence_rafter wrote:

I had a similar problem and found it was the lip that the cap twists onto. It seems to only be soldered on and the solder had cracked.  Silver solder and powder coating sorted mine out.


Is the solder around the base of the lip ?


"Neck" is probably a better description. At it's base, where it's joined to the tank, is where mine leaked.


Thanks for the info, I will have a careful look tonight and let you know if this is the problem

Re: 650ss oil leak from tank

Posted by anna jeannette Dixon at June 23. 2017
Previously david_metcalf wrote:

I have recently restored a 1967 650ss and have only just got it running. I have found that after a few miles when the engine is warm, there is a steady trickle of oil coming out of the oil tank cap. Obviously first thoughts were too much oil in the tank but this is not the case. The breather from  the crank case is clear and to the chain guard is clear. I have checked the oil immediately after a run and it is quite frothy (not sure if this is normal) but is nowhere near the top of the tank. I have changed the oil tank cap but has made no difference. Any suggestions would be greatly appreciated.

 

 
Hello Now to me this sounds like an engine breathing problem  pressurising the oil tank  check for blockages  in oil lines  and breaths    yours   Anna j

Re: 650ss oil leak from tank

Posted by john_marshall at June 24. 2017

I had this problem on an Atlas motor in an N15CS. Blew oil out of the oil cap hole at speed. I disconnected the engine breather from the oil tank & led it via a longer & wider pipe to the rear end & open air. I assume the breather was pressurising the oil tank, as has already been suggested. TTFN Jack

Powered by Ploneboard
Upcoming Events
Tay Valley Branch Camping Weekend - Applecross Jul 28, 2017 - Jul 29, 2017
CRMC Track Parade - Donington Classic Festival - 3 days Aug 04, 2017 - Aug 06, 2017 — Donington Park, Castle Donington, Derby DE74 2RP
Yorkshire Branch at the Hebden Bridge Vintage Weekend Aug 05, 2017 - Aug 06, 2017 — Calder Holmes Park, Hebden Bridge West Yorkshire, HX7 8EE.
Brittania Rally - Denmark Aug 18, 2017 - Aug 20, 2017 — Jolly Roger Mc, Nørre Langgade, 8840 Rødkærsbro, Denmark
2017 International Rally Aug 24, 2017 - Aug 28, 2017 — Open Huis, Ieperstraat 157 - 8840 Staden, Belgium
Upcoming events…
This is Brio Diazo Plone Theme