Oil Tank Leak

I know that this has been talked about quite a bit and I've pretty much read all the posts. It looks like I have an oil tank leak since oil seems to be seeping from above and running down the frame to drip more than usual. I've cleaned everything off and can't see leak while running so doesn't appear to be a hose or anywhere else. So I'm concluding that the tank is leaking at the bottom where the weak point is.

The CNW mod appears to be the simplest option so I'm wondering how difficult is it to get the tank out. Appears to be a bottom bolt with spacer and a top mount. Tank would appear to come out through side cover. Is there anything I should know about getting this tank out?

Year of the bike might help

Can't imagine why I would provide that. 74 Mk II

Just undo the front and rear top rubber mounts--remove from the tank-- if you want to--slot the rear mounting tab like the front --remove the bottom mounting bolt-- this bolt will not be used if you send the tank to CNW for repair--remove the two oil lines from the rear----the oil line on the top of the tank----and remove the large rear hex connector from the rear of the tank. Now if you kind of twist the tank as you are pulling the tank out --it should come out.

Oh yes-----do drain the oil first.

If you watch closely at the rear of the tank---the fixed oil line---may want to hang up and keep the tank hung up a bit-----I have cut off a bit of this tube to allow the tank clearance so it comes out fairly easy. Just leave enough of the tube there so you can connect the oil hose----you may need to install a new-longer hose--depending on how much of the tube you cut off.

The CNW fix is very very nice. Of course there are other methods to fix this leak---just have to creative and have access to the tools and equipment needed.

Are you doing the cap up tight?

splatt said:

Are you doing the cap up tight?

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First thing I thought of. When I drained the sump after winter I spilled a little bit of oil. So I let it drip for a bit and with nice weather used simple green and pressure washer to clean off the area. Ran it for a while and didn't see any leaks. Thought everything was fine but than saw it dripping down overnight. No hose leaking and no oil collection on top of tank. Figured that the only thing left was the bottom of the tank since you can't see there.

303mj, thanks for the info. I assumed it would be tight to get it out just figured best to ask before I started pulling it. Looks like the only oil leak on the bike.

Could be the bottom of the tank is fatigue fractured around the bottom mounting insert. If it's just a crack, it could be a slow drip. I made a rubber doughnut for the tank to sit on, glued to the plate on the frame, so there's no bolt in that hole, but the tank is supported with no stress on insert. Mine had been repaired by a previous owner for just that reason.

The doughnut was made from a rubber pad used to mount rooftop A/C units. They make them from rubber or rubber and cork to isolate unit vibration, and are available in a bunch of sizes and thicknesses.

In fact, my upper tank mounts and muffler mounts are industrial items, too. Same as what you'd get from Andover, except about $2 apiece.

JimR said:

Can't imagine why I would provide that. 74 Mk II

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Because there are central oil tanks prior to '71.
It is always good to provide years, makes and models of bikes when asking a tech question.
Some people put that info in their sig line along with some brilliant quote from someone or how many bikes they own.
Under their avatar they may say where they are from which helps with offering advice on shops and parts suppliers and clubs.
But then one could assume you are talking about the side tank as which is known to be prone to fatigue cracks.
No biggie.

Not only central oil tanks, MK3 is a real pig to remove if you have the original airbox. - unless anyone knows of simple mod to enable it to be removed easily.

Guido said:

JimR said:

Can't imagine why I would provide that. 74 Mk II

Click to expand...

Because there are central oil tanks prior to '71.
It is always good to provide years, makes and models of bikes when asking a tech question.
Some people put that info in their sig line along with some brilliant quote from someone or how many bikes they own.
Under their avatar they may say where they are from which helps with offering advice on shops and parts suppliers and clubs.
But then one could assume you are talking about the side tank as which is known to be prone to fatigue cracks.
No biggie.

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Sorry if my reply seemed flip. It was an attempt at self deprecation. Seemed such an obvious thing to provide. You're right about putting it in the avatar.