Stihl MS650 fuel tank issue

[WVDieselcrawler]

Hello all... I just joined this site and this is my first post here.

At work we have a Stihl MS650 saw that has a leaking fuel tank cap. Thinking the cap was damaged from 13-14 years of snuging it down with the saw tool, and perhaps too tight, we bought a new cap. No luck... still leaks. It is almost as if the threaded hole is streched out just a hair too big to allow the cap's oring to seal properly.

Has anyone else had this issue? We are thinking that replacing the tank/handle/bottom frame assembly is the only true fix. What have others done when faced with this issue?

Thanks in advance for any input/replies.

WVdieselcrawler

[clww]

Welcome to the Forestry Forum.
Is it a static leak, a leak while running, or both?

[WVDieselcrawler]

It seems to leak anytime. I have just been only filling the tank about half full so it leaks less while in use, and laying the saw on it's side with the cap up when not in use. The cap is simply not sealing to the tank.

A google search for replacement tanks leads me to think the MS650, 660, and 066 all share the same tank. So surely other owners of thoes saws have had a similar issue.

The solution to the problem is simple, replace the tank... I guess I'm just trying to see if this is a common issue,  just our bad luck... or a lesson learned, dont use the saw tool to make the cap monster tight!

[thecfarm]

WVDieselcrawler,welcome to the forum.
I'm only guessing,a bigger,thicker,o ring on the cap might help??? Or maybe 2 o rings? I have no idea.

[Fifelaker]

According to mediacat the 650 shares a tank with the 660 but the 066 has a different part number. I would try two O-rings or a thicker gasket before I shelled out for a new tank. I believe there are some aftermarket options also.

[WVDieselcrawler]

The local Stihl dealer wants $180, but I have found the tank/handle/bottom frame assembly available online for about $65-70.

Brainstorming about other viable modificatons that will solve the problem cheaper/quicker.

I will look into the extra and/or larger oring.

[Magicman]

Welcome to the Forestry Forum, WVDieselcrawler.   

[AdkStihl]

I'm afraid (2) O-rings will worsen the issue.
Have you tried looking for a used tank?
I know someone who might have one.......
Not sure if he's a member here on THIS site, but I know he's active on a few others.
Try searching (bplust) and shoot him a PM.

[joe_indi]

Years ago before the 046 became the MS460, it too used to have these kind of caps. And, they too used to leak. The more you tighten them, the more they leaked. No relief in replacing caps or rings. The cause is not the caps or the rings. The cause for the leak is on the tank where the ring/washer seats. They thend to develop scratches or imperfections. The remedy is to use a polishing paper and gently rub out the imperfections or scratches on the tank.
Grease the washers the first time the caps are tightened down after the polishing.
The caps leak less frequently if you only hand tighten them instead of using a screw driver in the slot (used only for opening the cap)
Every week take off the caps, clean them and rotate the washers inside out.