Super 650 fuel leak

[Deleted]

I was using the Super 650 on some 30 inch trees and discovered a puddle of fuel after use.  No leaks after sitting over night.  The next day I took the saw out of the cold and brought it inside and tons of fuel leaked again.  I think pressure builds in the tank and pushes fuel through the carb.  Anybody have thoughts or ideas on what I should be looking for, I have no idea what to do.  Thanks, Eric.

[stillsawing]

If you notice fuel in the air box/carb area, take a good look at the fuel line. It might be time for a carb rebuild also.

[Deleted]

I rebuilt the carb last year and used it with no problems. The fuel is in the air box. I think what I will do is get the saw cold again, bring it inside and just wait to see if I can find the leak.

[Deleted]

I found two problems. One is a crack in the new fuel line. The other issue is a leak in the bottom of the tank. I cut my own tank gasket for a C-5 before and it worked great. I'm thinking of doing the same for the 650. Any thoughts guys?

[undee70ss]

Redcote works better for tanks

[blythkd]

I agree with Undee, I think sealing the tank with a coating from the inside is about your only option. Could be wrong, but I think your tank is probably epoxied together and not meant to be disassembled again. That's how most (if not all) of the "50's" were - meaning 350, 450, 550, 650 and 750. I haven't been around many 650's and never had to deal with a fuel tank leak but I have seen a few 750's, even owned a couple.

[Deleted]

Thanks guys. I've been away for a while. I haven't tried the red coat sealing before. I see Leon has some video information on it. I'll check it out and see what I can do.

[Deleted]

I finally got around to tearing this saw down. I pulled the tank and filled it with water. I can't find any leaks at all. I think all that fuel is coming from the carb. I took a really close look at everything this time, I don't remember where I saw fuel coming from the line, but it pressure tested fine. I also don't remember why I used rubber line, maybe I wanted to keep this saw closer to original, I don't know. I'll pull the carb and pressure test it. I'll have questions about removing stuck anti vibe mounts later. I can't source replacements. If anybody knows where to find part # A-12708-B I would be more than appreciative. Maybe I can clean the old ones really good and use some type of adhesive to cobble them back together, the rubber is a little hard, but I may have no choice.

[bobby167]

PM sent

[Deleted]

I pressure tested the carb and if anything it's holding too much pressure.  I got it up to 25 psi and it holds tight.  Carb number is WB2 dated August 1976. 

[Deleted]

I left the tank full overnight, outside is bone dry. I'm really at a loss here. I'm going to clean things up a bit, use Tygon lines this time and reassemble. Start the testing process over again. I am curious, maybe the extra pressure from cold fuel in a cold saw warming to room temp is enough to force a leak in the tank. I bet I can take a different fuel cap, remove the bronze screen and duckbill, fit some tubing and create a pressure test cap for the tank. I'll leave the carb off the saw and connect the fuel line to the carb. I hope that makes sense. I'll update and attach pictures of my experiment later. Any thoughts or suggestions would be very helpful. Thanks guys.

[Deleted]

Before I went through with setting up a pressure test with the fuel cap, I put a heater next to the tank and let the pressure build. I found some water coming out the seem. Can I use Red Kote that high up? I thought maybe laying the tank down and letting it set that way might work. I have never used Red Kote before.   Edit:  just watched Leon's video on Red Kote, pretty much explained everything.

[Deleted]

I'm doing the Red Kote today. It's a balmy 9 degrees this morning. Last night my phone took a dump and I lost all my pictures of how I disassembled the 650. Hopefully this goes well.

[Deleted]

Never got around to working on the 650 until today. Degreased the tank and it's currently drying. I cleaned up the anti vibe mounts and am considering using 3M 847 Nitrile High Performance Rubber and Gasket Adhesive to piece these things back together. Three are intact but two are in pieces. Has anyone tried this before?  Anyone have any thoughts? 

[onlyhomelites]

I've used straight up gorilla super glue with reasonable success, but I think the product you are using will be a good method!

[blythkd]

Those things take a beating. I would put the repaired mounts in strategic places. The ones on either side of the carb and up by the bar mount probably take the most abuse. Left front is probably the lowest stress area.

[Deleted]

Thanks for the input, guys. I didn't remove the two by the carb. I"ll place the good one by the bar mount. That's a really good idea, billy.

[blythkd]

Speaking from experience mostly on 350/360 mounts, but it's about the same thing, they just have 4 rather than 5 like the bigger saws.

I've swapped them around and turned them over to get more life out of them when some mounts just had a cut in one side but were otherwise still in good shape. You gotta do what you gotta do as parts become more and more scarce.

[Deleted]

Finished cleaning the inside of the tank with acetone early this morning. I dumped the Red Kote in and swished it around the tank, dumped the excess out. Currently waiting for vibration mounts to dry/cure. The adhesive I used seems to be some really good stuff, very tacky. 

[Deleted]

I removed the handle bar and the other too vibe mounts. One of the mounts was broken, so I cleaned and glued it back together. The adhesive I used is very strong, I tried to rip the repairs apart and they held up to a great deal of torque. I'm confident in the repairs holding for a long time. I gave the saw and all the parts a thorough cleaning. I gave the fuel tank an extra shot of Red Kote yesterday. I plan to reassemble the saw tomorrow. I'm actually kind of happy the tank was leaking. It gave me the motivation to disassemble and clean and repair everything. The engine on this saw has fantastic compression and now it should last many more years. I forgot to mention that the rubber for the vibe mounts are all in great condition, no cracks or tears.