Help Fixing JD GT Exhaust Leak

[Flowers]

Good evening,

I am battling a John Deere x485 exhaust leak this week. Kawasaki 2-cyl FD711D.

Ive replaced both the metal gaskets, but I notice the exhaust pipe flange doesn't seat very flat to the motor exhaust port on either side. They appear to be slightly warped.

Can I flatten the pipe flanges with a mill file and some sandpaper? Should I use Copper RTV? I am new to exhaust work and not too sure whether the gasket should seal with or without the help of RTV.

TIA for any information.

 

[Richard001]

Could you post some photos of the problem ?

Richard

 

[Flowers]

Yes, I will take some photos and post this evening.

 

[Flowers]

Ok, I did some more work on this problem tonight. The photo above is the left-bank exhaust. You may be able to see the flange is warped so the center of the gasket makes a very poor connection with the face of the ex port. In other words, it's only tight behind the nuts (I think). The right bank is not much better.

I haven't removed the muffler again to verify this bc I just noticed cracks in the exhaust pipes. Ordered a new muffler tonight.

When that arrives I plan to coat both gaskets in copper gasket spray (not RTV). Might help a little? I've also debated painting the new exhaust/muffler to prolong service life.

If anyone has experience with this, I'm open to all suggestions. Thanks very much.

 

[etpm]

Yes, use a file to flatten that flange. If you are careful you should be able to get the flange flat within a couple thousandths using just a sharp file. If you wish you can use sandpaper backed up with a file, especially if that is what you are most comfortable with. Be very careful to not rock the file. And when you tighten the bolts do be careful to not over tighten them because over tightening with a gasket, especially a thick gasket, is a common reason for warping a flange, just the way yours is warped.
Eric

 

[Flowers]

Thank you! Re over tightening, I have had a very hard time finding torque spec for this nut online. John Deere's technical manual provides torques in a table based on nut size, seems to indicate ~ 50 ft lb. I looked up the Kawasaki motor, and those sources indicate 15 ft lb ... I took these nuts to 20 ft lb. Can anyone verify what the tightness should be?