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MG TD TF 1500 - leakage on the rear carburetor

I found leakage on the rear carburetor when the ignition is on and the fuel pump starts work. The leak is on the jet assembly. I replaced the gland washer first by cork washers then by Teflon washers but still leaking. The rear carb only and it stops when the engine is running
Any Idea?
Thanks for help,
Guenter
Guenter

Guenther.
Take a close look at the moveable jet itself. Possibly the "U" shaped section is loose. They were screwed in place and if loose the fuel could seep down the threads and appear on the linkage.
Sandy
SANDY SANDERS

Guenter,

A leaky transverse plug in the float chamber arm that plugs the end of the hole drilled for the fuel to go to the carburetor can make it seam that the jet is leaking.

You need to know exactly where the jet is leaking. If it is the large cork washer, tighten the large nut a little each day. If the leak is coming from the new teflon seals, you may have poor seals. I like the cork better. Soak the cork jet gland seals for 24 hours in engine oil before you install them. They will swell up and fit properly.

Since the leak disappears on running the engine, there is an off chance that your fuel level is too high in the jet. Adjust the float down to shut off the fuel sooner. There is pretty wide latitude on the float height.

warmly,
dave
Dave Braun



"If it is the large cork washer, tighten the large nut a little each day"
>>> If the carb is assembled correctly, you can't do this. The big nut retaining the large cork seal and washer is dead tight already, whilst performing its role of securing the jet bearings in position. If it is loose, the jet bearings can shift, and there will be leakage down past the copper sealing washers for the jet bearings.

Common source of leaks today is crappy new jets. Burrs, scratches, bad machining all can damage the seals or just make it impossible to seal. I have a dead smooth flat file I use to show up & remove defects - it's amazing what it will show you!

FRM
FR Millmore

"Common source of leaks today is crappy new jets. Burrs, scratches, bad machining all can damage the seals or just make it impossible to seal."

This is doubly true when using teflon seals (by the way, if you are using the hard teflon seals, you need two in each position to effect a good seal) as teflon is very fragile and can (and will) be damaged by any imperfection in the surface of the jet. I even went so far as to round the sharp edge at the top of the jet and the cross drilled hole.

Sandy's admonition about the screw holding the linkage attachment point is something that I have had to deal with several times. Originally, I soldered everything shut in that area, but now just clean the threads and use a bit of Loctite. Cheers - Dave
David DuBois

"Common source of leaks today is crappy new jets. Burrs, scratches, bad machining all can damage the seals or just make it impossible to seal."

This is especially true when using teflon seals (by the way, if you are using the hard teflon seals, you need two in each position to effect a good seal) as teflon is very fragile and can (and will) be damaged by any imperfection in the surface of the jet. I even went so far as to round the sharp edge at the top of the jet and the cross drilled hole.

Sandy's admonition about the screw holding the linkage attachment point is something that I have had to deal with several times. Originally, I soldered everything shut in that area, but now just clean the threads and use a bit of Loctite. Cheers - Dave
David DuBois

OK thanks for al comments.
When I use the cork one I soak them in warm oil. Then I look for alternative and found the teflon once. As David said I used two in each position.
Next I'll check if they are damaged and I'll try to tighten the large nut day by day.
Cheers,
Guenter
Guenter

Guenter,

Fletcher recommended not to tighten the large nut day by day. According to him, once the jet is centered and the nut is tightened against the bearing, it can't be tightened any more. I still suggest you make sure that it is tight. Once you do, the leak has to be somewhere eles unless that cork seal and copper washer are not fitting.

warmly,
dave
Dave Braun

This is just to give you an update on this issue.
My memory was wrong when I told you I have had installed the PTFE seal in the carbs. I bought them last Year but I fund them today in my workshop packed in the original plastic bag.
This afternoon I have installed them - and for sure I checked it twice! Now the carbs are tight and no more leakage found.
Cheers,
Guenter
Guenter

This thread was discussed between 06/12/2009 and 02/01/2010

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