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MG TD TF 1500 - Replacing all SU seals... hints?

Hi All,

I have *severe* gas leaks coming down the jets in my TD. This is the car that hadn't really been run much in the last 27 years, and hadn't even been started since 8 years ago.

I suspect that the seals are dried out, so I bought a complete seal kit. I understand that some of the seals (in the jet) need to soak in oil for at least a few hours before installation... Any other hints, like should I soak any other seals in oil? Any problem areas to expect?

I have the shop manual, and an exploded view from a Haynes manual, but that's pretty much it... I *have* worked on SUs in the past on my '68 midget, but that was a while ago.

Thanks for any info,
Scott
Scott Linn

Scott - Some people have good luck with the cork jet seals. I am not one of those people, I have NEVER had any luck with them remaining leak free. The people who are successful are also people who drive their cars on a regular basis thus keeping the seal wet with fuel. I have had good success with Teflon 'O' rings. They don't dry out and leak and, unlike ordinary 'O' rings, even the ones the viton rings, do not swell and stick on the sides of hte jets, making it impossible to pull the jets down to give an enriched mixture for starting. The teflon 'O' rings are available from Tom Bryant in West Bath, Maine. His e-mail is: tbryant@suscom-maine.net I may have some of them left and will check for you. The other seal that works better in some other material than the supplied cork is the very large jet nut seal right at the bottom of the carb body. If I don't have some of those in Viton 'O' rings, I can at least get you the part number for it.
Cheers - Dave
David DuBois

Scott, I have some of the Teflon o-rings as above for next time, but haven't used. Recently I found that the corks from Abingdon spares were too short/small and leaked, with the ones from Moss working fine. Make sure the jet is very polished and without scratches. You can use very fine sandpaper and metal polish, etc. They tend to develop linear scratches from choke movement which will continue to leak if not polished out. George
George Butz

George'a advice about polishing the jet is very correct, especially where the teflon seals are concerned. Additionally, I always brake all sharp edges at the top and at the cross drilled hole (especially here), so there is nothing that will cut the teflon while installing the rings (teflon is very vulnerable to cuts). You will need r 'O' rings per jet (two top and two bottom) to make them work. Another thing you want to check is that the screw that holds the linkage fork at the bottom of the jet is not leaking. I woud go so far as to say remove the fork and screw and put some locktite on the screw to insure that this is not happening. I spent a lot of time fussing with the leaking jets in our TD when we first got it before realizing that the leak was coming from that spot.

Bob Jeffers wrote to me this morning to say that the e-mail I gave for Tom Bryant bounces. His phone number is 207-443-6338 - that has remained constant over the years. The large jet nut seal 'O' ring is a Parker 2-211 and should be available from NAPA. Cheers - Dave
David DuBois

While noodling around in the hardware store seals, I found one that had 3 sealing edges on all sides. A fancy o-ring design. I haven't used them, don't know if they'd stand up to gas, or if they'd hang up on the jet. But if anyone else wants to be the guinea pig, please reply with results. They are black in color, maybe neoprene, it didn't say on the box. I'm thinking they were called super seal or similar.

I have had decent luck with slathering vaseline around the jet and working it up and down. I'll have to fine polish my jets and see if that helps. Sure can't hurt.
Tom

Tom, It might be worth putting the super seals in a small jar of gasoline to see if they hold up or melt.
Evan Ford - TD 27621

Even if they are Viton (material that holds up to gas quite well without swelling), they still tend to stick to the jet and make it difficult to set the mixture. I used Viton 'O' rings for many years, changing them periodically as they became sticky, until I cam across Tom Bryant and his teflon 'O' rings. The teflon 'O' rings are available through MSC indrustrial supply http://www.mscdirect.com/ but the price through Tom is lower. Cheers - Dave
David DuBois

I see many comments in the TSO and on this bbs to use fine sandpaper for polishing carb parts. I assume that is if the jet has a reasonably deep score somewhere.

What about using medium fine/fine steel wool to just polish up a fairly nice jet? That is what I've been using for polishing up other metal parts on some of my other cars, like caliper guide bolts. Is there some reason I shouldn't use that on something like a jet?

Thanks,
Scott
Scott Linn

Scott - I normally use steel wool, with the jet chucked up (as best as possible) in the drill press. The importand thing, when using the Teflon seals is to make sure there are no sharp edges that will cut the rings as they are installed and that all burrs or other deformities are polished out completely. Good luck - Dave
David DuBois

Is it at all logical to turn the jets 180 degrees if they have a bit of a step on them? Probably not. Maybe better than not doing anything (staying centered).
Tom

I have had good luck with the jets by buffing them up on my buffing wheek with rouge. They shine up well.
I have had zero leaks doing it this way.
Sandy Sanders
Sandy Sanders

Hi All,

Thanks for all the comments.

So far so good... I took them apart, cleaned them up & put them back together and so far no leaks. This is a HUGE improvement over before, where both jets would drip for days after running the TD.

I think I need to change the float level though, it was set at 3/8" (like from the TD manual) vs. 7/16" which I see mentioned in the SU manual and other people have mentioned in the archives.

We'll see how long the seals last. I'll be buying some teflon seals from David just to be on the safe side however.

Scott
Scott

This thread was discussed between 29/09/2005 and 02/10/2005

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