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FMX Leaking at Shift Linkage.......Again!

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Last year I pulled my transmission out and replaced every seal. It was leaking from everywhere. For me that's a pretty big job so I was thrilled to get it back in the car and working again (one small hiccup). At first I was all smiles with my job but now I see that it's leaking again around the shift linkage. This really bums me out since it means I most likely need to pull the unit again.

But what really irritates me is that I somehow didn't fix the leak in the first place. I was very careful to meticulously clean every surface, inside and out, prior to installing the new o-rings. I also tightened and torqued everything to spec. I really don't know what else I could've done or that that I'd do differently if I pull it back out. I don't want to go through the whole exercise again just to find out it starts leaking again in a 1000 miles.

Thoughts?

 

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I have encountered seals that are not the exact right size in the seal kits that are in the market that leaked. If the shaft linkage is not damaged and if you use the right size seal, it shouldn't leak. Make sure the shaft where seal sits is smooth and find the right o-ring, may have to source the right o-ring instead of using the one in a kit.

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I know this shouldn't need to be done, especially since you already did the job right it sounds, but maybe a light coating of gasket seal on the o-rings would help? It sucks when you do a big job right and still have problems...happens to all of us I think. Since my fmx has always been a bit drippy...I've never needed to do a flush since it's always getting a fresh supply!!!

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I really hate to have to live with it. Drives me nuts. Also, it's often parked on a lift above another decent car and I don't want it dripping all over that one.

Does anyone know of a first-rate transmission person in the Dallas/Fort Worth area? I could pull the unit and just bring to him to have it done 'right'.

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3 hours ago, RPM said:

After fighting leaks on my fmx, and hearing many stories of others, I truly believe the fmx was meant to leak  :)

Had two back in the early-mid 1980's.  One behind a 351W and another behind a 390.  Never had any leaking issues back then.  They worked great and can take a fair amount of abuse in stock form.  I think something is being overlooked, seal not fitting very well, shaft worn, bore worn so shaft wobbles to much.

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I had the same problem with a GM turbohyrdromatic 350 transmission and I was able to purchase a special tool that could remove the old seal and it could install a new seal without dissembling the trans, just remove the shift arm from the end of the shift selector shaft and it would sorta of screw itself into the seal and then you would would tighten it up and it would pull the seal out. I forgot where I got the tool from but you could check online or take it to a transmission shop ant they could replace it without a taking off the pan off.

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After having pulled the linkage apart and reassembling it, I just can't see a way that it would be possible to replace the o-rings while the linkage is still in place. I wish that would work though.

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I had the same issue. Took it to a transmission facility and they had to remove part of the valve body to get to the seal. Was more of a job than I could handle. Still seeped even after replacing the seal. Even had a little seepage around the gasket and used the fiber type gasket that was recommended. Go Figure

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5 hours ago, CJC said:

I had the same issue. Took it to a transmission facility and they had to remove part of the valve body to get to the seal. Was more of a job than I could handle. Still seeped even after replacing the seal. Even had a little seepage around the gasket and used the fiber type gasket that was recommended. Go Figure

That's what I had to do. Same results. 


BTW, did they do this change while the transmission was in the car? I pulled mine out because I did the input/output shaft seals and wanted to generally clean the whole thing up top to bottom.

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1 hour ago, CJC said:

Yes, the seal change was done while the tranny was still in the car.

 

1 hour ago, CJC said:

Yes, the seal change was done while the tranny was still in the car.

Thanks

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