TH400 leaks...missing ring? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

406cid70Chevy · 11-09-2003, 03:05 AM

Well I finally got my truck running again, turned out to be a bad ignition switch and a bad wire.

Now I'm trying to fix the transmission leaks (TH400). I fixed all of the leaks besides where the gear lever/shifter goes in. I had the pan off and had that shifter shaft out trying to figure out why it was leaking. I put the pan back on and bought a new seal/ring, but it STILL leaks. So my question is...is there only one seal where the shifter goes into the tranny? or should there be another? I'm thinking maybe one is missing because the tranny was rebuit, maybe it was forgotten. The only seal/ring that was there was one that had a metal casing on it, but to me it didn't seem like it would hold very well on it's own, and it doesn't. Anyone know if I'm missing a seal or doing something wrong?

jhow66 · 11-09-2003, 05:10 PM

Mine was leaking also. There is a seal that goes on from the inside--there is a special tool to install it.

406cid70Chevy · 11-09-2003, 06:40 PM

Ok thank you, looks like someone forgot to put that seal back on.

11-09-2003, 03:05 AM	#1
406cid70Chevy Registered User Join Date: Nov 2002 Posts: 43	TH400 leaks...missing ring? Well I finally got my truck running again, turned out to be a bad ignition switch and a bad wire. Now I'm trying to fix the transmission leaks (TH400). I fixed all of the leaks besides where the gear lever/shifter goes in. I had the pan off and had that shifter shaft out trying to figure out why it was leaking. I put the pan back on and bought a new seal/ring, but it STILL leaks. So my question is...is there only one seal where the shifter goes into the tranny? or should there be another? I'm thinking maybe one is missing because the tranny was rebuit, maybe it was forgotten. The only seal/ring that was there was one that had a metal casing on it, but to me it didn't seem like it would hold very well on it's own, and it doesn't. Anyone know if I'm missing a seal or doing something wrong?

11-09-2003, 05:10 PM	#2
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Mine was leaking also. There is a seal that goes on from the inside--there is a special tool to install it. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

11-09-2003, 06:40 PM	#3
406cid70Chevy Registered User Join Date: Nov 2002 Posts: 43	Ok thank you, looks like someone forgot to put that seal back on.



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