Leaking Transmission Fluid - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chris1htx · 02-15-2016, 04:18 PM

Hello all,

I am leaking transmission fluid from the shift linkage on the side of the transmission. Is there a seal for that? I wanted to ask before I took anything off. Thanks for your help.

MalibuSSwagon · 02-15-2016, 06:31 PM

yes, the "shift shaft seal"

chris1htx · 02-15-2016, 07:09 PM

Thank you!

geezer#99 · 02-15-2016, 10:10 PM

10 bucks for the seal and 40 bucks for the correct seal puller and install tool.
Or 10 bucks for the seal, pry the old one out with a small pointed tool and tap the new one in with a little socket. Only to have it leak even more. Then take it to the trans shop to have the shifter shaft removed and put in a lathe to take all the little knicks out of the shaft the little pointy tool made in it. Only 200 bucks or more.
So, get the seal and the right tool and hopefully it won't leak.

**MikeB** · 02-15-2016, 10:21 PM

I have replaced a few in the TH350 trans over the years, and every time the leak was fixed. Sometimes the biggest challenge is an exhaust pipe that's in the way. It's also easier to do if you drop the pan and remove the shaft.

A few years ago, I was getting ready to sell a truck with a TH350 trans leak, but didn't have tome to mess with it. Labor and parts for new shift shaft seal, fluid, and filter cost me $150 at a trans shop. Well worth it!

On another note, a bad drivers side motor mount will let the engine move too much, causing a leaky shift shaft seal.

02-15-2016, 04:18 PM	#1
chris1htx Registered User Join Date: Jan 2013 Location: Houston, TX Posts: 178	Leaking Transmission Fluid Hello all, I am leaking transmission fluid from the shift linkage on the side of the transmission. Is there a seal for that? I wanted to ask before I took anything off. Thanks for your help.

02-15-2016, 06:31 PM	#2
MalibuSSwagon Registered User Join Date: Sep 2009 Location: Weare,NH Posts: 1,592	Re: Leaking Transmission Fluid yes, the "shift shaft seal" __________________ Eric 1992 Oldsmobile Custom Cruiser 1986 Chevrolet C10\|5.3L\|TKO600\|Shortbed\|Custom Deluxe 1983 Malibu Wagon\|TPI 305\|T5 5 speed\|3.73 non-posi

02-15-2016, 07:09 PM	#3
chris1htx Registered User Join Date: Jan 2013 Location: Houston, TX Posts: 178	Re: Leaking Transmission Fluid Thank you!

02-15-2016, 10:10 PM	#4
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,731	Re: Leaking Transmission Fluid 10 bucks for the seal and 40 bucks for the correct seal puller and install tool. Or 10 bucks for the seal, pry the old one out with a small pointed tool and tap the new one in with a little socket. Only to have it leak even more. Then take it to the trans shop to have the shifter shaft removed and put in a lathe to take all the little knicks out of the shaft the little pointy tool made in it. Only 200 bucks or more. So, get the seal and the right tool and hopefully it won't leak.

02-15-2016, 10:21 PM	#5
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,597	Re: Leaking Transmission Fluid I have replaced a few in the TH350 trans over the years, and every time the leak was fixed. Sometimes the biggest challenge is an exhaust pipe that's in the way. It's also easier to do if you drop the pan and remove the shaft. A few years ago, I was getting ready to sell a truck with a TH350 trans leak, but didn't have tome to mess with it. Labor and parts for new shift shaft seal, fluid, and filter cost me $150 at a trans shop. Well worth it! On another note, a bad drivers side motor mount will let the engine move too much, causing a leaky shift shaft seal. __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

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