Help: 1972 Blazer has a leaky TH350 tranny - The 1947 - Present Chevrolet & GMC Truck Message Board Network

GN72Blazer · 03-20-2006, 11:43 AM

Hello,

My 1972 Blazer's TH350 tranny is leaking in the bellhousing area, the tranny shifts just fine but leaks fluid.....is the tranny due for a rebuild or could the torque convertor be shot?

I do have a Turbo 400 tranny from a 2 wheel drive 1970's chev van that I could swap in, would this be a direct swap into a 4x4 1972 Blazer or will I need to swap out shafts and/or buy adapters of some sort?

Thanks for any advice!

GN

bouncytruck · 03-20-2006, 12:29 PM

First, welcome to the board. Where in WA are you located?

Second, the leak is most likely caused by a bad front seal. This doesn't mean a transmission rebuild, but you will have to drop the transmission and transfercase to get to it. I've got the same problem with the transmission in my '72. I don't want to do the work myself, so I'm just waiting until I can afford to have a transmission shop do the job. It is doubtful that your torque converter is shot, but if you decide to rebuild the transmission, it is a good idea to replace it or have it drained and cleaned at the same time.

Third, No. A 2wd transmission has a different tail shaft than 4wd. Additionally, the output shaft may be different and not mate with you transfercase (which should be an NP205).

GN72Blazer · 03-21-2006, 01:26 PM

Thanks for the reply, I live in Duvall.

If its just a front seal leaking I guess I will wait a little while before I pull the tranny and repair....I wonder if I dump a few bottles of a tranny leak fix fluid into the tranny that might help seal it up?

bouncytruck · 03-21-2006, 02:54 PM

I've used the Lucus transmission leak stuff. It helps a little, but has not stopped it yet. Most important is to keep an eye on the fluid level and make sure it doesn't run dry. If the transmission starts slipping, check the fluid. If it continues, it's time for a rebuild.

I'm just over in Bothell & work in Bellevue. I belived board member CG lives in Monroe, but he works over here by me in Bellevue. There are a couple other members out in the Monroe area too. I'm not sure if there is anyone in Duval specifically.

Post some pics of your rig when you get a chance.

03-20-2006, 11:43 AM	#1
GN72Blazer Registered User Join Date: Oct 2005 Location: Washington Posts: 14	Help: 1972 Blazer has a leaky TH350 tranny Hello, My 1972 Blazer's TH350 tranny is leaking in the bellhousing area, the tranny shifts just fine but leaks fluid.....is the tranny due for a rebuild or could the torque convertor be shot? I do have a Turbo 400 tranny from a 2 wheel drive 1970's chev van that I could swap in, would this be a direct swap into a 4x4 1972 Blazer or will I need to swap out shafts and/or buy adapters of some sort? Thanks for any advice! GN

03-20-2006, 12:29 PM	#2
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,038	Re: Help: 1972 Blazer has a leaky TH350 tranny First, welcome to the board. Where in WA are you located? Second, the leak is most likely caused by a bad front seal. This doesn't mean a transmission rebuild, but you will have to drop the transmission and transfercase to get to it. I've got the same problem with the transmission in my '72. I don't want to do the work myself, so I'm just waiting until I can afford to have a transmission shop do the job. It is doubtful that your torque converter is shot, but if you decide to rebuild the transmission, it is a good idea to replace it or have it drained and cleaned at the same time. Third, No. A 2wd transmission has a different tail shaft than 4wd. Additionally, the output shaft may be different and not mate with you transfercase (which should be an NP205). __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

03-21-2006, 01:26 PM	#3
GN72Blazer Registered User Join Date: Oct 2005 Location: Washington Posts: 14	Re: Help: 1972 Blazer has a leaky TH350 tranny Thanks for the reply, I live in Duvall. If its just a front seal leaking I guess I will wait a little while before I pull the tranny and repair....I wonder if I dump a few bottles of a tranny leak fix fluid into the tranny that might help seal it up?

03-21-2006, 02:54 PM	#4
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,038	Re: Help: 1972 Blazer has a leaky TH350 tranny I've used the Lucus transmission leak stuff. It helps a little, but has not stopped it yet. Most important is to keep an eye on the fluid level and make sure it doesn't run dry. If the transmission starts slipping, check the fluid. If it continues, it's time for a rebuild. I'm just over in Bothell & work in Bellevue. I belived board member CG lives in Monroe, but he works over here by me in Bellevue. There are a couple other members out in the Monroe area too. I'm not sure if there is anyone in Duval specifically. Post some pics of your rig when you get a chance. __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L



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