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Joined: Dec 2008
Posts: 108
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2008
Posts: 108 |
TH350... I didn't build but it feels like a good shift kit and from a visual the convertor may be aftermarket high performance type.
Car drives fine and will not leak at a show or after getting it home... but will leak a lot of fluid on my garage floor after sitting a few days.
Have rebuilt tail shaft housing: New bushing, seal and O ring at main body. Yoke was grooved and replaced with a yoke showing far less of a groove.
Speedometer bullet replaced with new steel unit with new O rings and the retainer tab was not holding bullet in tightly.. bent it a tad and its now tight...
Fill tube, coolant lines and that whole area are dirty but dry...
I can see the vent on top and tried to poke a wire thru it but it appears to be "sealed"
(Wire goes in a half inch and finds a very solid end)
From doing 101 Google searches this seems to be a issue with some internal seals?
And when the car is parked for awhile the fluid drains back, gets higher than the pan mating surface and finds whatever leakage point it can......
And "fixing" all these seals etc is just a bandage and the transmission needs a rebuild??????
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
The sump overfilling due to converter drain back is somewhat normal. This will cause a fluid leak at any of the places you mentioned. What wasn't mentioned is replacing the seal where the gear selector shaft passes through the case. There is a special tool made by KD that pulls the seal with out a major disassembly of the transmission. If intrested I will get the KD number of the tool (if it is still available).
Last edited by Chev Nut; 10/09/14 09:29 AM.
Gene Schneider
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Joined: Dec 2008
Posts: 108
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2008
Posts: 108 |
Please do....
Since the early 70s I've had 20? Chevys with a TH350 and never had this issue...
Just good luck I guess!
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Joined: Dec 2008
Posts: 108
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2008
Posts: 108 |
I guess the main question tho is....
What causes the drainback in the first place?
I know new Chevys with the TH350 could park for a month without dumping a quart of fluid on the garage floor...LOL
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Joined: Nov 2001
Posts: 19,758 Likes: 63
ChatMaster - 15,000
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ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,758 Likes: 63 |
Torque converter drainback is a common issue with the TH350 transmission as it ages. The solution is to drive the car every couple of weeks or at least start it and let run until everything is warmed up. Shifting a few times also helps. I have tried all the home or repair shop "in a can" remedies. None is a long term solution. If you can't live with it a teardown to replace the internal seals is needed. So far I have opted for a large drain pan and adding a quart or two of ATF to my '70 Caprice when I get it out after a few months storage. My '72 Chevelle with rebuilt transmission (1986) still behaves but I am sure will break its potty training eventually.
How Sweet the roar of a Chevy four!
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Joined: Dec 2008
Posts: 108
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2008
Posts: 108 |
I just got under car and laid there for awhile... finally saw a drop form and it was visually from the speedo bullet.... where it meets the housing... not where the gear shaft is.....
I put a new bullet in 50 miles ago.........
Yanked a bullet out of a junk TH350 and installed it... hard O ring and wrong gear.. but presto... laid there again and no leak...
Amazing that a bullet from a transmission that's been under my work bench for 30 years would seal better than a brand new one with new O rings...
Actually this old bullet only has the other O ring... inside is friction fit to the gear shaft... no inner O ring......
Anyone in Harris County do a good job fixing this type issue?
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
The inner O ring was "added" so as to prevent fluid from coming up the speedo. cable and dripping in the drivers lap. Rare but did happen.
The selector shaft seal puller has been discontinued but if you do a search of KD 2393 you should find one if needed.
Gene Schneider
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Joined: Dec 2008
Posts: 108
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2008
Posts: 108 |
Well this one doesn't have a speedo cable... has a box to an aftermarket electric speedometer so my carpets are safe...LOL
I wonder if you can just get after that seal and get it out with screwdrivers etc.......?
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Joined: Dec 2008
Posts: 108
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2008
Posts: 108 |
Just in case anyone follows this thread.. found this tool on EBAY.
G.M. Shift Lever Seal Remover & Installer Tool
(Shift Lever / Selector Shaft / Manual Lever)
The T-1001 has a tapered thread and is used to remove the selector shaft seal with the transmission in or out of vehicle.
The body of T-1001 is placed over the selector shaft, and tapped lightly to engage into the outer lip of the seal.
The body of T-1001 is then turned approximately 1/4 turn to fully engage the seal.
Then, the body is held, and the screw of T-1001 is tightened against the selector shaft to draw the seal from its bore.
Provides the easy removal and installation of the selector shaft (shift lever) seal.
Installs the selector shaft seal with the shaft either in place or removed.
Draining of the transmission fluid is not required.
The whole process takes just a few minutes.
Similar to:
Kent-Moore J-26282 & J-26401, Atec Trans-Tool T-1001, KD Tools 2393 and Snap-On YA9348.
These are some of the transmissions the T-1001 works on:
…Allison 540
…180,180C (3L30) (4L30-E) Short Shaft Only
…200, 200C, 200-4R
…250, 250-C, 350, 350C
…325,325-4L
…375,400 (3L80), 425, 475(3L80-HD)
…700-R4 (4L60) (4L60-E Pre-1995 Short Shaft Only)
…POWERGLIDE
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