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Old 12-11-2019, 07:54 PM
Dave Jeeper Dave Jeeper is offline
232 I6
Join Date: Sep 08, 2019
Location: Denver, CO
Posts: 53
G Wag- Transmission Stop Leak Additives

I have a 1989 Grand Wagoneer with a bad tranny leak. It sat for 15 years before I got it running this past summer. I have the 360 engine and I believe the tranny is a 727 torque flight with lockup. It has 93,500 miles. I tightened up the pan bolts on the tranny and the engine a while ago. I believe that the tranny leaks onto the crossmember support under the tranny, then leaks onto the ground. I parked it for 2 days in a new location and had a puddle about 12" in diameter on the driveway of red fluid. The tranny shifts smoothly, no lurching, no noises. Downshifts okay, maybe a little slow to downshift. I am concerned with the leak, not with trying to restore tranny function.

Has anyone had success with any transmission stop leak additives such as Lucas or Bar's, etc.

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Old 12-11-2019, 08:54 PM
twmattox twmattox is offline
350 Buick
Join Date: Feb 24, 2003
Location: Indiana
Posts: 1,282
I have had leaks slow down from these additives. But, never had a leak stop...
'83 Scrambler (CJ-8) / 258 / T-5 / D-300 / DANA 30-AMC20 (3.31)
'88 Grand Wagoneer (SJ) / 360 / TF727 / NP229 / DANA 44 (2.73)
'05 Wrangler Unlimited (LJ) / 4.0L / NSG 370 / NV231 / DANA 30-44 (3.73)
'15 Wrangler Unlimited (JKU) / 3.6L / 42 RLE / NV 241 / DANA 30-44 (3.73)
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Old 12-12-2019, 04:44 AM
wiley-moeracing wiley-moeracing is offline
350 Buick
Join Date: Feb 15, 2010
Location: arizona
Posts: 1,133
Fix the leak and not with stop leak, they do not work.
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Old 12-13-2019, 09:35 AM
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letank letank is offline
AMC 4 OH! 1
Join Date: Jun 03, 2002
Location: San Francisco
Posts: 3,885
as said, they do not work, especially for a 12" puddle in 2 days.... try to find the origin of the leak... it could be the NSS, the shift shaft seal, the easy to do dipstick tube, or the annoying leak in your face oil pan gasket, there is a sturdier oil pan gasket made by mopar that is reusable, but one has to be sure that the oil pan is not too deformed by overtightening the pan bolts.

I would order the oil pan and a new transmission pan with a drain plug to avoid oil shower when doing transmission service

The re-useable Dodge pan gasket # is 2464324AC. Be aware that the deep pans sometimes hit the crossmember.
74 wag, 349Kmiles on original ticker/trany, except for the rust. Will it make it to the next get together without a rebuilt? Status: needs a new body.
85 Gwag, 226 Kmiles. $250 FSJ test lab since 02, that refuses to give up but still leaks.

See Ouray 2013, Engine bits and Fuel and brake lines, and Body work
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Old 12-13-2019, 11:20 AM
Dave Jeeper Dave Jeeper is offline
232 I6
Join Date: Sep 08, 2019
Location: Denver, CO
Posts: 53
I figured out why I had such a large leak. The leak is over the cross-member where the tranny fluid accumulates. I normally park on a level or uphill (5 degrees) driveway. This time I parked downhill and the fluid ran off the crossmember and made a big stain. I parked it on the level street and it hasn't made a stain in 2 or 3 days.

I checked the dipstick and when it was cold (35 degrees) the level was 1/2 pint below the add a pint mark. I am not going to be able to deal with replacing seals, etc. for another 4 months, so I decided to try a 24 oz bottle of lucas tranny stop leak. It was very thick and took a while to get in the dipstick tube.

I can always flush out the system in the spring when doing the gaskets. I have a bunch of jeeps and I don't drive this one every day, so there won't be a ton of mileage on it this winter.

Do the main input or output seals tend to leak, or just the pan and the shift levers, etc?

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Old 12-14-2019, 05:02 AM
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fulsizjeep fulsizjeep is offline
Señor Jackhead
Join Date: Aug 21, 2002
Location: Jubilee Jeeps.SWCO
Posts: 22,292
If the tranny is original, it will not be a lockup style. The lockup style were used in 80-82 models.
Ran when parked.
88 GW, 401/727/208, 5" lift, D44s/4.10s/locked up, 35s with a few Evil Twin & TT's Fabworks mods
76 401 Wag, 77 401 Wag, 77 401 J20
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Old 12-14-2019, 09:32 PM
Dave Jeeper Dave Jeeper is offline
232 I6
Join Date: Sep 08, 2019
Location: Denver, CO
Posts: 53
I saw mixed info on tranny lockup for the Grand Wagoneers. Mine did not have a towing package. Some posts on this forum said that non-towing package G Wags had the lockup torque converters. Are you sure that none of the grand Wagoneers came with lockup converters?
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Old 12-15-2019, 12:32 AM
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FSJunkie FSJunkie is offline
The Nigel Tufnel of the FSJ world.
Join Date: Jan 09, 2011
Location: Not The Hot Part, Arizona
Posts: 3,994
You can tell a lockup transmission because you can feel the lockup clutch engage at 45 miles per hour.

Lucas Trans-Fix works for small leaks. It will not stop them, but it will slow them down. I doubt it would do anything for a leak as major as yours. Stop leaks work better on leaking lip seals, not so much on gaskets. A leak from the pan gasket basically requires removing the pan and re-doing the gasket.
'72 Jeep Wagoneer Custom, 360 V8

I love how arguements end as soon as Ristow comments. Ristow is right...again.
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Old 12-15-2019, 12:54 AM
Dave Jeeper Dave Jeeper is offline
232 I6
Join Date: Sep 08, 2019
Location: Denver, CO
Posts: 53
I have not felt any lockup at 45 mph. The shift to 3rd gear usually takes place around 55 mph when accelerating to get on the highway.

From the comments made here in this thread and others on the forum, it would seem to be prudent to identify all leaks and then repair them all at once, rather than just replacing the pan gasket. It seems that the pan needs to be removed to replace the other seals.

I still haven't heard any replies regarding the main input shaft and output shaft seals, if they tend to go bad. Replacing them would involve pulling the tranny I presume.
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