Transmission Leak

#1 13-03-06, 18:12

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#2 13-03-06, 20:53

Brad is it leaking ware the leather boot is?, cuz i'll need to check mine when i'm finished too , anyone out thier can help us? BIG MIKE

Tony Smith · #3 14-03-06, 00:58

If the leak is happening while the carrier's been standing, it can't be coming out the main shaft unless you've overfilled the case. The oil level should be below the centreline of the shaft. The other places for oil to get into the bellhousing area are the countershaft and the threaded holes for the bolts that hold on the front bearing retainer. The countershaft should be a tight fit and leak free and of course the bolts should be done up tight.
There is no oil seal in the front mainshaft, only a return drainage hole for any oil that should seep past the bearing. When installing the gasket, you should take care not to cover over the drain hole. It's not a factory fit on these gearboxes, but Jeeps also use a felt wick that should retain any excess seepage and return it to the drain hole.
When these gearboxes were designed, the bearings were plain roller bearings. With the choices available today, fitting a bearing with an outer seal will greatly reduce the amount of oil that gets past the bearing.

Now, of course, you ARE sure it is gear oil and not engine oil that's leaking?

Tony Smith · #4 14-03-06, 07:07

In this pic, you can see the oil drain passage in the bearing retainer and the hole back into the gearbox casing. The bearing with seal is shown, this type is a 6209Z.

Tony Smith · #5 14-03-06, 07:12

There no other sources for Oil leaks, there's just nothing there to leak. If the oil is leaking from the counter shaft (from a worn shaft or bore), applying some Locktite shaft seal when reassembling the box should eliminate any excess clearance.

Tony Smith · #6 14-03-06, 07:19

The oil is far more likely to be engine oil. The rear main seal on the crankshaft is a rope type wick and is notorious for leaking and a S**T to replace. The sump needs to come off, and in a Carrier, that means pulling the engine out

The design of the seal means it can't be replaced with a modern synthetic seal or be sleeved (Oh, Henry, what have you done?). When reinstalling the replacement rope seal, soak it in oil for 24 hrs beforehand to get it to swell and seal properly. Even then, expect some oil to leak. This is to ensure you don't get lazy and forget to regularly check and top-up your oil!

rob love · #7 14-03-06, 14:57

Brad
There was a guideline in the army: 1 drop per minute= serviceable, 2 drops per minute= KUO (keep under observation) and 3 drops per minute= repair

Of course, if you had a chev, any of the above leaks would actually be something to aspire to.

I incorporated a seal onto the bearing retainer during a Jeep t90/V6 conversion, and it worked well. Tonys one-side-sealed bearing idea is better and is a low cost solution.

Bryan · #8 14-03-06, 20:50

Hi all,

I have looked at all the photos of when I rebuilt the gearbox in the Alligator. I think its the same unit as you chaps have in your carriers and I cant see a oil seal anywere. But I do have an oil baffle fitted just behind the bearing.

Could this be missing from your box Brad?.

It is listed as part number 7040 it is shown in the exploded parts drawing taken from my 1932 - 1948 V8 Service manual.

I see that Tony has fitted a bearing with a rubber seal to try and keep any oil in. Thats a good idea but in practice these seals are only designed to keep the dirt and grime out of the bearing and grease in. Should the gearbox create any sort of preasure which is unable to get out the dust shield will be the first thing to pop out.

But thinking along the same lines If you were to fit a bearing with metal shields these are more secure and are less likly to come out.

Bryan

Lynn Eades · #9 18-03-06, 07:00

Brad I would put some sealant on that counter shaft pin as a matter of course if you are going to split the box from the motor. But make sure you havent overfilled the box first. If you are looking at replacing the input shaft bearing, use a high load bearing (slot filled) it probably has two or three more balls in it than the original, and if its double sealed or double shielded ( Id use the tin shield one) DONT forget to remove the one on the inside of the gearbox. in practice the oil flows freely through the bearing and flows back through the return drain hole as Tony talked about. The oil is kept back by the slinger thread in the thrust bearing support, when the engine is running but not when its stopped. So dont park it with its nose down hill or as I said before, Dont over fill it. Worst case is when oil runs down the shaft and into your clutch.

Tony Smith · #10 18-03-06, 12:06

Quote:

Originally posted by Bryan
Hi all,
I see that Tony has fitted a bearing with a rubber seal to try and keep any oil in. Thats a good idea but in practice these seals are only designed to keep the dirt and grime out of the bearing and grease in. Should the gearbox create any sort of preasure which is unable to get out the dust shield will be the first thing to pop out.
But thinking along the same lines If you were to fit a bearing with metal shields these are more secure and are less likly to come out.
Bryan

The bearing I fitted (as shown in the pic) has a metal sheild!

The gearbox can't create any pressure as the top of the box where the shift lever is fitted is not sealed air tight, and hardly even water tight.

Bryan · #11 18-03-06, 19:55

Tony,

Sorry for that I miss understod the photo.

When I rebuilt mine I fitted the same as what came out (no shields and it seams to be okay)

Bryan

Alex Blair (RIP) · #12 18-03-06, 20:10

Quote:

Originally posted by Tony Smith
The bearing I fitted (as shown in the pic) has a metal sheild! The gearbox can't create any pressure as the top of the box where the shift lever is fitted is not sealed air tight, and hardly even water tight.

Hi Tony..
The 7025 bearing shown is unsheilded..If it was sheilded one side it would be numbered 7025.Z.......Z being the code for sheild ,one side.
Both sides sheilded would be 7025.2Z..
FYI

Tony Smith · #13 18-03-06, 21:49

Alex, the 7025 is Ford's part number (actually BB-7025), not the actual bearing number. The bearing is a 6209, as I've mentioned above I fitted a 6209Z, which as you will agree is a single sided sheilded bearing.
Just to complete the story, the rear bearing on the main output shaft is a 6307. Because the output flange has a seal surface, there is not a lot to be gained in fitting a sheilded bearing on the rear.

Alex Blair (RIP) · #14 19-03-06, 03:43

Quote:

Originally posted by Tony Smith
Alex, the 7025 is Ford's part number (actually BB-7025), not the actual bearing number. The bearing is a 6209, as I've mentioned above I fitted a 6209Z, which as you will agree is a single sided sheilded bearing.
Just to complete the story, the rear bearing on the main output shaft is a 6307. Because the output flange has a seal surface, there is not a lot to be gained in fitting a sheilded bearing on the rear.

Hi Tony..
Yes ,I knew that,I was just using the Ford # ..I just wanted to point out the shielding codes...I should of XXXX.Z,XXXX.2Z but not everyone is as sharp as you and me....

#15 20-03-06, 19:04

Cheer up Brad

not all is lost, you can fix!!!!! it it's a minor problem.

Cheer BIG MIKE

Eric Korhonen · #16 20-03-06, 21:24

Brad:
Do you need a complete transmission or just or just the transmission body ? I have one on a scrap of an old carrier that has been cut real bad . The cover is missing off of it and has been exposed to the elements probably for 40+ years now . It is buried under the snow right now. All that is left of the carrier is the block, frame, transmission and the diff minus the axles. Let me know and i will go out and shovel it out and take a look at it if you like .

Cheers

Eric