FJ40 Idler Shaft O Ring Replacement While Installed In Truck. Has Anyone Succeeded With This? (1 Viewer)

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Ackcruisers

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Starting new thread on this. Attempting to replace the O ring without removal of transfer case. I’m following the below steps and have a few clarifying questions in yellow.
Has anyone successfully done this?


Removal:
1. Remove 12mm retaining bolt and keeper, making note of distance of shaft protruding out of housing.
2. Home made SST - Using a 15/16 socket with 8mm stud, washer and nut screwed into shaft. Thanks @Coolerman (here is link)
3. Keep frost plug in T-case housing (front of shaft). Is this possible? I do not want to introduce another leak...
4. Slowly tighten nut on stud and back out the shaft just enough to access O ring. To avoid thrust washers falling, or shaft dropping inside of case, does anyone have the distance from rear shaft to O ring? It appears to be about 10mm based on the image I found below.
C03AA49B-A801-47DF-828E-A29D318A51C5.jpeg

(NOTE: Image above is from the interweb and not my actual idler shaft. It is just for illustration purposes.)

5. Remove O ring ( if one was installed)

Install:
6. Install new O ring making sure to lubricate before placing on shaft.
7. Using soft hammer or drift, tap shaft back into place (Approx. 10mm)
8. Replace keeper and screw.

This is one of those procedures that comes with risk. Trying to mitigate it vs. overthinking.
 
Last edited:
I’m trying to avoid using “Right Stuff” gasket maker to stop leak at idler shaft. The information on The idler shaft O ring replacement without taking apart case is mixed. Hoping someone can weigh in here. Trying to avoid removing case.
 
Apparently no one wants to admit to doing this, so I'll fess up. IMHO it's not possible to do without taking the plug out of the front end of the shaft. If the front thrust washer drops down, you are screwed. The idler gear will want to drop immediately once the pin leaves the front boss, and the thrust washer wants to go with it. There's a tab on the washer and a corresponding groove in the case to keep it from spinning, but it's not enough to hold it in a vertical alignment.

I my case the opposite actually happened on the trail while climbing up a steep section. The thin piece of steel on the back end of the shaft for the retaining groove broke off, and with the retainer was still in place the shaft couldn't go out the back, but did walk FORWARD. Once oil started to puke out the back we knew we had a problem. Fortunately, my old-school Downey transmission adapter for plate my A/T stopped the shaft and it didn't not move far enough for the thrust washer and spacer shims to drop completely out. I stuck my finger in the hole while another guy used a bar to walk the shaft back in as I manipulated the washer and the Idler gear. We used a bolt in the back of the shaft, some washers and the retaining tab to keep everything in place.

My point is that this is possible to do what you describe, but again, IMHO, not without removing the plug. You need a way to keep track of the thrust washer because once it drops below the level of the hole you'll be pulling the t-case to fish it out. I don't the exact amount you have before the pin comes out of the boss, but suspect that it is probably marginally close to what you need to reach the o-ring.
 
Apparently no one wants to admit to doing this, so I'll fess up. IMHO it's not possible to do without taking the plug out of the front end of the shaft. If the front thrust washer drops down, you are screwed. The idler gear will want to drop immediately once the pin leaves the front boss, and the thrust washer wants to go with it. There's a tab on the washer and a corresponding groove in the case to keep it from spinning, but it's not enough to hold it in a vertical alignment.

I my case the opposite actually happened on the trail while climbing up a steep section. The thin piece of steel on the back end of the shaft for the retaining groove broke off, and with the retainer was still in place the shaft couldn't go out the back, but did walk FORWARD. Once oil started to puke out the back we knew we had a problem. Fortunately, my old-school Downey transmission adapter for plate my A/T stopped the shaft and it didn't not move far enough for the thrust washer and spacer shims to drop completely out. I stuck my finger in the hole while another guy used a bar to walk the shaft back in as I manipulated the washer and the Idler gear. We used a bolt in the back of the shaft, some washers and the retaining tab to keep everything in place.

My point is that this is possible to do what you describe, but again, IMHO, not without removing the plug. You need a way to keep track of the thrust washer because once it drops below the level of the hole you'll be pulling the t-case to fish it out. I don't the exact amount you have before the pin comes out of the boss, but suspect that it is probably marginally close to what you need to reach the o-ring.
Thanks for sharing your experience. I’m surprised there were not more responses to what appears to be a common leak point.

Today I replaced Idler shaft O ring without removing the TC. However, it did not go as planned. With the idler shaft securing tab and bolt removed, I threaded the M8 stud onto shaft expecting to need force to pull it from housing In order to expose O ring. What ended up happening was as soon as I inserted stud and turned it a few rotations, when I backed it out to then remove stud (was only testing threads) it hung up on last thread and with a little pull, shaft came out fast and moved way too far. However, I reacted instantly and pushed shaft back in and do not think washer and spacer fell. I then pulled shaft by hand just far enough to expose O ring. Used dental pick to remove and installed new O ring. Pushed back in used thread sealant on shaft retaining bolt and went for drive. The shaft is still leaking so applied Permatex Gear Oil RTV Did not test 4WD yet but hoping nothing fell when shaft came out too far. A full test will be performed tomorrow.

For anyone attempting this in future, do not thread bolt on end of idler shaft. First try to remove idler shaft by hand, then pliers and finally bolt with socket (27MM not 15/16) if needed. Be very careful as the shaft can slide out with almost no force. Made appointment with local transmission shop just in case.
 
I would pull the inspection cover and see if there is side play on the idler gear, if the washer fell you'll be able to tell. make sure it's in nuetral, trans & t-case, so the gears are not binding it while checking for side ti side movement of the idler.
 
Thanks for this post and comments. Very helpful.
I did this yesterday.
Discovered there was no freeze plug in place on my Tcase.
The shaft slid right out without any tools, just a push from the freeze plug side and some twisting, but only using my fingers.
Here is the pic of the shaft pulled out to where I could get the Oring off.

IMG_0068[1].JPG


Here is the other end where the freeze plug goes, showing in the position when the Oring was exposed.
IMG_0067[1].JPG

I would definitely recommend pushing the shaft through to pop out the freeze plug before attempting to remove the Oring, as it helped to have a finger on the freeze plug end. That made it easier to keep the shaft from moving too far out.
I was not able to get the oring off in one piece, it ripped in half pretty easily, but I had already order a replacement. They are no longer available from toyota, but FJ Parts in CA had one. I am glad I bought it ahead of time since it ripped and would have been difficult to buy the correct size.
I used the slot where the locking tab sits to help work the new one over the shaft, then it slipped right into the groove and the shaft slid back into place no problem.
Now time to get a freeze plug.
 
Nice work and thank you for posting the images. These will help others in future. FYI the plug is still available from Toyota. When you install yours, use some silicone before pressing it in.
 
Consider this. The shaft has a slight interference fit in the housing when both are in good condition. When a shaft slides easily, it is an indicator that the shaft, the housing or both are worn. This amount of wear is usually not critical to the gear contact. But it does increase the odds that the case will leak, even with a fresh Oring.
 
Consider this. The shaft has a slight interference fit in the housing when both are in good condition. When a shaft slides easily, it is an indicator that the shaft, the housing or both are worn. This amount of wear is usually not critical to the gear contact. But it does increase the odds that the case will leak, even with a fresh Oring.
Thanks for this. Not having anything to compare it to will make most of us think it’s normal to have it easily slide out. In my situation, the leak is not caused by O ring or shaft wear. It’s worn out around the case.
7E0629EE-EB69-44EA-8F33-A65C9A6E9A94.jpeg

3E6081ED-A0BF-489D-95AA-BB8BAD9B369C.jpeg
 

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