T90 Bellhousing Gasket and Leak Chasing

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   Afternoon All,
Apologies for the long post - just want to get as much info as I can out there for the experts! 

I finished up the T90/ D18 rebuild awhile back, and now I'm chasing leaks. Used the Novak kit with the sealed front bearing. If it's sitting still, and the gear oil is cool, I don't have much issue at all. When I drive the Jeep, an warm up the oil, it seems that it wants to wick through the threads. 

At first, it was leaking around the D18/ T90 mating surface. I've corrected that by draining, cleaning, and re-applying #2 gasket sealant to the bolts (a more generous amount than the initial build). 

Now I'm working on tracking down the leak that appears to be in/ around the bellhousing. Have any of y'all had a similar leak after a rebuild? I don't see much oil at all when I look through the inspection window, so it makes me think it's either from the oiler delete, or the counter shaft (it did come with the o-rings). 

After driving the other day, I parked it over a clean pan, and let it sit overnight - when I poured the pan off, it was maybe 3-4 ounces. I do tend to see lower levels in the T90; but it's hard to know the level change in the D18. I don't mind topping things up; but topping up that much on a recent rebuild is something I'd prefer to remedy. 

Would something like the gasket shown in this diagram (#7) help? Don't want to skirt the true issue, though. 

A couple notes:
1. I did delete the oiler (#21 in diagram), and replaced it with bolts, blue thread-locker, and nylon nuts. Should I have put sealant on them as well? 

2. I had to trim the lock plate from Novak for the counter shaft and reverse idler. I have the D18 with the thin cutout running between the two reliefs for the shafts. Everything seems to fit together well; but wanted to include that. 

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cyates176FA Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 12 Apr. 2022 Location: EAST TENNESSEE Status: Offline Points: 132	Post Options Post Reply Quote cyates176FA Report Post Thanks(0) Quote Reply Topic: T90 Bellhousing Gasket and Leak Chasing Posted: 18 May 2023 at 12:51pm
	Afternoon All, Apologies for the long post - just want to get as much info as I can out there for the experts! I finished up the T90/ D18 rebuild awhile back, and now I'm chasing leaks. Used the Novak kit with the sealed front bearing. If it's sitting still, and the gear oil is cool, I don't have much issue at all. When I drive the Jeep, an warm up the oil, it seems that it wants to wick through the threads. At first, it was leaking around the D18/ T90 mating surface. I've corrected that by draining, cleaning, and re-applying #2 gasket sealant to the bolts (a more generous amount than the initial build). Now I'm working on tracking down the leak that appears to be in/ around the bellhousing. Have any of y'all had a similar leak after a rebuild? I don't see much oil at all when I look through the inspection window, so it makes me think it's either from the oiler delete, or the counter shaft (it did come with the o-rings). After driving the other day, I parked it over a clean pan, and let it sit overnight - when I poured the pan off, it was maybe 3-4 ounces. I do tend to see lower levels in the T90; but it's hard to know the level change in the D18. I don't mind topping things up; but topping up that much on a recent rebuild is something I'd prefer to remedy. Would something like the gasket shown in this diagram (#7) help? Don't want to skirt the true issue, though. A couple notes: 1. I did delete the oiler (#21 in diagram), and replaced it with bolts, blue thread-locker, and nylon nuts. Should I have put sealant on them as well? 2. I had to trim the lock plate from Novak for the counter shaft and reverse idler. I have the D18 with the thin cutout running between the two reliefs for the shafts. Everything seems to fit together well; but wanted to include that.

Rick G Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 17 May 2015 Location: Amarillo, TX Status: Offline Points: 1467	Post Options Post Reply Quote Rick G Report Post Thanks(0) Quote Reply Posted: 18 May 2023 at 1:27pm
	Yes, that full-faced gasket (#7) is what I use to help stop the transmission from leaking at the front. If the case hole for your countershaft is slightly enlarged (from having the shaft driven out in the wrong direction) then this gasket will definitely help. In addition to that gasket, I put another gasket on top of that one that sits under the front bearing retaining cap. The bearing retaining snap ring causes the cover to sit just slightly proud of the sealing surface sometimes and this mimics a leak from an "unsealed" front bearing. Installing these two gaskets have eliminated all my front transmission leaks. I also use Permatex aviation sealer on the gaskets and bolt threads that penetrate into the case.
	1947 CJ2a #119929 "Gus" 1951 CJ3a #451-GB1-24268 “Newt” My Videos

cyates176FA Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 12 Apr. 2022 Location: EAST TENNESSEE Status: Offline Points: 132	Post Options Post Reply Quote cyates176FA Report Post Thanks(0) Quote Reply Posted: 18 May 2023 at 3:56pm
	Appreciate it! I drove the shaft out to the rear. But I suspect the T90 had been worked on before, so I can't say it's not been driven out the other way previously. Where did you source the #7 gasket from - or is that something that needs to be home-made? I believe that I have a spare of the small circular gasket that I could put over it.

Oldpappy Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 09 Apr. 2018 Location: Tennessee Status: Offline Points: 4904	Post Options Post Reply Quote Oldpappy Report Post Thanks(0) Quote Reply Posted: 18 May 2023 at 5:54pm
	Walcks had them, so maybe once they get all the stock moved over they will show up on the KW site. I usually buy gaskets in multiple quantities, so there is a small chance I may have and extra one. I'll take a look.
	If you can't get there in a Jeep you don't need to be there!

cyates176FA Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 12 Apr. 2022 Location: EAST TENNESSEE Status: Offline Points: 132	Post Options Post Reply Quote cyates176FA Report Post Thanks(0) Quote Reply Posted: 18 May 2023 at 9:37pm
	Thank you, sir! I will reach out to Mike at KW as well, to see if they have, or plan to have them in the future. It’d be good info for the group either way!

Rick G Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 17 May 2015 Location: Amarillo, TX Status: Offline Points: 1467	Post Options Post Reply Quote Rick G Report Post Thanks(0) Quote Reply Posted: 19 May 2023 at 3:20pm
	I just make mine from gasket material from the auto parts store.
	1947 CJ2a #119929 "Gus" 1951 CJ3a #451-GB1-24268 “Newt” My Videos

cyates176FA Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 12 Apr. 2022 Location: EAST TENNESSEE Status: Offline Points: 132	Post Options Post Reply Quote cyates176FA Report Post Thanks(0) Quote Reply Posted: 15 June 2023 at 1:20pm
	Afternoon, all! I am draining and pulling the T90/D18 over the next day or two. I plan to pull each bolt and re-seal it with #2 gasket maker. I have a few questions first (some may be dumber than others)... 1. I have deleted the oil slinger on the T90 and replaced it with bolts with blue Loctite and nylon nuts. Do those need to be pulled and sealed with #2 - or do Loctite and nylon nuts seal it? I'm wondering if #2 gasket maker and blue Loctite would "cancel each other out" or something. 2. The T90 primarily leaks once it warms up and the gear oil thins out. I plan, after sealing bolts and giving it 24 hours to set-up, to fill it with oil and check for leaks while it's up on the bench. What I am trying to decide, though, is how to simulate the thinning of the gear oil. Should I fill it with gear oil and use a heat gun to warm the case? Is there something I could substitute for the gear oil that is thin and won't damage anything or leave a residue? I was thinking maybe diesel - but wasn't sure if there was a better one. I may be over-thinking it; but I would like for this to be the last time I pull the transmission for awhile...

dasvis Members Profile Send Private Message Find Members Posts Add to Buddy List Member Sponsor Member Joined: 07 Sep. 2019 Location: Salem, Oregon Status: Offline Points: 1546	Post Options Post Reply Quote dasvis Report Post Thanks(0) Quote Reply Posted: 15 June 2023 at 1:49pm
	It won’t be.
	1947 CJ2A #88659 "Rat Patrol" 1953 CJ3A #453-GB1 11266 "Black Beauty" 1964 Thunderbird convertible ..... & one of them moves under it's own power!!

cpt logger Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 23 Sep. 2012 Location: Western Colorad Status: Offline Points: 3040	Post Options Post Reply Quote cpt logger Report Post Thanks(0) Quote Reply Posted: 15 June 2023 at 5:23pm
	The nylon nuts may seal the threads, but will not seal between them & the case. May I ask why you chose the blue Loctite over the #2 Permatex? As to your question on compatibility, call up either Loctite, or Peratex, or both on the compatibility issue. They are very helpful when I call for information on their products. I suspect it would be fine. Ask them. I would use diesel in this test. OTOH, There is no test like the road test with gear lube. IHTH, Cpt Logger.

cyates176FA Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 12 Apr. 2022 Location: EAST TENNESSEE Status: Offline Points: 132	Post Options Post Reply Quote cyates176FA Report Post Thanks(0) Quote Reply Posted: 16 June 2023 at 6:02am
	Blue Loctite was recommended in the Novak rebuild guide for omitting the oil collector. It seemed a bit over-kill in my mind at the time; but I figured it was in the directions for a reason. I will give them a call today to see what is recommended. If they do "react" with one another, I may just use #2 Permatex with a copper washer against the inside of the case with the nylon nut.

cyates176FA Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 12 Apr. 2022 Location: EAST TENNESSEE Status: Offline Points: 132	Post Options Post Reply Quote cyates176FA Report Post Thanks(0) Quote Reply Posted: 18 June 2023 at 6:40pm
	I pulled the transmission and transfer case, and here is what I've found so far. For reference, I used a set of feeler gauges that go from 0.008 to 0.026 to feel for gaps. 1. The front bearing cap was not torqued down, and had basically no sealant on the threads. I assume that during assembly, I skipped over the part where you torque them down (something like 10 ft. lbs.). I did take some measurements to make sure that it would seal up against the gasket, as it was mentioned that sometimes the snap ring on the front bearing can make the bearing cap stop short of the gasket. Without the gasket, I have ~0.020 clearance between the face of the T90 and the base of the bearing cap, so there shouldn't be any issue when I install the new gasket with the aviation gasket sealant. 2. I did a similar test on the transfer case. With everything tightened down, there was one spot (marked on an example pic below) where I had ~0.018 clearance between the gasket and the mating surface of the D18. From the looks of the side of the case, it may have been where someone pried them apart at some point. I feel confident that this is the source of the largest leak. I've let the oil drip out for a day or so, and now I plan to go in and clean and re-seal all the threads. Once I've let them set for a day or so, I plan to fill both cases with diesel to see if I can identify any additional leaks at the transfer case. Now for the question... In y'all's opinion, what is my best bet for sealing up the clearance issues on the D18/T90 mating surfaces? I feel like ~0.018 isn't something that would be a dealbreaker for the case, and just calls for a little thicker gasket to keep the oil on the inside. What I was thinking, would be to trace and cut new gaskets with the thicker gasket material I purchased from O'Reilly - and just brushing the aviation gasket sealer on each side.

cyates176FA Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 12 Apr. 2022 Location: EAST TENNESSEE Status: Offline Points: 132	Post Options Post Reply Quote cyates176FA Report Post Thanks(0) Quote Reply Posted: 26 June 2023 at 10:46am
	Another update, in case it helps someone in the future. 1. I bought some more substantial gasket making material from a local supply house. It has a little more "give" in it to help fill any gaps in the imperfect mating surfaces. I also used the Permatex Right Stuff gasket maker on the gasket as well. I didn't just heap it on; but I put enough to hopefully seal any imperfections in the mating surfaces. When I dry-fitted the gasket without the Permatex, I could not get any of my feeler gauges into the original trouble spots. 2. I pulled and trimmed down the locking plate for the cluster and reverse idler shafts. I have the D18 with the smaller cutout for the locking plate. I had cut it down; but there appears to have been one small piece that could've been pushing on the gasket and causing misalignment. When I tapped the cluster shaft out enough to remove the plate, I put a little bit of #2 sealant in the bore, then wiped off the excess when I tapped it back into place. 3. I pulled both the front bearing cap bolts and the oil collector bolts. None of them had very much #2 on them at all - a rookie/ cheapskate mistake. Instead of using nylock nuts and blue Loctite, I went with (new) nylock nuts and #2 Permatex, with the fiber washers that I received from QTM when I bought a new set of gaskets. Replaced the bearing cap gasket, and was a little more liberal with the aviation sealer, as well as #2 Permatex and fiber washers. I will fill it and check for leaks in the next couple of days, and hopefully not have any leaks that I can't live with.