Forum Home Forum Home > CJ-2A Discussion Area > Tech Questions and Answers
  New Posts New Posts RSS Feed - Rear main seal Again!!!! UGH!
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Rear main seal Again!!!! UGH!

 Post Reply Post Reply
Farmer John View Drop Down

Joined: 01 Sep. 2020
Location: Roaring Branch,
Status: Offline
Points: 29
Post Options Post Options   Thanks (0) Thanks(0)   Quote Farmer John Quote  Post ReplyReply Direct Link To This Post Topic: Rear main seal Again!!!! UGH!
    Posted: 21 Nov. 2020 at 6:09pm
Well putting engine back together, end play set, everything smooth as silk, very nice machine shop job. I put in the neoprene seal from KW gasket set about six times now and it all but locks up. Checked everything and this new seal is about 1/16 proud when cap main bolts to block snug up and it starts to tighten, torque bolts and you basically can hardly turn crank. When I take it back apart it does not exhibit seal line like a normal lip seal in assembly lube but looks like one of those flat seals that's going to melt and take out a meticulously assembled engine, seal journal is wiped just about dry. I've put it in flush and indexed it makes no difference even took crank out and torqued journal to make sure ends were seated  Asked K/W and person told me they've sold thousands of these seals no problem, I had no idea there were that many folks doing 134's right now, :) . Anyhow feels about 100% this is gonna' be a fail at best, crank destruction at worst. Spec on journal is 2.310 as far as I can tell perfect for lip seal. I've been told that "BEST" company lip seal is ok or good, I need some input from the wizards on this. I can always put a rope seal in but lip seal really should be superior or We wouldn't have put them in billions of engines and trillions of other shafts. I've put in countless seals of all kinds from graphite cord to leather, to neoprene to ceramic, this shouldn't be this tight. OK O' great ones what thinkest thou ? 
Thanks J.

FWIW.- I almost cannot distinguish a lip on this it almost looks like a flat seal and yes what little lip that may be there is facing in with metal backing out back of engine. You really can't almost tell there is a lip like you normally see on a lip seal.
Back to Top
Frank View Drop Down

Joined: 18 Nov. 2006
Status: Offline
Points: 254
Post Options Post Options   Thanks (0) Thanks(0)   Quote Frank Quote  Post ReplyReply Direct Link To This Post Posted: 21 Nov. 2020 at 10:34pm
Farmer John,

For what it is worth...............

Read the text about the crank size ,

Good luck,

Back to Top
squidtone View Drop Down

Joined: 05 Mar. 2016
Location: CT
Status: Offline
Points: 41
Post Options Post Options   Thanks (0) Thanks(0)   Quote squidtone Quote  Post ReplyReply Direct Link To This Post Posted: 22 Nov. 2020 at 12:04am
If you do decide to go with a rope seal, I suggest the "Best Gasket" brand graphite impregnated teflon rope. I tried the Felpro rope that comes in the gasket kits, and it's fiberglass or kevlar or something. After installation, the crank was locked up solid. No good at all in my situation.
AS for the Best Gasket teflon rope seals, I've used them twice, once in a 60's Pontiac, and just two months ago an L134.
For the L134, you should install a single roll pin (provided) in the bottom of the groove of the cap. It sticks up and is "insurance" that the rope won't spin/rotate.

In my situation, my crank seal surface was pitted, and I wanted to go with rope for this reason. By the way, my crank seal surface measured 2.309".  I bought the Best Gasket kit, and installed it as instructed.
For the step where you mash the seal into the grooves, you mash it down, and when you think it's good, just keep mashing. Then mash it down again. It MUST be bottomed into the grooves. I used a big socket on it's side and pounded it to get it fully mashed into the grooves. The rope ends are a mess after this step. A shim is provided and you cut the excess off all the ends. I then very carefully pushed the edges of the  ends and folded them into the center of the rope end face to absolutely make sure no strands would get between the mating surfaces of the rear cap and block. Before installing the cap, I ran a very thin line of gray RTV from the rubber dowels to the edge of the rope ends.

After torquing the caps, I measured the torque required to turn the crank (no pistons or cam) at about 5 ft/lbs.

I've since completed the build, run the engine, and driven about 50 miles. Probably about 20 cold starts. The seal is dry as a bone. My Pontiac, after thousands of miles, is also dry as a bone.

Sorry for the long post, but I've seen so many complaints about rear main seals. The aftermarket tolerances (or blueprints they use) are now out of control and it's a toss up if you get anything that fits.
The Best Gasket solution is a bit finicky to install, but I think they are a good solution.
If you want to see a couple pictures of my seal installation, it's on page 12 of my "build" thread of my CJ3A on

Good luck!
Back to Top
Bruce W View Drop Down

Joined: 29 July 2005
Location: Northeast Colorado
Status: Online
Points: 8623
Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce W Quote  Post ReplyReply Direct Link To This Post Posted: 22 Nov. 2020 at 1:18am
  KW, eh? Don't tell me, let me guess - Omix- ADA?
It is NOT a Jeep Willys! It is a Willys jeep.

Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You!

We Have Miles to Jeep, Before We Sleep.
Back to Top
oldscot3 View Drop Down

Joined: 22 Oct. 2019
Location: texas
Status: Offline
Points: 545
Post Options Post Options   Thanks (0) Thanks(0)   Quote oldscot3 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Nov. 2020 at 2:20am
Go to youtube and look up metalshapers channel. He has a video about rubber lip seal main seals, what he uses, and what he has done to the crank to make them work. He also has a video on the method he uses to make a rope seal work. 

While I have no personal experience myself (I've built many engines and installed many main seals, just not a willys flathead [yet]) I have a hunch he knows what he's talking about. If nothing else, you can take some notes, pull some measurements, and see how what he says might apply to your situation.

Good luck, I hope you have success.
James 4:6 God resists the proud, but gives grace to the humble.
Back to Top
drm101 View Drop Down

Joined: 12 Dec. 2012
Location: Clarkston, MI
Status: Offline
Points: 1306
Post Options Post Options   Thanks (0) Thanks(0)   Quote drm101 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Nov. 2020 at 12:29pm
I feel your pain. The kit I ordered had both the lip seal and rope seal, and I tried the lip seal and it did the same thing. I installed the rope seal and no issues. 
'47 CJ2A "Mud Hen"
The less the Power the More the Force
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.05
Copyright ©2001-2022 Web Wiz Ltd.