International Full Size Jeep Association
Home Forums Reader's Rigs Tech Library Trail Stories FSJ-List
International Full Size Jeep Association  

Go Back   International Full Size Jeep Association > Tire Kickin' > General FSJ Tech

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-26-2011, 03:16 PM
Raincheck Raincheck is offline
New Member
 
Join Date: May 26, 2011
Location: Colorado
Posts: 11
Crank shaft thrust

I've got a 360 in a GW that seems like a very solid engine. Just bought it recently, and it has great compression and power. Runs smooth. I'm not sure, but all indications are that it only has 79K or so original.

I was putting a new MSD ignition in it, and noticed a ton of thrust forward on the crank. Visible. I don't want to say 1/2", but it could be that much. Pulled the starter to make sure it wasn't a loose pully/balancer bolt, and sure enough...

Reading the other posts about bearing wear and so on, I guess this is going to need a new crank at least. What I can't understand, is why it runs so great. It leaks some oil, but not a lot, and most of that seems to be just from the oil pan.

What's likely to happen if I run this a bit longer, in some low strain situations? I plan to take the oil pan off when I can get it on a lift and see how scary it looks, but is there any other reason this might be happening?

I guess I'm just in denial 'cause it runs so good. Anyone have experience with this bummer situation?
Reply With Quote
  #2  
Old 05-26-2011, 03:40 PM
Dr. Marneaus's Avatar
Dr. Marneaus Dr. Marneaus is offline
360 AMC
 
Join Date: Jun 16, 2010
Location: Reno, NV
Posts: 2,888
1/2"? That seems like an insane amount of endplay...

how are you moving it? By pulling on the balancer? or prying it from behind? I checked mine by prying it from between the TC and the flexplate.

I've heard that balancers can wear out. The rubber seal goes and the weight on the outside can move forward and backward a bunch.
__________________
Quote:
Originally Posted by FSJunkie
Dr. Marneaus is now officially my idol.

The Mag - The Wag

The Beast Build Thread:Marns '73 Wagoneer Thread
1973 Wagoneer - 1987 360 w/ factory 4bbl - TH400 - D20 - D30/D44
Reply With Quote
  #3  
Old 05-26-2011, 03:46 PM
Raincheck Raincheck is offline
New Member
 
Join Date: May 26, 2011
Location: Colorado
Posts: 11
Just prying on the balancer Doc. Thanks for the reply.
Reply With Quote
  #4  
Old 05-27-2011, 07:22 AM
chrism chrism is offline
327 Rambler
 
Join Date: Apr 07, 2002
Location: Derby, NY
Posts: 634
I had a cherokee with the same issue. The 360 ran awsome good power and compression at 82K. One day the flywheel started making a grinding noise (hitting the dust shield) and 727 started leaking from the front. It got progressively worse until the tranny finally died when I was towing a uhaul trailer moving from MA to NY.
When I pulled the pan what I found was that the thrust bearing had machined out a nice slot in the crank. I ended up selling the jeep before I fixed it but an engine shop should be able to weld it up and make it good as new if that is the problem.
If your really lucky it might just be the thrust bearing...I'm never that lucky.
__________________
1979 Cherokee
1979 CJ-7
Reply With Quote
  #5  
Old 05-27-2011, 08:08 AM
Raincheck Raincheck is offline
New Member
 
Join Date: May 26, 2011
Location: Colorado
Posts: 11
Thanks very much for your experience and insight chrism. It helps me get a handle on this. I think I'll pull the pan, look at what's going on, and baby it along until I can afford a complete rebuild.

If I get way lucky, maybe I can just do bearings, but I'm not going to plan on it. You have the kind of luck I was given —not much. But, once in a while I do get some.
Reply With Quote
  #6  
Old 05-27-2011, 05:44 PM
letank's Avatar
letank letank is offline
AMC 4 OH! 1
 
Join Date: Jun 03, 2002
Location: San Francisco
Posts: 4,018
[quote=chrism
---- the thrust bearing had machined out a nice slot in the crank.----
[/quote]


That can be fixed, you take the crank off and a machine shop can weld a bead, them machine it for the appropriate thrust bearing, and crank bearings at that point.

1/2" is way too much, max is not more than 1/4".

Make sure that it is not your harmonic or crank pulley that is loose.
__________________
Michel
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
Reply With Quote
  #7  
Old 05-27-2011, 05:45 PM
Ristow Ristow is offline
 
Join Date: Jan 20, 2006
Location: The Great Googley Moogley Midwest.
Posts: 17,274
1/4 inch?!?





max is not more than about .010".

i don't see that there could be a half inch of movement.
__________________
Quote:
Originally Posted by Hankrod
Ristows right.................again,




Quote:
Originally Posted by Fasts79Chief
... like the little 'you know what's' that you are.




Quote:
Originally Posted by Fasts79Chief
I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!


→ Where the kids hang out...

fsjbuilder.org come for the mindless chat,stay for the hand drawn emoticons.

It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...
Reply With Quote
  #8  
Old 05-27-2011, 06:52 PM
azpackrat's Avatar
azpackrat azpackrat is offline
Master Mechanic
 
Join Date: Oct 20, 2009
Location: Phoenix, Az.
Posts: 836
You can probably find a crank from a 304 or another 360 cheaper than you can repair the one you have. Baby jeepers swap out 304's for 360's or SBC's often, so check Craig's list, I've seen 304's complete for a hundred bucks often. Most important is to fix the cause, usually a worn out Torque Converter, sometimes a shoddy bearing job (not in spec). My Dad wiped the thrust face on a 401 by towing too heavy, 8,000lbs daily for over two years (grade tractor, who says Quadra Trac's aren't strong?) at least that was our best guess.
__________________
“A free man must not be told how to think, either by the government or by social activists. He may certainly be shown the right way, but he must not accept being forced into it.” Col. Jeff Cooper

"Any fool can know. The point is to understand." Albert Einstein
Reply With Quote
  #9  
Old 05-28-2011, 07:20 AM
Raincheck Raincheck is offline
New Member
 
Join Date: May 26, 2011
Location: Colorado
Posts: 11
I wondered about that... if this was caused by the previous owner pulling a rolling house all over our Colorado mountain passes.

Thanks for the advice.
Reply With Quote
  #10  
Old 05-28-2011, 07:24 AM
Raincheck Raincheck is offline
New Member
 
Join Date: May 26, 2011
Location: Colorado
Posts: 11
REPLY to Ristow - - - - I know what you're saying about the half inch and still be running, let alone running like a champ.

But like I said, I pulled the starter out, pryed on the front of the shaft, and I could still see everything move forward in the starter hole.

I'll post the diagnosis when I get it on a lift with the pan off.
Reply With Quote
  #11  
Old 05-28-2011, 10:47 AM
azpackrat's Avatar
azpackrat azpackrat is offline
Master Mechanic
 
Join Date: Oct 20, 2009
Location: Phoenix, Az.
Posts: 836
For that amount of movement I would think the engine was reassembled without a thrust bearing (as in five regular bearings), and the crank is just free-floating. Doesn't bode well for wrist pins and rods.
__________________
“A free man must not be told how to think, either by the government or by social activists. He may certainly be shown the right way, but he must not accept being forced into it.” Col. Jeff Cooper

"Any fool can know. The point is to understand." Albert Einstein
Reply With Quote
  #12  
Old 05-28-2011, 02:57 PM
Raincheck Raincheck is offline
New Member
 
Join Date: May 26, 2011
Location: Colorado
Posts: 11
Wow... never even thought of that possibility. That's the only thing that really makes sense so far. Of course, I'm too old and have seen too many things that don't make sense to completely throw out something totally nutty.

That WOULD explain 1/4 - 1/2" better than anything so far. Thanks AZ.

BTW... Dittos to Col. Jeff Cooper
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
stock 4L crank shaft rod size??? NCOfab General FSJ Tech 2 11-29-2009 08:42 PM
crank shaft scrappers brubakes General FSJ Tech 23 11-20-2009 03:14 PM
Manual tailgate conversion crank handle... 78 Arizona Chief General FSJ Tech 2 01-21-2008 11:30 PM
J20 Steering Box plumbed for assist and rebuilt Elliott Off-Road FSJ Tech 12 09-08-2005 11:42 AM
*EDIT* 31 spline shaft makes it STRONGER! *EDIT* dnixon Off-Road FSJ Tech 19 11-19-2004 07:26 AM


All times are GMT -6. The time now is 02:08 PM.


Powered by vBulletin Version 3.5.4
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
corner corner