Engine knocks when shutting down. - Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today



Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 06-23-2013, 01:30 AM   #1
Jeeper
 
Docvinkman's Avatar
 
Join Date: Mar 2013
Location: Mesa, AZ
Posts: 178
Docvinkman is on a distinguished road
Engine knocks when shutting down.

I have a 1987 yj with 4.2L. In last few days she has started intermittently shaking and knocking when I shut her off. I know there are probably many things that can cause this. What I am looking for is ideas to explore. I am not very knowledgable but I am learning. Thank you in advance.
Docvinkman is offline   Quote
Old 06-23-2013, 02:25 AM   #2
Jeeper
 
RednekYJ's Avatar
 
Join Date: Feb 2007
Location: LITH IL
Posts: 1,590
RednekYJ is on a distinguished road
Sounds like diesling. Old motor could be carbon buildup. New it could be running lean.

RednekYJ is offline   Quote
Old 06-23-2013, 02:47 AM   #3
Jeeper
 
Docvinkman's Avatar
 
Join Date: Mar 2013
Location: Mesa, AZ
Posts: 178
Docvinkman is on a distinguished road
Quote:
Originally Posted by RednekYJ View Post
Sounds like diesling. Old motor could be carbon buildup. New it could be running lean.
Ok I will do a research dieseling. What do you do to treat or repair this.
Docvinkman is offline   Quote
Old 06-23-2013, 09:50 AM   #4
kik
Jeeper
 
kik's Avatar
 
Join Date: Dec 2008
Posts: 8,296
kik is on a distinguished road
Tune up, check your timing and idle. Idle hot in park/neutral should be no more than 800 rpm's. Worse case scenario, extreme carbon build up or a bad distributor. I would make sure everything is set to spec. You might just need a tune up.
kik is offline   Quote
Old 06-23-2013, 02:08 PM   #5
Jeeper
 
Docvinkman's Avatar
 
Join Date: Mar 2013
Location: Mesa, AZ
Posts: 178
Docvinkman is on a distinguished road
Quote:
Originally Posted by kik View Post
Tune up, check your timing and idle. Idle hot in park/neutral should be no more than 800 rpm's. Worse case scenario, extreme carbon build up or a bad distributor. I would make sure everything is set to spec. You might just need a tune up.
Very interesting, because the RPM's recently have been going up to 1500 when I put her in park. I thought that was a little high, I did not realize she was supposed to be at 800. What are other symptoms of bad distributor?
Docvinkman is offline   Quote
Old 06-23-2013, 11:24 PM   #6
kik
Jeeper
 
kik's Avatar
 
Join Date: Dec 2008
Posts: 8,296
kik is on a distinguished road
Quote:
Originally Posted by Docvinkman View Post
Very interesting, because the RPM's recently have been going up to 1500 when I put her in park. I thought that was a little high, I did not realize she was supposed to be at 800. What are other symptoms of bad distributor?
That's your problem. If you shut it down at 1500 rpm's hot it's going to diesel/run on. Bring your idle down. It actually should be 700-750 rpm's but they seem to like to idle at 800. That should be max. Your distributor is probably fine, start with the proper idle adjustment.
kik is offline   Quote
Old 06-23-2013, 11:46 PM   #7
Jeeper
 
Docvinkman's Avatar
 
Join Date: Mar 2013
Location: Mesa, AZ
Posts: 178
Docvinkman is on a distinguished road
Quote:
Originally Posted by kik View Post

That's your problem. If you shut it down at 1500 rpm's hot it's going to diesel/run on. Bring your idle down. It actually should be 700-750 rpm's but they seem to like to idle at 800. That should be max. Your distributor is probably fine, start with the proper idle adjustment.
Thank you, I will have to look up how to adjust idle. Is it a tricky process where I should take it to a professional or is it something you can just look up on Internet?
Docvinkman is offline   Quote
Old 06-24-2013, 12:13 AM   #8
Jeeper
 
Billmummey's Avatar
 
Join Date: May 2013
Posts: 98
Billmummey is on a distinguished road
It is just a screw, I have a weber and its on the back side of the carb, just look for where your throttle linkage is and there should be a screw to adjust the position

Billmummey is offline   Quote
Reply

Thread Tools

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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 11:15 AM.


User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC
« Back

Enter your email address:

Delivered by FeedBurner