Engine hot spots: questions about thermostat, spark plugs - Jeep Wrangler Forum
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 06-05-2009, 12:20 PM   #1
KTC
Jeeper
 
Join Date: Jan 2009
Posts: 43
Engine hot spots: questions about thermostat, spark plugs

I get a convulsive shudder from time to time when I shut down my 4 cyl '87 YJ. Also starts slowly, sounds like cylinder's are starting out of synch, whenever I start back up right after the weird shuddering shut down. Starts fine every other time.

Based on info I got in the forums and elsewhere, I'm thinking I have hot spots in the engine.

People have recommended replacing the thermostat and switching to cooler spark plugs. I'm gonna try both.

Questions are: what's the difference between hotter and cooler spark plugs? (yeah, I'm that much of a n00b).

Also, I understand about how the thermostat works, but I keep finding 195║ OEM style thermostats, and 160║ "high performance" thermostats. Other than the fact that they open up at different temps, what's the functional difference between the 160║ and the 195║? Since they're both open continuously above a certain temp (if I understand right), will it really make a difference with my hot spots?

Love my Jeep. Just learning as I go along. Any and all advice appreciated.

KTC is offline   Quote Quick Reply
Old 06-05-2009, 01:18 PM   #2
Jeeper
 
Brunolinski's Avatar
 
Join Date: Dec 2008
Posts: 44
Check the timing. What condition is the carb in? Original condition? I am unfamiliar with diagnosing the shuttering you have described. Does it backfire?

Cheap thermos fail soon. All thermos will fail. Some are engineered to fail in the open position, leaving you with a motor that warms up poorly and doesn't blow warm air. Or you have a failed thermo in the closed position reulting in overheating and some part of your Jeep needing to be replaced in addition to the thermo.

Robert Shaw is good stuff. But not the only brand worth using. This is a part you should not cheap out on.

__________________
89 YJ, 4.2L MC2100 carb conversion, nutter bypass, AX-15 tranny conversion, rhino lined tub, 33" Treadwright Mud, 2.5" RC lift, 4.10 gears, Aussie locker front and back
Brunolinski is offline   Quote Quick Reply
Old 06-05-2009, 01:29 PM   #3
Hacks off Parts while Lit
 
whitebuffalo's Avatar
 
Join Date: May 2005
Location: The Sandhills of South Texas
Posts: 2,290
if by shudder you mean it chugs an extra time or two, i'd be looking at timing. that'll also make it slow to crank when the engine is started hot.

im running a 180 tstat, fwiw
__________________
'90 YJ, ford 8.8, SOA, lincoln front, aussie rear, 4.88s, swampers.
whitebuffalo is offline   Quote Quick Reply
Old 06-05-2009, 04:28 PM   #4
KTC
Jeeper
 
Join Date: Jan 2009
Posts: 43
How do I check the timing?
KTC is offline   Quote Quick Reply
Old 06-06-2009, 06:49 AM   #5
Jeeper
 
Brunolinski's Avatar
 
Join Date: Dec 2008
Posts: 44
You should take it to a shop that you trust and ask them to give it a good once over. Then you will know where you stand with timing, fluids, proper operation, etc. If you are not experienced with this type of thing, let an expert look at it before you spin your wheels too much.

Be safe!
__________________
89 YJ, 4.2L MC2100 carb conversion, nutter bypass, AX-15 tranny conversion, rhino lined tub, 33" Treadwright Mud, 2.5" RC lift, 4.10 gears, Aussie locker front and back
Brunolinski is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
rebuilding your engine?? Get Stroked!!! jeeper95yj YJ General Discussion Forum 6 01-01-2014 04:47 PM
Spark plugs mechanicforme TJ Tech Forum 12 02-09-2009 12:22 PM
2005 wrangler spark plugs Nordin TJ Tech Forum 3 02-08-2009 09:12 PM
Spark plug questions 2002TJX TJ Tech Forum 13 01-25-2008 06:03 PM
spark plugs LIL_red_JEEP TJ Tech Forum 32 10-02-2007 03:24 PM


logo carid shop wrangler parts carid fender flares custom wheels store avs deflectors at carid
» Rates
Get low rates on auto insurance in Canada!

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 02:35 PM.



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