dumb question.. cant stop thinking about it - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > dumb question.. cant stop thinking about it

JK Front 3 Link Prototype - Clayton Off RoadDon't forget the Jeep Forum discount, 10% off!Ruffstuff Axle Simple Swap Kit!

Reply
Unread 07-05-2011, 08:33 PM   #1
worsrider4047
Registered User
1998 ZJ 
 
Join Date: Jul 2009
Location: cedarburg, Wisconsin
Posts: 195
dumb question.. cant stop thinking about it

ok so i was overheating and it was on and off so i thought it was the thermostat, bought and installed a new one, problem is, its still doing it, i installed the spring down which i believe is right but when i think about it, it seems wrong cause doesnt the coolant come from the top end after the thermostat opens? which it opens downwards?
i dont get how that works lol shouldnt the pressure push up to open

worsrider4047 is offline   Reply With Quote Quick reply to this message
Unread 07-05-2011, 08:37 PM   #2
little_Jeep
Registered User
1998 TJ Wrangler 
 
Join Date: Nov 2006
Location: Louisville, KY
Posts: 5,947
Quote:
Originally Posted by worsrider4047 View Post
ok so i was overheating and it was on and off so i thought it was the thermostat, bought and installed a new one, problem is, its still doing it, i installed the spring down which i believe is right but when i think about it, it seems wrong cause doesnt the coolant come from the top end after the thermostat opens? which it opens downwards?
i dont get how that works lol shouldnt the pressure push up to open
The spring end goes into the block of the engine. When thermostat opens, hot coolant is allowed to flow from the engine into the top radiator hose and to the radiator....as the hot coolant travels down thru the radiator, it is cooled and then passed thru the lower radiator hose and back thru the engine.
little_Jeep is offline   Reply With Quote Quick reply to this message
Unread 07-05-2011, 08:41 PM   #3
worsrider4047
Registered User
1998 ZJ 
 
Join Date: Jul 2009
Location: cedarburg, Wisconsin
Posts: 195
yea i know that lol i just confused on how it opens down, hot coolant should expand to push open not suck down to open, idk maybe im just crazy but its stuck in my head and i cant stop thinking about it
worsrider4047 is offline   Reply With Quote Quick reply to this message
Unread 07-05-2011, 09:01 PM   #4
little_Jeep
Registered User
1998 TJ Wrangler 
 
Join Date: Nov 2006
Location: Louisville, KY
Posts: 5,947
Quote:
Originally Posted by worsrider4047 View Post
yea i know that lol i just confused on how it opens down, hot coolant should expand to push open not suck down to open, idk maybe im just crazy but its stuck in my head and i cant stop thinking about it
I understand what you are saying. However, in real World, the flap pulls downward to open thermostat.
little_Jeep is offline   Reply With Quote Quick reply to this message
Unread 07-05-2011, 11:45 PM   #5
ratmonkey
R.I.P.
 
ratmonkey's Avatar
1997 ZJ 
 
Join Date: Dec 2006
Location: , Pennsylvania
Posts: 19,794
It opens from the bimetal strip, not pressure.
__________________
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

ratmonkey is offline   Reply With Quote Quick reply to this message
Unread 07-06-2011, 12:10 AM   #6
jnicewan
Registered User
1995 ZJ 
 
Join Date: Dec 2010
Location: Norman, OK
Posts: 2,006
The cylinder shaped bulb just inside the spring has a special wax in it. When the wax gets heated to a certain temperature it causes expansion to push a piston which is pinned to the top the thermostat. This forces the bulb down, which is attached to the valve, therefore allowing coolant to open. They do not open due to pressure or expansion of the coolant.

This pics shows what an open vs shut thermostat looks like. Notice how the bulb part has moved down when the valve is open.
jnicewan is offline   Reply With Quote Quick reply to this message
Unread 07-06-2011, 07:43 AM   #7
Foundrydude
Registered User
1995 ZJ 
 
Join Date: Jan 2011
Location: Flatsville, IA
Posts: 2,692
Shift your thinking toward the clutch fan for intermittent overheating.
Foundrydude is offline   Reply With Quote Quick reply to this message
Unread 07-06-2011, 07:57 AM   #8
little_Jeep
Registered User
1998 TJ Wrangler 
 
Join Date: Nov 2006
Location: Louisville, KY
Posts: 5,947
Quote:
Originally Posted by jnicewan View Post
The cylinder shaped bulb just inside the spring has a special wax in it. When the wax gets heated to a certain temperature it causes expansion to push a piston which is pinned to the top the thermostat. This forces the bulb down, which is attached to the valve, therefore allowing coolant to open. They do not open due to pressure or expansion of the coolant.

This pics shows what an open vs shut thermostat looks like. Notice how the bulb part has moved down when the valve is open.
I always install "Fail Safe" thermostats... they cost a little more, but if your vehicle's coolant overheats, the "Fail Safe" thermostat freezes in the open postion, where as a normal thermostat will freeze in the closed postion when overheated.
little_Jeep is offline   Reply With Quote Quick reply to this message
Unread 07-06-2011, 12:06 PM   #9
coralman
new wrangler prototype
 
coralman's Avatar
1998 ZJ 
 
Join Date: Jul 2010
Location: florida
Posts: 4,523
My friend who has a gmc might argue the "fail safe" route, he said they ought to make a fail safe for the fail safe lol. I've seen several makes for the I6 and always wound up doing the dealer thing. One difference I noted was the little bypass mechanism in the dealer stat. Don't know exactly what it does but some parts houses will sell one that doesn't have it. The duralast {what a name} does have a similar mechanism. Is it an air bleed after draining the system?
coralman is offline   Reply With Quote Quick reply to this message
Unread 07-06-2011, 04:57 PM   #10
Bishop3854
Registered User
1995 ZJ 
 
Join Date: Mar 2011
Location: union, ohio
Posts: 32
if your talking about the lil hole with the metal piece in it then yes, it help break up air pockets and makes filling alot easier.
Bishop3854 is offline   Reply With Quote Quick reply to this message
Unread 07-07-2011, 11:25 AM   #11
tcar
Registered User
2000 WJ 
 
Join Date: Sep 2007
Posts: 854
1. Pressure has NOTHING to do with it... as everyone said, it's temperature. Does not matter where the spring is.

2. Only use a Mopar thermostat from the dealer. Most aftermarket t-stats don't work properly in the Jeep there are a couple brands (one that used to be OK isn't anymore), but to be safe, buy a mopar.

Go buy a Haynes Manual.
__________________
00 Limited 4.7 V8 SelecTrac
94 Limited V8 SelecTrac
98 5.9 Platinum
95 Limited V8
tcar is offline   Reply With Quote Quick reply to this message
Unread 07-07-2011, 11:29 AM   #12
little_Jeep
Registered User
1998 TJ Wrangler 
 
Join Date: Nov 2006
Location: Louisville, KY
Posts: 5,947
Quote:
Originally Posted by tcar View Post
1. Pressure has NOTHING to do with it... as everyone said, it's temperature. Does not matter where the spring is.

2. Only use a Mopar thermostat from the dealer. Most aftermarket t-stats don't work properly in the Jeep there are a couple brands (one that used to be OK isn't anymore), but to be safe, buy a mopar.
Go buy a Haynes Manual.
Say What?
little_Jeep is offline   Reply With Quote Quick reply to this message
Unread 07-07-2011, 11:41 AM   #13
tcar
Registered User
2000 WJ 
 
Join Date: Sep 2007
Posts: 854
What.




The factory t-stat has a small valve on the side that cheap aftermarket stats don't have.
__________________
00 Limited 4.7 V8 SelecTrac
94 Limited V8 SelecTrac
98 5.9 Platinum
95 Limited V8
tcar is offline   Reply With Quote Quick reply to this message
Unread 07-10-2011, 10:48 AM   #14
AAA
Registered User
1997 ZJ 
 
Join Date: Apr 2010
Location: Los Angeles, CA
Posts: 114
What?
AAA is offline   Reply With Quote Quick reply to this message
Unread 07-10-2011, 11:03 AM   #15
TallyZJ
Registered User
1996 ZJ 
 
Join Date: Nov 2008
Location: Tallahassee, Florida
Posts: 1,140
Quote:
Originally Posted by tcar View Post
What.




The factory t-stat has a small valve on the side that cheap aftermarket stats don't have.
Some t-stats had a hole in the restrictor plate to help eliminate trapped air. This hole was to be installed where it was at the top. Had nothing to do with cooling or the operation of the t-stat itself. I remember this hole on the t-stats for the Cherokee but not the Grand Cherokee.
__________________
1996 Jeep Grand Cherokee Laredo 4x4 - 4.0L
Capital City Jeepers
Build Thread Here
TallyZJ is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
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


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.