Coolant system not under pressure - 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 CJ Forum > Coolant system not under pressure

UCF Black Friday SaleLOCKERS!!!! - ARB, Auburn, Detroit, Eaton, OX, Spartan, YuRIGID LED Light Blowout Sale - All Sizes, All Series, all

Reply
Unread 01-02-2010, 07:44 PM   #1
mmerlina
Image Glassworks, Inc.
 
mmerlina's Avatar
1986 CJ7 
 
Join Date: Mar 2007
Location: Danvers, MA
Posts: 1,668
Coolant system not under pressure

Hey what happens when a coolant system is not under pressure? I have one of those radiator caps with that safety air pressure release tab on the top of it.. every now and then I'll pop my hood and see it flipped up..

I wasn't loosing any coolant out of it, just air pressure I'm guessing.. what would cause that to flip up and what could happen if the system isn't pressurized?

__________________
Mike

1986 Jeep CJ7 (photos)
Remanufactured 258, ARB lockers front & rear, 4.10 Yukon gears, 35x12.5" Super Swamper SSR's, Motorcraft 2100, 4.5" Rubicon Express Extreme-Duty lift, York 210 OBA, Big Daddy steering, Tatton rear CV driveshaft, Herculined interior, TJ flares, lots of body & upholstery work
mmerlina is offline   Reply With Quote Quick reply to this message
Unread 01-02-2010, 08:55 PM   #2
scooter
Registered User
1982 CJ7 
 
Join Date: Oct 2009
Location: ca
Posts: 217
Water boils at 212 at seal level,pressurizing the system raises the boiling point x degrees every PSI the pressure is raised in the system. There is a formula/value I dont recall. The other side is air in the system,not long ago there were no overflow bottles etc,the system pressurized and blew out what it could when hot,then as it cooled it sucked air back in and you had a system with air in it. The idea with a closed system is to eliminate this, so in a nut shell go break the bank and buy a new cap, it dosent have to be one with a lever as long at its the same pressure value.
scooter is offline   Reply With Quote Quick reply to this message
Unread 01-02-2010, 11:16 PM   #3
wrongway92407
Member
 
wrongway92407's Avatar
1986 CJ7 
 
Join Date: Nov 2009
Location: Devore Ca.
Posts: 483
buy a new cap, w/o the lever
__________________
Wrongway
My fleet:
86 CJ7 5.7 vortec. 4L60,D44's,OBA,Air tank bumpers w/D rings detroits,4.88,35" bfg, mt's 9500ti warn
86 CJ7 2.5 detroits, OBA 4.56, air tank bumpers, w/D rings,9500I warn 31x10.5x15, Trxus
86 CJ7 bone stock, w/factory 44 never seen the dirt soon to be for sale
87 Wrangler also never seen the dirt.
wrongway92407 is offline   Reply With Quote Quick reply to this message
Unread 01-03-2010, 12:27 AM   #4
mmerlina
Image Glassworks, Inc.
 
mmerlina's Avatar
1986 CJ7 
 
Join Date: Mar 2007
Location: Danvers, MA
Posts: 1,668
Hmm okay, yeah I'll get a new cap without one of those damn things.. I don't even know how it ended up on there to be honest with you.

What happens to a standard cap when/if the pressure exceeds the rating of the cap? I see on quadratec it looks like a stock cap for a CJ is 16 pounds.. but I see other caps at 13. Not like I'd experiment with it or anything, just curious.
__________________
Mike

1986 Jeep CJ7 (photos)
Remanufactured 258, ARB lockers front & rear, 4.10 Yukon gears, 35x12.5" Super Swamper SSR's, Motorcraft 2100, 4.5" Rubicon Express Extreme-Duty lift, York 210 OBA, Big Daddy steering, Tatton rear CV driveshaft, Herculined interior, TJ flares, lots of body & upholstery work
mmerlina is offline   Reply With Quote Quick reply to this message
Unread 01-03-2010, 10:14 AM   #5
CJunk
Registered User
1984 CJ7 
 
Join Date: Jan 2009
Location: Cape Cod
Posts: 809
If you have an overflow bottle and a nipple on the radiator, (under the cap) you will be fine. Dont know the info on the cap rating though.
CJunk is offline   Reply With Quote Quick reply to this message
Unread 01-03-2010, 10:30 AM   #6
scooter
Registered User
1982 CJ7 
 
Join Date: Oct 2009
Location: ca
Posts: 217
If the cap does not meet the requirements of the cooling system/vehicle its going on it may blow radiator seams or otherwise,some run a lower rating cap on old systems to prevent this. Best bet is the correct cap and a overflow bottle set up correctly. If done right the cap will allow coolant out into the bottle when hot,then later when things cool and contract the coolant will actyally be sucked back into the systen thru the cap which acts like a check valve basically. If you have no recovery bottle it will as mentioned blow out some coolant leaving a void of air in the radiator which for one decreases your cooling capacity and allows air into the system which will begin to oxidize things.
scooter is offline   Reply With Quote Quick reply to this message
Unread 01-03-2010, 11:44 AM   #7
Cutlass327
Web Wheeler
 
Cutlass327's Avatar
1978 CJ5 
 
Join Date: Jan 2009
Location: Beach City, Ohio
Posts: 5,145
I would get the stock rated cap. If your radiator is weak and starts leaking, then it is meant to fail - no use "Band-aiding" a weak part with a lower PSI cap. The stock rated cap will help to run at proper temps, so that when you have issues with cooling or heat, then we will be able to help diagnose then since it is set up the way it is supposed to be.
__________________
Rick

1978 CJ5 258/T177/D300, '86 D30/D44 WT axles, 'glass tub windshield frame, and fenders, 31x10.5 BFG A/T, TDK galv'd frame - DD and weekend toy

http://www.jeepforum.com/forum/f8/ri...8-cj5-1223197/
Cutlass327 is offline   Reply With Quote Quick reply to this message
Unread 01-03-2010, 12:14 PM   #8
mmerlina
Image Glassworks, Inc.
 
mmerlina's Avatar
1986 CJ7 
 
Join Date: Mar 2007
Location: Danvers, MA
Posts: 1,668
Yep I'm going to get a stock cap.. I'd rather not cover up problems by lowering the pressure. I believe my radiator is in pretty decent condition, I've seen it from most angles and I've never seen anything to be concerned about. *knock on wood*
__________________
Mike

1986 Jeep CJ7 (photos)
Remanufactured 258, ARB lockers front & rear, 4.10 Yukon gears, 35x12.5" Super Swamper SSR's, Motorcraft 2100, 4.5" Rubicon Express Extreme-Duty lift, York 210 OBA, Big Daddy steering, Tatton rear CV driveshaft, Herculined interior, TJ flares, lots of body & upholstery work
mmerlina 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.