Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here XJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.

How to flush coolant and radiator

Thread Tools
 
Search this Thread
 
Old 10-15-2014 | 12:54 PM
  #1  
Sebastianc2012's Avatar
Thread Starter
Junior Member
 
Joined: Sep 2012
Posts: 43
Likes: 0
Model: Cherokee
Default How to flush coolant without starting the truck

I own a 96 XJ sport, with about 210k miles on it.

Im in the midst of replacing the water pump for the first time, after it failed and the belt slipped off while driving due to im guessing the bearings failing.(made the pully incredibly hard to remove).

Ive removed the electrical fan and belt, and after removing the lower radiator hose from the WP, the coolant was really rusty and sludge like, and only drained a really small amount. Most of it had leaked out after the pump failed, but what leaked out at that point was a bright green almost new looking coolant.

Ive searches and read a few threads and think ive confused myself quite a bit. A lot of places say to fill the radiator with water and let the truck idle for a bit, is this doable with the belt removed? I dont want to overheat or cause any problems.

With the lower radiator hose off, can i just pour water into the radiator until it comes out clean? Or will i have to pull the drain plug? Also the coolant in the resevoir needs to be drained aswell.

Last edited by Sebastianc2012; 10-15-2014 at 01:18 PM.
Old 10-15-2014 | 02:36 PM
  #2  
Sebastianc2012's Avatar
Thread Starter
Junior Member
 
Joined: Sep 2012
Posts: 43
Likes: 0
Model: Cherokee
Default

Came across this bit of advice, wondering if this would be the way to go

"Disconnect the top rad and heater hoses from the t-stat cover. Disconnect the bottom rad hose from the water pump. Stick a garden hose in the heater hose and flush. Stick the garden hose in the heater hose nipple on the stat cover and flush. Stick the garden hose in the top rad hose and flush."
Old 10-15-2014 | 02:54 PM
  #3  
IJM's Avatar
IJM
CF Veteran
 
Joined: Jan 2014
Posts: 1,349
Likes: 287
From: District of Columbia
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by Sebastianc2012
Came across this bit of advice, wondering if this would be the way to go

"Disconnect the top rad and heater hoses from the t-stat cover. Disconnect the bottom rad hose from the water pump. Stick a garden hose in the heater hose and flush. Stick the garden hose in the heater hose nipple on the stat cover and flush. Stick the garden hose in the top rad hose and flush."
I just did this yesterday, and it works perfectly. So much crud came out. Multiple drain and refills of the radiator is OK if all you need to do is get fresh coolant in there, but it won't get all the crud/mud/rust/etc. out. The nice thing about the XJ setup is that you can easily flush the radiator, block, and heater core. My VW and Mazda, not so much, as they use a closed system with a pressurized bottle. That, and the GTI's cooling system is redonkulously complex.
Old 10-15-2014 | 03:04 PM
  #4  
Sebastianc2012's Avatar
Thread Starter
Junior Member
 
Joined: Sep 2012
Posts: 43
Likes: 0
Model: Cherokee
Default

Originally Posted by IJM
I just did this yesterday, and it works perfectly. So much crud came out. Multiple drain and refills of the radiator is OK if all you need to do is get fresh coolant in there, but it won't get all the crud/mud/rust/etc. out. The nice thing about the XJ setup is that you can easily flush the radiator, block, and heater core. My VW and Mazda, not so much, as they use a closed system with a pressurized bottle. That, and the GTI's cooling system is redonkulously complex.
Okay, one last thing im concerned about is where the return is for the water that should be going to the heater core through the heater hose.

If im correct, top rad hose return should be lower rad hose and the return for the water being flushed into the t stat cover from the heater hose nipple should be the nipple on the upper left of the water pump?

If so, then is the return for the water that goea theough the heater core going to come out through the hose that connects to the upper left nipple of rhe WP?
Old 10-15-2014 | 03:18 PM
  #5  
Kingfisher's Avatar
Senior Member
 
Joined: Mar 2014
Posts: 552
Likes: 0
From: Central Indiana
Year: 1996
Model: Cherokee
Engine: 4.0
Default

Just flush both direction.
Old 10-15-2014 | 03:28 PM
  #6  
dschappell's Avatar
Seasoned Member
 
Joined: May 2013
Posts: 410
Likes: 0
From: North Atlantic - Delaware
Year: 1999
Model: Cherokee
Engine: Inline 6 4.0
Default

I was planning on this this as well, early next week. Thanks for the info, helped me!!!
Old 10-15-2014 | 04:45 PM
  #7  
IJM's Avatar
IJM
CF Veteran
 
Joined: Jan 2014
Posts: 1,349
Likes: 287
From: District of Columbia
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by Sebastianc2012
Okay, one last thing im concerned about is where the return is for the water that should be going to the heater core through the heater hose.

If im correct, top rad hose return should be lower rad hose and the return for the water being flushed into the t stat cover from the heater hose nipple should be the nipple on the upper left of the water pump?

If so, then is the return for the water that goes through the heater core going to come out through the hose that connects to the upper left nipple of the WP?
Yes, but flush in both directions as Kingfisher said. I got more gunk out on the back flush than the forward flush. Do it both ways several times until it comes out clear.
Old 10-15-2014 | 11:43 PM
  #8  
djb383's Avatar
CF Veteran
 
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Default

Originally Posted by Sebastianc2012
Okay, one last thing im concerned about is where the return is for the water that should be going to the heater core through the heater hose.

If im correct, top rad hose return should be lower rad hose and the return for the water being flushed into the t stat cover from the heater hose nipple should be the nipple on the upper left of the water pump?

If so, then is the return for the water that goea theough the heater core going to come out through the hose that connects to the upper left nipple of rhe WP?
A '96 XJ has a heater control valve (unless it has been eliminated). U must stick the garden hose in the heater hose that's after the heater control valve in order to flush the heater core. Perfect time to eliminate the heater control valve, if u have one.

Sticking the garden hose into the heater hose, water will come out the water pump, Sticking the garden hose in the heater hose nipple on the stat cover, water will come out the water pump. Sticking the garden hose in the top rad hose, water will come out the bottom rad hose. Flush in that order......heater core 1st, motor 2nd and rad 3rd.

Last edited by djb383; 10-15-2014 at 11:57 PM.
Old 10-16-2014 | 09:11 AM
  #9  
Sebastianc2012's Avatar
Thread Starter
Junior Member
 
Joined: Sep 2012
Posts: 43
Likes: 0
Model: Cherokee
Default

Originally Posted by djb383
A '96 XJ has a heater control valve (unless it has been eliminated). U must stick the garden hose in the heater hose that's after the heater control valve in order to flush the heater core. Perfect time to eliminate the heater control valve, if u have one.

Sticking the garden hose into the heater hose, water will come out the water pump, Sticking the garden hose in the heater hose nipple on the stat cover, water will come out the water pump. Sticking the garden hose in the top rad hose, water will come out the bottom rad hose. Flush in that order......heater core 1st, motor 2nd and rad 3rd.

Is completely removing the heater control valve something i want to do?
Old 10-16-2014 | 09:45 AM
  #10  
HarleyRob's Avatar
Member
 
Joined: Jun 2014
Posts: 106
Likes: 1
From: Magnolia State
Year: 1999
Model: Cherokee
Default

Originally Posted by djb383
A '96 XJ has a heater control valve (unless it has been eliminated). U must stick the garden hose in the heater hose that's after the heater control valve in order to flush the heater core. Perfect time to eliminate the heater control valve, if u have one.

Sticking the garden hose into the heater hose, water will come out the water pump, Sticking the garden hose in the heater hose nipple on the stat cover, water will come out the water pump. Sticking the garden hose in the top rad hose, water will come out the bottom rad hose. Flush in that order......heater core 1st, motor 2nd and rad 3rd.
Is there a way NOT to flush? I mean is there one certain thing to be sure you DONT do when flushing? Like flush in wrong direction some how?
Old 10-16-2014 | 10:03 AM
  #11  
Roler's Avatar
CF Veteran
 
Joined: Jan 2012
Posts: 3,170
Likes: 311
From: Australia
Year: 1997 (RHD)
Model: Cherokee (XJ)
Engine: 4.0 ltr
Default

Originally Posted by HarleyRob
Is there a way NOT to flush? I mean is there one certain thing to be sure you DONT do when flushing? Like flush in wrong direction some how?
LOL. I'm sure there are many ways not to flush or things not to use when flushing. But regarding your question, there is not so much of a 'wrong' direction. You will find with flushing the heater core for instance, that you get actually more crud out if you ' reverse' flush it, so opposite direction of how the flow through the core normally is. See the core as a bit of a funnel; the stuff that accumulated is better flushed out the way it came from, so to speak.
You will probably notice that one direction goes somewhat better than the other when flushing.

Flushing up the lower radiator hose wont do much. To reverse flush the radiator you either need one of those pressure kits, or remove the radiator and do it out of the Jeep.
Old 10-16-2014 | 10:30 AM
  #12  
HarleyRob's Avatar
Member
 
Joined: Jun 2014
Posts: 106
Likes: 1
From: Magnolia State
Year: 1999
Model: Cherokee
Default

Originally Posted by Roler
LOL. I'm sure there are many ways not to flush or things not to use when flushing. But regarding your question, there is not so much of a 'wrong' direction. You will find with flushing the heater core for instance, that you get actually more crud out if you ' reverse' flush it, so opposite direction of how the flow through the core normally is. See the core as a bit of a funnel; the stuff that accumulated is better flushed out the way it came from, so to speak.
You will probably notice that one direction goes somewhat better than the other when flushing.

Flushing up the lower radiator hose wont do much. To reverse flush the radiator you either need one of those pressure kits, or remove the radiator and do it out of the Jeep.
OK, thanks. Thats what I meant...which direction. My logic (though may be wrong) is to unhook said hoses and flush in/out every opening till clean.
Old 10-16-2014 | 03:16 PM
  #13  
djb383's Avatar
CF Veteran
 
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Default

Originally Posted by HarleyRob
Is there a way NOT to flush? I mean is there one certain thing to be sure you DONT do when flushing? Like flush in wrong direction some how?
U bet there is a way "not to flush". The last thing u want to do is flush crud from the heater core and motor into the radiator. Following the directions I post will prevent crud from entering the radiator.
Old 10-16-2014 | 04:10 PM
  #14  
HarleyRob's Avatar
Member
 
Joined: Jun 2014
Posts: 106
Likes: 1
From: Magnolia State
Year: 1999
Model: Cherokee
Default

Originally Posted by djb383
U bet there is a way "not to flush". The last thing u want to do is flush crud from the heater core and motor into the radiator. Following the directions I post will prevent crud from entering the radiator.
ok, thanks. and the heater core is the thing where the thermostat is? i'm learning
Old 10-16-2014 | 05:03 PM
  #15  
djb383's Avatar
CF Veteran
 
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Default

Originally Posted by HarleyRob
ok, thanks. and the heater core is the thing where the thermostat is? i'm learning
The large heater hose and the top radiator hose attach to the t-stat cover. The small heater hose and bottom radiator hose attach to the water pump.


Quick Reply: How to flush coolant and radiator



All times are GMT -5. The time now is 01:06 PM.