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Unread 03-27-2009, 07:46 PM   #1
LordBronz
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Cooling System Flush

I am thinking about doing this after seeing my buddy flush his system. It was pretty nasty looking, and I have a feeling my XJ is in the same boat. It can't hurt even if it isn't though. Is there anything I need to look out for when I do this? Will I have to replace anything? Is the procedure as simple as turning a drain plug loose?

Thanks.

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Unread 03-27-2009, 07:50 PM   #2
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Remove the lower hose from the radiator, instead of messing with drain plugs.
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Unread 03-27-2009, 07:55 PM   #3
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Definitely don't apply more than 18 psi, especially directly to the heater core. That would cause it to leak, and is a 12+ hour job to replace. Definitely a good idea to do (carefully), should increase your heater ability as well as cooling ability. Gunk does build up and needs cleaned out.
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Unread 03-27-2009, 08:11 PM   #4
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Ok, just remove that lower hose. Can do. How do I really flush all that junk out? My friend used a tool he hooked up between the hoses and hooked a water hose to it and flushed it. Is that what I need to do? Where do I hook the hose up to?
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Unread 03-28-2009, 12:52 AM   #5
chris87xj
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Autozone carries flush-n-fill kits and they work pretty good. http://www.prestone.com/products/pri...ll+Kit&regTM=1
These are good too. http://www.prestone.com/products/coo...Treatments.php
They all come with intructions on how to use. Be sure to flush well afterwards to remove all cleaner by removing the petcock and radiator cap and running engine while allowing garden hose water to overflow through until very clean.
Here's some basic info as well. http://www.advanceautoparts.com/engl...20010501rm.asp
And here. http://autorepair.about.com/od/regul...lant_flush.htm

Start with a cold engine and don't pressurize with garden hose while radiator is sealed up. Remove the cap and open the petcock. Read the instructions on the flush-n-fill kit and cleaner bottle and you'll be fine. I pulled my grill for easy radiator petcock access low on the passenger side. Don't use 50/50 pre-mix to refill after a flush because a lot flush water will remain behind after flushing inless you feel like pulling block drains. My '96 4.0L Xj has a 3.7 gallon cooling system. After draining all flush water possible without removing block drains, I was able to squeeze in just short of two gallons of pure anti-freeze, which yielded just about the ideal mixture. I was kind of surprised at all the crap that came out, but nice and green and good heat now too.
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Unread 03-28-2009, 05:34 AM   #6
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LordBronz-

I am new to working on my Jeep and I did this yesterday. Take Chris' advice.

1. I used the Prestone kit. You install a T fitting in the Heater hose that goes to the top of the engine. It was simple to cut the hose and install the T fitting. This allows you to flush the system at the hose with a simple connection point. Just follow the directions. I read them three or four times to make sure I had it.

2. The kit comes with an L tube to press into the radiator fill. There are two ends. The shorter fatter end appears to be the end designed to be pressed into the radiator fill tube under the pressure cap. It was too wide to fit mine so I turned it around and pressed the smaller end of the longer side into the radiator fill tube. Worked well but the flushing fluid ended up only extending a few inches out from the tube so the flush ran down into the engine compartment along the back of the grill. A post and video link posted on this site suggested the flush would shoot out away from the car. My water pressure must be too low to get it to flow forcefully enough. http://www.jeepforum.com/forum/f11/rad-flush-kit-165642/ Next time I will find a tube/hose to attach to the L tube and get the flush away from the engine compartment. See Also: http://www.jeepforum.com/forum/f11/whats-best-way-flush-cooling-system-171554/ Note recommendation for re-filling while engine running.

3. The instructions did not say to release the engine block drains although I would have if I could find them with some confidence that what I identified were the correct drains. It is at the bottom of the system, there has to be some gunk in there.

4. In my system, someone had mixed incompatible fluids, I used the Prestone which is supposed to be compatible with other fluids to refill.

5. I thouuoght you had to actually remove the piece that you unscrew to open the petck. I now understand you merely unscrew it to open the petcock to allow the fluid to flow out. It is not removed. Seems stupid that they have the petcock oriented horizontally and aiming to the rear. If it was oriented downwards you could fit a hose on it to direct the fluid into a container.

6. Chris- I thought you were recommending removing the lower radiator line instead of opening the Petcock on the bottom of the radiator. Sounds good to me. I finally figured out I had to remove the entire front grill/trim in order to gain sufficient access to the radiator drain plug. At first I just removed the grill and then the passenger headlight housing but it was not enough to allow purchase on the drain. Is there a better plug to install? I saw where one poster used a sawzall to cut away part of the fiberglass around the area to give better access.

7. After too many hours I did not use the flush cleaner. Some here have suggested it is a waste of time anyway. The flushing water looked pretty good. Maybe next time.

8. Replace your Radiator Cap while you are at it.
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Last edited by Reader; 03-28-2009 at 08:01 AM..
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Unread 03-28-2009, 08:37 AM   #7
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Quote:
Originally Posted by LordBronz View Post
Ok, just remove that lower hose. Can do. How do I really flush all that junk out? My friend used a tool he hooked up between the hoses and hooked a water hose to it and flushed it. Is that what I need to do? Where do I hook the hose up to?
X2 on the "flush and fill kit" that Prestone sells (just don't use their sh*tty "all makes all models" antifreeze).

It also helps a whole lot to find and remove the square-head drain plug on the side of the engine block. This lets you drain ALL the dirty water out of the block when you're done (I just leave it open when I'm flushing the system). It can be a PITA to remove the first time, so hit it with some Kroil or other penetrating oil the day before you try to pull it out. Its the same thread size and pitch as a replacement old-school radiator draincock, so my V8s all have radiator draincocks in their block drain plugs and flushing is extra easy.

The main thing about flushing is that you want to force coolant to go "backward" through the system to push any grit that might be stuck in a passage to go back the way it came, then out on the ground.

For antifreeze- I recommend either Zerex Max Life (conventional silicate like Jeeps came with) or G-05 (the new Mopar/Ford stuff, but it works well in old engines too.) NEVER use DexCool- one of the organic acids in Dex is incompatible with many gaskets, and it also forms a sludgy goo if you get air in the cooling system. It just sucks, and I can't for the life of me understand why GM is still trying to make it work. Don't bother with Toyota/Honda long-life coolants either, they're too similar to Dex for comfort.
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Unread 03-28-2009, 09:15 AM   #8
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Quote:
Originally Posted by 440_Magnum View Post
X2 on the "flush and fill kit" that Prestone sells (just don't use their sh*tty "all makes all models" antifreeze).

It also helps a whole lot to find and remove the square-head drain plug on the side of the engine block. This lets you drain ALL the dirty water out of the block when you're done (I just leave it open when I'm flushing the system). It can be a PITA to remove the first time, so hit it with some Kroil or other penetrating oil the day before you try to pull it out. Its the same thread size and pitch as a replacement old-school radiator draincock, so my V8s all have radiator draincocks in their block drain plugs and flushing is extra easy.

The main thing about flushing is that you want to force coolant to go "backward" through the system to push any grit that might be stuck in a passage to go back the way it came, then out on the ground.

For antifreeze- I recommend either Zerex Max Life (conventional silicate like Jeeps came with) or G-05 (the new Mopar/Ford stuff, but it works well in old engines too.) NEVER use DexCool- one of the organic acids in Dex is incompatible with many gaskets, and it also forms a sludgy goo if you get air in the cooling system. It just sucks, and I can't for the life of me understand why GM is still trying to make it work. Don't bother with Toyota/Honda long-life coolants either, they're too similar to Dex for comfort.
440 Magnum-

1. I will use something else next time. I used the compatible with all types of fluid because I was told someone had put DexCool in (Yellow-Orange color) and it certainly had formed a sludgy goo.

2. Is the drain plug for the engine block on the passenger side or the driver's side of the block?

Thanks
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Unread 03-28-2009, 10:05 AM   #9
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Found the answer on another post. The plug is on the driver's side behind the manifold.

Quote:
There is a block drain plug on the drv's side of the block behind the exhaust manifold. Download the FSM from the FAQ/Tech sticky and find the closest to your year 88-(87-90), 93-(91-95), and 00-(96-01). Some things may be different, but I believe the block drain hasn't cahnged.

Taking the Tstat out and disconnecting the lower rad hose should do the trick juat about as well though.
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Unread 04-16-2009, 02:02 PM   #10
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Where exactly is the thermostat housing? I followed the top radiator house to a metal piece connected to the engine. Is this metal piece the thermostat housing? Do I just disconnect the entire metal piece and run water through where it was connected?
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Unread 06-29-2009, 07:07 AM   #11
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Great write up. Thanks!
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Unread 06-04-2013, 10:19 AM   #12
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valve location:

On passenger side, push front headlight cover up. On the radiator about 2 inches up you will see a toggle shaped plug. Unscrew to open. Easy as pie.

No replacement parts.

Green coolant.

My lower hose is metal; I can't disconnect it without damaging it.
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