I have an 89' cherokee 4.0 with an auto transmission and a potentially incorrect cooling system plumbing. My problem is that I dont not know how the hose from the radiator is supposed to connect to the rest of the system. I am assuming it should connect to the reservoir where I have provided an arrow, but dont know how.... If anyone has an older XJ like mine, could you take a look at these pictures and suggest how the system should be assembled.

 

i got a 90 4.0l auto but i dont got a rad cap on my rad i onlly got the expantions tank the plastic one and the hose in mine goes to a 3 way metal piece witch runs out of the top of the head and to the heater core and to the expantion tank. did you put that plastic expantion tank in yur self or is that how the 89s come cause from what i know the 89 -90 are spose to be the same. my rad is in the grill. if you put that rad in your self then i think you would need a over flow tank but they usually mount close to your rad cap, you could always try callin a chrysler dealer ship and explain whats goin on their would be able to tell you. sry man all i know hope this might help

 

someone has put a updated radiator into your jeep. but left the pressure bottle... i did the same thing with mine.

that is not a overflow bottle... its a pressure bottle that is made for closed loop cooling systems that have no radiator cap. like your jeep came stock.

you need to add an overflow tank someone and plumb that hose into it. i put one right between the fender and the air box on mine... and i also left the pressure bottle.

you could also take out the pressure bottle, and just put a double barbed hose fitting and connect the two hoses...

the open loop system is about 15500000x better than the closed loop junk.

 

Mostly correct - but I take exception to the last line.

I've had five RENIX XJs - one was bought converted. It ran hotter than the other four (by about five degrees,) and I was never able to do anything about that.

Properly maintained, there is nothing wrong with the "closed system" cooling. If it's so bad, why are OEMs going toward it? My wife's 2005 Verona has a closed cooling system, I had a 1992 Corsica with closed cooling, Volvo's been doing it for years. I'm quite sure there are more.

The only real problems with the closed cooling system:
- The OEM radiators tend to clog up and fail around 150-180Kmiles, per Jeep techs I know. Experience has borne this out. This has nothing to do with the closed system - replace it with a quality aftermarket radiator (CSF, Modine, Performance Radiator) and forget about it.
- The volume tank (plastic tank near firewall) is a little iffy after a few years. Keep a spare on the shelf, and replace it every five to seven years. I write the date on new ones when I put them in out of habit. Replacements can be had from Morris 4x4 Center for a reasonable price, including the cap (replace it as well, keep a spare in the glove box.)
- The cap can be difficult to locate - ergo, keeping a spare handy.
- When you change the coolant (flush and refill every two years!) an air bubble tends to form behind the thermostat. This can be dealt with by either "burping" the system (covered over and over again elsewhere) or by drilling the thermostat (which I've covered in several place, and don't want to go through again.) I prefer the latter - makes it automatically self-purging in case you manage to get a "steam void" in the cooling jacket.

Apart from those small concerns - which are common and easily handled - there's nothing wrong with the closed cooling system! Conversion is often an unnecessary expense and a needless amount of work - since it's typically done about the time the radiator loses efficiency anyhow, it's replacing the radiator that solves the issue (which gets done during the conversion - masking the fix in the first place.)

 

everyone has an opinion... but the closed loop in the xj are junk in my experience... couple it with the already borderline cooling capacity of the system...


ive blew up about 3 of those bottles before getting rid of it... overheated going up hills...

its not really a good thing when you have to do a bunch of stuff just to make the stock stuff work...

 

These posts have helped greatly on the subject. I ordered up a radiator from autozone because the existing radiator has a crack and hopefully the new part will sort out the problem. Thanks again fellas!

 

How did you get rid of the pressurized system cause that's what I want to do and I want to know how you did it the bottle is a piece of ****

 

Here we go again.....someone says a "open" system is better than a "closed" system, so let's do a conversion (and take the chance of doing it wrong). Nothing could be more false, wrong, incorrect, whatever.

Neither system is better at cooling the motor than the other. They both work fine when all of the components r in good shape. Both systems are pressurized. One has a pressurized bottle (closed system) and one has a non-pressurized bottle (open system). But again, both cooling systems r pressurized. If the bottle is bad, or whatever is bad (either system), replace whatever is bad, it's that simple.

Don't be suckered in when someone says a "open" system cools better than a "closed" system......it just doesn't. If something is broken (either system), repair/replace what's broken. Neither system is immune to something breaking.

 

Is the overflow tank needed? Could we just let the overflow tube dangle out and drain?
My 1990 needed a new radiator and the new one came with a cap and overflow hose.

 

If your new radiator came with the cap and overflow line, then I would go ahead and convert to the later "open" style. Sound like you're most of the way there if you're missing the heater control valve. Plumb straight to the heater core and eliminate the surge tank. Then add an overflow bottle for $10 to the line from the radiator cap.

 

lawsoncl is right on track. I did that with my 90 years back when that stupid pressure tank kept failing and the jeep would overheat often. Get the heater core hoses for a later XJ and an overflow bottle. SO much simpler that way. Will likely need to splice your hoses for the heater core IIRC because they are different sizes in the early years. A quick search of the forum for 'convert to open cooling' should get you the results you need.

 

No, you MUST have an overflow tank, do NOT let that hose simply drain out. That hose works two directions. When the coolant gets hot it expands, and that expansion is compensated by the cap valving to go out into the over flow tank. That tube must be dipped into the tank too, or enter the tank from the tank bottom. When the engine is off and things cool down, the fluid in the engine contracts, and the valving in the cap will now allow suction pull the coolant from the overflow tank back into the engine/radiator. (this is the reason why that tube must be dipped into the tank or be connected to the bottom of the tank, so it is at a level to be able to suck the fluid back into the engine/radiator.

If you simply allow that tube to vent to the ground, you will lose coolant, and suck air back into the cold system.

So get an overflow tank, that is a must.

You may also now eliminate the pressure tank for better reliability. I mounted my overflow tank near where the pressure tank was.

 

Do you still have the heater control valve? If not, how is that surge tank actually plumbed since it has two connections?

 

 

Looks like the PO used the same pipe from the return lines to replace the heater valve.

Instead of those "Y splitters" branching off to the coolant bottle and the heater core, you plumb directly from the WP to the Core and ditch that whole mess, including the expansion bottle.

As Robsjeep says, you still need an overflow bottle. Most folks mount it where the expansion bottle used to go (remove the mounting plate too). You then run a long hose all around the engine bay to the overflow. You can also mount the overflow pretty much anywhere you want as long as there's room and it remains vertical (cap on top).