help with my open conversion

88 cherokee chief, 4.0 manual

My radiator took a dive int the recent cold weather we are having here in wisconsin. I am going to convert my cooling system to open. I have a three row CSF radiator coming in Fed-Ex.... any one who has done this and could lend any suggestions or tips I would appreciate it. I have already searched old threads so.... thanks

A consideration is the radiator: if you are fortunate, it will have a bung to accept the temperature sensor for the electruc fan. If not, the work-around seems to be to use a late-model thermostat cover, which has a threaded port, and dig up an suitable temperature sensor to fit. This temp sensor has to be a switch, not the variable resistor type.
For an overflow reservoir, I just walked around a u-pull yard and found two that looked like they would fit in the area where the OEM factory bottle sits. One came from a japanese car, and one from a chrysler product. I bent an aluminum bracket to screw to the shelf where the OEM bottle mounts, to hold the new one. Worked quite well on two 1990s.

Heres a good write up for your open conversion
http://www.olypen.com/craigh/rad.htm
Here are some more to check out
http://www.olypen.com/craigh/tech.htm

that was the 1st mod I did to my cherokee when I bought it. Even before the lift. LOL
SO EASY, its like it was always meant to be.

I did the following and highly recommend it:
New 3 core radiator
Newer style elec fan, they are much better at cooling.
Manual switch to new fan to override it while crawling trails.
new radiator cap
And a full coolant system flush.

1st: Flush the coolant system with old radiator in it if you can., why muck up the new one.
2nd, remove old radiator and upper and lower hoses.
3rd, the new radiator just drops right in, and install new upper and lower hoses.
4th: Tighten it all down and filler up with distilled water and coolant. I NEVER use tap water in a cooling system. WAY to many chemical deposits and hard water issues.
Let it run up to temp with the radiator cap OFF. This should effectively BURP the system. If you find it still getting warm, there is the temp sending unit on the drivers side of the engine block in the back. Jack the vehicle up so that this is the highest point in the engine and keep filling the radiator until water and coolant starts coming from there, then its full and AIR free.

I have done this and have NEVER had a cooling issue. Pretty cheap mod also.

Good luck.:looser:

I have checked out the olypen web site... good for reference but part numbers seem to be off. i currently have the cooling fan on a manual switch for just what you mentioned... just wondering if any body has done this conversion recently and might have some part numbers thanks

You can eliminate the heater valve entirely and plumb directly to the heater core - just remember to plug the leftover vacumn line. One of the heater core lines is bigger, but I had no trouble getting the heater hose to stretch over it after hitting the hose with a hair dryer for a few minutes. Don't forget to flush the heater core back and forth with a garden hose. You'll be surpised at all the crap that comes out. Might as well do all the hoses at the same time.

I grabbed a overflow bottle at the junk yard and really went too big. I was thinking how the level went from nearly empty to nearly full in the old closed surge tank and thought I needed something that big. Once I installed it, I found the level in the nearly 3/4-gallon bottle only moved up/down about an inch. A quart bottle would have been plenty.

Otherwise, I think the conversion is pretty straight forward.

lawsoncl said:

You can eliminate the heater valve entirely and plumb directly to the heater core -

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Is it still possible to reduce the heat or is it hot all the time?

No, newer vehicles don't even have heater valve, and coolant rushes through the heater core all of the time. The idea is that the engine will stay cooler since the coolant is continuously running through the core (regardless if heat or A/C is on) and that the coolant in the heater core won't get murky and clog it up when you aren't using heat during the summer months, since it is continually flowing year round.

I've heard some Ford 3500 drivers complaining that their air conditioning wasn't the greatest, and installed a manual valve in the line going to the heater core.....so they can turn it off during the summer months. They do notice cooling improvements in the cab....so, do what you want and see what happens.

I don't know if I'd be flushing the heater core.......unless you don't mind taking the dash apart to replace it once it starts leaking. It's like a mini radiator. Last time I flushed my radiator, it started leaking, and I had to replace it....I mean a major, all-over-the-engine burst. Luckily the radiator is easy to replace. The heater core ISN'T!

Blaine B. said:

I don't know if I'd be flushing the heater core.......unless you don't mind taking the dash apart to replace it once it starts leaking. ?

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I flushed mine on a Friday...guess what I spent my weekend doing?

Curious, was that just a flush with water, or did you use a checmical flush? I can't see how flushing back and forth with water would cause a problem, but I can see how a chemical flush could eat away at the copper heater core.

lawsoncl said:

Curious, was that just a flush with water, or did you use a checmical flush? I can't see how flushing back and forth with water would cause a problem, but I can see how a chemical flush could eat away at the copper heater core.

Click to expand...

Nope, just a garden hose straight into each tube of the core...I guess it's a good thing it happened when it did though. Otherwise I'm sure the first time I kicked my heat on it would've done it anyway.

See?

What prompted you to change it? Was whatever was inside started dribbling out and you notice this, or what?