Study up on rads and pay close attention to total core thickness. Modern OE rad designs consist of a single (very wide) row, aluminum core/plastic tanks. Just because a rad has 2-3 rows doesn't mean it's 2X-3X as thick as a 1 row OE style rad. Aluminum wide tube design is more efficient than copper/brass narrow tube design. FWIW, radiators have 1 core....the core will consist of 1 or more rows of tubes.

 

Today I found another option (and much cheaper) for converting to an open system without buying a new radiator. I could simply splice an in-line filler neck in the upper radiator hose, get rid of the coolant reservoir, install a puke bottle and run new lines as applicable. I got this idea from this thread: http://www.jeepforum.com/forum/f11/w...system-425252/

Seems very promising but I have questions. This person got rid of the heater control valve. Wouldn't that cause you to blow hot air all the time? The valve is what allows the hot coolant to flow through the heater core. The more you slide your temp adjuster up to HEAT the more hot coolant flows through the heater core. If its always flowing its always hot, right?

P.S. Yes, I'm still replacing the t-stat, water pump, fan clutch, and sensor. I don't have a definite need to replace my radiator because its not leaking. Its only a little over a year old.

 

Some things to remember when converting......keep the rad cap location as high as possible AND the recovery bottle must fill/empty from the bottom AND the bottle must have a vented cap.... no pressure build-up in the recovery bottle.

I would strongly recommend while u have the stat and pump off, flush the motor thru the stat hole AND that u REMOVE the radiator, turn it upside down and flush by sticking a garden hose in the rad outlet (that's up) and flush out to the inlet (that's down). If a cooling system hasn't been well maintained, it doesn't take long for solid sediment particles to start to partially fill/clog the rad from the bottom up, even in a fairly new rad. U can't look inside a XJ rad and see the bottom and tell if sediment is collecting/blocking tubes. The only way to tell if 100% of the tubes are clear and flowing is have a rad shop separate the tanks from the core.

 

Appreciate the tips. Are you able to answer my question? Will it blow hot air all the time if you take out the heater control valve?

 

Quick search yielded this post. Later model XJs don't even have the valve. He deleted his and said everything worked as before. Be sure to plug the vacuum line well.

I did the full on conversion (radiator, etc) on my Waggy and have been more than satisfied with it. In my opinion, swapping the whole system out is the right way to solve the problem, but I understand wanting to save some $$, etc.
Here's my build thread with that conversion, part numbers, and costs.

Good luck! Overheating licks *****....

 

Here are some pics of how mine is wired. It goes into the harness and straight to the c101 connector. From there it goes directly to your idiot light / temp gauge on the cluster.

Mine's not red, but same difference.



and to the c101:



Hope this helps.

 

have you checked the temperature switch on the driver side of the radiator? that controls when the e-fan turns on. your electric fan is wired like this.

a/c--------\
SPACE???|---- trigger side of electric fan relay.
sensor---/


if that sensor is bad, then your e fan will only come on with the a/c. not engine temp.

-also-

i still have the closed system. not bad in my eyes. doesnt overheat even though i have a huge 12k winch in front. like it was mentioned before, make sure all the components in the complete cooling system are good (t-stat, mech fan clutch, water pump, radiator, sensors, etc). they all work together.

and i run at 210 consistantly.

 

Thank you so much for the pics! As soon as the rain stops/slows I will head out and look for that wire.

I found out about the temp sensor that turns the fan on earlier today. There's also a diode that under the air filter box (that goes to the temp sensor). I appreciate the input on a closed system. Taking into account low cost of converting to an open system, ease of future maintenance, and increased reliability, I am going to upgrade.

Thank you all!

 

the open system is no more reliable than the closed. less parts, easier maintanence.

 

i am going to say this before someone goes "nuh uh your an idiot"

90% of the time people are flaming the closed system, is because its obviously old, and they dont keep up maintenance. mine is 25 years old, still stock cooling system, never had an issue because i keep up on it (which you have to do with an open system as well)

 

Nice preemptive rebuttal!

 

Bingo! Well said....a properly maintained cooling system, open or closed type, should keep it's cool....neither type has an advantage over the other with regard to cooling performance. Plenty of 2012 model vehicles use a closed cooling system.

 

I learned my lesson on this recently. I had to replace EVERYTHING because I neglected it. AND since I neglected it I'm going to have it chemically flushed every few months until I get all the corrosion and tap/well water out of it.

Flushing the block is an excellent thing to do when changing the water pump. But hose water is hose water and can lead to corrosion that turns a new radiator old fast. So you gotta stay on top of it until the system is back to near perfect state.

The point I'm trying to make is don't assume the new radiator is not clogged.

 

My thoughts are.....rather than use harsh chemicals every few months (they can eat stuff), drain it, flush it and refill with at least 50/50 mix of fresh coolant. Check coolant color/level weekly....at the 1st sign of coolant color changing, drain/flush/refill with fresh. Each time this is done, the longer the coolant will remain yellow/green and clear. Rust/corrosion don't occur in a well maintained system.

Good point on "don't presume rad is not clogged".

 

Not being a smart a## when I ask this but what would they eat? I'm under the impression if they were detrimental we wouldn't use them. I'm just guessing that it would take a few frequent flushes to get all the non distilled water and rust out.

See, no you got me wondering about flushing MY stuff. LOL