Radiator pressurized overflow?

I want to give my 90' 4.0 towing package included, with 180k a freshening up. My dash temp gauge barely reaches the halfway point at its hottest moments, but i still want to run cooler (i am aware TOO cool is not good for these motors however) because at times the hood is almost too hot to touch for opening which can maybe be attributed to the sun as well.

Within the next week I'm going to order an electric fan to replace the mechanical one. One from a 97+ is what I'm thinking of going with?
I am also considering putting in a new aluminum radiator, however I have never done this before but I think i can handle it. I'm assuming i will have to safely drain the system and then its mostly wrench work from there and some re-plumbing?

In my newbie ways i have kinda decided to just go with the aluminum one found in 97+ xj's, if i should go a different route please let me know.

When searching i found http://www.ironrockoffroad.com/Merc...en=PROD&Store_Code=IROR&Product_Code=IR-X_RAD
but what are they meaning i will have to do with my pressurized overflow? I searched :: through google and only found two threads on the topic.

XJ-Mayhem said:

I want to give my 90' 4.0 towing package included, with 180k a freshening up. My dash temp gauge barely reaches the halfway point at its hottest moments, but i still want to run cooler (i am aware TOO cool is not good for these motors however) because at times the hood is almost too hot to touch for opening which can maybe be attributed to the sun as well.

Within the next week I'm going to order an electric fan to replace the mechanical one. One from a 97+ is what I'm thinking of going with?
I am also considering putting in a new aluminum radiator, however I have never done this before but I think i can handle it. I'm assuming i will have to safely drain the system and then its mostly wrench work from there and some re-plumbing?

In my newbie ways i have kinda decided to just go with the aluminum one found in 97+ xj's, if i should go a different route please let me know.

When searching i found http://www.ironrockoffroad.com/Merc...en=PROD&Store_Code=IROR&Product_Code=IR-X_RAD
but what are they meaning i will have to do with my pressurized overflow? I searched :: through google and only found two threads on the topic.

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Your 90 is a closed system, and it sounds like you want to convert to an open system.

Do a search for "open system conversion", lots of how-to threads.

I know aluminum radiators have their fans, but I am just old-school enough to want brass and copper, two or three core.

Lots of people on here run two electric fans. I, however, am a proponent of upgrading the manual to a ZJ HD fan clutch, $44, NAPA part number 272310, direct fit replacement. If you do decide to go with the two electric fans, I highly recommend you wire them in with two separate circuits so that when one fails you won't be left dead in the water.

Not a fan of aluminum radiators either. The CSF 3 row 100% brass/copper is the best.

joe_peters said:

Your 90 is a closed system, and it sounds like you want to convert to an open system.

Do a search for "open system conversion", lots of how-to threads.

I know aluminum radiators have their fans, but I am just old-school enough to want brass and copper, two or three core.

Lots of people on here run two electric fans. I, however, am a proponent of upgrading the manual to a ZJ HD fan clutch, $44, NAPA part number 272310, direct fit replacement. If you do decide to go with the two electric fans, I highly recommend you wire them in with two separate circuits so that when one fails you won't be left dead in the water.

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thank you, good info.

why do you like to run the ZJ HD clutch instead? what i was looking forward to was having the fans on switches, as well as getting a little free'd up power from less drag. i was planning on doing two different circuits because i have read about that before.

Ecomike said:

Not a fan of aluminum radiators either. The CSF 3 row 100% brass/copper is the best.

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ok, like i said i am a newb when it comes to these cooling issues. where can i find this CSF 3 row brass/copper radiator you speak of? if its not insanely more expensive i will go with it.

Well, the ZJ HD fan clutch will flat out move more air through the radiator than any efan, with the possible exception of the twin-fan taurus upgrade. Down side is no command switch so you can't kill it in a deep water crossing, and it is noisy when engaged.

When you eliminate the mechanical fan you are putting all of your chips in one or two baskets, and those baskets are held together with wires, relays, the battery and the alternator. When playing in the mud or deep water crossings one of the most vulnerable accessories on the XJ, unless modified, is the alternator. Now, if the alternator can't put out, or its output is severly reduced, well, you can drive a long way on a discharging battery, without overheating, with a mechanical fan. Twin efans, in particular the taurus setup, well, bye-bye battery juice and bye-bye head gasket?

Don't get me wrong, three vehicles sitting in my yard are efan only, and my FS Bronco ran with a twin electric fan setup for years.

It is just my humble opinion that you will be better off with a mechanical fan, with an aux efan if you want one, than with electric only.

BTW, go ahead and start the flames, I happen to have asbestos drawers on! LOL!

joe_peters said:

Well, the ZJ HD fan clutch will flat out move more air through the radiator than any efan, with the possible exception of the twin-fan taurus upgrade. Down side is no command switch so you can't kill it in a deep water crossing, and it is noisy when engaged.

When you eliminate the mechanical fan you are putting all of your chips in one or two baskets, and those baskets are held together with wires, relays, the battery and the alternator. When playing in the mud or deep water crossings one of the most vulnerable accessories on the XJ, unless modified, is the alternator. Now, if the alternator can't put out, or its output is severly reduced, well, you can drive a long way on a discharging battery, without overheating, with a mechanical fan. Twin efans, in particular the taurus setup, well, bye-bye battery juice and bye-bye head gasket?

Don't get me wrong, three vehicles sitting in my yard are efan only, and my FS Bronco ran with a twin electric fan setup for years.

It is just my humble opinion that you will be better off with a mechanical fan, with an aux efan if you want one, than with electric only.

BTW, go ahead and start the flames, I happen to have asbestos drawers on! LOL!

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Very valid and good points, which make a lot of sense. Now you are making me consider.
But for my situation, I don't really need to worry about the water/mud because i like the hard compact unforgiving stuff, rocks hehe.
Still, it would be a bit worrysome to think all my cooling is riding on how well i wired up the fans, and how well my electrical system holds up.

with my minimal google searching i have not been able to find the csf 3 row all metal radiator, any help/links?

Are you changing over to the open system--cap on radiator, coolant recovery bottle instead of pressure bottle?

joe_peters said:

Are you changing over to the open system--cap on radiator, coolant recovery bottle instead of pressure bottle?

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I havn't looked at the How To's yet, but if i am going to gain the best cooling performance from this, as well as reliability, then yeah i will. Also as long as its not way to complicated for me to do.

Here is a link for some CSF 3-cores.

BTW, many don't care for the closed system (it does have some, shall we say, peculiar traits), but those systems are quite common on vehicles today and are, when correctly setup and maintained, just as good as the open systems.

joe_peters said:

Here is a link for some CSF 3-cores.

BTW, many don't care for the closed system (it does have some, shall we say, peculiar traits), but those systems are quite common on vehicles today and are, when correctly setup and maintained, just as good as the open systems.

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haha i think your oldsheimers kicked in because i don't see a link :shhh:

i'll look into the differences more before making my decision.

http://www.drivewire.com/brand/csf-cooling/radiator/jeep/

Late in the day! LOL!

Why do you want to change what is working good? The only thing I can pick up is that your hood is too hot. Your temp gage says you're good. The weak link in the closed system is the shitty XJ pressure bottle. Many vehicles used the closed system including police and taxi Crown Vics. Ecomike has been battling with his system and has covered improving the stock pressure bottle cap. You don't even sound like you have his problems, but you could see what to watch for.

Radiatorbarn.com and DPG offroad (SP?), they are one of our naxja sponsors here) have the CSF radiators.

im still running the closed system on my 89. ive owned my 89 since 90 and have gone through my share of problems with it. my 89 has a manual trans and no air conditioning which means it didnt come stock with an e-fan, so i rely totally on the condition of the cooling system and the mechanical fan.

first problem was the single core radiator. the engine would creep up to the red just from sitting/idling in traffic in the summer. reving the engine at idle would slowely bring the temp down. after replacing the radiator in the early 90's with a 2 core i never had that problem again although im probably on my 3rd radiator since then. im also on my 3rd water pump.

next problem was the pressure bottle and cap. sometimes the tank would crack or the cap would not hold pressure. im still using a pressure bottle from quadratech(crown) and dont seem to have any problems except the cap stopped holding pressure. right now im using a hose clamp around the cap to hold pressure. ive run it this way for a few years without issue.

if there was any major change i would do would be to use a different plastic bottle such as the volvo bottle and cap or a metal tank from mac's radiator or moroso.

the closed system also needs to be burped(bleeding the system) or several cycles of filling the pressure bottle and running until the thermostat opens and refilling. i drill a 1/16 hole at the 12 oclock position of the thermostat to let air pass and i also disconnect the top radiator hose from the thermostat housing and pour the coolant down the hose into the radiator. this allows more coolant into the system and less air.

ive stayed with the closed system only because im used to it, while others feel that if your going to sink money into a a new pressure bottle, you might as well spend the money on the conversion to an open system.

another weak link in the system is the heater control valve to divert coolant into the heater core. over the years the valve gets brittle and leaks. the one on my 89 is still the original.

as far as i know, if you keep the closed system, you need to use a radiator for the 87-90, so a 97 and up will not work.

Just dump the heater control valve and use a late model Crown Vic bottle from the JY.

Just my personal opinion, but I think we will all have to convert to open systems eventually.

Not 100 percent sure on the years, but I think 87-90 (possibly 91) have the closed systems, and that is about 24 percent of production. Take away those that have gone to the Great Recycler, and at some point demand will become so low that production of the closed system radiators and bottles will cease. The bottles are no big deal as just about any pressure bottle will do, but you see my point--eventually the only new radiators for sale will be open system style.

great response's guys, really appreciate the input.
i just got back from my SB job site and 10pm - 6am shifts, looking forward to putting that money into my new rusty's tie rod and drag link conversion
as well i'll contemplate my motor "issues" unless im just a hypochondriac

XJ-Mayhem said:

putting that money into my new rusty's tie rod and drag link conversion

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im not a rustys basher as i started with his 3" lift, but i have not heard enough positive responses about his steering conversion to run it. you may want to do a search on steering, there are a ton of threads on the subject.

There is nothing wrong with the closed system, they still use them in fords and a few others, just pop a hood and look for a surge tank. As for the mixing valve I could swear that there is a metal one that replaces the plastic one, I've seen it posted here in the past.
As for the fan clutch out of the ZJ, consider the ZJ has a narrow rad, my 97ZJ has that and I often wonder how it keeps that 4.0 cool in traffic even with a bigger diameter fan.
I also have one of those ZJ HD napa fan clutches, just have not put it in yet.