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TOTM: Rear mounted radiators

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ashmanjeepXJ

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Discussion starter · #1 ·
Welcome to the next contribution to the
The Official Pirate4x4.com Jeep Talk Bible

Topic of the Month Rear mounted Radiators

Show pics and discuss modifications you have done to relocate your radiator to the rear. Topics include: hose plumbing, hose safety if ran inside, placement of the radiator, what pump or pumps were used. Cooling is a "system" so tell us your complete setup that works.

This does not include discussions as to why you would want a rear vs front mounted radiator.

Also see:
TOTM: Engine cooling
GriffinThermalProductsKingoftheHammersRadReview
The Pirate Cooling Bible
 
#2 ·
I actually searched everywhere for some xj's with rear mount radiators. For the rest of the jeep club the radiator doesn't seem to interfere quite as much, but try to narrow a xj nose and it's the first speed bump. If I had some ideas on throwing it in the back then the nose would be narrowed and I could have very little lift with 38"s. I would love to see some unibody's with rear mounts for cool ideas.:flipoff2:
 
#4 ·
I did the rear mount on my XJ but it really isn't much of an XJ anymore. Maybe everyone can learn from it regardless.

First I made up some mounts for the new Griffen

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Then Timmay welded up the rad for the electric fans

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Welded on the lower mount. And used shock tabs for the upper mount so the radiator can be easily removed.

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The hose I used is marine coolant hose. It is some extremely tough stuff.

Next time I am at the shop I will get more pictures of the coolant hose routing.
 
#5 ·
I'v done a couple rear mounts in FSJ's that we'd race. I'd used exhaust tube all welded up. Worked real well, big issue was gettin the air out of it.....kind of like the old renix plastic bottles, but worse.

Everybody says put a petcock up high to release air, bullshit dont work for crap. You sometimes have to force water through the system to get the air to move. One thing that might work is placing a rad cap inline at the motor at the highest point. All we did was run one of those inline "T's" in a looped heater hose(we ran a restrictor plate no thermostat) so it'd push everything back to the rad.

It cooled real well, only issue was if you did overheat it you were screwed. It'd always build a airpocket in the block and you'd have to flush it.

OlyWa
 
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#7 ·
Are you guys hardmounting the radiators? Do you need to worry about chassis flex, and cracking the radiator?
 
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#8 ·
Twisty said:
Are you guys hardmounting the radiators? Do you need to worry about chassis flex, and cracking the radiator?
Click to expand...
Mine's not hardmounted, there will be insulation material to act as dampener in between the radiator and the mounts.
 
#10 ·
I moved mine to the back when I buggied it for 1 reason only, I was trying to move as much weight from the front to the rear, I also moved the battery back there also. XJ's are really nose heavy from the start and I wanted to try and balance it out as much as possible
 
#11 · (Edited)
I have been running a rear mount for quite a while, and it was fairly simple. I am using a Griffin radiator, a 2-speed fan from a 5.9 zj, and route the coolant through exhaust tubing with the only rubber hoses being at the radiator and engine. The radiator cap is the highest point in the system, and for the initial fill, I removed the temperature sending unit to bleed air. I also used a funnel that fits the radiator neck and holds a large amount of coolant while waiting for the thermostat to open. Because I could, I used my forklift to lift the rear and then the front, to allow air pockets to escape. I use an overflow tank located within a foot of the radiator.

Despite the fact that I get no airflow through the radiator from forward motion of the jeep, I never find it necessary to run the fan on high speed. It is obvious that the exhaust tubing itself helps shed some of the heat. Both of the coolant tubes are routed down the passenger side, along with the exhaust pipe. I am running a 190 thermostat, and in the SC heat, my temperature stays cool. I mounted my transmission cooler in front of the radiator, which allows one fan to cool both it and the radiator. Transmission fluid is routed through the radiator first, to bring it up to a decent temperature.

I, like everyone else, had multiple reasons for relocating the radiator. I have narrowed my front 13", the winch(a Warn 9500)is completely behind the grill(weight distribution and approach angle), and i also needed to move weight to the rear.

Before I tested this setup, I eas concerned that the waterpump would not be adequate to circulate the coolant when the rig was at extreme angles, and considered adding an electric pump. As it turns out, this was not needed, as the stock 4..0 pump does a great job.

This has been one of the best modifications I have done to my rig.
 
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#12 ·
Buddy of mine did a rear mounted Rad in his XJ.

he did it because after 2 races in ECORS he took out 2 rad's so he moved it to the back.

build thread:
http://nc4x4.com/forums/showthread.php?t=74532

how the rig started:


and then with rear rad installed:







he used .120 1.5" DOM tube to run the lines along frame rail and up into engine bay.
Rad is a griffin alum rad with a loud as heck fan on it.
 
Discussion starter · #13 ·
On steve's stagnant XJ project three houses down the street.

This is a ron davis, way overkill, dual pass so inlet and outlet are on the same side. Use mostly 1.5in 120wall tube with minimal rubber couplings, around each rubber coupling is a sheet metal heat shield incase a hose bursts. Most of the work was done my the previous owner Mike, we just relocated it after the frame chop. Reason to move it was to do a narrowed front and shorten the front bumper hood and fenders for better approach angle. Mounts will accommodate frame flex or bending in a roll.



packaged nicely.
Image
 
#14 ·
What are you guys running for fans?

What happens if the fan takes a crap?

How much do you have to spend to get a fan that is reliable enough to not take a crap? (I've seen from $80 fans to $500 fans)
 
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#15 ·
XJ_ranger said:
What are you guys running for fans?

What happens if the fan takes a crap?

How much do you have to spend to get a fan that is reliable enough to not take a crap? (I've seen from $80 fans to $500 fans)
Click to expand...
I can't remember the exact application my fan is from but I am pretty sure it is off a big front wheel drive V6 car/SUV. OE fans can really push/pull air and are made to run for a long time.

Depends on the situation. I did a 10 minute test run in my without the fans running and it never got over 180. Good amount of throttle running around the shop. But in a race situation you are going to be screwed if the fans aren't working.

My fans were free. My company makes them. :flipoff2:
 
#16 ·
XJ_ranger said:
What are you guys running for fans?

What happens if the fan takes a crap?

How much do you have to spend to get a fan that is reliable enough to not take a crap? (I've seen from $80 fans to $500 fans)
Click to expand...
best fan I've found to run is an OE taurus fan..its 2 speed and that mother will move some air. Being from AL we see humid 100+ days pretty much all summer and no one ever overheats. Rivals many of the fancy twin fan setups on comp buggys and you can pick it up at pull-a-part on the cheap
 
Discussion starter · #17 ·
XJ_ranger said:
What are you guys running for fans?

What happens if the fan takes a crap?

How much do you have to spend to get a fan that is reliable enough to not take a crap? (I've seen from $80 fans to $500 fans)
Click to expand...
I like SPAL Fans but some are not rated for off road high dust environments so look at the spec sheet before buying.
 
#18 ·
Seems like bleeding these systems and keeping them bled is a big problem. Anyone have any thoughts as to what a 'fool proof' design would be, after having run what you have for a bit? Would a return pump help to keep the block from being full of air? What about having the overflow tank the highest point in the system so that when there's nothing in the lines in either direction, it fills them?

I've heard great things about the Taurus fans, I see no reason why they couldn't be adapted to a rear radiator, but I've never done it. Some 12V wiring and brackets should do the trick.

Trying to get ideas for my set up in the future. Thanks.
 
#19 ·
I would love to do this to save space up front, but with my rig being full bodied I assume the noise would be WAY to much to bare on trail runs.
 
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#20 ·
I have a taurus fan on my rear mounted rad, made some brakets and trimmed the stock shroud it came with and it works perfect, I placed mine on the backside and have it pulling air. For now I have it wired for the higher setting, one of these days I may look into setting it up to run both speeds according to temp but it has not been a priority at this point
 
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