Rear mount rad in a MJ, plumbing?

[DirtyComanche]

I've been working on this MJ for a while...


But the current trend with it is to narrow the front clip up and run the rad in the back.


It's something like this right now:



Other than it has an intake/exhaust manifold and a propane mixer on it. And I cut a little more out of the hood in prepration of bending tube.

And I've got this pile on the back of it.




Anyways, figured I'd mount the rad either above the tank, or behind it. That will be the easy part. The nightmare seems to be the plumbing. I've waffled on this quite a bit. I was going to run it through the cab by just laying down two peices of 1.25" exhuast tube in the floor and running some flexible abrasion reistant hot water hose to it. But I'm afraid I will literally cook in the cab during the summer. It's hot already... And I don't want something that I might burn myself on.

And there sure isn't much space below the cab because it is flat-bellied (flush with the bottom of the frame rails) and I've got to fit the exhaust under there too.


So I was thinking about going back to one of my early ideas. That is to run the coolant through my rock sliders and then to the rad. They're 2x2x.188, so they aren't exactly indestructible. However, I doubt I will be able to damage them enough to actually lose coolant pressure.

What bothers me about it is that I'm going to weld the cage to the sliders. So I don't want to compromise their structure by drilling a 1.25" hole in them to weld in a pipe nipple or such. Especially because where I want to tie in the A-pillar hoop is right where I'd need to weld in the nipple...


So, is there any chance I can cut into the rocker panels at the front and rear to run a peice of exhaust tubing through? Or is there a bunch of shit inside them that will hamper me just slipping a pipe in them?


Is there any other obvious routing options I've missed?

Or shoudl I just move the winch to the rear of the truck and find a rad to fit where it is (winch is a POS anyways)?

[rustrtal]

What have you got bolted through the Unibody rail? Can you cut the floor out in the cab and run some tube inside the rail and patch it back in?

[brcook_00]

Originally Posted by rustrtal

What have you got bolted through the Unibody rail? Can you cut the floor out in the cab and run some tube inside the rail and patch it back in?

I'm actually considering this idea for my MJ. There's plenty of space inside the frame rail and you could build vibration resistant mounts in, somehow. I would consider making those patches removable in case you ever have to go back into the frame to repair anything.

[Fullsizexj]

you can run it underneath with exhaust tube and flex hose to connect on each end, I did the same on mine. You need to remember to keep it at about the same height as the original for the water pump to work right. Also keep in mind that by adding the extra length of tube and all to connect it that you will end up with about 4 extra gallons of water in there so it will run a whole lot cooler. I had the thermostat go out on mine this last weekend so I pulled it out and the thing ran at about 120 degrees all day long, I could hold my hand on the rad no problem at all all day long

[magoo117]

we are using aluminum tubing running from motor to rad

[magoo117]

also pic of narrowed nose

[MudderChuck]

Not exactly answering your question, but this may be helpful in the planning and layout. If the pipes go down then back up again, you have to have some way to easily bleed the air out of the motor end. I cut in one of those Prestone garden hose connectors (for flushing) on the top heater hose, outlet from the thermostat. I had to bleed air out periodically for awhile, till all the air in solution worked it's way to the top of the system. You should also connect a loop from the thermostat heater outlet and the water pump inlet (if you remove the heater and heater valve). The circulation/bypass helps the thermostat work better and faster. This can minimize those wild temperature swings as the thermostat opens and closes.
I had to go back and figure out why mine wasn't working well, maybe this will save you some trouble.
I used regular old water pipe in the exposed places (fairly bulletproof), exhaust tubing for the protected areas and universal type rubber radiator hoses for the ends.
I found some hard foam insulation (comes in different sizes and thicknesses) at a refrigeration and plumbing place (and the glue for it), kind of like roll bar padding, to keep down the heat where it was necessary.
I had two fans, a 12 inch pulling and an 18 inch pushing. The 12 inch was fairly low amp, constant on (with the key), the 18 inch was on a switch. I rarely needed the 18 incher.

[JuryRigJalopy]

Originally Posted by MudderChuck

I rarely needed the 18 incher.

I've never tried an 18 incher either...or a 12 incher...pushing or pulling. But it's nice to know you have an open mind. Thats just dirty.

[MudderChuck]

Originally Posted by JuryRigJalopy

I've never tried an 18 incher either...or a 12 incher...pushing or pulling. But it's nice to know you have an open mind. Thats just dirty.

You can compensate for lack of diameter by increasing RPM's

[JuryRigJalopy]

Originally Posted by MudderChuck

You can compensate for lack of diameter by increasing RPM's

Just make sure that the unit can handle that many RPMs, dont want to burn it up.

[MudderChuck]

Originally Posted by JuryRigJalopy

Just make sure that the unit can handle that many RPMs, dont want to burn it up.

If it bypasses to much air flow, time for a tradein.

[800MJ]

you should be able to route it through the cab without increasing the temp inside. insulation would be fine. and running your motor at 120* all day sounds like a fucking dream

[Fullsizexj]

It is true, 120 degree all day Max from Crawl was riding with me and saw it, rad was cold to the touch the whole time, I could lay my hand on it for as long as I wanted without a burn at all