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Old 9th June 2015, 18:04   #1
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Talking Moving the Radiator to the Rear!

Moving the Radiator to the Rear!-10644159_10152875029316963_2209923375583483000_o.jpg

Well, after your Jeep emerges triumphantly from that dirty mud pit, its not all smiles for a long time. The radiator gets clogged with muck, and stops heat transfer from the coolant. Add to the fact that you revv the nuts out of that engine trying to conquer the next slushy incline, and you are looking at a steamy engine bay, and probably some fried rings.

Well, I could live with the above fact with a bit of caution, some manual cleaning and a very light right foot. However, last month I decided to plonk in an AC in the Jeep. That means, there'll be a condensor just in front of the radiator. So, there's a muck coated plate in front of the radiator, muck in between the condenser and radiator and muck in the radiator fins. Now, even a service center will find it difficult to clean. So, its either the condenser or radiator which needs to move & I opted to move the radiator to the back.

I did the job at my FNG, and will share the pros, cons and basically what I did.

Pros:
  • With the radiator at the back, you no longer need to worry about its security. Like I mentioned above, even after coming out of a thick mud pit, you wont have any heating problems. Radiator will still be clean and will cool.
  • You dont need to worry about the drive-train moving front and hitting the radiator on jumps. Even if the engine mounts are gone, or you don't have a spike arrestor?
  • No more protruding sticks and bushes puncturing the radiator.
  • More coolant volume, and hence more cooling. (You get accommodate more coolant, along the lines to and fro the radiator<>engine.)
  • I used GI Pipes. Hence, Heat dissipation along the lines too.. Result: More cooling.
  • Loads of space freed up in the engine bay. For condensor, intercooler, huge horns, Weird lights, or what not.
  • You can have any number of fitments, and any size fitments in front of the grille, And no more worries of blocking the airflow to the engine. Eg: Warn 8274 high speed winch.
Cons:
  • Practicality goes out of the window. No more rear seat occupants. No more Jeep carrying loads. Now, its strictly an offroading maching. Nothing else.
  • Radiator just behind your cabin means, loud fan noise whenever on.
  • Longer plumbing. Meaning, earlier you just needed to carry a couple of spare radiator hoses. Now, I have 8 hoses in the system. Should be very alert to maintain in the prime condition.
  • That also means, more areas prone to leaks. Should be very alert.
  • Its a pain to refill the system from zero without airscrew. You need to fill it from all possible sides. Run the engine engine>stop the engine>check>repeat. many times.
  • Should sheild the cabin from the radiator. Or its risky if it pops a leak.
Installation points:
  • Pretty much straight forward. Move the radiator to the back, hence bring the pipes to the back to too.. Everything is the same - The upper pipe from the water pump, to the top of the radiator, and bottom one to the bottom of the radiator.
  • I have used rubber, radiator hoses in joints and bends, and 1.5" GI pipes for the rest. Now, these serve two purposes. When the chassis flexes the hoses flex too. And the GI pipes dissipate heat.
  • I have routed the pipes along the chassis so that they are protected.
  • Even though pipes are routed along the chassis, I have secured them (clamped) to the drivetrain. Not the chassis. The engine and chassis move at a different rate, and the pipes need to flex along with the engine movement. Otherwise, they will just pop out.
  • Reduce 90 degree bends as much as possible.
  • Important: Keep the radiator cap as the highest point of the cooling system.
  • I have used two fans. Both, manually operated with switch. I need to connect one to an automatic maruti or indica thermostat.
Here's a couple of pics. I'll post more as soon as I take the jeep for the next underbody wash.

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Moving the Radiator to the Rear!-img_0294.jpg

Moving the Radiator to the Rear!-img_0297.jpg

So, thats pretty much it. Fellow members please feel free to add/correct to the above.


Thanks!

Last edited by dhanushs : 9th June 2015 at 18:22.
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Old 9th June 2015, 18:53   #2
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Default re: Moving the Radiator to the Rear!

Quote:
Originally Posted by dhanushs View Post
Attachment 1380189
[*] I have used rubber, radiator hoses in joints and bends, and 1.5" GI pipes for the rest. Now, these serve two purposes. When the chassis flexes the hoses flex too. And the GI pipes dissipate heat.


Thanks!
Interesting.

For longevity of hoses, and better looks, you could try silicone hoses.

There seems to be couple of Indian manufacturers. Google throws up these:
http://www.unitedrubber.net/products.asp
http://siliconhose.in/
http://www.siliconehoseindia.com/silicone-hoses.html

Cheers
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Old 9th June 2015, 19:43   #3
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Default re: Moving the Radiator to the Rear!

Since, the radiator is forward facing, you can as well make an Air duct blowing to the radiator from the sides (behind the Driver & Passenger seat). I assume fan rotation is sucking type.
My Van has OE fiber pipes. The radiator placed in the front & engine mounted at the rear.
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Old 9th June 2015, 20:03   #4
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Default re: Moving the Radiator to the Rear!

What about the water pump? Wouldn't its effectiveness be reduced due to the larger circuit?
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Old 9th June 2015, 20:11   #5
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Default re: Moving the Radiator to the Rear!

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Originally Posted by CrackedHead View Post
What about the water pump? Wouldn't its effectiveness be reduced due to the larger circuit?
+1

Check the water pump specs and see whether it can handle the new circuit. Our experiment with relocating radiator to the rear (big vehicle) ended up with engine seizure.

We had to change the water pump to make it work.
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Old 9th June 2015, 20:36   #6
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Default re: Moving the Radiator to the Rear!

Quote:
Originally Posted by gthang View Post
Interesting.

For longevity of hoses, and better looks, you could try silicone hoses.
Thanks, yes, will eventually migrate to better hoses.
Quote:
Originally Posted by narendra.vw View Post
.. you can as well make an Air duct blowing to the radiator from the sides...
I have completely eliminated the need for ram air. The Jeep doesnt heat up. There is a lot of coolant volume.
Quote:
Originally Posted by CrackedHead View Post
What about the water pump? Wouldn't its effectiveness be reduced due to the larger circuit?
Yup, it pumps nicely. Its easy to check. Just remove the top/inlet hose to the radiator and see.
Quote:
Originally Posted by Latheesh View Post
Our experiment with relocating radiator to the rear (big vehicle) ended up with engine seizure.
Dude, Very Very important.. Keep a sharp eye on the temperature guage. Why cant you just switch the engine off once it shoots outside the operating range? Anyhow I guess all mods undergo elaborate testing?

Meanwhile - Its important that you prime the system properly. Or else, there will be no flow. It'll be like the water pump isnt pumping enough.
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Old 9th June 2015, 21:10   #7
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Default re: Moving the Radiator to the Rear!

Hi,
Not uncommon mod for mudpluggers abroad.

Quote:
Originally Posted by dhanushs View Post
Anyhow I guess all mods undergo elaborate testing?
Instrument, and evaluate readings.

Quote:
Meanwhile - Its important that you prime the system properly. Or else, there will be no flow. It'll be like the water pump isnt pumping enough.
Properly filling up systems like these can be a major PITA. From the picture one sees that the radiator has top/ bottom tanks. And the filler neck is attached to the top tank. Is that the highest point of the circuit? Any local highs?

Regards
Sutripta
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Old 9th June 2015, 21:58   #8
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Default re: Moving the Radiator to the Rear!

Quote:
Originally Posted by Sutripta View Post
From the picture one sees that the radiator has top/ bottom tanks. And the filler neck is attached to the top tank. Is that the highest point of the circuit? Any local highs?
Hi Sutripta,

My radiator has tanks on the side. Yes, the radiator cap is at the highest point in the circuit. However, filling through the radiator cap doesnt fill the system.
Quote:
Properly filling up systems like these can be a major PITA.
Tell me about it!
  • I need to fill up the radiator.
  • Need to remove the top hose (Water pump outlet, radiator inlet), fill up water from both sides (radiator side & water pump side)
  • Need to remove the bottom hose (Waterpump inlet, radiator outlet), fill up water from both sides (radiator side & water pump side)
  • Thankfully now, blowing hard from any one side works in removing the air.
You do this, and you see the water pumping.

This is temporary. I will need to design a set of air screws so that I can fill the system up by myself with no external help.
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Old 9th June 2015, 22:33   #9
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Default re: Moving the Radiator to the Rear!

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Originally Posted by dhanushs View Post
Keep a sharp eye on the temperature guage. Why cant you just switch the engine off once it shoots outside the operating range? Anyhow I guess all mods undergo elaborate testing? [/u]
We were checking other important things and our assistant kept the engine on to the glory. Lucky that we could afford to do that, and water pump just could not handle the new big and longer circuit. We had to upgrade the water pump to make it work. It was for an earth moving equipment project.
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Old 10th June 2015, 16:30   #10
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Default Re: Moving the Radiator to the Rear!

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Originally Posted by CrackedHead View Post
What about the water pump? Wouldn't its effectiveness be reduced due to the larger circuit?
Exact thing popped up my mind too. So much additional load and it can give up? You need to ensure to carry a spare all the time. Any possibility of changing to any other pump that can take up this load? (I got no clue and just asking)
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Old 10th June 2015, 19:10   #11
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So much additional load and it can give up?
Hi, what are the variables affecting the 'load' of the water pump? And how do they affect a cooling system?

Length of the circuit? Diameter of the inlet/outlet/pipes? Avg height? Number of bends? Angle of bends?

Quote:
Any possibility of changing to any other pump that can take up this load?
http://www.team-bhp.com/forum/4x4-te...-vehicles.html (Electric Water Pump for Off-Road Vehicles)

Which is not needed for Nissan SD25, with the plumbing I've done.

The stock pump, with a 10% smaller pulley diameter is more than enough in pumping water through the system.
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Old 10th June 2015, 19:31   #12
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Default Re: Moving the Radiator to the Rear!

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Originally Posted by dhanushs View Post
Hi, what are the variables affecting the 'load' of the water pump? And how do they affect a cooling system?

Length of the circuit? Diameter of the inlet/outlet/pipes? Avg height? Number of bends? Angle of bends?
Just thinking back to the time I studied hydraulics...

1) There is no load on the water pump, the load is on whatever that is driving the pump, the engine in this case. But let's not worry about load just yet.
2) The pump will move X amount of water at a given rpm. I don't think that will change with the change in the length or width or bends of the new pipe.
3) What changes is the time that is required for the hot water to move out of the engine, get cooled at the radiator and then return to the engine. If the water in the circuit has increased by 4 times, it might take 4 times longer to cool at a given rpm. In other words cooling efficiency may be down to 25% of the original, for a given engine speed.

The above is just logical deduction... feel free to poke holes in it.
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Old 10th June 2015, 22:12   #13
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Default Re: Moving the Radiator to the Rear!

Those are some neat looking welds on the gi tubes. Did you use arc welding? Its a bitch to weld zinc coated metal with mig/tig as zinc tends to explode. Scrubbing it off robs off precious protection. The black portions are steam pipes?

Thumbs up to the twin fan shrouding as well. Was it fabricated or found ready made?

Congratulations for acquiring a base to make a cab heater for the upcoming winters!
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Old 10th June 2015, 23:50   #14
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Default Re: Moving the Radiator to the Rear!

Quote:
Originally Posted by CrackedHead View Post
What about the water pump? Wouldn't its effectiveness be reduced due to the larger circuit?
Quote:
Originally Posted by dhanushs View Post
Hi, what are the variables affecting the 'load' of the water pump? And how do they affect a cooling system?

Length of the circuit? Diameter of the inlet/outlet/pipes? Avg height? Number of bends? Angle of bends?

[/b]
Quote:
Originally Posted by Samurai View Post
2) The pump will move X amount of water at a given rpm. I don't think that will change with the change in the length or width or bends of the new pipe.
3) What changes is the time that is required for the hot water to move out of the engine, get cooled at the radiator and then return to the engine. If the water in the circuit has increased by 4 times, it might take 4 times longer to cool at a given rpm.


1) I believe at highway speeds usually the fan is supposed to stay off and most of the coolant heat is removed by the opposing flow of air across the radiator due to high speeds of the vehicle. So in your case it seems there is very little heat transfer from the oncoming air and fan will probably stay on most of the time especially when moving slowly with the low range gearbox. Did you notice the temperature gauge to be higher than normal when cruising the highway?
2) Are those the orignal fans or somehow modified?
3) I am glad you avoided sharp bends, centrifugal pumps will dish out smaller flows at a given rpm when the plumbing is increased. The length of circuit, number and type of bends and diameter and material/roughness of piping and fluid characteristics will all have an impact on the flow you get out of the pump. Your coolant flow is definately LOWER than it was before you modified. This reduction in coolant flow should be adequately compensated by increasing the air flow across the radiator

Last edited by bullrun87 : 11th June 2015 at 00:15.
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Old 11th June 2015, 00:03   #15
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Default Re: Moving the Radiator to the Rear!

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Originally Posted by Samurai View Post
J...
3) What changes is the time that is required for the hot water to move out of the engine, get cooled at the radiator and then return to the engine. If the water in the circuit has increased by 4 times, it might take 4 times longer to cool at a given rpm. In other words cooling efficiency may be down to 25% of the original, for a given engine speed.
Hi Sharath,

Thanks for the comments.

I'd say, just think of the engine/waterpump as a separate unit. The amount of water leaving the system = the amount of water entering the system.

So, the rate of cooling the engine will depend on: (1) the speed at which water flows through the engine and (2) the temperature difference between the hot engine parts and cold water fed into the system, and of course the heat transfer coefficient of the coolant, which is constant.

Last edited by dhanushs : 11th June 2015 at 00:22.
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