Improved Engine Cooling?

Nadir_E

Nadir_E

Adventurer
Hi All,
Since I've had my '94 NAS D-90 I've wanted a more robust engine cooling system. As it is now, I can't run the AC on a trail without risk of overheating unless the truck is moving at something like street-speed (most of the time when I'm out it's in a hot ambient temperature). I don't normally mind this, but when I bring the S.O. out for a trail run, she tends to wilt once temps in the truck break 90 (about 32C for the metric-ites).

A friend helped me wire the AC fan separately from the AC so I can use that for added cooling, but obviously without the AC itself running.

Have any of you added supplemental fans with good results? How about a larger radiator?

Any other suggestions welcome!

Thanks,
-N
 
G

greenmeanie

Adventurer
Before you go spending a lot of money you should make sure the existing system is up to snuff as it shouldn't overheat at 90°. These aluminium engines can crud up pretty nicely if you are not really diligent on your maintenance.

I'd start by running a cleaner in the coolant. Then pull the radiator hose and run water through the system in reverse of the normal flow direction. Replace the thermostat. Feel the radiator for cool spots which indicate clogging. On a ten year old truck I'd probably replace the radiator hoses as good practice. Also make sure that the radiator fins are clear and not clogged with mud or crud. That includes the aircon condensor and the space between the two.

You should also check that the viscous coupling for the fan is operating properly.

If that doesn't work and your only overheating at low rpm you basically need to move more air through the radiator. At that point your looking at big set of electric fans. I heard of people having success using Flexalite 210 or 410s whihc shift a lot of air.
 
KevinNY

KevinNY

Adventurer
Good advice. How often have you changed your coolant? Consider pulling the radiator and getting it boiled out too.
 
sinuhexavier

sinuhexavier

Explorer
Nadir-

Chances are that it is your fan clutch. I have had 3 such experiences on 3 different trucks. I believe your 94 Defender is the same as the 94-99 Discovery.

Here is a list of parts so you don't have to get the $200 OEM. It is a very easy job.

Let truck sit over night with a shot of PB Blaster on the nut. Your lack of burns on your forearms will make sense.

Use a fan clutch tool, $20, to loosen. Righty tighty, lefty loosey, as you are facing the engine from the front.

Remove fan with the 4 bolts.

You will have to drill out the fan holes for the new bolts that come with the new fan.

Replace fan.

Kragen etc.: Hayden 2786 (heavy-duty), Ready-Aire 4858R (heavy-duty), Imperial 215158 (severe-duty)
NAPA: TEM 271312 (severe-duty)
AutoZone: TorqFlo 922744 (heavy-duty), 922786 (severe-duty)

All - reverse rotation (serpentine belt!).

****COURTESY OF DISCOWEB****

I did the severe duty on my last job because it was the only one they had in stock. It is a rocket engine and way, way over kill. I am going to replace it with the Heavy duty and keep the severe duty as a spare as they are prone to fail.
 
048642

048642

Adventurer
I've used the water wetter in my 1962 UNIMOG S404 for several years. It provided me a 10 degree F drop in operating Temp.
 
Nadir_E

Nadir_E

Adventurer
Thanks, Guys - looks like I have a couple of projects to get started on!

To clarify - it's not overheating at 90-degrees ambient - UNLESS - I'm crawling AND running the AC. Just running around in the heat with no AC it runs fine, perhaps a little above normal operating temps if it's really hot outside.

-N
 
kellymoe

kellymoe

Expedition Leader
I had a real problem with overheating a few years ago with my Defender. I flushed the radiator used Redline, made sure my fan was in good working order and still had issues. I realised the overflow cap was not sealing properly, changed it out for a new one and it solved the problem. I took it to the Saline Valley last August and climbed the North Pass in 116 degree heat and it stayed well within normal running limits.


I have a twin electric fan sitting on my work bench that will be going into my truck soon, I think that is a worthy modification for the Defender and have heard good things from people who have done it.

I also use all water and one bottle of Water Wetter in the Summer months, too much coolant reduces the effectiveness of Water Wetter.
 
R_Lefebvre

R_Lefebvre

Expedition Leader
Did the truck originally have any radiator ducting, and if so, is it still in place?

I've seen many people with cars remove it for various reasons, often because of fitting new bumpers, and then have cooling problems while stationary. All the radiators and fans in the world won't help if the air is being drawn through the rad, heated up, then moves back up front to be drawn back through the cooling package again.

Yes, it's true that pure water cools better than a glycol mix. However, I don't think I'd trust pure water with WW in my Rover engine.
 
ntsqd

ntsqd

Heretic Car Camper
I have run into the radiator cap aging and not holding the design pressure, which shows as an over-heating problem. This has actually happened twice with the same truck during my custody of it. Can't recall the brand of the first one, but the second was a Stant.
 
H

Hank

Guest
R_Lefebvre said:
Did the truck originally have any radiator ducting, and if so, is it still in place?

I've seen many people with cars remove it for various reasons, often because of fitting new bumpers, and then have cooling problems while stationary. All the radiators and fans in the world won't help if the air is being drawn through the rad, heated up, then moves back up front to be drawn back through the cooling package again.
Click to expand...

Do you even know what a Land Rover looks like?
 
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