How to increase cooling system's efficiency - Defender Source
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  #1  
Old October 9th, 2012, 10:34 AM
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Sam Odio
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How to increase cooling system's efficiency

I just purchased a d-90 (with an unknown maintenance history) so I've been spending the last few weeks replacing seals, hoses, fluids, etc. First on the list was the oil cooler lines (which were leaking). I replaced them with power steering hose.

One of the things I need to sort out is the cooling system. The vehicle doesn't overheat (often) but it does get hot. This especially occurs when offroading or climbing mountain roads. The thermostat will get 3/4ths of the way up before I slow down to let it cool. It seems like the resting thermostat level while the engine is on is around 5/8ths of the way up (slightly above 50%).

I'd like to know:
a) is this unusual?
b) what should I prioritize to increase the cooling system efficiency? I'm currently flushing the system. I'm considering a new, larger radiator, new fans, etc.

I'm of the belief that the head gasket & sealing issues in land rovers are at least partially due to an underpowered cooling system.

I've searched the forums & read http://www.defendersource.com/faq/En...ngCooling.html. I'm more looking to answer the question: what, if anything, should I do first?
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  #2  
Old October 9th, 2012, 11:04 AM
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Bill Adams
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Actually Sam, a Land Rover's cooling system is more than adequate. You really shouldn't rely on a gauge as they can vary wildly in their accuracy.
All automotive cooling systems are pressurized to at least 14psi. That means the coolant can get hotter than boiling. For a number of reasons you want the engine to operate around 180F.
The fan is for conditions where there is not enough forward motion to move sufficient air thru the radiator. At high speeds the fan does very little to help with cooling. So, when you are moving slowly off road you want to be sure that your fan is pulling properly (viscous coupling). Going up hill, you are generating a lot of heat due to the rich mixture. Slowing down is actually not the thing to do until you are over the top as you are reducing the air flow thru the radiator. If you are getting too hot going up hills it may be due to the radiator losing efficiency from blockage. You can also turn on the heater (!) to help as this will act like an extra radiator.

Other things that can mess you up are, in no particular order: thermostat not installed or installed upside down, water pump vanes eroded away, blockage in engine coolant passages, blockage in radiator, collapsed hose, and the ever popular blown head gasket.
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  #3  
Old October 9th, 2012, 11:10 AM
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John B.
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Test out the viscous coupling first. They have a very high failure rate. When it is "overheating", take a rolled up newspaper and carefully try and stop the fan. If it stops, the viscous coupling is dead. If it does not, then we need to look for other problems.
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Old October 9th, 2012, 11:14 AM
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Sam Odio
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Thanks Bill, those are good suggestions. I have had to use the heater in the past. We'll see if the radiator flush helps at all. I guess additional electric fans would help for offroading but less for the hill climbs.

Based on searching these forums it seems like the best way to measure engine temp is with a point-and-shoot infrared thermometer. Is that the case?
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Old October 9th, 2012, 11:23 AM
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Steve Maietta
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Sam, the thing is, a properly operating LR cooling system shouldn't need any additional fans. So adding one to keep it cool is only a band aid, and running with a malfunctioning coolant system is bad bad news for these aluminum v8's..

get it sorted, start w.the viscous. Take temp to see perhaps your gauge is inaccurate. Perhaps the previous owner isntalled a higher temp thermo, which would make your engine run hotter all the time.

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Old October 9th, 2012, 11:41 AM
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Sam Odio
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Thanks, I'll check the viscous coupling.

So a properly operating V8 D90 shouldn't get hot on hill climb or during moderate (not extreme) offroading? I just figured that's what they do and if I wanted to keep them cool, I'd have to go aftermarket. Guess I was wrong.
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  #7  
Old October 9th, 2012, 11:42 AM
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Replace viscous coupler is the most likely cure. Test as Bill said above. Could be other issues, but that would be my guess. All and all most D90s need or have had a new VC, water pump and rad by now in their lives.

Also, if you have AC, make sure the electric fans work.
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  #8  
Old October 9th, 2012, 11:54 AM
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I had similiar issues and decided to change viscus fan, water pump and t-stat all at the same time and keep the pump and fan as trail spares. Temps never go above mid-point off road or when climbing to 5k feet as it used too.

Don't mess with high temps. These parts are cheap and easy fixes.

Clay
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  #9  
Old October 9th, 2012, 01:58 PM
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Do a pressure test on the system ... I pressurized my system and found a tiny hole ... I also figured the radiator cap wasn't sealing properly.
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  #10  
Old October 9th, 2012, 02:36 PM
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There is a modification, I think it's called the "in-line thermostat mod" but not sure, to improve the cooling of the V8. I don't have more details, but basically it's a relocation of thermostat from bottom hose to top hose. More info on dweb.
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  #11  
Old October 10th, 2012, 06:26 AM
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Tom Rowe
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I'd do more than an engine flush. Pull the radiator and have if checked out by a radiator shop. The can boil it out and if needed (I wouldn't be at all surprised if it is), rod it.
While it's out, make sure the transmission cooler and AC radiators (if you have them) aren't clogged with debris.
As mentioned, make sure the viscous clutch for the fan is in good shape. Replacements are cheap, about $50, so if it's at all questionable, replace it.
US made thermostats seem to be spec'd different from the OE so make sure the thermostat is the correct temp. If it's from your typical auto parts store it's likely too hot. Every listing I've seen says a 195 which is way too hot. You want a 180. The Stant Superstat - 45858, $9.99 at Advance Auto, should work. It's a good quality thermostat with the jiggle pin. Otherwise get an 88c from one of the Rover parts places.
If you really care about your engine, I'd install a mechanical full sweep temperature gauge. When you install it, clock it so "normal" is straight up.
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  #12  
Old October 10th, 2012, 03:26 PM
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FINALLY SOMEONE POSTS A PART NUMBER!!!!!!!!!!!!!


Inline thermostat is for Bosch engines.
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Old October 10th, 2012, 03:51 PM
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Julien Dalbin
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Quote:
Originally Posted by rover4x4 View Post
Inline thermostat is for Bosch engines.
Any details will be very much welcome, the info I found on dweb is quite confusing.
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Old October 10th, 2012, 04:15 PM
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Quote:
Originally Posted by JFD View Post
Any details will be very much welcome, the info I found on dweb is quite confusing.

This has been beaten into the ground. I have not dealt with the Bosch engines, seems there is a way to convert those trucks to run a lower temp higher volume thermostat..
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Old October 10th, 2012, 04:44 PM
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Julien Dalbin
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Quote:
Originally Posted by rover4x4 View Post
This has been beaten into the ground.
Exactly, and that make it confusing. I haven't been able to find clear instructions for the DIY mechanic. I haven't search for a while, may be there is new stuff on internet.
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  #16  
Old October 10th, 2012, 09:39 PM
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Check discoweb, I think it involves a BMW rad hose. If I ever bought a DII this "mod" would be done the day it came home.
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  #17  
Old October 13th, 2012, 08:51 AM
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My radiator needed record new core and the shop showed that I cou,d put a four core back in the place of the stock three. This is my daily driver and on the hottest days it never got hot like it did before the change. I Kidd also put in a new fan clutch as well and I'm very pleased.

My 2c
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