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I seem to have a cooling problem. My range rover classic recently had a beautiful new top-hatted 4.6 built for it, and with that went a new airtex water pump, all new hoses, and a new thermostat. The radiator was replaced a few years ago with an inexpensive plastic and aluminum one (perhaps mistake number one) and always worked fine for the tired stock 3.9. The temperature with the new motor is fine most of the time, but since I even more recently had the AC revived (it had never worked since I bought the car) I found the engine gets quite warm when the AC is on and the car is under load. The other day I drove it out to go camping, fully loaded with gear and 3 people, and when climbing hills with the AC on, I could watch the temp needle start to move further and further to the right (up to about 3/4 on the gauge) with the outside temp at only about 72F. Come level ground, it would drop back to center. doing the same thing with the AC off resulted in no change of the temp needle. This concerns me, because should I want to go somewhere in the desert during the summer (90-100F) I fear I might roast it. My engine builder thinks that the aluminum radiator cant handle the extra heat from the condenser when the AC is on, and that I should try to find a stock copper/brass radiator to put back in. My goal is to be able to climb mountains in 100 degree heat with the AC on, which should be possible, is that the way to go? Is the factory copper/brass unit that good? Or should i try to find one of those crazy expensive welded all aluminum ones?
 

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Yes it's fully bled, had to backfill it thought the heater lines to get all the air out, but it's been good for a while. The cooling system had ben performing fine for the past couple months, the issue started when the AC was bought back to life. It seems the added heat from the condenser in front of the rad is more than the system can handle.
 

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1970-1995 Range Rover Classic
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I would check/replace the viscous fan clutch. Mine behaved similarly when it began to fail.
 

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Discussion Starter #5
Sorry forgot to mention viscous fan replaced with 4 big electric fans (5000CFM+) about 2 years ago.
 

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1970-1995 Range Rover Classic
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basically any V8 radiator offered for these trucks is hilariously oversized for its application. when working properly (i.e. not clogged or corroded to death) it’s the last thing you need to worry about
 

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Sorry forgot to mention viscous fan replaced with 4 big electric fans (5000CFM+) about 2 years ago.
This may be an odd question – could you have possibly swapped the polarity on the fans when you installed the new 4.6? Are they now pushing air instead of pulling air through the radiator?
 

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1970-1995 Range Rover Classic
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generally overheating when standing leans toward fans first. overheating when moving fast leans toward radiator first. on my 95lwb I have installed an "autometer" water temp gauge directly into the top of the radiator. along with the factory gauge I can see the temperature building before the factory unit starts to rise. although it gets to 220+, that's not boiling under pressure, but the factory gauge is slow to move. I bring this up as I also see a big jump in temperature when pulling a hill with the AC on. I have all new radiator, tstat, and hoses too. other than getting a custom radiator; flip off the AC for a minute or so and it comes right down. I do live in AZ and I am talking summer and mountains, but the AC really works good!
 

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Discussion Starter #9
generally overheating when standing leans toward fans first. overheating when moving fast leans toward radiator first. on my 95lwb I have installed an "autometer" water temp gauge directly into the top of the radiator. along with the factory gauge I can see the temperature building before the factory unit starts to rise. although it gets to 220+, that's not boiling under pressure, but the factory gauge is slow to move. I bring this up as I also see a big jump in temperature when pulling a hill with the AC on. I have all new radiator, tstat, and hoses too. other than getting a custom radiator; flip off the AC for a minute or so and it comes right down. I do live in AZ and I am talking summer and mountains, but the AC really works good!
Can I ask what radiator you put in?
 

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Discussion Starter #10
This may be an odd question – could you have possibly swapped the polarity on the fans when you installed the new 4.6? Are they now pushing air instead of pulling air through the radiator?
To be honest I haven't checked, but I will definitely do so. I would think that would have a bigger effect when stationary than at speed though, and so far it idles at a good temp.
 

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my new radiator is a stock one from AB. pricey but when I needed it I was not in a position to explore options. it was cheaper to pay overnight charges than hotel nights!!
 

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Discussion Starter #13
my new radiator is a stock one from AB. pricey but when I needed it I was not in a position to explore options. it was cheaper to pay overnight charges than hotel nights!!
Is the one you bought the factory copper/brass one they have? How does it compare to the original one in your car? Is it a 4 core or a 3 core?
 

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The question earlier about bleeding the air out of the system. It should, if it has the large plastic header tank with supply hose going to the waterpump "bottom radiator hose" be a self bleeding system.

But this also depends on those two small bore hoses that go to to left of radiator. They each do a different thing and should have internal arrangements (just inside the radiator) that promote air bleeding from both highest points of radiator and engine to "manage" excess air into the top of the expansion tank.

If it doesn't work correctly it effectively boils the coolant local to the combustion chambers as it doesn't clear that area fast enough with consistant uninterrupted flow. Any build of air in that area of the block will give variance of overall temperature.
 

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I always bleed the air with a large, coolant-filled funnel fitted to the plug on top of the radiator, and let it idle through a couple t-stat open/close cycles.

If I were getting a new radiator, I would look for a NOS genuine or get one from Allisport. I replaced a D1 radiator 8-9 years ago and had to return 3 to get a good one (AB sourced).
 

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lance, I don't know/remember if it's 3 or 4 rows, but it is copper/brass/metals. anyway it works good, but with the temps I sometimes have to endure here in AZ, I could use more. best thing I have done for cooling is the install of the aux temp gauge.
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I had a Turner Engineering 4.6 put in my 95 SWB a couple years ago, I was concerned about temps and pulled the trigger on having the original radiator recored (HD MX spec). No issues with overheating at all. Do you happen to have the original, maybe you can have it recored.
 

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I seem to have a cooling problem. My range rover classic recently had a beautiful new top-hatted 4.6 built for it, and with that went a new airtex water pump, all new hoses, and a new thermostat. The radiator was replaced a few years ago with an inexpensive plastic and aluminum one (perhaps mistake number one) and always worked fine for the tired stock 3.9. The temperature with the new motor is fine most of the time, but since I even more recently had the AC revived (it had never worked since I bought the car) I found the engine gets quite warm when the AC is on and the car is under load. The other day I drove it out to go camping, fully loaded with gear and 3 people, and when climbing hills with the AC on, I could watch the temp needle start to move further and further to the right (up to about 3/4 on the gauge) with the outside temp at only about 72F. Come level ground, it would drop back to center. doing the same thing with the AC off resulted in no change of the temp needle. This concerns me, because should I want to go somewhere in the desert during the summer (90-100F) I fear I might roast it. My engine builder thinks that the aluminum radiator cant handle the extra heat from the condenser when the AC is on, and that I should try to find a stock copper/brass radiator to put back in. My goal is to be able to climb mountains in 100 degree heat with the AC on, which should be possible, is that the way to go? Is the factory copper/brass unit that good? Or should i try to find one of those crazy expensive welded all aluminum ones?
I believe you need a greater cooling capacity radiator. If it overheated when stationary it would be inadequate air flow, so the fans would be suspect. The fact it's when you're rolling and aggravated with extra load from the A/C and also hills, where the engine has to work harder, it has to be an inadequate radiator. If you haven't already, I would replace the thermostat with one that opens at a lower temperature. You might consider an electrically operated water spray directed across the front of the radiator that you could activate when necessary but a better radiator appears to be the solution.
 

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Discussion Starter #19
I believe you need a greater cooling capacity radiator. If it overheated when stationary it would be inadequate air flow, so the fans would be suspect. The fact it's when you're rolling and aggravated with extra load from the A/C and also hills, where the engine has to work harder, it has to be an inadequate radiator. If you haven't already, I would replace the thermostat with one that opens at a lower temperature. You might consider an electrically operated water spray directed across the front of the radiator that you could activate when necessary but a better radiator appears to be the solution.
That was what I was afraid of, fo you have a recommendation? I've been trying to find a better one, but other than the $1000+ allisport aluminum one, or the $1400 genuine LRDirect one, I haven't found anything reasonable.
 

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Bearmach and blue box still sell new OE style copper rad last time I checked. Look up ESR3687 and ESR74 on any non-US site
 
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