Test results of several clutch/fan/thermostat combinations:

Overheating project started months ago, with guidance from this forum I replaced a bad fan clutch (free wheeled) with a used one, changed fan from 9 blade to 11 blade (Range Rover), had radiator rodded out and acid flushed (big change), replaced water pump (leaky, no performance change), cleaned out space between rad and condensor (leaves), and found PO had wired replacement AC fans backwards (kept over heat at idle only with AC on), replaced used fan clutch with new $49 Chevy non A/C model from tech sticky, also tried the AC model, but it was a 7 inch and did not fit without spacers. Ran the $49 model for a while. It is pix #3, a smmoth side toward the fan. Heavier duty units look like a heat sink.

Changed stat to 180 high flow version. Was still 198F at 60 mph in afternoon with AC on, 207 at idle after a few minutes.

With summer here I wanted to cool things off at idle, so I tried one of the extreme clutches, Imperial 215158 (the 215157 is the $49 Chevy model).

That got me down to 178-183 in cool part of day, and 192-194 in afternon.

Decided that since it was for a Chevy, perhaps I could find something in salvage yard. Got a 6 inch reverse rotation clutch and fan from a 98 GMC Sierra for $10. Bolted up great, but fan was too big, had to remove shroud, and then it would not cool as well. Pix of GMC/Chevy used clutch and fan with Rover for comparison.

Put shroud back on, used Rover fan on Chevy used clutch, still not big change in cooling (did see some, because Chevy clutch is full engaged at 95% of shaft speed).

Decided Chevy fan was greater pitch than Rover, it was also nylon, so took kitchen shears and cut it down to fit inside shroud. Would run at 178F to 183F on roadway. Pix of cut down fan.

Decided that I would try 160 stat, installed it also.

Results at 95 degree day:

163F at 60 mph no A/C Scanner says closed loop, tranny shifted into 4th at 53 mph just like it always did.
173F @ 60 mph, AC on.

At idle reached 207 F in 15 minutes with AC on.

Tried removing the rubber strips that seal the radiator to condenser. This seemed to help at idle, put made things worse at road speed.

Strips out - idle 45 minutes - no AC - 201F
strips out - idle 10 minutes more with AC - 212F
strips out - 50 mph - 167-169 no A/C
strips out - 50 mph - 176-186 with A/C

Put the darn strips back. Put in 11 balde Rover fan on Rover stock clutch:

169-171F @ 60 mph with no A/C
180-185F @ 60 mph with A/C

idle with AC - in 5 minutes increases from 189 to 192F
idle without AC - 180F and rising

Changed back to chevy modified fan and used Chevy clutch:

Idle 174 F, rise to 178 after 5 minutes, no A/C

Conclusions:

1. If a Rover fan clutch is not available then a Chevy/GMC of late 90's - early 2000's, six inch, reverse rotation, will bolt right up. Older Chevy fan clutches has a skinny mounting fitting. You get them off just like ours, and even a little easier, because their "nut" is longer, and allows a large adjustable wrench to fit it, then whack the handle sharply. to the left.

2. The stock Rover fan has less pitch than the typical Chevy, so the Chevy will move more air, once trimmed to fit. Water pump wear and tear may increase.

3. The increased air flow provides increased cooling while on the road and while at idle. But a marginal cooling system, like my old rodded out radiator, may not produce the cooling it once did. And idle temp may still crawl up to some place you don'r want it, just will take longer. Gas MPG has yet to be evaulated ( I was getting 16 mpg with rover fan/Rover clutch, no front prop shaft [rebuilding]).

4. A 160 stat can be fitted, and they are less than $10. On a warm day, the system as a whole probably can't stay at 160 no matter what. Once fully open, the 160 esentially functions as "no thermostat" and water flow time in the radiator may not be slow enough to exhange all the heat that could.

5. I didn't hear gurgle sounds with the 160. I did once in a while with the 180, (but not with 195) even though I ran Water Wetter. It may be that I have read so many ideas on getting rid of air bubbles that I actually got most of it out. Or it could be that I am operating at a temp that is keeping Mr. Montgomery Scott from going to Warp Factor (perhaps the head gaskets will hold Captain, if we don't heat them quite so high). Of course, this could be short lived.

6. Old radiator could still be the weak point - when it was rodded out I have no idea how many tubes may have been closed off. Will be thinking about a new one, and doing a cooling pressure test. Have not lost coolant, no white smoke (knock on wood). Pressure cap good, and system does pressurize, upper hose firm, not rock hard.

7. These tests are by no means laboratory grade. Weather conditions change by the hour around here, etc. Length of time to swap fans and clutches varies with the commands from she-who-must-be-obeyed.

 

Simply put a 160 is too cold. A US 180 is what meets Land Rover's thermostat spec. Or an 88c from the UK.

You seem to be spending an awful lot of time on other stuff when you don't even know if your radiator is any good.

If you have a good radiator even the stock clutch will maintain the temp within spec in normal every day driving.
I only went with the severe duty for two reasons, to fit the metal blade so I didn't have to worry about the plastic one destroying my radiator, and for the assurance of good cooling at low speed with heavy loading.

 

Tom,

I have come to the same conclusion. I had radiator rodded out and acid flushed a few months back. But what a lot of shops do is if a tube won't hold water, they fold it over and solder it up, reducing the capacity of the radiator. Do that several times, and maybe it is 10 - 15% below spec. Get to really warm weather and it shows up. And if those bypassed tubes are in the middle, it would mess with the fan clutch by making it too cool to activate.

So I'll be looking for a new rad soon. In the mean time, compensating by increased air flow, decreased gas milage. Need to deal with the front prop shaft rebuild first.

I guess no coolant loss and no white smoke and no gurgle is a good sign.

And I can see why Rover makes the guage the way they do, if you saw what was happening it can make you nervous.

 

If your tanks are in good shape you can have it recored.

 

That's a good thought as well, will call my indy shop. Remebered that I took out a newer aftermarket radiator at the salavage yard, but changed my mind, figuring it would just be the clutch. The radiator had one of those catus emblems on it. Duh.

 

The purpose of the fan shroud is to direct air flow through the radiator, if you put that shroud infront of a box fan you would feel the air speed increase.
Without a fan shroud the fan pulls less air.

 

Agreed, that is why I cut down the length of the used Chevy fan, blades are nylon. Tried it without shroud when it was full size, which even though it moved more air it did not make up for the missing shroud. Tom's idea about radiator makes sense too, when I drive in the early morning, temp will stay just below or above what ever stat is in there. In the afternoon, warmed up day, add 10 degrees or more. Change of exterior air temp won't impact water flow thru water pump, so not much is left other than marginal radiator. And two months ago it was better, but we were below the really high weather temps.

Now the chevy fan does move more air than the stock one. I've got an anemometer (cfm meter) somewhere, may test it. I've gotten really good at taking a fan clutch off the truck. I noticed that the alternator is about 30 degrees cooler than normal with the chevy fan.

And I agree with one of you previous posts - if a 180 stat won't do it, you have a cooling system problem. I do wonder if the hot air blast from the rear of the fan makes the temp read by the ECU and two wire sensor a little higher at idle than it really is.

While playing with this today also changed tranny oil, plus replaced the EVAP purge valve, plus put on about 70 miles road testing.

 

I made mention in the other thread about the fan's position within the shroud makes a difference as well. Fan blades are suppose to be half in, half out of the shroud to make proper use of the shroud.

With these Chevy fan clutches where some are deeper than the stock LR ones, the fan would be forced deeper into the shroud.

 

It's raining on the shade tree, so the pix is a little fuzzy. Appears the blade is pretty close to 50/50, based on the edge of the venturi on the left that would be below the tab to latch the removable part. But that small part won't make the difference of the 10 degree increase when you switch on the AC, or morning operation vs afternoon. I'm afraid I have a marginal radiator.

2nd pix is original test with complete Chevy fan (too big for shroud).

Of course, during all this, from 150 to 210 F, guage stays right about 8:00. So the average owner would think everything is peaches and cream.

Please note that I have reduced my RTV usage (blue line) to below 10 gallons per job per LRD2&ME.

 

Well in that second pic I can see the condition of your radiator, it is shot.
You need a new one.