If you're really worried get an infrared thermometer, shoot the clutch temp when hot and ask Hayden/Imperial if it's working as intended.

 

Well, the 215158 is for things like an S10 pickup, so it might not be a "thermal" match for the Rover. The Hayden web site says they have introduced a model 2991 for 4.0/4.6 liter Rovers. At the moment, I put the stock back on for more tests. It seems if I maintain constant speed at 60 MPH in 95 degree temps my coolant will go up to 192 - 194 on the scanner, but in the morning when cool over same route it stays at 178-182 (180 stat). So my rodded out radiator may not be 100%, or they may have closed off some tubes that were too bad to repair. I recently changed water pump, and have water wetter installed with 50/50 green/distilled water. Just don't think coolant should be way over stat temperature when motoring down the highway. No white smoke or coolant/oil crossbreeding.

What does your truck run on the highway on a hot day, AC on?

 

I don't use the AC, I don't like it.

 

So Tom, how hard is to grind properly? You need to do it on a bench I assume. It seems like I could mess this up although maybe not.

 

I changed my mind three times in the last hour.

I'm going with the exact set up you have Tom. Any pointers on cutting the fan down? Straight across the top end there intersecting the cutaway?

That's the only mod right?

SB..You seemed more comfortable with the mods before and less so now. I wish you were on board with this.

 

I've been running my own tests this week with a 180 stat. It runs 178-183 in the morning, but 192-194 on the afternoon return the same route, and down here the elevation only changes like 100 feet in 30 miles. Stock fan clutch. I am thinking that my rodded out radiator is maybe at 90%, and on a hot afternoon it needs to be 100%. I believe I will be going back to the extreme clutch, because it is only a fraction of the cost of a new radiator. I'm going to check my mpg today on the 180, on the 195 I was getting about 14. I purchased a 160 to experiment with as well, keep in mind that in my area we get maybe 10 days a year below 30F, must be something to that global warming....

But the realistic part of my brain thinks that once you are 10 degrees past the rated point of the thermostat, it is as wide open as it can be, and the rest of your cooling system can't keep up - water pump gallons per minute flow rate, and radiator heat transfer. By increasing the fan clutch, I can pull a little more air through the radiator, but at what cost mpg I don't know. Now as far as the metal fan, have not decided on that yet. Not sure if it is easier to modify the cowling of the radiator, or cut down the fan AND maintain critical balance which impacts water pump life and clutch life.

And maybe I should get brave and do a combustion gas in coolant test and really give myself indigestion...

What I would like is stable temp while road running on any day (my old Mercedes just stays nailed on 78 degrees C), and when idled stay somewhat close.

 

I pulled the trigger and bought the 215158 SD online from Advance. I could not arrange store pick up for the fan so I will hopefully get it when I pick up the viscous. BTW, the Advance deal was excellent...if it was US, you could probably get the fan and viscous for $69 with one of the code discounts.

You think I should use the original fan. It's not brittle by now? Tom seems to have had success with his cut down metal one.

Yeah, I don't want to do that test either.

 

Also, I bought the Lucas Super Coolant yesterday because I could not find the Water Wetter. Since then I found the WW so I will get that. Does anyone have experience with the Super Coolant by Lucas?

 

I just measured from the center to the end of the stock blade, transferred that measurement to the metal blade, measured how much I needed to remove from the metal one then made a butch of marks on each blade and drew an arc intersecting them all.
You do want to get them as even as you can so you don't unbalance the blade.
Then fit it, install the top cover of the shroud and turn the fan by hand to make sure it doesn't rub. Maybe apply light pressure to the top of she shroud to allow for any flex that happens while driving. I didn't do that and it rubbed some and I had to take it off and grind more.

 

If using a domestic thermostat I've found that a 180 is what is required if it's to be fully open at the temp Land Rover specifies.