I am having an issue with my coolant temps: At idle with new rad (3 months old), fan clutch & grey thermostat (1 week old), I reach 185 in driveway and I can stay there seemingly indefinitely.

When driving at fast or close to highway speeds (where I would assume air flow would keep temps down) it can get as high as 215, then when I stop at a light, it will back down to 195 until I resume driving. The temps also seem to creep much quicker with the AC on (I confirmed that the electric fan is operating properly)

The only thing I can think is my new rad (from Genesis) is junk OR my water pump (original) isn't working properly...

Also, I am running about 60 water/40 Dex (very fresh coolant...3 months)

Should I run 80/20 in these Tropical latitudes?

Thanks so much as always!

 

You only run 50/50 in any vehicle.
215 is not a bad number at the 90 to 100 degree mark and your other numbers sound great.

 

Yeah don't think your numbers are bad but you seems to operate opposite of mine. In the 90 degree heat with the AC on, be it in stop and go traffic or idling for long periods of time, the hottest I have seen is 208. On the highway I see 188 to 195 on average.

The headgaskets on mine were done before I bought it and I found out it had a 180 t stat in it already only after I bought one to do as maintenance (backup I guess). It is filled with green stuff so based on my temps sounds like who did the work got the mixture pretty spot on.

I have had some cars with failing water pumps and they had issue more in stop and go traffic than on the highway but that isnt to say that isnt it. I know you say thermostat is new but any chance its stuck open?

 

I would say that your radiator is not getting rid of enough heat. My tired old D1 with a 180 stat will get to maybe 187 at 75 mph. With AC on. You should warm up a little as you slow down because you don't have as much air flow and motor is still cooling down.

I'd want to make sure both electric and mechanical fan are blowing the correct direction, and that when either is on air is sucked toward the grille (use a platic bag to test). Don't care if it is power wires reveresed to fan, mechanical fan mounted backwards, or fan belt routed wrong. If you are "fighting" the airflow from forward progress of the vehicle you are subtracting cooling.

Wonder if radiator lower hose is collapsing at speed, should be able to see this when stopped and revved up, might not want to do that in the neighborhood.

Check the water lines to the 180 thermostat. The center line on top goes to the "T", the one to the side goes to the water pump. If you remove stat and look at the holes in the disk under the center line, they should be free of clogged junk.

Old water pumps tend to have so much scale and corrosion that the impeller is frozen on the shaft and still turns. If the start to wobble the pulley leaking oiut the nose won't be far away.

You might want to measure temp on the fins on your radiator, if something has clogged it up, the lower rows will be more than 10F cooler than the top.

Deexcool, sorry, not a fan, too many pix of dexmud.

We had a member post a pix of 182F at 75 mph. He liked his new thermostat.

 

That sounds... kind of backwards. In other words: normally you would see higher temps sitting in traffic at idle, and a drop whilst at highway speeds. If your rad is new and your water pump is old, my guess would be your water pump (and probably fan clutch) are about to poop the bed.

 

Fan clutch not likely, you can take off the fan and drive 70 mph. Just don't hang out in the drive thru lane. At 60 mph, you have 5280 feet per minute of air flow. At idle, the air flow drops to like 800 ish. Temp should rise.

Also, IMHO, from the top of the branches of the shade tree, in a deep FM radio voice; why would you want to run hotter than the wide open temperature of the stat for long periods of time? It starts to open at 180. It will be fully open at 15-20 F above that. Once you go beyond that, the thermostat is basically wide open and can't control things, that is why the fans kick on a 212F to try to cool down things.

On the D2, the factory stat is wide open at 204F. Fan kicks on at 212F, turns off at 202F. If you are running the Land Rover (not MotoRad) 180 stat you should have better performance.

Running down the road on flat land (like the swampy sandbar you live on) and you are way above wide open temp. What's gonna happen if you need to take it up a notch, or go up hills? No room left in the cooling system.

If the radiator volume has been reduced by sludge, that'll be a problem. If water pump running wrong direction from belt route, that'll be a problem. You can inspect water pump for the cost of a $3 gasket (it is paper). You might be able to poke a long zip tie in on the end, and touch the impeller, then rotate impeller and "feel" each blade go by.

If you replace the WP, they are about $5 at the boneyard, if you find a shiny new one that someone else bought because they could not come to grips with head gasket goblins. BP Utah has nifty aftermarket with a larger bronze impeller.

If you do replace fan clutch or water pump, do them both, they become a mated pair from millions of spins around the dance floor. Imagine that the old water pump is dancing with the new Brazilian body builder babe; he won't last long, he could barely stay ahead of the old weak clutch.

Pix of 180 stat performance, internals, clogged rads, water pump. When they wobble, they are eating aluminum. Some even grind an arc in the front cover.

If you have new Dexcool, maybe you had some old Dexcool as well in the system. Dexmud can make half a radiator...

 

To all with a special mention to Savannah,

I am a new owner of a 2003 Disco. Just wanted to send a quick note of thanks for your detailed explanation.

I have just received my geniune Land Rover 180-degree (gray) thermostat from Rovers North. I will be doing the modification this weekend. Your advice above has been very useful.

 

At your mileage, if you are still running Dexcool, consider also replacing your coolant pressure cap cause Dexcool tends to destroy them.

 

russburcham's 60/40 mix will provide more cooling than than a 50/50 mix. The specific heat of antifreeze is less than that of water. That means that the antifreeze will carry less heat each time it circulates from engine to radiator and back, than water will.

In addition antifreeze is more viscous than water, therefore reducing the flow rate thru the cooling system.

The standard recommendation is to use a 50/50 mix of antifreeze and water. This is a compromise between cooling efficiency and the ability to prevent the mix from freezing during cold weather. The initial purpose of antifreeze is to prevent freezing.

As you increase the % antifreeze by volume, specific heat drops, boiling point increases and viscosity increases (reducing flow rate)


Here is some more info: http://hellafunctional.com/?p=629

 

See Coolant Mix and Overheating

I'd say that less anti freeze and more water will cool better. Guys that fill up with pure antifreeze instead of diluted usually overheat. And you need some antifreeze to prevent corrosion. Over at the track, antifreeze is too slippery and is frequently banned, and guys run water with Water Wetter (which is rated to drop 20 degrees - but Water Wetter and 50/50 is rated to drop 6 degrees and it did make 3 degrees change on mine).

Always used distilled water, and dang sure never well water (to much dissolved calcium).