The difference between the lower temp thermostat and an original one in terms of heat is that it takes a little bit longer for the car to warm up with the lower one. That being said it seems your temps are high. I replaced the original with the lower temp and brought my temps down 10 to 15 degrees. The other thing you need to check is if the aux fan is working. It should go on around 210 degrees. If it not, you need to replace it ASAP. It is an easy job, just need to take the front grill of and unbolt it. I bought a used one from Paul Grant (regular contributor here.) Way cheaper than a new one.

 

re: was of the impression that running temp was between 200 and 220. Maybe I need to read some more.

The RAVE says the oem stat starts to open at 179 and is fully open at 205 F. It is remote from the coolant temp sensor, so you add just a few degrees for that. If you are running above 205, the thermostat is not controlling anything, it is wide open. You are left to the effectiveness of the sludged radiator (Dexcool), main fan (powered by Miss Fanny Clutch), and the electric fan which should pop on at 210F. So if you are running don the road at 60 mph and making 220 F, things are not what they could be.

Radiator sludge shows up as cooler rows on the bottom, by more than 10F comapred to top rows. Enough sludge, and you have half a radiator. And can block heated air flow to Miss Fanny Clutch, and she has to get heated up to go back to full power.

The computer does the best job it can to maintain a specific fuel air mix. When cold it would run richer to warm up the engine. But the 180 soft spring stat runs above that temperature, so no problem there.

Not knowing where you are located - hard to judge heat in winter issues. But to make it to next winter driving around at 220 is not the way to get there.

 

Good to know that I have an overheating problem now. Dang!

Makes me wonder if I did not get the right thermostat. I'll have a look at it's numbers. It's a Calorstat Vernet, on the box there is nothing but a sticker with a bar code and numbers 154 2002. There are no numbers on the new thermo's housing.

It was pretty gummy in there. I gently flushed the rad and engine with the garden hose (treated city water, softened) and then filled it with distilled water. I've been waiting for the rain to stop so I can drop the water and put in coolant. The heck with the rain. I have tarps.

So after I drop my water and put in coolant, I will run it and use my hand held laser temperature gauge thingy on different parts of the radiator. Are there any other parts on the engine that I should note?

If temps remain high after this, maybe I should try and put my original thermostat back on to see what happens.

Thanks for all the help so far.

It goes in to the shop on Monday so I only have a few more days to mess a bunch more things up!

 

On my replacement Thermo, if you look down (up or down, I don't remember) the top hole, it has 180 printed on the metal inside. I bought .

I don't remember what your Disco is exactly though. Maybe yours is different year, engine size?

 

99 Disco 2. 4.0 V8

I think I've managed to put that info in my signature now. Lets see if it works.

 

According to Amazon, the one I listed does not fit your Disco. Maybe someone here will know better. It seems it should be a fit, but I don't know that. Anyone else have input on this?

 

Wow. I just pulled my new thermostat. Inside the housing on the thermostat itself is the rating.

92 C ! That's 197.6 degrees F!

If this is the normal thermostat? Let me look in the rave;

Thermostat opening temperature:
􏰀 Initial opening 82 °C (179 °F)
􏰀 Fully open 96 °C (204 °F)



Obviously I don't have the right thermostat. I'm going to get and install the recommended thermostat.

I'll see if I can find one locally.

 

I scooted off to the dealership and bought a replacement thermostat. It is a Genuine Land Rover Part PEM100990.
They could not tell me what what it's temperature rating is. Can anyone here tell me. I'm not being successful with a google search. It is like my original one and does not have any rating stamped on the thermostat.

I put the Thermostat in. Filled with coolant. (followed the RAV and it took exactly how much it should and didn't seem to need to be bled again) Went for a drive.
I now sit at 195 to 200 F. It pretty much sat at 197 on the freeway and 199 in traffic.It briefly shot up to 204 for a few seconds.

The fan seems to be operating properly.

I will order a 180 soft spring thermostat and put that in when it gets here. I'll put in the Wetter Water then too. I did not pull the fan shroud and check radiator temps with my temp gauge.

It was still raining and I had a pizza in the back seat.

 

The oem should start to open at 179 and be fully open at 205. There is some variation in how Euro stats are marked vs US. In the US they are marked for start to open, and I believe many Euro are marked for fully open temp.

The point about thermostats is you would want to run somewhere inside their range. If you have to drive around with thermostat wide open always, then you have other cooling problems.

 

I took it to my rover shop today. As was suspected, they came to the conclusion that it was the coils.

3 hours shop time plus parts. I went ahead and booked the appointment. It was a moment of weakness for that inner mechanic in me that so desperately wants to come out.

I'm hoping the coils is the problem. I'll verify when I get it done.