Every Disco I've seen run that cool either had a different thermostat (so it would run cooler), a cooling additive (fluid in the coolant that helps the car run cooler), had a thermostat problem, improper coolant mixture (50-50 to 30-70), or had a faulty temperature sensor. If a car runs too cool, it doesn't run as efficiently as it should. If it's really cool, you won't have heat in the winter (in the colder states). Too hot, and these engines warp and gaskets crack.

I wouldn't be too concerned with 195, but I would want to keep an eye on it. It's on the lower side of dead center normal temperate according to your temp gauge. I would have an extra thermostat on hand just in case. I prefer to see a little too cool than a little too hot on any car. If you're below like 160, something needs to be fixed right away. If you're over 235, something needs to be changed right away. The closer to normal temp, the better. Within a certain range, something is starting to go bad and just needs to be watched.

Within another range, everything is fine and there's nothing to worry about. With your numbers, I would just want to keep an eye on it. Like my truck is running a little warm now, so I drive with the sensor on it like once a month or every couple weeks. If I start to run at 230, I'll see what I need to replace right away. At 220's I would be concerned if I didn't know about the TD5 thermostat, but I still keep a close eye on it because I know the damage that can be caused by running too hot.

 

I base that temp on my ultragauge, and I've never added anything but premixed Prestone 50/50 OAT approved coolant. I'm very religious about coolant and oil changes, and the Dex-cool flush was done prior to me buying the car (at least I assume. There was green coolant in the car, and I have flushed it maybe 5-10 times without seeing any sludge). I bought the car with something like 50k on the clock 7 years ago, so its possible the Tstat was changed, but it looks OEM to me.

 

I've also never changed the head gaskets (or any gasket for that matter), nor have i ever had an oil or coolant leak (knock on wood). My tranny blew due to a faulty torque converter, and my SLS went out (both covered by warranty), but other than that I've never had a problem, until I finally got the three amigos about 500 miles ago.

 

I just looked it up in the service manual. The V8 should basically be between 202 and 212, based on the cooling fan sensor which should cut on at 212 and shut off at 202. The thermostat begins to open at 179 and fully opens at 204 degrees. The TD5 fan shuts on at 230 and shuts off at 221.

The ultragauge is a scan tool and still relies on the car's temperature sensor, so it could be a problem with the sensor.

If you've flushed the coolant using a chemical flush and didn't blow out the flush with air, the coolant is not pure 50/50, a surprising amount stays within the engine block and the heater core. I always run air through the system until everything is out of it before putting new coolant in the system.

As long as you stay on top of the oil, coolant, and trans fluid (which it sounds like you have), you shouldn't have a problem.

I started forcing air through the system because I had an overheat problem on one and I flushed out the system. It got better, but it still overheated because it turned out there was still a lot of crap floating around in the system, even after flushing it. I took a water hose and flushed everything out with the hose, then used the air to force out all of the tap water. That was the only way I was able to do a full flush and be left with only the good fluid. You could get a transfer machine, but I don't know how well they work. If you had sludge in the system, it would cause an overheat a lot quicker than under temp.

It sounds like you're okay. If you have the ultragauge, just keep an eye on it to be safe. I would also point the overflow relief valve so it will spray right onto the exhaust manifold, just in case there is a problem with the sensor and it starts to overheat without you realizing it. That way the steam will get your attention. But I wouldn't really be concerned about a slight under temp like that.

 

Did you hook up a compressor to the radiator to blow it out? I like that idea, but what's the best way to blow it out with air? I'm hesitant to do a chemical flush, I did that on my SHO and blew a head gasket shortly there after. I do not like the idea of putting another chemical through my cooling system, as you never know what your gaskets, hoses, radiator, etc. can handle, and you don't know the long term effects of doing such a thing. I know a lot of people here swear by the chemical flush, but hey, if you go back 3 years on this forum, you'll see some pretty prominent forum members, who shall go nameless, swearing that Dexcool is the ONLY coolant to put in your system. And we all know how that worked out

 

Yes, I use an air compressor and I gradually increase the pressure being careful not to put too much pressure because the radiator can be damaged under high pressure. I separate the hoses and force air into the different parts, one at a time. I do the heater core by itself. I do the radiator by itself. I force air into to engine block using both of the hoses that go from the top of the engine into the heater core and from the thermostat end. I take the lines off of the expansion tank and force air through both of those hoses (in and out). I like to do both directions, just incase anything is lodged in there and I start from reverse flow first. I do it with a water hose first, then the same thing with the air.

I also don't like to use chemical flushes anymore. I prefer to just use a water hose to force clean water through the system. I force water through the entire system, then I take the hoses apart and do it the same way I do the air (of course the water is first, then the air). I like to run water through each part of the system until it runs clear, and then I let it keep running for like two minutes after it's clear. If I did do a chemical flush, I would do the flush and then flush it with water, but doing it the way I do is usually good enough. I only had one problem doing that way with a Jeep Liberty, but then it allowed me to find a problem in the radiator because it did give a problem. The system wasn't overheating or anything, but there was a clog in that system. I ended up just leaving it alone because the problem was between the bottom hose and the drain plug.

 

The factory stat is open at 180, full open at 204. If a sensor fails, the engine computer uses a default value of 185. If temp gets up to 212, extra cooling is called for. Why run so hot that you have no time to deal with a blown hose?

 

I think you're asking me. The hose wasn't blown. There was a slight leak at the connection. The hose clamp was too close to the edge of the hose and coolant was leaking slightly. The cooling fan on the V8 starts at 212, but it doesn't cut on until 230 on the TD5.

 

I've never understood this "extra" room for cooling that you think is needed, if you blow a radiator hose it is going from normal to overheat in about half a second.
Even a 160*F t-stat will not help with that.
The cooling system is designed to run at a specific temp, it is designed for optimal engine life, performance, MPG, and all the cooling capacity that it needs as long as the cooling system is in proper repair.
I run a 195*F t-stat, I have since I bought the truck back in '07 with 152k on the clock.
The hottest it has ever gotten was 235 and that was while off roading in August with a bad fan clutch and the a/c on, I had no idea the fan clutch was bad until then.
Turned the a/c off, engine temp dropped, turned a/c back on, temp went up, turned a/c back off.
Replaced fan clutch a few days later.
My truck runs between 195 and 200, 215 off road, oh yeah, my head gaskets are original too.
I'm the second owner, I had all service and repair records, dealer only until I bought it.

And for the OP, as far as I know my water pump is original, 213k.
Changing the coolant every 2 years is the key IMO, the coolant lubricates the water pump bearings, the lubricant in the coolant wears out just like motor oil.
I bought a new water pump years ago, it sits in the box in the garage.

 

It's not something really that needs extra room for cooling (if I understand correctly). The system is set up to let the engine warm up as quick as possible, then allow the coolant to keep the engine at that temperature range by opening the thermostat. If the engine runs hotter than it should, the electric fan turns on in order to help the air flow through the radiator. The normal range is quite wide, and even within that middle spot we all like to see our temperature needle is between 160 and 240 degrees. So there is a normal range of temperatures, but not really "extra" room for cooling.

And if you blow a hose, you will overheat quite quickly. If there is a small hole in a hose, not so quickly.