How Hot is too Hot?
 

I took my rover out today in 98F weather, probably wasn't the best idea, but I did. I took along my OBD scanner and it seemed to be ok staying at about 194 to 199F in the morning, it was about 80F outside at the time. After lunch, I took it back to work and it was roughly 93 or 94F outside and the temp was hovering around 199 to 202F and was starting to frighten me a bit. After work, when it was scorching out at 98 to 100F I went home, with the A/C on full blast of course and the temp seemed ok. EXCEPT when I would stop. It go up to about 206F and the gauge was moving near the red zone. Once home I decided to let it sit in the drive way with the a/c on and see how hot it actually gets. The gauge hit the red zone and the light would fluctuate on and off. The OBD scanner was reading the coolant temp as 210F. The front fans would kick on high when the A/C was engaged and would stay on even if the A/C was disengaged until the temp went down to 206F again. I know my gauge is off because, there is a short in the system so, I could cause the needle to move in the red zone and the light to come on by simply turning the headlights or heated seats on.

My question is, what is the normal operating temp range on these vehicles. I have done searches on the forum and it seems like 190F is the norm so I think mine is running a bit hotter than it should. Thanks in advance!

You mentioned the front fans, but how about the viscous fan? I would think it would be engaged at these temps. If not, I would replace it. Please post if you are able to fix that short in your gauge. Getting the gauge on mine to work properly is kind of an ongoing long term project for me. If I figure it out first, I will be sure and share. My next step is to remove the gauge cluster and check the ground directly at the gauge for resistance and re-run it if necessary. I know it does not read right, but it sure is stressful to see it go into the red while stuck in traffic. I run my RR on about a 70/30 mix of water to antifreeze and I also run Redline Water Wetter in it. Of course, I am in South Carolina where it rarely gets cold enough to need antifreeze. Good luck!!

This is not normal, your front fans should always be on when in stop and go traffic at operating temp, not just with the a/c on.
You have a temp sensor that may have failed. In the mean time, quit letting the temp run into the read, unless you want to buy a new engine.
As for the mechanic fan, check and make sure it is still active, at your mileage, it could be bad.
As for the outside temp, I have left my D2 idling in 120 plus degree, Death Valley, during the summer, while on a group run and it never heats up, they are not supposed to.

Wilson, who told you to run a 70/30 mix? It is always 50/50 except in the Arctic. The Water Wetter or Purple Ice is a good touch, but your over all boiling point is way to low.

Wilson, there is a kit on Atlantic British's site that will fix the gauge issue, I think it is around $50 or so. I haven't bought it yet, but I am going to here shortly. I'm tired of the needle nagging me for no reason. I also replaced the fan clutch about 2 months ago.

Disco Mike, I was just wondering what the normal operating temperatures of these vehicles are since I can't trust my temp gauge and have to go off my OBD scanner for now. Some sites say the 12 o clock position is between 190 to 220F. If that is the case then I am within range and the vehicle is cooling itself properly. If not, then I have a problem that needs to quickly be addressed. I won't be driving it until I have it figured out.

Thanks for the input guys!

mine is a disco II

I'm not dicso mike, but if you dont mind, the rave manual says the thermostat is wide open at 204 degrees. i monitor mine and reads from (in summer heat) 198 on the highway, and 204-206 around town and 207-211 at stop lights and idle whan its hot. with or without the ac on.

i did read a 115 one time, but attribute that to lack of burping the system properly.

Hey thanks!

I took my daily driver econo box out today and had the scanner on it to see what it was doing. The hottest it got was 196F at a stop light and was running at about 192F while driving. I talked to my mechanic on the phone and he said the typical range on vehicles is 190ish to 210-220 at the hottest. I asked him at what temp will damage start to be done, his response was "250F over time will destroy an engine".

wife's car runs 188-193. both my Discos from the what i can see have run hotter than a lot of other cars.
sounds like you are in the range.

I took it out again today, this time the max it got to was 199. I didn't use the a/c as much this time. I still think 210 is a bit too hot but, I guess I better just keep my eye on it. Thanks for the input jay!

My personal belief is that these engines run a bit on the hot side. I think that maybe that is why they recommend premium fuel in them.

I think you are right. I looked at the comparison between the P38 and the Classic and noticed that the classics seem to run cooler than the P38 GEMS. I think it has to do with emission standards because, the P38 and classic engines are practically the same.