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How hot is too hot?

25K views 32 replies 9 participants last post by  4advtr 
#1 ·
Just wanted to get a quick survey of folks' normal operating temp during this heat wave in many parts of the country.

It's 114 degrees in Phoenix and my disco can get up to 204 - seems a little high to me but what say you?
 
#2 ·
My truck runs up to 190 max.
Even in temps in the mid to high 90s (we don't get the extreme heat up here in the north)
Usually runs 185 around town, 183 highway and 189 stop and go traffic

Everything is stock but new with the exception of a 180deg stat and eliminated the throttle body heater.

I would not freak out about 204 but personally would like to see it lower
 
#4 ·
It's 114 degrees in Phoenix and my disco can get up to 204 - seems a little high to me but what say you?
Depends upon operating mode. If at 35-45 mph may be higher than optimum as my normal temps are less than 190 and creeps up to mid 190s when at idle. If yours at idle in traffic would not be concerned. Granted ambient temps not as high here but my temps don't vary with season.

Water wetter?
Gets mixed reviews all over the net. May be more snake oil than producing positive results.
......
 
#5 ·
The stock radiator seems to underperform in my case. Did you notice a change, or lack therof in a best case scenario where temp remained more stable and ceased to fluctuate 10 degrees with a brand new radiator? I have replaced everything except the radiator but I have flushed/drained/refilled my system several times and it's always been clean as a whistle. Temp is not getting anywhere near high enough for me to consider replacing the radiator, I just wonder if that would keep operating temp more constant or is that wishful thinking? I have a 180 inline Tstat with the bypass deleted. I used to be 183-189 but since the ambient temp went to the upper 90s, it spends the majority of its time at 190 with AC and will get up to 194. May get a 170 and then it will maintain a 180 F operating temp. Possibly.
 
#6 ·
According to my paper manual the book says the hot light (high engine coolant temperature warning lamp) will come on when the temp reaches 121C which is an astounding 250F; it goes back off when it goes down to 118C(244F). The thermostat is fully closed at 82C(179F) where it then begins slowly to open. It is fully open at 96C(204F).

That sounds way too high at 250F to drive without damaging the engine waiting for it to drop to 244F - at least to me.

I recently began tracking my temps with a head up display and found it running around 100C. That was somewhat worrisome although way below the specs in the book. I noticed the coolant was a little low and topped it up. Since then it has been running about 95C which looks OK.
 
#7 ·
If you hit 250 you are almost definitely screwed.!

Even at 100 c /212f you are cooking it,
95 / 203f is pushing the limit of my comfort zone.
You need to keep these things in the 180s or low to mid 190s
I have not figured out how yet but would like to set an alarm of some type to let me know if mine ever hits 200. If it does I will shut it down and not drive it til it's sorted out.
 
#9 ·
If you are overheating and must drive for a little, then turn on the heater and put the thermostat on its highest temp. Run the fan on high and it will suck off some of the heat.

But you should pull over as soon as possible.

This is just if it is approaching the red; if it hits the red, I would turn it off immediately. In fact I would not wait that long.
 
#11 · (Edited)
"approaching the red..." are you serious right now? just stop giving advice. Don't even comment with ignorant suggestions like this. Some poor guy is going to take heed to this and cause catastrophic damage to his engine.

Here everybody. this quote is taken from another website forum today. The dash gauge does not work the way that you think it does. Stop referencing it. Don't tell others to refer to it. Get an aftermarket sender and gauge or a digital unit that will tap into the ECU via OBD plug.


chasen7:
"All in-town driving, 71 degrees and sunny, cool 15-20mph breeze. Coolant temp rises quickly. It goes right past the normal temp range right on up to the low 220's, settles, then climbs again to 235-239, stabilizes. Then for no apparent reason to me (regular driving, no AC on), it will shoot to the high 240's to high 250's (259!!! was the highest). The dash gauge climbed up to the red zone, threw the red light at me for about 10 seconds, then went off, and it cooled back to 235 and stabilized there. At stop lights, 240-245, then go green it's back down to 230's, occasionally low 220's, but never dropped below 221.

Most of the time, other than the spike at 259, the dash gauge showed right in the middle, so slightly above, even at 244 it was only slightly above the middle range. That just goes to show me that the dash gauge is worthless."

If you are using that factory temperature gauge on a D2 it will read "normal," needle in the middle and the coolant temp could very well be over 230 degrees. This is why there are SO many junkyard/recyclable D2s. People keep referring back to that damn dash cluster gauge for the oil and water but these are nothing but 3-position senders that read ZERO, average, and YOU'RE FUCKED! With that being said, if the needle starts moving up past halfway toward 12, its going to keep going all the way up. its not going to stall at say 2 o'clock position where you would think that its getting hot but not necessarily over-heating. Not the case with a D2 in that if the needle moves past halfway then the engine is already overheating, not "just starting to get hot."

If your needle ever hits the red in a D2 more than a couple of times, the possibility of the block cracking or cylinder sleeve coming loose is pretty good, nevermind the head-gaskets. We aren't talking about Toyota Camry or Honda Civic. The Rover V8 is one of the most poorly manufactured blocks ever put into a vehicle. 2003-2004 was the worst and whenever Ford or Tata bought it in 2005 they completely changed the Discovery and took this engine block out of production because it was junk and nobody wanted to invest in a total rebuild of tool and equipment used in the manufacture of the old V8 so they went with a new Ford-design used in Jaguar. LR had to replace so many of the 4.6s due to the oil pump and engine block failures that they practically ran out of replacement engines and everyone started taking up the slack making rebuilt short blocks with top-hatted liners from the originals that failed.

Just keep your coolant temps under 200 F and you do that by buying an aftermarket gauge and sender so you know exactly what you are working with.
 
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#10 ·
180 stat for sure. A good O.E one not an aftermarket. A good rad too. Make sure you get all the crud out of the block ( pull the drain plugs) proper mixture 50/50 standard coolant.
 
#12 ·
Actually Chubbs you are probably correct on this. I had forgotten that the DII temp gauge is not incrementally progressive and will not creep up to the red. On other vehicles like my Mercedes you can dump heat and drive some as I suggested but it is probably not a good idea with the DII.

My bad.
 
#13 ·
Back to the OP's question. I agree with you, 204° is a "little high, but it's nothing to worry about. The auxiliary fan doesn't even kick on until something like 215°.

The fact that you can say that it gets up to 204° means that you are using a ScanGauge, and UltraGauge or something similar. Just keep an eye on it.

I have a friend whose '04 DII consistently ran for years around 210° with no apparent ill effects even though the radiator, water pump and thermostat were all changed.
 
#14 ·
Back to the OP's question. I agree with you, 204° is a "little high," but it's nothing to worry about. The auxiliary fan doesn't even kick on until something like 215°.

The fact that you can say that it gets up to 204° means that you are using a ScanGauge, and UltraGauge or something similar. Just keep an eye on it.

I have a friend whose '04 DII consistently ran for years around 210° with no apparent ill effects even though the radiator, water pump and thermostat were all changed.
 
#16 ·
Thanks Rover NC. I am definitely keeping a sharp eye on it, but would still like to see the temp readings at 200F or less.

With relatively new radiator, viscous and t-stat I'm just not sure how to trouble shoot and get to sub-200F without shotgunning parts.

If it makes any difference, I was reading 197F consistently until the Arizona temperatures really got up to 115F ish. Coincidence?
 
#19 ·
Update/report:

Test drove this morning.

95F outside temp in Phoenix.
Total running time for trip - 45 minutes.

Truck temp readings:
Left driveway 176.
Got to grocery store 197.
Let idle while in grocery store, 201.
Drove up and down freeway 10+ miles 201 to 206.
Exited to surface streets and at stop lites in particular, 194 to 197.
Home and let idle for a few more minutes, 199.

Odd that it seems to be running hotter at higher speeds. I would have expected the opposite.

Does this tell is anything?

My first thought - viscous clutch; BUT it has very substantial resistance when turning by hand.
 
#20 ·
2nd Test:

Drove it to work.
10 miles / 30 minutes.
Surface streets the whole way.
97F outside temp.

Leave driveway 188.
Before even leaving neighborhood 197.

194 to 197 for first 5 miles.
199 to 201 for next 5 miles.
Kissed 203 at one point.

Note: it would drop DOWN a few degrees when stopped at a traffic light.

Got to work 197.
Sat and idled for about 5 minutes 199.

This is all just curious to me.
Am I being paranoid?

Remember, yesterday muggy hot afternoon (it was 115 outside) I got a 215F reading.

Will repeat test for drive home at 5pm when it's 110ish outside.
 
#21 ·
Yes you're being paranoid. You're fine. Go find a different problem to worry about. You drive a Rover; there'll be plenty! :)

And BTW ambient humidity makes no difference but ambient temp does.


Sent from AutoGuide.com Free App
 
#22 ·
I agree that your current temps are o.k.
Yes sub 200 is definitely the preferred.
I know how much work you have put into this engine over the past 6 months and can't blame you for being preoccupied with your temperatures . I constantly monitor mine with my scan tool even after it has proved to run below 190 consistently

Couple questions to throw into the mix

I'm sure you are running the 180 thermostat (read it in one of the posts) but what make is it / where did you get it?

Are you running the truck with the a/c on? Is the electric booster fan operating?

How many miles do you have on it since your top end rebuild?

Are you going through any coolant? Is the level staying the same?
 
#23 ·
Drove home from work. 105 F outstide.
10 miles / 30 minutes in regular surface street traffic.
195 to 201 the whole way.

Atlantic British PEL500110 / Motorad t-stat.

Yes, AC is on and so is the aux fan.

Maybe 700 miles since the head gasket job.

No coolant loss.

Red, how is your truck coming along????
 
#24 ·
Mine is still sitting and patiently waiting for its turn.
Busy as hell at work, kids finishing up school, swimming classes, dance rehearsals and recitals, also had to help out my mother with purchasing a new vehicle (got her a nice used Suburu outback) should finally get the opportunity to work on my own stuff this weekend.:wink

I guess you can blame the 215f on your wife's aggressive driving style:grin

Maybe try an o.e. Thermostat. I have heard of problems with aftermarket stats.

I bought mine through Brittish parts of Utah, and had it in about 4 days (international shipping to Canada)
 
#25 ·
I would consider doing a couple simple mods that will improve the reliability of the cooling system if I were keeping this motor.
Inline 180 thermostat chubbs referred to earlier.
20% under drive pulley (D&D)
A NEW stock radiator or an aluminum vertical core from a custom builder like Griffin. Some knowledgeable builders suggested that I move the cat convertors further back and put vent louvers onto the hood to remove excessive heat in the engine compartment. All good suggestions had the plan been to keep the stock motor. I just wore out on watching the gauge, watching the coolant level, watching for leaks and expecting the worse. To me not worth it considering I really like the truck.

Doug
 
#27 ·
FYI, my thoughts after 10+ years of ownership of a DII in various climates. The majority of those years I've had a Scangauge attached with the water temp as one of my gauge options. In the summer, running AC I regularly see temps in the 210-215 range and occasionally see them reach 225 when driving in traffic in town. The ambient air temp is generally around 100* here in the high desert of Western Colorado. With cooler temps it will run around 200-205 with general driving.

For a little more background. I recently performed head gaskets, new cam, new water pump, hoses, radiator, coolant reservoir cap, 180* genuine thermostat and Viscous fan. Everything was drained (including coolant plugs) and refilled with green cooland (not dexcool) along with the appropriate amount Royal Purple Purple Ice. In my opinion my truck can have a better cooling system. I do have an ARB with 2 moderately sized lights on it so there is some airflow loss.

The reason I'm posting is I feel there is a lot of misinformation in this thread and it's creating a lot of paranoia in this thread around coolant temps. It's quite normal for them to be over 200* in the southern climates when running AC. I say focus your OCD elsewhere on the truck. There's always something else wrong on these trucks! I've basically rebuilt mine top to bottom of the past 10 years and can always find something to fix...
 
#28 ·
4advtr - your post sounds reasonable to me. The thermostat is designed not to open fully until it reaches 204F so apparently the LR engineers are OK with what seem to us to be pretty high temps. I am seeing my DII run just below 100C or 212F in Atlanta this summer so this seems to agree with your observations.
 
#29 ·
Wrong.

That stock Tstat you are talking about, the one opening at 204 or whatever, LR went back on that and started producing the 180 because of all the problems associated with the 200+ coolant temps. It took them 6 years or so, but that's their name stamped on the superceded 180 version for a very real reason. If these trucks were at 180-190 from the beginning, these "routine" head gasket repairs wouldn't be nearly as commom. At 210 degrees, the thermal expansion of the steel liners compared to that of the aluminum block causes a very minute variance at the distance between the head gasket and top of the cylinder liner. This is when the head gasket loses its integrity and everybody starts having problems which are not associated with any other production engine in human history. If your temps are over 205 or 210 then you are re-creating that environment suitable for failure.
 
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