[SS-Traveller]

Originally Posted by gd1418

One more puzzling phenomena encountered by me was the fluctuating engine temperature.
I've not found any tangible explanation to this till now.

Originally Posted by hvkumar

I faced this problem in my Matiz ...And have faced the same problem in my Scorpio

Were you running the cabin heater while driving, when this happened? That should explain it. Or else, the thermostat valve is faulty (stuck in open position).

[Roshun]

On our Ladakh trip, GD1418's Scorpio was the only non-CRDe among the four, and was the only one exhibiting this phenomenon of the needle going all the way to the C mark. In the other 3 CRDe there was a minor drop in temperature on decents, but not all the way down, it never came below the 1/4 mark.

My theory about this too was a thermostat that was staying open. But we didn't dwell on this as it wasn't a problem that affected performance in any way.

Cheers,

[SS-Traveller]

Originally Posted by Roshun

My theory about this too was a thermostat that was staying open.

Another reason this might happen is if the AC switch is left on. When the compressor runs, the AC cooling fan also runs compulsorily. At very low ambient temperatures going downhill, the temp meter will then behave like it did.

[jaysmokesleaves]

Seems more like a case of Scorpio AMS.
I can tell you how to start it though. Light a fag, Switch on ignition and leave it on for 5 seconds, pray and switch off. Repeat process 5 times and then crank the starter. Trust me guys, thats the cure for Scorpio AMS.
If it still doesnt work, cuss the car as best as you can, and then keep cranking till it starts.
This time it will.

Note: for non smokers> do the entire process with a toothpick in your mouth.

[gd1418]

Neither did I use the heater or the AC in this trip after Manali. Wanted to enjoy the fresh & cool air.

Originally Posted by SS-Traveller

Were you running the cabin heater while driving, when this happened? That should explain it. Or else, the thermostat valve is faulty (stuck in open position).

Originally Posted by SS-Traveller

Another reason this might happen is if the AC switch is left on. When the compressor runs, the AC cooling fan also runs compulsorily. At very low ambient temperatures going downhill, the temp meter will then behave like it did.

Now coming to your as well as SS-Traveller's theory about thermostat remaining open or stuck, as I understand, the thermostat valve opens when the temperature rises so that the coolant starts circulating thus bringing the temperature down. It remains closed till the ambient temperature is reached. Only when you switch on the AC, the valve remains constantly open.

How do you explain the fact in my car that while descending the temperature fell (unless defective, the valve should close) and rose when I hit flat surfaces. How did the valve, everytime on cue came un-stuck if that was the case?

Secondly, there was no fluctuation in temperature after I headed home from Manali. The problem should've continued. In all my hill journeys till date barring Leh-Ladakh, I never experienced this at all.

Originally Posted by anupmathur

While descending, the fuel cut-off is at work, if you are in gear (as you should be, during descents). With very cold ambient temperatures and no combustion going on, the coolant temperature rapidly drops with chilled air flowing past the radiator.

This issue is possibly also to do with less than perfect siting of the coolant temperature sensor, which is why not ALL cars will show the same behaviour.

What Anup says about the wind chill rapidly cooling the radiator on descent seems plausible, but what puzzles me when he says that the combustion is off. How & why?

Originally Posted by Roshun

My theory about this too was a thermostat that was staying open. But we didn't dwell on this as it wasn't a problem that affected performance in any way.

Cheers,

I would like Suman's view on this if he experienced any temp drop, howsoever minor, while descending the passes..

[gd1418]

May you suffer a flat in all the 4 wheels in the middle of Moorey Plains..

Originally Posted by jaysmokesleaves

Seems more like a case of Scorpio AMS.
I can tell you how to start it though. Light a fag, Switch on ignition and leave it on for 5 seconds, pray and switch off. Repeat process 5 times and then crank the starter. Trust me guys, thats the cure for Scorpio AMS.
If it still doesnt work, cuss the car as best as you can, and then keep cranking till it starts.
This time it will.

Note: for non smokers> do the entire process with a toothpick in your mouth.

[suman]

Originally Posted by gd1418

I would like Suman's view on this if he experienced any temp drop, howsoever minor, while descending the passes..

During all descents, the needle returned to its usual position (it would hover close to the half way mark during the steep climbs). So technically, yes there was a temp drop during the descents but nowhere close to what you experienced.

When I say "usual" position, this is what I'm referring to

[gd1418]

The usual position that you've posted for Safari is not the ususal for Scorpio. Ours is slightly higher than yours..

[tsk1979]

Even I see this. Once on a very cold winter foggy night I drove continously 1400rpm in 4th gear. Besides getting 17kmpl, I also saw that the temp guage never reached the half way mark, and was always at a much lower level.

[suman]

Originally Posted by tsk1979

Once on a very cold winter foggy night I drove continously 1400rpm in 4th gear. Besides getting 17kmpl, I also saw that the temp guage never reached the half way mark, and was always at a much lower level.

In the plains, my 3.0 liter never reaches the half way mark, irrespective of how hot or cold it may be outside

[tsk1979]

Neither does mine, its always a notch below. However I am talking about 1/4th mark

[anupmathur]

Originally Posted by gd1418

What Anup says about the wind chill rapidly cooling the radiator on descent seems plausible, but what puzzles me when he says that the combustion is off. How & why?

How & Why? On a descent, if the car is in gear (maybe second or third, whatever) fuel injection will be in 'cut-off' state, since engine braking is being used and no throttle is applied.

BTW, I have never seen the temp needle fluctuate AT ALL in my car. Steady as a rock! Always.

[suman]

Originally Posted by anupmathur

BTW, I have never seen the temp needle fluctuate AT ALL in my car. Steady as a rock! Always.

Really? Not even a couple of degrees here & there?? That seems strange.

[anupmathur]

Originally Posted by suman

Really? Not even a couple of degrees here & there?? That seems strange.

Not a micrometer, LOL! Once the car has reached steady state I've never seen the needle move even a wee fraction! This includes upto an hour of 4WD Low in second gear in any weather hot or cold. In hot weather I always have the AC on and in cold it's still ON in bi-level AC mode to prevent fogging of the windscreen and to keep the cabin warm.

[suman]

What about when you're climbing (not gentle inclines but steep ascents) & change gear midway (say from 3rd to 2nd), wouldn't it have gone up marginally just before the moment you change?