Running temperature

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langley

New Member
Posts
372
Location
Bristol UK
Hi,

Ive noticed that everytime i drive my vehicle it gets up to temp quite quickly and the temp gauge goes to the centre position. It is stable there and doesnt deviate and further or drop.

Is this normal?
What should be expected?
If not, whats the most likely candidate?

Thanks
 
langley said:
Hi,

Ive noticed that everytime i drive my vehicle it gets up to temp quite quickly and the temp gauge goes to the centre position. It is stable there and doesnt deviate and further or drop.

Is this normal?
What should be expected?
If not, whats the most likely candidate?

Thanks
Click to expand...
Yes....

It should sit at 12 o'clock with no wavering...

My DSE used to run cool (I suspect there was no thermostat in it - never checked) and only ventured into the middle zone on long hills doing hard work....

If yours sits at mid point and is still as a rock - no problems....

If it ventures towards the Red it could indicate a duff Viscous Fan Unit or dodgy Pump....

My Current L322 - the temp neddle is bang on 12 o'clock and doesn't faulter....

Warmup time shows your Viscous fan is working as it should by allowing a rapid warm up and also that it is maintaining the set temp....

Keep up the great work on the cooling system and fix ANY niggles with it asap....but at the moments sounds like yours is doing the job.:)
 
Mine hovers just below the centre pretty much regardless of what I do :p (DHSE)

The mid point is ~90°C which is a nominal operating temperature, so so long as all your cooling's working, it will try to told it there for efficiency's sake :)
 
Most modern coolant temperature gauges are actually multi-function warning lights masquerading as gauges. They will read in a linear fashion until the minimum acceptable "warm" temperature has been reached - then the gauge will be fed the right voltage to sit it on the centre of the gauge - no matter how much the temperature fluctuates - as long as it sits within the normal range the gauge will not move - so you won't get a feel for how efficiently your cooling system is functioning as you did in the "old days". Plug in a OBDII reader and watch the temp fluctuate quite markedly as proof - the coolant temp gauge will not budge.

Most temp gauges now have four modes above the warm up phase: 1) "normal" (needle pinned in the middle of the gauge) once the temperature is into the normal range. 2) "hot" Once you are over the normal range, depending on the car manufacturer, most gauges will either read an analogue approximation of the temp as to when it is in the normal to over heated range - or will just sit at 3/4 - perhaps with an amber light. 3) "overheating" above "hot" will put the gauge in the red which is the "stop as soon as possible" warning - often with solid red light. 4) "Critical" temp, where a red warning light with flash and/or system message appears- this is the temperature at which the manufacture would expect engine damage to occur. Not sure if the P38s has a separate 3&4 like most modern cars, or just a single overheating "in the red" mode.

What always ****ed me off with P38s is they beep at you for everything, door not shut? Beep, bonnet not closed? Beep, key in ignition? Beep. Lights left on? Beep, sunroof not shut? Beep. Transmission left in gear? Beep. But engine temp gauge pinned in the red, potentially leaving you with a £5K repair bill? Nothing nada - not a squeak! Aghhhhh!!
 
StuckAgainSteve said:
Most modern coolant temperature gauges are actually multi-function warning lights masquerading as gauges. They will read in a linear fashion until the minimum acceptable "warm" temperature has been reached - then the gauge will be fed the right voltage to sit it on the centre of the gauge - no matter how much the temperature fluctuates - as long as it sits within the normal range the gauge will not move - so you won't get a feel for how efficiently your cooling system is functioning as you did in the "old days". Plug in a OBDII reader and watch the temp fluctuate quite markedly as proof - the coolant temp gauge will not budge.

Most temp gauges now have four modes above the warm up phase: 1) "normal" (needle pinned in the middle of the gauge) once the temperature is into the normal range. 2) "hot" Once you are over the normal range, depending on the car manufacturer, most gauges will either read an analogue approximation of the temp as to when it is in the normal to over heated range - or will just sit at 3/4 - perhaps with an amber light. 3) "overheating" above "hot" will put the gauge in the red which is the "stop as soon as possible" warning - often with solid red light. 4) "Critical" temp, where a red warning light with flash and/or system message appears- this is the temperature at which the manufacture would expect engine damage to occur. Not sure if the P38s has a separate 3&4 like most modern cars, or just a single overheating "in the red" mode.

What always ****ed me off with P38s is they beep at you for everything, door not shut? Beep, bonnet not closed? Beep, key in ignition? Beep. Lights left on? Beep, sunroof not shut? Beep. Transmission left in gear? Beep. But engine temp gauge pinned in the red, potentially leaving you with a £5K repair bill? Nothing nada - not a squeak! Aghhhhh!!
Click to expand...

Temp gauge on the P38 is damped as is the fuel gauge. This is so it does not go up and down like a brides knighty as the stat opens and closes to regulate the temperature. You can do a function test with Nanocom that drives it through it's spectrum.
 
Excellent, thanks for information.

Sounds like my wagon is ripe for a electric conversion then to try and get a little more efficiency in running.

As a side point, is the 2000 model OBD1 or OBD2, im looking to get a diagnostic and am unsure which one. But, dont want to have to resort to getting the only proposed options of some sites.

Thanks
 
langley said:
Excellent, thanks for information.

Sounds like my wagon is ripe for a electric conversion then to try and get a little more efficiency in running.

As a side point, is the 2000 model OBD1 or OBD2, im looking to get a diagnostic and am unsure which one. But, dont want to have to resort to getting the only proposed options of some sites.

Thanks
Click to expand...

You need Nanocom or similar, OBDI or OBDII no good for anything on a diesel. They only do certain engine diags on the petrol models. ALL the other P38 Range Rover systems cannot be interrogated by them.
 
langley said:
Excellent, thanks for information.

Sounds like my wagon is ripe for a electric conversion then to try and get a little more efficiency in running.

As a side point, is the 2000 model OBD1 or OBD2, im looking to get a diagnostic and am unsure which one. But, dont want to have to resort to getting the only proposed options of some sites.

Thanks
Click to expand...

I can give you a mod to use the aircon fans for cooling. PM me with an Email address if you want details.
Avoid Kenlowe.
 
wammers said:
Temp gauge on the P38 is damped as is the fuel gauge. This is so it does not go up and down like a brides knighty as the stat opens and closes to regulate the temperature. You can do a function test with Nanocom that drives it through it's spectrum.
Click to expand...

Yes the damped gauge usually indicates the older (truthful) system. The voltage supplied to is is presumably via the BECM - not the temp sender as per most cars these days is this reading merely split off to the gauge or driven by the BECM One of my past assignments was to write a driver routine to control the CT gauge for a particular car made by a blue ovally manufacturer - which is what I based my post on! :D A good test would be to drive the coolant temp sender circuit with various voltages (or resistances depending on system employed) through its range and see what the gauge does. On most modern Jags and (non budget) Citroëns you'd get the "fixed" response I explained above - obviously budget cars still run the old damped gauge driven directly by a temp sender but these are becoming rarer, the coolant sensor usually supplies the engine management with a reading which is then used to drive the gauge either using the same voltage (becoming rarer) or via a logic routine like I described.

The pinning of the needle into the centre of the gauge regardless of temp was pioneered by a German manufacturer whose research showed that drivers were comforted by a gauge (over warning lights) but the gauge fluctuating worried them! Most top-end cars have used this system for years - I'd be surprised if the P38 is any different - but then it is an old car I guess made by a manufacturer who expects the cars to be used in extreme circumstances demanding a "proper" gauge? Interestingly Citroëns with digital "bar" temp gauges work in a purely linear fashion with no predefined "normal" range like the old fashion cars, top-end Citroëns with "analogue" gauges lie about the temperature as I described! Weird. Perhaps market research found that drivers didn't mind horizontal bar gauges fluctuating but liked to see traditional gauges pointing straight up?! It would be interesting to find out what the P38 does. Many budget Citroëns only had overheat warning lights for years - this trend is coming back as increasingly mechanically-illiterate drivers don't care about coolant temp. Citroën were ahead of their time!

The advantage of driving the gauge by ECU logic is you don't need (slightly more) expensive damped gauges - note how most modern cars, the coolant temp (and often fuel level) gauges flick immediately to their correct reading when you turn the ignition on (or to zero immediately when you turn the ignition off) - a lack of gauge damping is usually the clue that you are being lied to by your coolant temp gauge and that is is being driven by program logic not a fluctuating analogue signal reflecting the actual coolant temperature.

Perhaps Range Rovers being proper off road cars, made by a proper off-road manufacturer still have proper coolant gauges?

For the fuel gauges they are driven electronically because modern cars (particularly diesels) should never be allowed to run out of fuel - damage to the expensive high pressure fuel pump by running dry would usually be terminal. Many modern (particularly diesel) cars warn you of low fuel, show an empty reading (and 0 miles range) on the gauge, they then shut the fuel pump down before actually running out of fuel to protect the pump as soon as pump surging is detected or after a predetermined amount of fuel has been burned after the 0 range warning has been given, the added bonus of this system is the fuel supply system does not need to be bled as it is still actually primed!
 
Saint.V8 said:
Not on the Diesels - the Petrols are OBDII (EOBD) compliant by EU Law - but the Diesels aren't OBDII, they use there own protocols.......
Click to expand...

Only some functions on the P38 petrol engines Ant. Think only vehicles made in or after 2004 are compliant by EU law. Before that it was very loose. The diesels have an OBDII socket that's about as compliant as they ever got. Don't know, but would doubt if ancillary items, suspension, transmission, aircon Etc are truly OBDII compliant even yet. :):)
 
Depending on the accuracy of the onboard Diagnostics on the L322....

Via a hidden menu you can pull up the Engine Temp digitally onto the Message Centre, I noticed that the needle gets to the middle at around 75degC all the way up to the vehcile operating temperature of 105degC - the warmest I have seen it at was 111degC and the needle was still in the centre so the range of the L322 mid point is atleast 40degC I'd say - bar obviously when I was having stat problems when the needle rose to 3/4 but I didn't have the Hidden Menu item displaying at that time....
 
langley said:
As a side point, is the 2000 model OBD1 or OBD2, im looking to get a diagnostic and am unsure which one. But, dont want to have to resort to getting the only proposed options of some sites.
Click to expand...

The 2000 Thor (Motronic) ECUs use the ISO9141 ODBII protocol - as long as your reader supports ISO9141 it will read the engine and emissions related data. I'm not sure what the older GEMS systems use or whether they are ODBII compliant at all.
 
wammers said:
Only some functions on the P38 petrol engines Ant. Think only vehicles made in or after 2004 are compliant by EU law. Before that it was very loose. The diesels have an OBDII socket that's about as compliant as they ever got. Don't know, but would doubt if ancillary items, suspension, transmission, aircon Etc are truly OBDII compliant even yet. :):)
Click to expand...
Noted - also as you say I don't think the other systems are OBDII as they don't need to be by law I should think....

Certainly on the P38 all the other systems use their own bespoke language...
 
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