Dashboard Temperature Gauge
 

I've been reading the current thread (started 24th December 2019) about an overheating KV6 engined car.

Embedded in one of the responses (number 12) is a reference to being able to "adjust" the
temperature window, at which the gauge stays at a constant 9.00 pm.
The term used was "Buffer zone"

Could this be used to other peoples advantage, to make the gauge more useful, I wonder?

I have pasted below the relevant response.

Regards

Mike

Originally Posted by T-Cut View Post
I guess by 'over half way', you mean the gauge needle was above the '9 o'clock' i.e. the 'normal' position. If so, then it has somehow lost its calibration. The gauge is calibrated such that at 75C, the needle just hits the 'normal' mark. It will then stay in that position (the 'buffered zone') until it reaches 115C. At 116C the needle will begin moving up and rapidly hits the red light at around 120C.

It seems your gauge is over-reading, so it reports an overheat when the temperature is in the normal running area. Perhaps a T4 specialist can adjust the calibration? I know it is possible to alter the settings of the 75-115C buffered zone, so it might be possible to fix it.

TC

Hi Mike,

Phil T4 replied to that thread to inform us that, alas, T4 cannot overwrite the temperature gauge programming so I think that idea will remain wishful thinking. :}

Simon

That thread might have been me with my project ZT v6.

I think its possible that I got my facts wrong when I said temp gauge was over half way at what ever low temp I had said.

Bit of a thread revival...

Yes, It is possible to adjust the temperature gauge scale.
I have been test driving some revised values in my car recently, and am now confident to be able to say that it is all working as I intend :)

The standard gauge is not much use, as pointed out previously, the dash has the following standard values

Start moving (bottom of Blue) = 15
End of Blue (Cold) = 52
1/4 Mark = 64
Arrive at halfway (start of buffer) = 75
leave halfway (End of buffer) = 115
3/4 Mark = 120
Red (overheat) = 125

When looking in to the fan behaviour on the different engine variants I have found the following information: (edit - Updated with the information SD1Too Supplied in post 6)
1.8
Low speed: on 104, off 98
High speed: on 112, off 106

KV6
Low speed: on 100, off 96
Medium speed: on 106, off 102 (not used on 2 speed systems)
High speed: on 112, off 108

Diesel
Low speed: on 100, off 98
Medium speed: on 106, off 102 (not used on 2 speed systems)
High speed: on 112, off 110
This means that on all engine variants the cooling fan is running at high speed before the temperature gauge has even moved above the half way point (ie things are getting really out of hand already).

so I have changed the following values on my car :
start of buffer = 80,
end of the buffer = 95
3/4 = 110

This means that the gauge starts to move above 'normal' before the fans come on, and is at nearly 3/4 before the high speed fan comes on.

With a petrol I would be tempted to apply lower values to the end of buffer & 3/4 point to better reflect the actual fan behaviour (possibly starting with end of buffer = 90, and 3/4 = 105).
I could do with some details regarding 'normal' temperatures seen when driving on a 1.8 & V6 to see if these values make sense - edging slightly above 'normal' in stop start traffic is fine, but there is no point going above 'normal' for normal driving (the risk is the driver ignores the gauge as 'it always goes above half now')

I have now driven for a month with my settings, and have seen the gauge rise above the halfway point when in stop start traffic towing a caravan, but usually it stays in the 'normal' position.

(Testing has also involved writing lower values across the range to force the gauge to declare an overheat condition, as I don't think I can achieve those temperatures on a diesel without doing silly things that might actually damage the engine).

If anybody local wants their gauge modifying, contact me - As pointed out previously this is not something the standard T4 can do (and I don't believe this is something that TOAF can do either),

Chris

This sounds interesting.

Radiator fan switching points
 

Hi Chris,

Where did you obtain the figures in this format? I'm afraid that they are inaccurate and misleading. The fan does not operate in the manner suggested. Here is the official RAVE data:

1.8
Low speed: on 104, off 98
High speed: on 112, off 106

KV6
Low speed: on 100, off 96
Medium speed: on 106, off 102 (not used on 2 speed systems)
High speed: on 112, off 108

Diesel
Low speed: on 100, off 98
Medium speed: on 106, off 102 (not used on 2 speed systems)
High speed: on 112, off 110

As you can see, the greater of the two values is the temperature at which the fan switches on and the lower value is when it switches off. The author of the figures you've posted has got it the wrong way around (as well as quoting some incorrect values)!

However, making the range of "normal" temperature readings on the gauge more practical is a very interesting modification!
My KV6 runs in the low nineties when moving, say 92 to 95. When stationary for a length of time in traffic the temperature can slowly rise to 100 which is when the low speed fan starts running. This will also happen when manoeuvring at slow speed after a long distance journey. I'd therefore be happy for the KV6 temperature gauge to remain at "normal" until the medium fan speed triggers at 106 degrees. Does that help?

Simon

Hi Simon,
Thanks for clarifying the fan behaviour - you have explained them clearly. Where I found them there was just the ranges quoted (eg for 1.8 low = 98 --> 104, high =106 --> 112, which left a bit of a gap at 105, and above 112 - where the fans were not in either of the valid states, so I took a guess what the actual behaviour would be).

Thanks for the information about your normal running temperatures - that is useful information.

Rover decided that overheat was appropriate at 125 so all we are doing is increasing the amount of headroom between the gauge leaving 'normal', and reaching 'overheat'.

From the figures you have quoted I think 115 for 3/4 is the right value - The high speed fans are on, and the cooling system is doing everything it can - it now needs the driver to help get the temperature down - with 10 degrees headroom left before the temperature gauge reaches 'Red' (Which I suspect Rover specified slightly lower than engine damage but probably not much)

The point at which to leave the buffer zone is perhaps slightly more difficult to judge. I agree with it being after the low speed fan has come on (as that is 'acceptable' behaviour) but whether it should be as high as the medium speed fan starting is questionable - If in slow moving traffic I could accept medium speed fan being on, but If I am driving normally I would be concerned if the medium speed fan was enabled. So I would possibly err to wards leaving the buffer zone before the medium speed fan is enabled.

Regards
Chris