Hi all,
A week or so back I read a post that included some of Roachie's coolant temperature readings from his 'hot' TD42T Patrol. Can't find it again now, so I thought I'd start a new thread about similar findings.
A few months ago, a customer asked if I could rig one of my EGT gauges to also monitor coolant temperature, with a suitable mechanism to switch between the two sensors. [Roachie, we talked about this some time ago, as I recall - switching between thermocouples needs to be done with care to avoid errors in the readings.] As it was for the same engine as
mine (Land Rover 300Tdi), I made up a prototype on my vehicle and then duly sent off a kit to a happy customer (
well, two actually, one for his son as
well. Both Land Rover owners - what a nice,
well-adjusted family??) .
However, I didn't get around to actually fitting my coolant sensor to the thermostat housing until a couple of weeks ago, when we were in
Darwin. Then we had to back-track to Mt Isa for a work assignment, so we got to try it out in some heavy duty conditions - towing a 2200kg tandem caravan in ambient temps up to 40-41C and sometimes into headwinds.
The coolant sensor confirmed that the thermostat opens at 88C, where it would sit happily while driving around town. Long idling at lights followed by 'robust' acceleration up to the speed limit would see it climb up to, say, 92C then settle down again. A day trip to
Jabiru in the car saw it in the range 90 to 96C at 100-110 km/h in ambients around 35C, depending on acceleration, hills, etc.
The towing the 'van south to
Katherine,
Tennant Creek and on to Mt Isa saw some higher temps. The official maximum temps on these days was 36-37C but out on the highway our thermometer (with it's sensor poked out the rear door in the shadow of the spare tyre) recorded over 40C. In the hilly country between
Darwin and
Katherine around Hayes
Creek, we peaked at 108C when I deliberately held full throttle up a long rise (EGT in the high 600s). For most of the 1600km trip we would have been running in the 94 to 104C range, with the rise and fall of the road clearly indicated by the movement of the coolant temperature.
A couple of points of interest (I hope):
. The standard coolant gauge reached it's 'normal' position (just below half-scale) at 88C and DIDN'T MOVE FROM THAT POINT, even when the actual temp was at 108C. [I've only ever seen the original gauge move above 'normal' twice, both times towing in VERY hot weather: once at the top of Bang Bang Jump-up on the
Normanton to
Cloncurry road on a 43C afternoon and the other on the Stuart Highway near
Coober Pedy on a day that was officially 45C but we measured 47.9 'out the back door'. I shudder to think what the 'real' coolant temp was on those occasions...]
. The 'real' coolant temp moves around constantly when under heavy load (i.e. when the thermostat is fully open) and indicates headwinds and/or slight inclines before you'd otherwise notice them.
. I don't know how to do it without sacrificing my engine in the cause of R&D, but it'd be interesting to see what the thermocouple reads on loss of coolant - a sudden fall??
. Land Rover 300Tdi's are tough little b*gg*rs.
Hope this is of interest. Does any else have 'real world' readings from accurate instruments?
Ian