Friday, Sep 30, 2016 at 19:45
Hi Dave - then it bears little correlation to actual water temp.
The procedure is to get you vehicle up to operating temp and note the temp on the Watchdog.
My petrol V8 is 73 degrees where to coolant temp is about 85. You then set the alarm at about 15 degrees higher - so in my case 88 degrees (close to your 90).
You then drive and note the temp that your Watch dog shows - eg in my case in normal use the range is always between 70 and 75. If I go down a big
hill in winter it might get down to 68 and if I drive up a big
hill in summer it might get up to 80 - the coolant temp gauge changes a lot more - cooler when the thermostat is closed and hotter up to 95 when climbing that
hill. The thermostat moderates the engine temp and there is a little lag on the temp on
the block as you would expect.
For me the temp on the Watchdog goes up in summer when I stop at traffic lights where the fan is not generating a lot of air over
the block so heat from
the block raises the sensor temp. Likewise when the engine is turned off the heat soak from
the block can raise the sensor temp quite high.
If you have your Watchdog set at 90 then if the alarm goes off when you are driving the coolant temp will be up somewhere around 100 or higher.
I think it is important to understand that
the block temp is different to the coolant temp is different and you need to monitor temp changes from your baseline. Eg if I have 80 on the watchdog when normal driving I have an issue.
So monitor your coolant temp gauge, monitor what your Watchdog temp is doing (they can be doing different things) and I agree with the others for an older diesel an EGT gauge is also helpful - the computer does that on my diesel and makes changes if they get too high so I don't have to worry.
Cheers
Garry
PS - once you have determined you "normal temp" and set your alarm do not change it if it goes off in abnormal use - is a bit like putting in a bigger fuse if it blows - do something to reduce the temps not change the alarm temp.
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