Mike,
I recently fitted the Skydrive kit, less the reading instrumet because I
connected the temp. sender to an available auxiliary input channel in my
Grand Rapids EIS. As recommended by Skydrive I installed the temp.
sender in the coolant hose from cyl. no. 3 to the common expansion tank
on top of the engine. Should be one of the two aft sylinders because
they run hotter due to less direct cold air flow. It is tight there, at
least on my 912S installation, but if you plan well before you cut the
hose it is no problem. I use 50/50 battery water/glycol.
I do not see the merit of measuring the temperature of the coolant in
the expansion tank, as this will be a mix of the coolant from all 4
cylinders where the two front ones have significantly lower CHT.
Trust you have the latest revision of the Rotax SB addressing the alarm
limit for the coolant temperature.
For those reading this and having used the 4 ring thermocouples
delivered by Grand Rapids for CHT: I insulated the visible part of the
thermocouples and the attachment bolts and an inch around where
installed, using the red high-temperature Locktite sealant. Put on a
good, thick blob. It made a noticeable difference in the readings for
the two front cylinders, now reading some 15-20 degr C higher than
before but still well below the two aft ones. The measuring points are
directly in the cold air coming in through the two openings in the
cowling. The measuring point in the VDO sender used by Rotax Flydat
picks up the temperature deeper in the CH and is therefore not as
directly exposed to the cooling air as the thermocouples are.
Regards,
Svein
LN-SKJ
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