912 coolant sensor installations?
in 912 / 914 Technical Questions
9 years ago
I've wondered for years, how does others install an actual coolant sensor for a 912 series engine?
That's for the decades of engines that only had a CHT sensor port, not the very new cylinder heads that actually have a coolant sensor port.
Back in the 2000s, Rotax put out bulletins emphasizing actual coolant temp sensing rather than just CHT -- unless the airplane manufacturer had test flown the configuration and determined that CHT is a suitable proxy for coolant temp (with any necessary conversion factor). And now with the new heads, they obviously care even more about the matter.
But online I never seem to find anyone actually measuring coolant temp. In a decently engineered system, under typical conditions, CHT seemed enough. I used to measure coolant temp on my 912 because it had a custom brass rad which was tapped to add the sensor. But now I'm going to a Rotax standard rad and need somewhere to put the sensor.
(Aircraft: Zenith/Zenair CH601 HDS. 1995 Zenair cowling. Flypass (Ontario) rad kit c. 1997. Back in the days when the whole cowling & rad setup options was poor / ugly / experimental / draggy or some combination of the same. My cooling situation wasn't ideal -- COOLANT temps could get high while CHT and oil temps were really nice.)
I've looked at automotive 'performance' sites and there are a few adapter blocks out there, to install a sensor inline with a coolant hose. Only a small number are available for 1" hoses (~26mm), because few cars use so small a hose, although snowmobiles and motorcycles seem to.
There are a few ugly, poorly designed adapters out on the market. Most of the rest seem all to come cheap from China. I tried one but it was machined to the wrong dimensions. Another one might work better, who knows.
Attached is an example of one of the Chinese adapters. If I get one that is machined right, it does seem a smart solution. There's a thick threaded section which keeps a VDO sensor from blocking the flow much. And one can get VDO sensors in the 1/8NPT thread they usually use. (I've found a different sensor adapter that used the British thread instead; not useful to me.)
So I'm wondering who else might have put a coolant temperature sensor into their 912 series system with an adapter block ... and what adapter they got.
[other keywords: water temperature]
That's for the decades of engines that only had a CHT sensor port, not the very new cylinder heads that actually have a coolant sensor port.
Back in the 2000s, Rotax put out bulletins emphasizing actual coolant temp sensing rather than just CHT -- unless the airplane manufacturer had test flown the configuration and determined that CHT is a suitable proxy for coolant temp (with any necessary conversion factor). And now with the new heads, they obviously care even more about the matter.
But online I never seem to find anyone actually measuring coolant temp. In a decently engineered system, under typical conditions, CHT seemed enough. I used to measure coolant temp on my 912 because it had a custom brass rad which was tapped to add the sensor. But now I'm going to a Rotax standard rad and need somewhere to put the sensor.
(Aircraft: Zenith/Zenair CH601 HDS. 1995 Zenair cowling. Flypass (Ontario) rad kit c. 1997. Back in the days when the whole cowling & rad setup options was poor / ugly / experimental / draggy or some combination of the same. My cooling situation wasn't ideal -- COOLANT temps could get high while CHT and oil temps were really nice.)
I've looked at automotive 'performance' sites and there are a few adapter blocks out there, to install a sensor inline with a coolant hose. Only a small number are available for 1" hoses (~26mm), because few cars use so small a hose, although snowmobiles and motorcycles seem to.
There are a few ugly, poorly designed adapters out on the market. Most of the rest seem all to come cheap from China. I tried one but it was machined to the wrong dimensions. Another one might work better, who knows.
Attached is an example of one of the Chinese adapters. If I get one that is machined right, it does seem a smart solution. There's a thick threaded section which keeps a VDO sensor from blocking the flow much. And one can get VDO sensors in the 1/8NPT thread they usually use. (I've found a different sensor adapter that used the British thread instead; not useful to me.)
So I'm wondering who else might have put a coolant temperature sensor into their 912 series system with an adapter block ... and what adapter they got.
[other keywords: water temperature]
coolanttempsensoradapter-example.jpg (You do not have access to download this file.)
