Substitute for Rotax water temperature sensor

jimmyd · #1 05-18-2015, 07:32 PM

Hi guys. I fly a RV7A but am in need of a part for a motor glider with a Rotax912 U 80 hp engine. My water temp sensor has failed and was going to order one. Price is preposterous. Is there an aftermarket part number that anyone knows? I may have to pay the Rotax price but will do my best not to.
I actually found one in Europe for $30 bucks but it is a problem getting it here. If anyone has any info it would be appreciated. My email is
Jimkulbeth@twc.com.

Thanks
Jimmy

mburch · #2 05-19-2015, 12:01 AM

Jimmy,

If the part you are replacing is a Rotax 965531 150°C thermistor, it is electrically equivalent to any other 150°C thermistor. A substitute automotive part that seems like it should work would be the VDO 323-057, which can be had from your local auto emporium for about twelve bucks.

You may find this document helpful for the part number references: http://thermostasis.com/includes/tem...ting-rotax.pdf

Disclaimer: If you choose to use a non-Rotax part for your aircraft, be sure to test it with a pot of boiling water first to make sure the one you selected really is equivalent to the OEM part.

- Matt

h&jeuropa · #3 05-19-2015, 05:19 AM

Jimmy,

I ran into this problem recently. The VDO sensor with the correct metric threads is just not available anywhere except Rotax dealers at a very large price.

However, there are several VDO sensors available from automotive suppliers that have threads that are a larger diameter than the M10x1.5 required to fit Rotax. A machine shop can easily machine off the threads of one of those and cut new M 10 x 1.5 threads. The one Matt identified is 1/8 NPT which is too small diameter to do this.

I found a good selection of VDO sensors at Summit Racing, a national mail order store. Just be sure to get a 300 deg F sensor.

Jim Butcher

jimmyd · #4 06-17-2015, 05:33 AM

Thanks to all for the information. I will look at all suggestions. For the life of me , I can not understand the terrible prices charge for some of these items. You would think a few hundred percent mark up would be good. All they do is put enterprising minds into action on how to get around it and lose sales.