Rotax 912 Honeywell Oil Pressure Sender

My CH750 is powered by the Rotax 912S engine. To date I have 90 trouble free hours on the engine with no adjustments required other than tightening a radiator hose clamp. While flying the other day the engine oil pressure started to fluctuate and go full scale both directions on the D180. This really gets your attention! I selected a field for a forced landing, but after flying the approach with Rotax humming along happily (all oil temps & cylinder temps normal) I reasoned I was risking more damage to my CH750 than remaining airborne with a running engine... my home airfield was only 10 minutes away. It was an anxious, but uneventful flight home. I doubt the Rotax 912 would continue running much longer than a minute or two with zero oil pressure. My Rotax 912S has a 2000 hrs TBO, and a new style Honeywell electronic oil pressure sender that replaced the standard Rotax VDO sender used previously.

The Honeywell sender is $400 vs. the VDO sender $45 that Rotax previously used. Bob Robertson of Light Engine Services (Rotax @ Salmon Arm B.C.) sent me a new Aviasport oil pressure guage to wire in as the Honeywell sender (and guage) requires a 12 volt supply to work. By installing this "stand alone" oil pressure guage I was able to prove the Honeywell sender was defective... and not my Dynon D180 as suggested by Rotax. The Honeywell sender is being replaced by Rotax under warranty, and Rotax maintains they have never had a history of failure. In the future if the Honeywell sender fails again (not under warranty) I will replace it with the older VDO sender. It is then a simple change in the Dynon D180 setup menu to select the VDO sender and your back in business. Note :The Rotax 912 in my CH601HD has the older VDO sender..... and 1200 hrs with no trouble.




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Comment by Wes Lorier on December 10, 2014 at 1:47pm

Thanks again Bob.  I called…..very knowledgeable guy and great to talk with.  He fixed me up!  The oil temp sender is indeed a metric thread, so I just bought one from him.

Comment by Bob McDonald on December 10, 2014 at 11:11am


Simplest answer is to phone Bob Robertson of Light Engine Services 1-250-832-8786

He is my "Go To Rotax Guy" and is always correct with the right parts or advise on these engines.

Comment by Wes Lorier on December 10, 2014 at 10:48am

Thanks Bob.  Now for the oil temp sender.  It appears to have straight threads, and all the vdo temp senders seem to have 1/8 pipe. It appears that I'll need an adapter and I don't know how to spec it because the threads on the existing one are unfamiliar to me.  Any clue?

Comment by Bob McDonald on December 10, 2014 at 6:55am

The VDO sender for a Rotax 912 threads into the same fitting the Honeywell sender is threaded into.

Comment by Wes Lorier on December 9, 2014 at 11:52pm

The vdo sender has 1/8 pipe thread……what is required to change from the honeywell to the vdo?  I haven't pulled my honeywell off yet.  Is an adapter required?

Comment by Bob McDonald on June 24, 2011 at 4:46pm
It is a Honeywell that comes on the Rotax 912 series engines after about 2009. I bought my Rotax 912S through Bob Robertson of Light Engine Services 1-250-832-8786. If you want you can order your engines and ask for the older VDO sender...exchanged no-charge. I put the older VDO Rotax sender on, single wire to run and selected VDO in the Dynon D180 menu and it was good to go.
Comment by Rodney Rix on June 24, 2011 at 3:56pm
Bob can you tell me is it a  Honeywell sender that comes standard on the new 912S, or VDO?
Comment by Bob McDonald on April 14, 2011 at 6:48pm
Tach issues are usually electrical connection loose or bad ground. One of the best trouble free, 15 minute install, battery powered tach/hobbs units I have ever used on an aircraft is a Tiny Tach (Aircraft Spruce). Its low also cost to purchase.
Comment by Paul Hammond on April 14, 2011 at 6:25pm

G,Day  Bob thanks for the info i will go down to the local auto parts store today and buy a sender . 

But i also just remember my tacho goes a little sometimes too.Like Dave i have had so many tractor and machinery companys say to me that i was the only that has ever broken on

Comment by Bob McDonald on April 14, 2011 at 7:01am


It is probably not an issue with the Dynon unit. Those oil pressure senders are subject to a high heat and vibration enviroment. Simply replace the oil psi sender first if it a low cost item, then if your problem goes away you have already fixed the problem while trouble shooting the issue. The Dynon is backed by a rock solid warranty...the oil psi senders are "consumables".

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