Severe Jittering Oil Pressure
in 912 / 914 Technical Questions
9 years ago
I have been flying my Van's RV-12 ELSA since May of this year. The power plant is a 912
ULS. Since day one, I had noticed that my oil pressure had significant fluctuations (jitter), but
only after the oil had warmed up to operating temperature. When cold, the pressure is
rock solid.
Because I had some unrelated teething problems with the Dynon Skyview (a
defective SSD), I decided to add a backup mechanical oil pressure gauge (in parallel) in
case the Dynon were to fail while I was on a x-country trip. I wanted at least some
insight into what the engine was doing in the potential absence of the Skyview.
The installation of the mechanical gauge confirmed my jittering oil pressure issue and
that it was not caused by the transducer or the Skyview. The jittering was so bad (+-20
lbs) that it was impossible to read the mechanical gauge with any accuracy.
After doing some research on the issue, I discovered that Rotax had a replacement for the
steel ball in the oil pressure relief valve that was supposed to address this issue. It
is a "mushroom valve", that has a stem which helps guide the valve properly and eliminate
the bouncing oil pressure. I installed it at 30 hours of engine time, and sure enough,
the problem was immediately resolved.
That fix lasted about 25 hours, but the problem has now come back just as bad as before.
I pulled the mushroom valve out of the regulator only to find it was badly galled on the
stem. The spring had also galled the inside if the screw plug. Obviously, it had beating
itself to death from the constant chattering.
This is basically a new engine with about 55 hours of total time. It originally came with
the new type plug screw (part 841-983), but with a steel ball instead of the mushroom
valve. From what I understand, this is the way they are shipped currently.
I am now very concerned about the possibility of metal traveling through my engine as a
result of the galled oil relief valve parts. A week ago Monday, I enlisted the help of
Southland Rotax (F70) to try to get some answers regarding possible causes from the Rotax
mother ship. We filled out the Rotax CSIR form and sent it off through CPS with email
pictures attached. To date, we have not heard anything back from Rotax.
I'm curious if anyone in the group has experienced this problem and what the cause and
long term fix was. Also, please provide some input into how I can get some attention from
Rotax. My airplane has been down now for over a week now. Thanks in advance for your
input.
Alex
ULS. Since day one, I had noticed that my oil pressure had significant fluctuations (jitter), but
only after the oil had warmed up to operating temperature. When cold, the pressure is
rock solid.
Because I had some unrelated teething problems with the Dynon Skyview (a
defective SSD), I decided to add a backup mechanical oil pressure gauge (in parallel) in
case the Dynon were to fail while I was on a x-country trip. I wanted at least some
insight into what the engine was doing in the potential absence of the Skyview.
The installation of the mechanical gauge confirmed my jittering oil pressure issue and
that it was not caused by the transducer or the Skyview. The jittering was so bad (+-20
lbs) that it was impossible to read the mechanical gauge with any accuracy.
After doing some research on the issue, I discovered that Rotax had a replacement for the
steel ball in the oil pressure relief valve that was supposed to address this issue. It
is a "mushroom valve", that has a stem which helps guide the valve properly and eliminate
the bouncing oil pressure. I installed it at 30 hours of engine time, and sure enough,
the problem was immediately resolved.
That fix lasted about 25 hours, but the problem has now come back just as bad as before.
I pulled the mushroom valve out of the regulator only to find it was badly galled on the
stem. The spring had also galled the inside if the screw plug. Obviously, it had beating
itself to death from the constant chattering.
This is basically a new engine with about 55 hours of total time. It originally came with
the new type plug screw (part 841-983), but with a steel ball instead of the mushroom
valve. From what I understand, this is the way they are shipped currently.
I am now very concerned about the possibility of metal traveling through my engine as a
result of the galled oil relief valve parts. A week ago Monday, I enlisted the help of
Southland Rotax (F70) to try to get some answers regarding possible causes from the Rotax
mother ship. We filled out the Rotax CSIR form and sent it off through CPS with email
pictures attached. To date, we have not heard anything back from Rotax.
I'm curious if anyone in the group has experienced this problem and what the cause and
long term fix was. Also, please provide some input into how I can get some attention from
Rotax. My airplane has been down now for over a week now. Thanks in advance for your
input.
Alex
