O

oliverj1

I'm New Here
Hi, I have 17 hours on my RV-8A. My van's Tach worked for about one flight then quit. I replaced the sender unit and again, it worked one hour then quit. I just can't seem to figure out what's happening. I have 2 drive keys, one original length and one the optimal length in van's drawings but changing them makes no difference. The sender is on a Superior XP-360 engine. All the wiring checks 4.0 plus the gauge did work for at lease an hour. When I remove the sender and the drive key, I noticed that the geared cup that turns the bottom of the sender came out of the socket. However, the key does turn it. Just lost on this one. Any ideas?

Joe Oliver
DeLand, FL
 
For what it's worth, I'm using the same sender on my XP-360, but using it to drive the tach on my Dynon EMS. Coming up on 200 hours now and it hasn't skipped a beat.

The sender just sends x number of pulses per revolution so I would think you could just put a scope on the sender wires, connect some power to it and turn the sender on the ground with an electric drill. If you are getting pulses, try the same thing with the sender on the engine.

If the sender is working, that only leaves one thing -- the gauge.

It may seem obvious but I would also double-check your power and ground connectors for the sender and tach as well. You never know.

Good luck with the remainder of your phase I.
 
Tach Gauge

My Van's tach. gauge with Van's sender has 275 hours with no problems to date.

Dick DeCramer
RV6 N500DD
Northfield, MN
 
My first sender

lasted 200 hours. So far I've got 190 on the second one. I'm hoping for the best.:D
 
I have this sender on my RV-10 and it quit working after 7 hrs. Van's sent another one and I noticed the key was shorter. I looked at my bad sender and noticed that it had a bulge in the back. I took it apart and discovered that the internal wheel had been driven into the back and finally broke. The problem was that the key length varies from unit to unit. My key was about 1/4" too long, which pushed the internal sending unit wheel into the back case making it fail. So, after several measurements and calculations, I determined what the key length should be and ground the key to length. I installed it and it is working so far.

Kevin
RV-6A
RV-10
 
Pulse Measurements from Vans Sender

On a similar vein ...

Does anyone have the specifics for the Vans tach sender ? specifcally, how many pulses per RPM and the amplitude ? I tried tying the tach sender signal from the pMag into my vans tach guage and that didn't work right - it reported RPM's, but the wrong value. I varied the settings on the pMag for pulses per RPM without any success. I'd like to be able to remove the vans sender and this info would certainly assist in that goal.
 
Pulse number

I don't remember the pulses per rev offhand; however, you can power it up and hook it to a voltmeter and count the pulses while turning it be hand. Then you'll know for sure how many pulses it makes per revolution.
 
N520TX said:
On a similar vein ...

Does anyone have the specifics for the Vans tach sender ? specifcally, how many pulses per RPM and the amplitude ? I tried tying the tach sender signal from the pMag into my vans tach guage and that didn't work right - it reported RPM's, but the wrong value. I varied the settings on the pMag for pulses per RPM without any success. I'd like to be able to remove the vans sender and this info would certainly assist in that goal.
Click to expand...

I have this value configured in my Dynon EMS, but I don't remember what it is. If I remember correctly, it's something weird, like 4.5. I should be going out to the airport tonight and/or tomorrow so I'll try to remember and check.
 
Well, mine lasted a little over 350 hours. The intermittent failure appears to be caused by internal wire fatigue right at the end of the strain relief.

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Paige
 
I went through at least three before I realized that the input shaft cannot have any thrust load. I.e., must be completely free axially. Leave a little room for thermal growth.
 
I finally opted to install a short tach drive cable which allowed me to mount the tach sender on the firewall. I had concluded the failures were vibration-induced just by watching the gauge as the sender failed. It seems Paige's observations have gone a level deeper into root cause.

We have about 300 hours on the current remote-mounted sender with no troubles. An additional "plus" to this arrangement is the tach drive cable is easier to work around on the back of the engine than having the tach sender mounted there.
 
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