FlyingMonkey Posted November 4, 2013 Report Share Posted November 4, 2013 Took off with the wife this morning to go look at the fall colors in the North Georgia mountains. We had barely left the pattern, climbing at 5200rpm WOT climbing through 2500ft for 5500ft. Everything looked great, all temps perfect, when the oil pressure suddenly started to spike. It went rapidly up to the high redline at 95psi. I notified the wife there was a problem and immediately leveled off. No change. Throttled back, no change. Turned back into the pattern and made a precautionary landing. In the pattern pressure returned to normal and stayed there throughout ground taxi. Did a couple of run ups and pressure stayed good. I took the cowl off and looked over everything to make sure the sensor and engine had no obvious problems. I restarted and took the plane back around the pattern, pressure never moved from its normal pressure of 40-50psi. All temps dead perfect. I'm pretty confident this is just a sender problem, but want to make sure I'm not missing anything. I already have a replacement I bought when a ground was causing a low pressure indication. In hindsight maybe that was just the first sign of trouble. So any other ideas on this, or just a failing sender? Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted November 4, 2013 Report Share Posted November 4, 2013 I just went through this, I assumed it was a ground and didn't worry about it. Recently Jeremy installed a dedicated ground and a new sending unit. Rock solid now. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 4, 2013 Author Report Share Posted November 4, 2013 I checked and tightened all the grounds already...I think the sender itself is puking. Link to comment Share on other sites More sharing options...
mocfly Posted November 4, 2013 Report Share Posted November 4, 2013 Andy, Put in the remote sender, run a single ground wire to the unit itself directly from the db9 connector on the pressure guage. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 4, 2013 Author Report Share Posted November 4, 2013 Hey Chris...I already have a new sender, and the remote kit requires a different unit with a separate ground. I'm thinking I'll have the one I have installed, and if it fails again I'll get the remote kit with the correct sender. How does the remote kit work exactly, is it just a high-pressure line run from the sender boss to the firewall location with the sender attached at the end? Link to comment Share on other sites More sharing options...
Jacques Posted November 4, 2013 Report Share Posted November 4, 2013 http://ctflier.com/index.php?/topic/1102-remote-oil-pressure-sender-wiringmounting/ Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 4, 2013 Author Report Share Posted November 4, 2013 Thanks Jacques. Link to comment Share on other sites More sharing options...
Runtoeat Posted November 5, 2013 Report Share Posted November 5, 2013 Andy, the sender has a wiper contact arm connected to a pressure sensitive bellows which causes this wiper to slide over a resistance coil. This setup works OK but eventually vibration from the engine takes a toll on it. Your sender may have a frayed resistance coil or spec of dirt? Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 5, 2013 Author Report Share Posted November 5, 2013 New sender was installed yesterday, and the behavior of my gauge changed significantly. The old sender pretty much always showed 30-50psi, and usually very consistent around 35-40psi, even on start up. The new sender on startup swept up to 70psi, then settled back to around 50psi. The problem was that when the engine was run up to 4000rpm, the pressure would drop and fall into the yellow, about 25-30psi, with the pressure going lower with increasing rpm. A poor ground was suspected, because the sender was originally installed "conservatively" to avoid over-tightening. Snugging it down a bit more until nice and snug (but not really torqued down or bottomed) led on restart to a very steady 50psi pressure. Increasing RPM caused the pressure to "blip" down slightly lower, then come back to 45-50psi. This behavior seems more in line with what we'd expect, so we called it good, and it does seem like a failed sender. It was getting dark so flight test will come later today if winds allow. The sender was replaced with similar issues just before the airplane was delivered to me, so I think these VDO senders are not very rugged, but I guess the good news is that having it replaced is only about 45min of labor including ground tests, so it doesn't cost much to have it changed out. If it fails again I'll have the relocation kit and sender with separate ground installed and see if that makes things more reliable...but I'm hoping this one will last a while. Link to comment Share on other sites More sharing options...
S3flyer Posted November 5, 2013 Report Share Posted November 5, 2013 Andy, You'll find the VDO sender lasts anywhere from 10 to 200 hrs when installed on the engine. I bought 4 of them online (for $25) to reduce my downtime when they failed. I originally thought I'd just replace them at each oil change since they were only $25 but time-in-service doesn't appear to correlate to failure. I've since upgraded to Dynon's Kavlico sensor with no failure in the last the year (fingers crossed). Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 5, 2013 Author Report Share Posted November 5, 2013 Andy, You'll find the VDO sender lasts anywhere from 10 to 200 hrs when installed on the engine. I bought 4 of them online (for $25) to reduce my downtime when they failed. I originally thought I'd just replace them at each oil change since they were only $25 but time-in-service doesn't appear to correlate to failure. I've since upgraded to Dynon's Kavlico sensor with no failure in the last the year (fingers crossed). Thanks Dave...I don't think anything other than the VDO is approved for the CTs, sadly, but when relocated away from the engine vibration they seem to be much more reliable. Amusingly, the VDO packaging says "for motor vehicle or motorcycle use only, not for use in aircraft"...well, there's the problem! Link to comment Share on other sites More sharing options...
Anticept Posted November 5, 2013 Report Share Posted November 5, 2013 Dave at FDUSA says we can use the sensors provided by rotax. I've installed the new sensor that they use, and the relocation kit. Takes a little rewiring (provided by the dynon ems d120 installation manual), but I like it. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 5, 2013 Author Report Share Posted November 5, 2013 Dave at FDUSA says we can use the sensors provided by rotax. I've installed the new sensor that they use, and the relocation kit. Takes a little rewiring (provided by the dynon ems d120 installation manual), but I like it. Good to know, thanks! do you have a link or part number for it? I'd like to investigate that. Link to comment Share on other sites More sharing options...
Anticept Posted November 5, 2013 Report Share Posted November 5, 2013 Part number 456-180. More information: Pg 79-00-00 http://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-020r7.pdf Also, there are two manufacturers out there of these sensors. Honeywell wast he original (pn 956413), and they discontinued. Now there is a new one, but it is functionally the same. MAKE SURE YOU READ THE DYNON MANUAL for your installation. As said, this new sensor needs modifications to the wiring for an EMS D120, and you need to set sensor type 4. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 5, 2013 Author Report Share Posted November 5, 2013 Thanks. EDIT: Wow, I hope it's a really good sender, it's $238 at CPS! Link to comment Share on other sites More sharing options...
FastEddieB Posted November 5, 2013 Report Share Posted November 5, 2013 Amusingly, the VDO packaging says "for motor vehicle or motorcycle use only, not for use in aircraft"...well, there's the problem! When I replaced a similar VDO sender my Sky Arrow uses for fuel pressure, it came with a red warning tag - "NOT TO BE USED FOR FUEL", or words to that effect. Makes you wonder. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 5, 2013 Author Report Share Posted November 5, 2013 When I replaced a similar VDO sender my Sky Arrow uses for fuel pressure, it came with a red warning tag - "NOT TO BE USED FOR FUEL", or words to that effect. Makes you wonder. Mine had that as well, I just assume they don't want you using it as a fuel pressure sender. The innards are probably not up to the solvent properties of gasoline. Link to comment Share on other sites More sharing options...
Anticept Posted November 5, 2013 Report Share Posted November 5, 2013 Mine had that as well, I just assume they don't want you using it as a fuel pressure sender. The innards are probably not up to the solvent properties of gasoline. Or, ya know, since these gauges use wipers, they might be concerned about a spark starting a fire . None of these sensors are supposed to have oil or fuel actually in the gauge, they rely on air pressure though a highly restricted oriface mounted on the part or the engine. Anyways, pn 956413 was the honeywell sensor. Pn 456180 is the new manufacturer. They are functionally the same. They are piezoelectrical, instead of mechanical. Honeywell's version kept failing though, but this new manufacturer produces these sensors for mission critical industrial applications, so hopefully it proves more reliable. I am not sure if it has to be remote mounted, like the VDO sensors. I already had the remote mounting kit, so i figured we might as well. Still works well! Link to comment Share on other sites More sharing options...
FastEddieB Posted November 5, 2013 Report Share Posted November 5, 2013 The innards are probably not up to the solvent properties of gasoline. Again, makes you wonder why 3i chose that sender. Link to comment Share on other sites More sharing options...
Runtoeat Posted November 7, 2013 Report Share Posted November 7, 2013 Andy, I recently paid $223 at CPS for the new fuel pump that Rotax mandates. After doing this, my FBO purchased another pump for less than $100 from another source (Leading Edge, I think). Shop for the best price. Link to comment Share on other sites More sharing options...
Roger Lee Posted November 7, 2013 Report Share Posted November 7, 2013 Hi Dick, If you had used the promo code that Kevin from CPS posted here on the forum that pump would have been $98. This special price was to get people to swap out the old AC pump with the new pump. Still $223 sounds high. I'll check my price sheet. Link to comment Share on other sites More sharing options...
Runtoeat Posted November 8, 2013 Report Share Posted November 8, 2013 Hi Roger. Didn't see the promo code. I had my FBO purchase my pump in advance from CPS so it would be on hand for my upcoming condition inspection. A few days after I got my plane back, I see that the pumps were $98 at various suppliers. I think even Rotax advertised them for this price! Link to comment Share on other sites More sharing options...
Tip Posted November 8, 2013 Report Share Posted November 8, 2013 I ordered a new fuel pump from CPS 5 - 6 weeks ago. It is in route now and I should have it tomorrow. I have been calling them for updates for a delivery date as it should have been shipped on October 1. The first time I called, I was #24 of the 24 pumps that they were receiving from the Bahammas. The next time I called I was # 17 of the 24 available. There should be a few left from that shipment. Link to comment Share on other sites More sharing options...
Gmoore7 Posted December 26, 2013 Report Share Posted December 26, 2013 New sender was installed yesterday, and the behavior of my gauge changed significantly. The old sender pretty much always showed 30-50psi, and usually very consistent around 35-40psi, even on start up. The new sender on startup swept up to 70psi, then settled back to around 50psi. The problem was that when the engine was run up to 4000rpm, the pressure would drop and fall into the yellow, about 25-30psi, with the pressure going lower with increasing rpm. A poor ground was suspected, because the sender was originally installed "conservatively" to avoid over-tightening. Snugging it down a bit more until nice and snug (but not really torqued down or bottomed) led on restart to a very steady 50psi pressure. Increasing RPM caused the pressure to "blip" down slightly lower, then come back to 45-50psi. This behavior seems more in line with what we'd expect, so we called it good, and it does seem like a failed sender. It was getting dark so flight test will come later today if winds allow. The sender was replaced with similar issues just before the airplane was delivered to me, so I think these VDO senders are not very rugged, but I guess the good news is that having it replaced is only about 45min of labor including ground tests, so it doesn't cost much to have it changed out. If it fails again I'll have the relocation kit and sender with separate ground installed and see if that makes things more reliable...but I'm hoping this one will last a while. Link to comment Share on other sites More sharing options...
Mac Bowden Posted January 15, 2014 Report Share Posted January 15, 2014 Can someone kindly show me a photo of the connection of the remote sender braided pipe at the engine end. I want to see if it's a 1/8 npt male to male with the braided pipe screwed on to it. Roger, I've downloaded the F.D. document but it's not very clear. Mac Link to comment Share on other sites More sharing options...
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