---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Wed 04/18/18: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:16 AM - Re: 912 Cylinder head coolant temperature Gauge (MacDonald Doug) 2. 05:31 AM - Re: Re: 912 Cylinder head coolant temperature Gauge (John Hauck) 3. 12:52 PM - Re: 912 Cylinder head coolant temperature Gauge (rampil) ________________________________ Message 1 _____________________________________ Time: 04:16:28 AM PST US From: MacDonald Doug Subject: RotaxEngines-List: Re: 912 Cylinder head coolant temperature Gauge Another source of temperature spikes I have found is with the absolute jun k VDO gauges that tend to develop erratic needle swings as they age.=C2- I spent one summer changing out well over 1000 dollars worth of electrical components chasing "voltage spikes" on=C2- my CH-701 only to find out the problem was a bad VDO gauge.=C2- I had even tried another (albeit used) VDO voltage gauge and still had the same "spikes".=C2- Turned out it was the crap VDO volt meters and there was actually nothing wrong with my elect rical system.=C2- Since then, I have been slowly converting my panel over to Stewart Warner gauges and have been happy with the results.=C2- I hav e an erratic oil temperature gauge right now that will be getting replaced at annual. While I won't claim to be an expert and know very little of the OP's proble m, he did mention he has a VDO gauge and I would replace that before gettin g to carried away chasing a potentially phantom engine problem. Doug MCH-701/ 912-UL ________________________________ Message 2 _____________________________________ Time: 05:31:05 AM PST US From: "John Hauck" Subject: RE: RotaxEngines-List: Re: 912 Cylinder head coolant temperature Gauge Since the early days, ultralight pilots have freaked out over instrument indications. They spent hours and lots of money, and probably destroyed lots of engines and airplanes chasing engine instruments, trying to get that two stroke engine dialed in perfectly. I think of all the other two stroke engines in my life back then that had no instrumentation. Never worried about EGT and other temps. They seemed to run forever with good fuel and oil, and a new spark plug every once in a while. Usual the problem was improper prop loading. Rotax did a good job of setting up the engines at the factory, but if the Westach instrument told them their EGT was a little high or low, they'd start chasing their tail, changing jets, needles, spark plugs, and anything else they could find to change. I was one of them. I have a situation with my 9121ULS that irritates me. I randomly get low oil pressure and high engine oil temp indications. I was on a flight to Oregon many years ago when this first started happening. Was irritating, but proved to be harmless. It is still happening, but the temps are always reading the same, even though they are incorrect. Annoying, but not critical. BTW, they are VDO marine gauges. I can shut down the battery and the indications return to normal. Must be wiring, probably poor grounding, or the gauges. john h mkIII Titus, Alabama From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of MacDonald Doug Sent: Wednesday, April 18, 2018 6:16 AM Subject: RotaxEngines-List: Re: 912 Cylinder head coolant temperature Gauge Another source of temperature spikes I have found is with the absolute junk VDO gauges that tend to develop erratic needle swings as they age. I spent one summer changing out well over 1000 dollars worth of electrical components chasing "voltage spikes" on my CH-701 only to find out the problem was a bad VDO gauge. I had even tried another (albeit used) VDO voltage gauge and still had the same "spikes". Turned out it was the crap VDO volt meters and there was actually nothing wrong with my electrical system. Since then, I have been slowly converting my panel over to Stewart Warner gauges and have been happy with the results. I have an erratic oil temperature gauge right now that will be getting replaced at annual. While I won't claim to be an expert and know very little of the OP's problem, he did mention he has a VDO gauge and I would replace that before getting to carried away chasing a potentially phantom engine problem. Doug M CH-701/ 912-UL ________________________________ Message 3 _____________________________________ Time: 12:52:29 PM PST US Subject: RotaxEngines-List: Re: 912 Cylinder head coolant temperature Gauge From: "rampil" My 2 cents as an EE: There are NO rapid temperature changes. Not physically possible. How much energy do you think is available to heat and COOL the coolant through wide swings. VDO are cheap crappy mechanical gauges, emphasis on cheap crap. Automotive or snowmobile quality, no better. I like Rotax hardware, but the VDO garbage should be thrown away on delivery and replaced with airworthy meters. The temp. swings are most likely vibration induced mechanical resonances in the needle/coil/spring system in the indicator. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=479432#479432 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.