Michael Christmann Posted May 9, 2012 Report Posted May 9, 2012 I recently observed a slightly higher reading on the right CHT indicator. In cruis it is about 12 to 15 degrees higher but during pattern work it can be 30 degrees higher and exceed 270 degrees. I exchanged the right and left probe with no change in readings. My next plan is to check compression. Any other ideas?
Michael Christmann Posted May 9, 2012 Author Report Posted May 9, 2012 My WOT is right around 5200. How and how much do I adjust the Neuform 2 blade?
Michael Christmann Posted June 28, 2012 Author Report Posted June 28, 2012 Well, here is the follow up. We changed the pitch and got 5200 static and 5560 dynamic rpm. Still high CHT. We decided to continue with the hose replacement for the ROTAX and had the same results. Next we had the carburators overhauled. No change. We replaced the ignition, because the right o e had failed. No change .next we replaced the thermostat and got slightly better results but noticed that the temperatur dropped, when we switched off the master avionics. We recleaned the ground contacts and got rid of that problem, vut still experienced 230F on the left and 250f on the right, which Lockwood considers to high even in 96F. Any comments?
Tad Olmsted Posted June 30, 2012 Report Posted June 30, 2012 Have you slaved in a (known good) mechanical gauge to rule out the instument? Sounds like it should be running in the normal range from what I have read.
airhound Posted September 1, 2012 Report Posted September 1, 2012 250F is too high for 96F. 215F-230F would be more in line. So you replaced the coolant hoses. The carbs should not have made any difference. The ignition should not have made a difference. Since you replaced the coolant hoses are any kinked, even slightly? The hose they have been using kinks easier. You can drop the temps by making sure the rubber piece under the radiator is faced forward and not backward. Make sure the radiator is square and not even 1" off to one side. Are you using 50/50 coolant? I hope not Evans. It is possible that the thermostat is the issue by not opening all the way. Personally I see no reason for the oil or coolant thermostat in most US states. If these have any restricted flow at all the temps will rise. Are the other temps up across the board as well? Since you rebuilt the carbs are the needle clips in the #3 position? What are the EGT's? If they are high too then you are a little lean and the needle clip could be move to the #4 slot. (Last resort, do the other things first) If these items above are all okay then I would suspect a slight restriction in the thermostat. Yank the thermostat itself out of the body and just do a test run to check the temps. If they are down you have your answer. I guess it probably got resolved somehow.....Could plug gaps influence CHT?
FlyRatz Posted September 1, 2012 Report Posted September 1, 2012 If the temperatures are real high and it is for sure that it is not a sensor, electrical or gauge problem, then I would assume that the radiator became clogged. This happens sometimes due to chemical processes with the coolant. If you have access to another radiator, it would be worth to change and test. Markus
Jim Meade Posted September 1, 2012 Report Posted September 1, 2012 If the temperatures are real high and it is for sure that it is not a sensor, electrical or gauge problem, then I would assume that the radiator became clogged. This happens sometimes due to chemical processes with the coolant. If you have access to another radiator, it would be worth to change and test. Markus Markus, Can you expand on this idea? Which coolant? What processes? What conditions? How much time does it take? Thank you.
airhound Posted September 1, 2012 Report Posted September 1, 2012 Anyone---can mis-gapped plugs cause heat problems?
FlyRatz Posted September 5, 2012 Report Posted September 5, 2012 Markus, Can you expand on this idea? Which coolant? What processes? What conditions? How much time does it take? Thank you. Hi Jim, I have such a glogged radiator in my workshop. I sent it to a radiator manufacturer for a capacity test and they attested a performance of 35 %. This means, that this particular radiator has lost 65 % of its original cooling capacity. To identify the chemical processes, I need the help of a expert. I found a laboratory which is willing to do the diagnose for me. But this takes time. I expect a result at the end of this year. The radiator was used with 50:50 coolant (G48) and regular water from the water-cock. If I have details about the chemical process, I will post it here. Best to you Markus
Ed Cesnalis Posted September 5, 2012 Report Posted September 5, 2012 ...The radiator was used with 50:50 coolant (G48) and regular water from the water-cock... Is it a tame water-cock?
chanik Posted September 5, 2012 Report Posted September 5, 2012 Hi Jim, I have such a glogged radiator in my workshop. I sent it to a radiator manufacturer for a capacity test and they attested a performance of 35 %. This means, that this particular radiator has lost 65 % of its original cooling capacity. To identify the chemical processes, I need the help of a expert. I found a laboratory which is willing to do the diagnose for me. But this takes time. I expect a result at the end of this year. The radiator was used with 50:50 coolant (G48) and regular water from the water-cock. If I have details about the chemical process, I will post it here. Best to you Markus Tap water is usually OK to mix, but hard water, with lots of dissolved minerals can give rise to corrosion which can plug up radiators. That's uncommon too. The REAL risk from tap water is obliquely related to hard water and that is if you use SOFTENED water. Water softeners leave quite a bit of salt in the water. At high temperatures that salt will do an impressive job rusting out the thin steel/brass in your radiator first plugging it and then making it leak. You should see the orange/green discoloration in the coolant if that is going on.
Doug G. Posted September 5, 2012 Report Posted September 5, 2012 Is the two years a Rotax recommendation or requirement, or a Roger Lee practice?
airhound Posted September 6, 2012 Report Posted September 6, 2012 All my practices come right out of many years of Rotax school and the manuals. I didn't make a single one up. It is recommended by Rotax. (Rotax school) Just like the oil it is recommended and if you want to leave the oil in for ever I guess someone could do that. It does say in one document to change it by at least the overhaul. That would be 15 years or 2000 hours. That's an utter joke and it gets discussed in school. Stay with 2 years. It's only 2/3 of a gal. and won't break anyone's bank and it only takes a few minutes. We don't have a large quantity of coolant that will stay more stable over time like a car or truck. Kind of like anything in life. You have those that keep things new, have every thing done documented and it stays maintenanced and spotless. Then there are the others. We all get the freedom to pick our poison. That's why we have the Darwin awards. I just had two calls just today about two ruined 912 engines. Different issues. Fixes are going to cost $5K-$6K. Maybe they could have spent $100-$200 back then and would have saved the other $5K. That old saying does hold true some times: pay a little now or a lot later. I get 8-10 calls a day from all over the world on the 912 (half that from CT owners) so I get a unique chance to hear a lot of issues and problems and very fortunate to help some along the way. That's the best part for me, the call back saying problem solved. Makes my whole day. Roger, you made my whole day, the Tanis arrived and what a class act....Thank You! What would be a good reference to use when changing radiator fluid? Are there any Cautions??
Doug G. Posted September 6, 2012 Report Posted September 6, 2012 Thanks Roger. Makes sense. Especially when I will be doing my own annuals. Doug
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