Rotax 912 cylinder running hot
in 912 / 914 Technical Questions
12 years ago
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Re: Rotax 912 cylinder running hot
by Gary Van Meter » 12 years ago
Since I'm experiencing a similar issue (high CHT's but low coolant/oil temps) I will check the ground wire. BUT what is the CHT redline for a 912 ULS using 50/50 Dex coolant? The Rotax Owners Manual says it is 275 F but you can even go to 356 F for up to 30 minutes. However the manual says the coolant exit temperature should not exceed 248 F. Looking at the Lockwood and CPS sites I see CHT gauges . But some are marked with 248 f redline and some with 275 f redline. Clearly the coolant redline is 248 when using 50/50. But what about CHT for the 912 ULS?
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Re: Rotax 912 cylinder running hot
by Gary Van Meter » 12 years ago
Problem solved! We cleaned the ground connection to the engine (it had a slight bit of corrosion), put on a new radiator cap (because the maintenance manual listed that as a potential problem), and replaced the sealing tape around the radiator that keeps the baffles in place and tight so that the incoming air goes through the radiator rather than going around it. It now works great. We climbed at maximum climb speed for 30 minutes at 90 degrees f and it stayed in the green. Yes, the old radiator cap was also 1.2 bar and did not leak or sizzle. Now we need to resolve oil temps that are too low because we have a big oil cooler.
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Re: Rotax 912 cylinder running hot
by Mark Taylor » 11 years ago
I would definitely be looking at a lean condition. A small leak between carb and intake manifold, carb not jetted correctly or a loose needle valve clip. Maybe a missing or leaking plug on the compensation tube between the carbs.
I am looking for lean condition on my 1995 912UL as I am getting a hotter EGT on one side than the other. I need to get new EGT probes too, I think.
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