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Oil cooler cracking.

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Oil cooler cracking.

Unread postby Mikey » Sun Feb 26, 2017 3:28 pm

This is most likely a question for Kalus- I think that's how you spell it?

My Cessna 206 had a cont io520 engine. The factory oil coolers crack so it's very common for that cooler to be removed and one remotely mounted in the front tunnel area under the engine.
I'm most likely going to replace my 520 with an IO550N. This engine has the cooler mounted at the rear of the crankcase rather than the front.

Does anyone know if they still crack the coolers in that location once put on floats or did that shift fix the problem?

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Re: Oil cooler cracking.

Unread postby jjbaker » Sun Feb 26, 2017 3:37 pm


I've written Klaus about your topic. Lots of people barely show up here, so any kind of activity is likely going to take a while to trigger any sort of response.

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Re: Oil cooler cracking.

Unread postby BGH » Sun Feb 26, 2017 7:33 pm

I'm not familiar with the oil coolers cracking on the IO52D in the 185's & mine has been on floats for over 10,000 hours.

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Re: Oil cooler cracking.

Unread postby KlausNW » Sun Feb 26, 2017 11:11 pm

Over the years we would have some engines that produced oil leaks or cracked coolers more than other engines. Some of the senior mechanics blamed the cracks on the hydraulic lifters. We would pull all the lifters out and clean them or change them. The engines would finish their time without oil coolers leak but, that usually only meant the last 500 hours or less. The other thing we have done is balance the prop/engine with a chadwick by someone who know what they were doing.

For the most part, we came to believe that an engine shaking/vibrating from propeller balance or valve timing issue caused the cracking. If nothing else the engine usually finishes it's life with less oil seepage or leaks after the above recommendations.

One other thing that 'WILL' help your engine life is turning the Max. takeoff RPM down to 2800 or less. Many commercial operators wanted every bit of power they could pull from the engine but, the engine would have a lot more cylinder, cooler, case half, intake system, exhaust system and accessory problems. Propeller tips breaking the speed of sound is not only noisy but also vibrates the engine and airframe with 300 horsepower of force. Continental knew about this problem many decades ago so they developed the replacement IO-550 with a takeoff RPM of 2700 or less.
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