BillL
Well Known Member
FYI - There are dehydrator threads, and water collection in the oil separator threads and winter flying threads. All relate to water/moisture in the crankcase and corrosion issues.
As a datapoint, yesterday I helped (watched) a 10 friend with his first engine start. We checked for leaks then cowled and he did some taxi runs to break-in the brakes. All went well. With 2100 rpm mag checks and such - I guess it was 45 min of running (correction 20 min). Very little at idle and it was preheated to 145F with a Reiff preheater system overnight. OAT was 40F with wind. Oil temp at end of testing was 165F
I have been looking at dehydrators and cobbled one together for experimentation. I thought it would be good to use on a first start because, it is cold, short run, rich and expected some blowby.
Post run, we hooked the dehydrator, powered with a little aquarium pump, the dry air into the breather pipe and moist air out the oil fill tube (540).
About an hour later, there was water collecting in the exit hose. The warm, moist air was condensing water in the hose! - He estimated 1.5 tablespoons!
We were both shocked to see that much water. The desiccant was not weighted or measured, but surely there was more water coming out via adsorption.
Now you know, definitively, how much water you could leave in the crankcase for a short engine run. Decisions about dehydrators, water returning to crankcase via oil separators and such are left to other treads, but everyone about to expose your expensive new engine to a joyful first start should take note of this situation.
As a datapoint, yesterday I helped (watched) a 10 friend with his first engine start. We checked for leaks then cowled and he did some taxi runs to break-in the brakes. All went well. With 2100 rpm mag checks and such - I guess it was 45 min of running (correction 20 min). Very little at idle and it was preheated to 145F with a Reiff preheater system overnight. OAT was 40F with wind. Oil temp at end of testing was 165F
I have been looking at dehydrators and cobbled one together for experimentation. I thought it would be good to use on a first start because, it is cold, short run, rich and expected some blowby.
Post run, we hooked the dehydrator, powered with a little aquarium pump, the dry air into the breather pipe and moist air out the oil fill tube (540).
About an hour later, there was water collecting in the exit hose. The warm, moist air was condensing water in the hose! - He estimated 1.5 tablespoons!
We were both shocked to see that much water. The desiccant was not weighted or measured, but surely there was more water coming out via adsorption.
Now you know, definitively, how much water you could leave in the crankcase for a short engine run. Decisions about dehydrators, water returning to crankcase via oil separators and such are left to other treads, but everyone about to expose your expensive new engine to a joyful first start should take note of this situation.
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