breaking in a cylinder

getonit

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I had to replace a cylinder on my io-235 in my 152 and the mechanics told me to run the engine above 75% for "a while" and use 100 weight mineral oil. I have been flying around for "a while" waiting for oil consumtion to stabilize, and I think it has, it isn't using any more or less oil than before, and then everything is supposed to be OK, ie normal operations. I have asked around and gotten multiple answers and just want another opinion.
Thanks.
 

UnAnswerd

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getonit said:
I had to replace a cylinder on my io-235 in my 152 and the mechanics told me to run the engine above 75% for "a while" and use 100 weight mineral oil. I have been flying around for "a while" waiting for oil consumtion to stabilize, and I think it has, it isn't using any more or less oil than before, and then everything is supposed to be OK, ie normal operations. I have asked around and gotten multiple answers and just want another opinion.
Thanks.
Is there a question in there???....:confused:
 

avbug

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Most manufacturers recommend break-in using mineral oil, though the truth is that AD multiweight works just as well. The need for use of mineral oil, and it's necessity, is an old myth.

You should adhere to manufacturer recommendations where breaking in; generally 25 hours of breakin is more appropriate, though of questionable necessity.
 

TrafficInSight

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avbug said:
Most manufacturers recommend break-in using mineral oil, though the truth is that AD multiweight works just as well. The need for use of mineral oil, and it's necessity, is an old myth.

You should adhere to manufacturer recommendations where breaking in; generally 25 hours of breakin is more appropriate, though of questionable necessity.
We use regular 100 weight AD and a 3 hour cross country breakin when it's just a new cylinder and we get good life out of them. We're a flight school though so our planes fly a lot.
 
T

TDTURBO

It's common practice to run the new cylinder at 75% power or better to prevent glazing, don't baby the engine, it's the worst thing you could do unless you plan on changing tops every 300hrs. In order to do this, never fly higher, (non-turbo), than 5000 ft for the first 25hrs or until oil consumption has stabilized. Since you only replaced one cylinder, oil consumption will be negligable, so stick with the old rule of thumb.
 

jafo20

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Use the mineral oil. AD tends to generate a film between the piston and cylinder which screws up the break in. Can you get away with using AD? Probably. Still, why not go with manufacturer's recommendations and use the mineral oil?
 

bocefus

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jafo20 said:
Use the mineral oil. AD tends to generate a film between the piston and cylinder which screws up the break in. Can you get away with using AD? Probably. Still, why not go with manufacturer's recommendations and use the mineral oil?

ECI, who has more cylinder break in experience than Lyc or TCM, does not recommend Mineral Oil for break in. The recommendation is Phillips X/C 20W-50
multi grade. In addition, both LYC and TCM specify to not use mineral oil for break in on their respective turbocharged engines, Use of mineral oil for break in is an old myth with no basis.
 

jafo20

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Gosh. I have a TCM io-520 manual that talks about using straight mineral oil. Perhaps the manuals have changed over the years (mine is from the '80s)? In any case, factory recommended oil (min or AD) is the way to go.
 

jknight8907

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I don't know about all of their engines, but Lycoming's latest instructions on the TIO-540 are to use NO mineral oil. Might want to check on that.

Note: What's stamped/stickered near the oil filler may not be correct. For example on the Navajo, there's a sticker under the oil filler door which lists the correct mineral oils, but also a note that says to check the latest [instert lycoming maintenance directive # here] for directions---which at the moment say NO.
 

Peanut gallery

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The mineral oil thing again

Of course always follow manufacture reccomendations. The one thing that I feel is most important and has always worked for me is to make sure the honing of the cyl and a good cross hatching pattern is visible prior to installing the new cyl. I spend a considerable amount of time doing this and never rush the process. Works every time regardless of what oil was used.

Just my .02
 
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