preserved engine question

[jwilbur]

I hung my new-from-Lycoming IO540 last weekend. I installed the prop last night. The engine comes preserved and I understand I am not to rotate the engine until the preservative oil is being drained. While installing the prop and tightening the bolts there was a few times where I had small movement - maybe ~1/2" at the edge of the starter gear - enough to hear a little air moving in a cylinder (I have desiccant plugs in which don't appear to be entirely air-tight).

At the time I assumed such little movement is not an issue, but now I'm concerned that "don't rotate the engine" might mean "no movement at all." Can someone explain why we don't want to rotate when it's preserved? And what is appropriate to do if I did a no-no.

[lr172]

Originally Posted by jwilbur

I hung my new-from-Lycoming IO540 last weekend. I installed the prop last night. The engine comes preserved and I understand I am not to rotate the engine until the preservative oil is being drained. While installing the prop and tightening the bolts there was a few times where I had small movement - maybe ~1/2" at the edge of the starter gear - enough to hear a little air moving in a cylinder (I have desiccant plugs in which don't appear to be entirely air-tight).

At the time I assumed such little movement is not an issue, but now I'm concerned that "don't rotate the engine" might mean "no movement at all." Can someone explain why we don't want to rotate when it's preserved? And what is appropriate to do if I did a no-no.

During preservation, the cyl walls are coated to prevent corrosion. The pistron rings moving across the wall scrape off that film. I don't have enough experience to tell you how well the protectant does after being scraped by the ring. If it will be running in a couple of months, it probably isn't an issue. I wouldn't leave it unprotected for several years after that.

I simply coated my cylinders with oil during assembly. Engine sat for 6 months + with dehydrators in the plug openings. Engine was turned on several occasions. No corrosion on inspection prior to first start. However, I do not know anything about the properties of the preservative used.

There are methods to deal with this, so you haven't destroyed your engine.

Larry

[jwilbur]

Thanks for the answer. I do expect to be flying within a few months.