Cylinder Glazing

[senior]

What causes cylinder glazing?
My motor had noticable loss of compression (50lbs) on one cylinder & low on another one (65lbs) so I removed the offending cylinders yest to check out problem. When pulling cylinder I noted orentiation of rings was way off. On both cylinders the rings (3 ring pistons) had spun & were in very close alignment, both were glazed but one was far worse, on it the oil ring had spun to the bottom.
This is a 30 hr A-65 motor with very low total hrs. It had new rings & bearings when I rebuilt it & I did the vent & jet mod & spin the motor 2500rpm on take-off & cruise about 2400. It is a great performing motor.
So what can cause glazing?
Improper break-in oil?
Some-one suggested not running it hard enough on break-in?
One thing I just thought of now is when it was assembled & the plane was flown it was getting on in the fall, maybe I didn't get enough heat in it? I ran it during past winter on ice fishing trips & such. The oil intake was closed completely & the cyl cooling openings were partially closed off. The motor ran about 160-170 on oil temp, maybe that wasn't hot enough??

Suggestions?

[Ragwing nut]

Re: Cylinder Glazing

improper homing will do it, but usually not getting head temps high enough. Also you should have been altering the load on the engine during the intial flights by climbing and decending. chrome cylinders are more susceptable to glazing. Personally I would not have pulled the cylinders with only 30 hours, since it can take 40-50 hours to completely break one in. But since you have. hone the crap out of them, and put them back on.

[barnstmr]

Re: Cylinder Glazing

You really need to get the cylinder head temp (CHT) way up close to redline and get a couple of hours time in this way to get a good seating of piston rings. ESPECIALLY IF YOUR CYLINDERS ARE CHROMED. It is not as sensitive to oil temperature as CHT for a good break-in.

ONE MISTAKE MANY PEOPLE MAKE IS TO RUN THEIR ENGINE A LOT ON THE GROUND BEFORE GETTING A GOOD BREAK-IN FLIGHT. It is best to run only a minimal amount of time on the ground as needed to verify magneto/carburetor operation, no major leaks. Then its best to blast off as the brave test pilot we all aspire to be. Run her hard and change RPM frequently, too.

We have found that Nickel plated cylinders with plasma rings break-in a lot quicker than steel or nickel cylinders. Here at RAM Aircraft, we use Nickel exclusively.