Ask Paul: How would I know if my engine’s cam lobes are pitted?

Question for Paul McBride, the General Aviation News engines expert: I have a nearly new Lycoming that has been mostly well stored since it came from the factory in 1978. The engine had been stored in an air conditioned room until I got it in 2011. The engine did sit for a couple months in an open air garage in Florida before it was placed in a heavy duty bag with a hygrometer and renewable desiccant.

Over the past few years, the cylinder walls always looked like new whenever I inspected with a borescope. As my plane project was nearing completion (four years out), I almost pulled a cylinder to see if the cam lobes had any corrosion. Luckily an old hand convinced me that the risk was not worth the reward. If the cam was bad, it would let me know, and if it was good, then I risked loosening big bolts for just a “warm and fuzzy.”

Last fall I pre-oiled and started the engine. I had to run it numerous times on the ground, for a total of about an hour, to work out some issues which were due to a dumb installation error. I don’t think the cylinders got glazed, based on the absence of any brown tint on the walls as checked with a borescope.

Currently I have eight hours of air time on it and it seems to be running well.

Changed the oil at five hours and saw only a couple aluminum flecks in the filter. So far oil consumption has been 1/2 quart or less over the 8 hours.

I have two questions.

First, if the cam has been pitted I was told that it would run fine for about 40 hours before it started making noticeable metal. Do you concur?

Second, based on the model/serial below, can you tell me if this engine has hardened valve seats?

• AVCO Lycoming
• Model: IO-360-B1E TC: 1E10 (QA Tag says Final Inspect May 30, 1978)
• Ser No: L-19264-51A
• Normal HP: 180 @2700 rpm

Cylinder fins were marked with some light blue at the factory, so I assume it has nitrided cylinder walls.

Thank you for any light that you can cast my way.

I always enjoy reading your column, and usually learn something.

Mike Kusnir, via email

Paul’s Answer: Mike, you certainly have a unique situation here and I can only offer my thoughts that, I hope, will give you some peace of mind.

First of all, I must admit that an engine that left the Lycoming factory in 1978 may be a little concerning, simply because of the time it’s been in storage, especially in Florida.

Because of the salt air environment and the high humidity, I think you can understand that this does not go well for stored or inactive aircraft engines.

However, I admit that my concern for the lobes on the camshaft showing signs of corrosion is very low on the scale. I’m making this statement assuming that the engine wasn’t run for any extended period of time and that the oil was fresh at that time.

It’s the by-products of combustion that cause us concern because of the moisture and acidic properties that are found in the oil resulting from normal operation. My main concern would be signs of corrosion on the cylinder walls resulting from the times you exposed them to outside air while doing the borescope inspections.

However, I’m relatively confident that your cylinder inspections wouldn’t be cause for alarm when it comes to cylinder corrosion.

I am concerned about running the engine on the ground because it doesn’t allow the engine oil temperature to get high enough to boil off the condensation, but that’s water over the dam now, so let’s proceed.

Glad to learn that you pre-oiled the engine, have put eight hours of flight time on it at this point, that you changed the oil at five hours, and that the consumption looks very good. The aluminum flecks you observed are nothing I’d be concerned about at this point.

Getting back to your questions: If the camshaft lobes are by chance beginning to spall, I agree it may take a few operational hours before the metal contamination would show up in the oil filter.

You may want to consider having an oil analysis done so that you can start a baseline. It’s important that you use the same operational drain time in order to compare each sample.

If you are concerned, you may want to consider taking your oil sample every 10 hours for the first few oil drains and see how they compare with the previous results.

Please keep in mind that one or two samples isn’t enough to see if there is a trend, so don’t be alarmed by the report on the first sample. In the big scheme of things oil is inexpensive so I wouldn’t hesitate to do your samples at 10 hours as mentioned above.

I can’t concur with the statement that the engine would run fine for about 40 hours before it started making metal because that would depend on the degree of corrosion and operational hours.

To my knowledge, the engines built in 1978 have the same valve seats currently in production.

With regard to the light blue paint on the cylinder fins between the shroud tubes, yes that does indicate that the engine does have nitride cylinders.

Mike, I appreciate your kind comments regarding my articles and I hope I’ve offered some common sense answers in responding to your situation.