Rust on my camshaft!

[Dean Pichon]

I just "wasted" $1500 on a new camshaft. My engine was in the shop for a sudden stoppage teardown inspection and I was informed I would have to pay for a new camshaft due to corrosion.

I'm very frustrated as I feel I have always babied this engine and now have no idea how to prevent it in the future.

This camshaft is from a factory new (2001) O-360 A1A. I fly regiously once a week and have accumulated a little better than 450 hours over about 7 years since the first flight. It has always been hangered and for most of its life, it has been stored in a heated hanger. I change the oil and filter twice a year. I perform an oil analysis and add AvBlend at every oil change.

In the fall/winter, I block off the oil cooler and see oil temperatures around 180F. In the summer, I run between 190 and 200F.

The rebuild shop told me replacing the cam is very typical in this situation. The returned cam had very little visible corrosion, but I have no frame of reference with which to judge.

I could use help with two questions:

Have others had similar experience with needing a new cam early in an engine's life?

What can I do in the future to extend the life of this expensive part?

All input is most appreciated.

[gpiney]

I can't help you with your particular 'why' , but I recently saw a presentation by the formulator of the product 'CamGuard'. Not a sales pitch, an engine wear/corrosion/oil lecture. Most of the presentation is Here.
I Don't work for them, I Don't use the product.

[hevansrv7a]

I'm sorry for your troubles but perhaps this will help..

1. Camguard: I've seen the presentation, too, and I am impressed with the developer's credentials. I'd choose it over AvBlend which in automotive form has been controversial at best. I doubt it would hurt and it might help as it is designed to do so. Of course, if it's not on the cam then it won't protect it and I've seen much argumentation about just how long the oil film lasts. I have no specific reason for this but I would not use them both at once.

2. Rust - corrosion on steel - probably came from water rather than from acids in the oil. Is there corrosion elsewhere? Even with your nearly ideal storage conditions and frequent flying, you can't prevent moisture from forming inside the engine every time you shut it down. This is natural and unavoidable since CO2 and H2O are the result of combining O2 in the air with a carbon-hydrogen compound we call avgas. Since the hot air inside the engine can hold much more water in absolute terms than even the air in your heated hangar, condensation is inevitable every time you shut down. The dewpoint of hot moist air is higher than that of warm moist air. Ensuring that you get the oil hot on every flight, IMHO, does absolutely nothing to help with this problem as you are creating new moisture.
Try this calculator: http://einstein.atmos.colostate.edu/~mcnoldy/Humidity.html

OK, my suggestion is to keep the air in the engine way drier than ambient so that the dewpoint is always lower. Yes, you can pump dry air into the engine and thus remove the water that results from running it. You can dry out the engine before the oil drains off the parts. Tannis makes such a device. So does Engine Saver. See:
http://www.aviationconsumer.com/issu...rs/5585-1.html
This is what I use. When I got my engine, not pickled, it had those clear plastic dehydrater plugs in the top 4. After a while they started losing their deep blue color and going pink (from good to bad). When I hooked up the Engine Saver they went back to deep blue and stayed that way. I use it immediately after every flight and keep it running all the time, all year. Yes, you can make your own and there have been threads on this forum for that. Some of my friends have done that - copying my factory version. Lastly, I think that the chemical approach is superior to the compressor approach even though it's a PITA to monitor the indicator beads and bake the silica gel when necessary.

[rgbewley]

For what it's worth. The company that makes Camguard is Aircraft Specialties. They also regrind cams. Request that the cam be sent to them for regrind. Not a guarantee, but the chances are pretty good that it can be reground. If not, there aren't a lot of choices but to replace it.

Good luck.

[deene]

Dean, unfortunately, your cam situation is a common occurrence on Lyc's. Interestingly, a major cuprit in this situation are the cam followers. The mushroom followers are notorieous for rusting as they are cast iron which rusts very easily and quickly. Then each time you start the engine, they accelerate cam wear as the rust is worn off.

As suggested, try to get the cam reground...but don't expect too much luck as the hardened cam surface is not real deep. Otherwise, expect a big bill for a new cam, but do shop as discounts and prices vary.

The new roller cam followers offered by Lyc and others should help the situation, but I believe are not retrofits. And as noted earlier, many owners are beginning to use air drying systems after shutdown to lower the corrosion while some have used a low power heater (light bulb) for many years to keep the engine at a high temp than ambient to forstall moisture formation.

[Russ McCutcheon]

My Cam and followers only had 900 hours in 16 years, stored in an un-heated hanger hear in the NW. On tear down it looked pretty good and both the cam and followers where re ground and are running now with over 650 hours in 4 years.

If you say they have very little visible corrosion then they where probably still just fine and would have kept right on if you had not had the unfortunate opportunity of inspecting it early, maybe the shop was more worried the engine mite come back to them before TBO if they re installed your old cam. Send it to ECI or one of the other shops and have it inspected and reground to sell or use later, send the followers to.

[rocketbob]

Dean, what brand and weight of oil have you been running?

[mculver]

As others already mentioned, this is a realy issue with Lycomings. I have done four things to mitigate the problem on my Lycoming O-235, located in the Pacific Northwest (a terrible place in terms of rust):

1. I use a premium oil that Aircraft Consumer found to be superior in terms of protecting the cam when the engine is run infrequently (on weekends is infrequent). I use Exxon 20W50, which was their top choice.

2. I use an engine dehumidifier. Google for this term and any number of solutions pop up. BTW, in my opinion this is the #1 best thing you can do for your engine.

3. I also use CamGuard. BTW, Aviation Counsumer said that this is good enough to make premium oil less than cost effective.

4. I always get an oil analysis with each oil change, and keep an eagle eye on "iron" (rust). It is this analysis that tells me the dehumidifier is most effective, and in fact I am not as certain about CamGuard as the glowing reports frin others. (Because the reports don't prove it out as helping -- although I am waiting for the latest report as I write this.)

[rv72004]

Sorry about your cam. More often than not, rust is linked to geographic location. If you hanger in a area with high humidity and large temp fluctuations, it will form much more readily than in a dry climate. Lycomings cam is in the air, whereas Conti has their cam in the oil. This helps a lot with corrosion.
If you have corrosion on the cam, there should be some corrosion in the cylinders too. Was there any? What about on the gears?
Maybe a second opinion on the cam is called for. Im no engineer, but there is a quantity/limit to the corrosion allowable. Engine shops may vary on this decision as I have found.
Rhonda from Barretts and Mahlon from Mattituck post a lot on this site and could maybe enlghten us with facts/advice.

[gasman]

Originally Posted by rv72004

Sorry about your cam. Lycomings cam is in the air, whereas Conti has their cam in the oil. This helps a lot with corrosion.

So does this mean that when the engine is shut off that the cam is covered by the oil in the sump??..............

I don't think it works that way.