I don't want to be the best pilot in the world - Just the oldest
Join Date: Jun 2001
Location: Here and there
IO 360 Camshaft wear
Have had a couple of Lycoming IO360 camshafts that have had excessive wear on the lobes which was not detected until strip down for o'haul of the engine. By excessive I mean even I as an untrained person could look at it and say "WTF"? The symptom was a decrease of power but with the usual checks of compression and prop condition, the engineers were unable to pinpoint the problem. After the first overhaul with a new cam fitted the engine went like a dream but the new camshaft supplied by Lycoming has shown the same problem when stripped down due to a prop strke. This is after only about 1000 hrs. Is this a common problem with camshafts on the IO360? More importantly, what is Lycoming's position on these with regard to warranty?
Unfortunately, what you are describing is 'normal' for Lycomings. There has been a great deal of discussion over the years about Lycoming pre-mature camlobe and follower wear. There are a couple of STC's out to try and increase the oil supply to the affected areas. These apparently work. I have lost count of how many engines we have had stripped, either for inspection or overhaul, where the camshaft was shot, and well before the specified overhaul time.
Oh, and Lycoming blame everybody else and it is not their fault. i.e. no oil in the engine, wrong oil in engine, revving to max chat from cold, etc
Not too much experience or time with the IO360. The other person that responded when he said something about the location of the cam being on the top of the engine is the problem-a design flaw. Being on the top of the engine it does not get oiled. The fix I used is the Ney Nozzle. Do a google search. What he does is to drill into oil galleys in the case and installs nozzels that spray oil on the cam. Preoiler is another good idea. I believe with both install you should get long life from the 360!
Islander Jock, Just seen your latest post. 100 hrs is justifiable for warranty, providing that 100 hrs hasn't taken 5 years to clock up. I have seen camshafts that have failed inspection after 700 hrs, but not 100 hrs. If your engine was reassembled by an approved organisation (i.e. Part 145) who purchased the items either direct or through the local Lycoming agent, then I feel you have straightforward grounds for a warranty claim, including the labour. If it was done another way, you may have difficulty. As westafricaops says, the Ney Nozzle modification, which is one of the STC's I was refering to earlier, works.
The suface of the cam followers in contact with the cam shaft are 'case hardened'. As the engine gets older this hard casing breaks up and the followers become badly 'pitted' the casing that is left around each pit mark thus leaves sharp hard edges to the pits (a bit like a pot hole in the road). These pittings then serve only to distroy the cam lobe by shaving the metal off them. Once it has started there is no way to stop it. Prevention is the only way to keep your engine in good condition. A 'collapsed' hydraulic tappit should be investigated and rectified immediately, there should be no tappit noise, since the hammer action of the cam against the follower can chip the case hardening off the follower. The cam rotates at half engine speed, so any 'tapping' at that speed may indicate a collapsed tappit. Making sure you have the correct grade of oil for the operating temperature and allowing your engine to warm up before any 'speed' demands are put upon it, is very important. Thick oil in winter is a killer! once the engine has been run in, an oil additive has proved to be helpful (we used STP or Wynns), this these products leave a coating of lubricant on the mating surfaces of the follower and the cam lobe so that (especially when left for a while) the components do not start up in an unlubricated 'dry' state.
How did you turn out on your warranty? I am in a similar situation, my engine was torn down at 550 hrs due to metal contamination from the cam. Had a prop strike 17 mo later, 60 hrs on the engine, & the cam looks horrible. So far, according to my A&P the warranty is being denied, as it is over a yr. Any helpful hints and / or prevention tips from your perspective would be great. Thanks,
Thankfully, Lycomings now come with roller lifters. One thing to consider with the Ney STC is that you are stuck with that case, I don't think Lycoming would look kindly upon any core value during an exchange situation.