Rust on the cam?

[88drvr]

Hi guys,

Question for the group. I have quite a bit of J from years past and loved the airplane. I eventually got a job with the airlines and have had very little general aviation time recently. (because I was living in Florida throwing money at boats ) Now that I am in Ga, I am looking at getting back into an older J or possibly an F.

One common pitfall I see the group warning about is an aircraft that's has been "sitting" and issues with the camshaft. I don't ever remember this being a concern in the "J" search 20 years ago, but of course we didn't have user groups on the web either to warn of such.

So when doing a pre buy, you certainly want to get the cam inspected for rust, but it still seems there is concern here even if it isn't detected.

How few hours flown is too few and in what time frame? (I known it can't be a specific answer)

If the aircraft had sat, but now is flying regularly, does that generally mean it would concern you less?

I know that just like with boats, there is always going to be surprises and $$, but avoiding an immediate overhaul is a biggie.

Thanks in advance.

[RobertE]

This is an excellent question and I'm interested to see the answers. Let me tell you my little story. This is just a single data point.

I purchased a J that was in superb condition in all respects so I'm confident it had loving care. It lived in Denver, though and flew only only 30 hours per year for the last three before purchase. One year later on engine tear down after a prop strike one of the lobes was shown to be worn. The engine performed just fine in the meantime and my mechanic guesses it may well have made the next 1200 hours to TBO, albeit it with one cylinder not breathing as well as the rest. I don't know how precise a borescope inspection is. I do know that the lobe wasn't rusty, just out of spec. I wonder if that condition would have been identified.

[Marauder]

From my understanding, the only real way to determine the cam status is to pull a jug and look.

[FAST FLIGHT OPTIONS LLC]

You could find a bird with a run out engine that's priced right and start with a fresh engine.

[Alan Fox]

It happens , but it is not common , I bought a bird that was hangered for 18 years withoutr being flown , on a field overhaul.....65 hours in and it runs like a top....Cams dont always go because of rust......that being said , if you cant afford to overhaul the engine , you probably should be renting ,  these things break , and you should be prepared for major expenses at any given time, that way if there is no problem , than no problem....

[KSMooniac]

There are some reports on here of new owners getting planes that have little or no use over the previous few years, and then having cams give up within 100-200 hours of regular flying over the subsequent 12-24 months.  There is no easy way to inspect a cam short of removing a cylinder or two either, so keep that in mind while shopping.  

 

Regarding the lack of such tales from 20 years ago, I *think* that is due to better parts being made by Lycoming in the old days before bean counters took over and outsourced everything to the low bidders.  Flying was cheaper back then too, so I suspect more planes flew regularly compared to today with $6+ avgas and a crappy economy.  Lycoming has a spotty track record over the last 15-20 years with numerous cam and crank quality issues.  

 

If I were buying today, I would have to consider who did the overhaul and what was included as well as when it was done (or when the parts were made) along with the usage pattern and location.  A hangared dry country plane will always be better than a tied-down coastal plane in my book.  In between those extremes...well, you just have to dig deep.  I'd like to see a minimum of 75 hrs/year of regular flying, and oil analysis results, use of Camguard, etc. would be nice as well.  

[jetdriven]

There are some reports on here of new owners getting planes that have little or no use over the previous few years, and then having cams give up within 100-200 hours of regular flying over the subsequent 12-24 months.  There is no easy way to inspect a cam short of removing a cylinder or two either, so keep that in mind while shopping.  

 

Regarding the lack of such tales from 20 years ago, I *think* that is due to better parts being made by Lycoming in the old days before bean counters took over and outsourced everything to the low bidders.  Flying was cheaper back then too, so I suspect more planes flew regularly compared to today with $6+ avgas and a crappy economy.  Lycoming has a spotty track record over the last 15-20 years with numerous cam and crank quality issues.  

 

If I were buying today, I would have to consider who did the overhaul and what was included as well as when it was done (or when the parts were made) along with the usage pattern and location.  A hangared dry country plane will always be better than a tied-down coastal plane in my book.  In between those extremes...well, you just have to dig deep.  I'd like to see a minimum of 75 hrs/year of regular flying, and oil analysis results, use of Camguard, etc. would be nice as well.  

 

That's about what I think as well. We bought a plane with 1100 hours since overhaul, and it was underflown the previous two years, 70 hours and 35 hours. We did pull the #1 cylinder and looked around with a flashlight and a mirror. It looked fresh inside the engine. 200 hours (and 16 months) later, 3 spalled lifters, two ruined cam lobes, and a filter with a 1/2 teaspoon of metal. Trashed.

 

I have done a lot of reading about this and the most likely culprit is the lifter faces. Somewhere in the mid 1990's until 2005, the lifters were made of a substandard metal which gets corrosion, forms small rust pits, then works on the cam and eventually it fails. I am not eve sure pulling BOTH cylinders on one side will find it, the pitting occurs where the lifter meets the camshaft, and you really need to pull the pushrods and retract all 8 lifters off the cam to see the entire lifter face to find any pitting.  It begins as faint parallel scratches that can barely be seen. It progresses to tiny pits, then chunks breaking out of the lifter face.  Eventually the entire lifter face grinds out and that sends metal through the entire engine and pretty much trashes the whole thing.

 

  Curiously it seems to manifest itself as failure around 1200 hours SMOH on mid 90s and later engines. You don't really see this in Lycomings built before then. This board is full of tales of Mooneys with engines built before the mid 90s which still soldier on today.  We got burned and to solve the problem, installed a roller cam factory Lycoming engine. The roller cam engine has proven itself with 8 years of service now and the only failures I have ever heard of were two that the factory had when they first started building them.  You don't see an adjustment in the Aircraft Bluebook or in Jimmy's valuation calculator for a roller cam engine, but knowing what I know now I'd pay an extra ten grand for one that has it. You completely eliminate the #1 reason for early engine failure.

[KSMooniac]

FTR, I'm flying behind a 1991 factory overhaul and 2000 SMOH.  /knocking on wood.  I had to freshen the cylinders at 1650 SMOH with honing, new pistons/rings, 1 exhaust valve, and new seats/guides all around.  Cylinders looked great and I'll likely overhaul them whenever my time comes.  My plane was hangared in WI and AZ with the first owner (1977-2003) and then in KS with the second owner (2003-2007) and still hangared in KS today.  Regular use throughout her life, although the last few years in AZ were pretty light before the original owner sold it.  He flew it *to* Lycoming for the factory OH and they did the R&R as well.  (and he had some nagging issues judging from the paperwork I have)

[aaronk25]

All you can do is inspect the logbooks and see if there is a period of inactivity prior to purchase. Roll the dice, but be cautious in allowing extra money for a engine that is only 1/2 way to TBO.

Run the engine every week for at least an hour and I bet the cam would make it 3,500 hours 1.5 times past TBO.

Hard to wear a engine out, but with frequent running and keeping temps in check they last one hell of a lot longer than the manufactures suggest.

[88drvr]

Good stuff. Thanks for the replys everyone.

[88drvr]

It happens , but it is not common , I bought a bird that was hangered for 18 years withoutr being flown , on a field overhaul.....65 hours in and it runs like a top....Cams dont always go because of rust......that being said , if you cant afford to overhaul the engine , you probably should be renting ,  these things break , and you should be prepared for major expenses at any given time, that way if there is no problem , than no problem....

I agree, but for me it is not a question of being able to "afford" an overhaul if and when it breaks. It is trying to make sure that the purchase price reflects any additional "risk" that an overhaul might be required sooner rather than later. None of us want to pay a premium on a "low time engine" when it may have no reasonable shot of making it to tbo because of inactivity.