Is DLC Lifter Coating the Cure for Lycoming?

[MBDiagMan]

I have read and experienced the problem with the high cam Lycoming. With the cam high, if the engine is left unstarted in a humid climate for long enough, the oil can drip off the cam and corrosion will form. If the time comes when there is enough corrosion, a pit will form. Much like a chuckhole in pavement, a small piece will come out when the cam lobe wipes over it. Then another tiny particle and so on which results in metal in the oil filter, and ultimately can wipe the lobe off of the cam. This can also happen in a Continental, but I don’t think it happens nearly as frequently.

There are oil additives which keep the oil clinging to the cam and lifter. That helps. If the plane is flown regularly and/or kept in a dry climate this is often not a problem.

Roller cam followers help this problem immensely with reduced friction being a side benefit, but retrofitting to rollers at rebuild time is a pricey venture.

Lycoming is now manufacturing lifters with what is called: Diamond Like Coating (DLC.)

At this point, these lifters are very difficult to find, but fortunately I found a set for my current overhaul. An overhaul that is the result of the cam and lifter corrosion process that I described.

I don’t know how long they have been producing the DLC coated lifters, so I don’t know how tried and true they are, but it seems that this could be a major improvement.

[KSMooniac]

I bet it is, and I sure wish they were available when I overhauled 6 years ago. I did add the Centrilube STC, use Camguard, fly every week or two, and use a dehydration rig to improve my chances... I don't want to lose a cam lobe again either!

Sent from my LM-V405 using Tapatalk

[N201MKTurbo]

Diamond Like Carbon 

[N201MKTurbo]

Don’t let your plane sit and you won’t have cam problems.

[MBDiagMan]

Well, since the sitting happened before I got it, except for the fact that I bought it anyway, that was out of my hands, but I agree that frequent flying is the best cure.

In my defense, at the time of purchase the cylinders had been removed, everything inspected, fresh rings and back together so I thought all was good.

BTW, thanks on the correction.  I had read “coating.”

[N201MKTurbo]

Well, you can’t change the past. That Lycoming is a strong reliable engine that will take a lot of abuse. Just think happy thoughts and it will treat you well.

[MBDiagMan]

I know that.  It was running really nice when it started making metal.  It will be a great engine when we’re done.

[jetdriven]

19 minutes ago, N201MKTurbo said:

Don’t let your plane sit and you won’t have cam problems.

There’s no guarantee of that, in fact some people have flown their airplane more than once per week and after a few hundred hours had to do it again too  Such as @aaronk25

[N201MKTurbo]

8 minutes ago, jetdriven said:

There’s no guarantee of that, in fact some people have flown their airplane more than once per week and after a few hundred hours had to do it again too  Such as @aaronk25

But, thousands of them make it to TBO there are so many variables.

[MBDiagMan]

Although the cam and lifter corrosion problem is probably the Achilles heel of these engines, they are still susceptible to the same wear problems as any other engine.  Sure, operating regularly probably eliminates the Achilles heel, but it is still a mechanical device that wears and things happen.  Properly cared for and flown regularly I expect that it is as good as anything out there.

In my case, since it’s apart anyway, and since the Achilles heel was the cause of the tear down, the DLC lifters seem to be a great improvement.  If not for my benefit, maybe the next owner will end up having to let it set for awhile and will be hangaring it in a high humidity area.  It might be what keeps him from going through the same thing.

[jetdriven]

6 hours ago, N201MKTurbo said:

But, thousands of them make it to TBO there are so many variables.

There are a few variables.  But in the past few years, just noting locally, pretty much every engine I know that is torn down shows signs of cam/lifter distress.  The latest was a 252, which had corrosion on the lifters and cam, was allowable by Continental.  But all the Lycomings displayed spalled lifters.  Buy an engine, take a chance. But this board is full of people with the same story. 

Edited May 25, 2021 by jetdriven

[MBDiagMan]

Jetdriven, have you seen any evidence that the DLC coated lifters are helping this situation?

[jetdriven]

I don’t know anybody that’s torn one down yet but according to the guys at Lycon, it fixes the problem. I’d run them. 

[ArtVandelay]

According to Lycoming, if they had this technology back in the day, they would have never gone with roller lifters.

[N201MKTurbo]

If you want DLC on your tappets bodies, send them out and have them coated. Be prepared to wait. We had some parts done about a year and a half ago and the fastest turn we could find was 6 weeks. It is probably a lot worse now. They are hesitant to do small lots. They are up to there eyeballs in big orders.

[N201MKTurbo]

When I took my engine apart, it had no spalling on any tappet. There was a very small amount of micro spalling on one of the cam lobes. Would have easily made it to TBO. The engine had 1700 hours on it. 
 

I should go talk to the guys at the engine shop. They do hundreds of engines a year, mostly for the flight schools around here. I wonder if location makes a difference? We don’t have corrosion around here. Our atmosphere will actually dehydrate an engine.

[A64Pilot]

DLC on the lifters will help but it’s not a cure.

Why do I say that?  Because it’s cam spalling that is what causes us to tear down and we aren’t coating the cam. Even the description at the top of the page says oil drips off of the cam, and the cam corrodes. But you can’t coat both parts, apparently that doesn’t work

‘Actually even that may not be really what’s happening, it could well be blow by that’s the culprit as the location of a Lycoming cam puts it directly in line to be sprayed by blow by, and the blow by may be what starts the corrosion.

‘If it were simply humidity, every aircraft in Florida would lose a cam, and not one in Arizona would ever, and that’s not exactly what’s happening.

My Maule lived all of it’s whole life in Fl., was owned by a fruit Company and it flew them from one farm to the other. I owned it less than a year beforeI overhauled it just short of TBO and the cam and lifters looked perfect. It flew an average of just under 100 hours per year, for 20 years in Florida.

So we have some “experts” stating things that sound logical, so we go with that, but we aren’t sure.

‘If it’s moisture in the air, then connecting an air drier to the crankcase vent after each flight will absolutely 100% cure it.

‘Surely if that were the case then Lycoming would recommend it, and just about everyone would and there would be no problem?

I do not proclaim to have an answer, just saying it may not be as simple a problem as we are being led to believe, it could be that there is some kind of chemical difference in 100LL from the fuel back in the day, and that’s aggravating it?

It didn’t use to be the issue it is today or I don’t remember it anyway, but then we didn’t have the internet and forums either, so information didn’t disseminate like it does now.

On edit, it seems I’m often misunderstood here, I am NOT saying don’t use DLC lifters, I believe you would be crazy not to if you could.

What I am saying is that in my opinion it will help, but I doubt it will be the absolute cure, but I certainly hope that I’m wrong

Edited May 25, 2021 by A64Pilot

[mike_elliott]

11 hours ago, N201MKTurbo said:

Don’t let your plane sit and you won’t have cam problems.

Actually, there are planes that have been flown regularly that had cam and tappet part numbers show up in the suction screen. CarolAnn Garratt's J was flown weekly for hrs at a time and needed a new engine at about 1400 hrs from cam and tappet disintegration. Cant blame corrosion on this one. If it is corrosion causing the problem, why would LYC fix the effect (DLC tappets) instead of fixing the problem? I know, conspiracy theory. None of this first principal thinking allowed.... back to our group think Florida is bad for Mooneys..

 

[N201MKTurbo]

5 minutes ago, mike_elliott said:

Actually, there are planes that have been flown regularly that had cam and tappet part numbers show up in the suction screen. CarolAnn Garratt's J was flown weekly for hrs at a time and needed a new engine at about 1400 hrs from cam and tappet disintegration. Cant blame corrosion on this one. If it is corrosion causing the problem, why would LYC fix the effect (DLC tappets) instead of fixing the problem? I know, conspiracy theory. None of this first principal thinking allowed.... back to our group think Florida is bad for Mooneys..

 

I never said anything about Florida. Just everywhere that’s not AZ, NM AND CA east of Palm Springs.

[mike_elliott]

1 minute ago, N201MKTurbo said:

I never said anything about Florida. Just everywhere that’s not AZ, NM AND CA east of Palm Springs.

I know you didnt, but it is common group think to have corrosion blamed on FL on this forum as you are well aware. Bottom line, corrosion in any state is bad. Corrosion in an engine is bad. Poor lubrication is bad, Poor metallurgy is bad.

[A64Pilot]

As a Fl resident I can state unequivocally that Fl is bad for aircraft.

There is a reason that Davis / Monthan is not in Fl, but there are other reasons  to pick a place to live, and the humidity in Fl can be managed, IF you have a hanger with electricity.

‘I run a dehumidifier in my hanger and it keeps humidity to below 60%. I plan on installing a mini-spilt to do the same in the heat of Summer.

A 2 ton mini split with an SEER of about 20 can be had for $800 or so, I think it will cost about $100 a month to run it to dehumidify a 3,000 sq ft hanger. Not really to cool it like a house, just knock the humidity down. To really cool it woud require good insulation and that is beyond the $$ that I have.

‘It appears that you can knock out a home brew engine dehumidifier for $75 or so, certainly less than $100 and that’s with a timer, continuous run for maybe $50?

Edited May 25, 2021 by A64Pilot

[N201MKTurbo]

1 hour ago, A64Pilot said:

As a Fl resident I can state unequivocally that Fl is bad for aircraft.

There is a reason that Davis / Monthan is not in Fl, but there are other reasons  to pick a place to live, and the humidity in Fl can be managed, IF you have a hanger with electricity.

‘I run a dehumidifier in my hanger and it keeps humidity to below 60%. I plan on installing a mini-spilt to do the same in the heat of Summer.

A 2 ton mini split with an SEER of about 20 can be had for $800 or so, I think it will cost about $100 a month to run it to dehumidify a 3,000 sq ft hanger. Not really to cool it like a house, just knock the humidity down. To really cool it woud require good insulation and that is beyond the $$ that I have.

‘It appears that you can knock out a home brew engine dehumidifier for $75 or so, certainly less than $100 and that’s with a timer, continuous run for maybe $50?

There are two reasons the bone yard is here. No corrosion and our soil is so hard and dense a B52 will not sink when parked on the dirt.

[jetdriven]

4 hours ago, A64Pilot said:

DLC on the lifters will help but it’s not a cure.

Why do I say that?  Because it’s cam spalling that is what causes us to tear down and we aren’t coating the cam. Even the description at the top of the page says oil drips off of the cam, and the cam corrodes. But you can’t coat both parts, apparently that doesn’t work.

usually the lifters go first, since theyre chiled cast iron. Especially the regorund kind with no nitride layer.

‘Actually even that may not be really what’s happening, it could well be blow by that’s the culprit as the location of a Lycoming cam puts it directly in line to be sprayed by blow by, and the blow by may be what starts the corrosion.

‘If it were simply humidity, every aircraft in Florida would lose a cam, and not one in Arizona would ever, and that’s not exactly what’s happening.

My Maule lived all of it’s whole life in Fl., was owned by a fruit Company and it flew them from one farm to the other. I owned it less than a year beforeI overhauled it just short of TBO and the cam and lifters looked perfect. It flew an average of just under 100 hours per year, for 20 years in Florida.

if it was built before 1993 then yes, before they switched to crappy steel suppliers.

So we have some “experts” stating things that sound logical, so we go with that, but we aren’t sure.

‘If it’s moisture in the air, then connecting an air drier to the crankcase vent after each flight will absolutely 100% cure it.

‘Surely if that were the case then Lycoming would recommend it, and just about everyone would and there would be no problem?

nobody says dehydrators absolutely cure it, however, rusty tools in the toolbox lend that humid climates are harder on steel parts. And rust goes up dramatically above 50-60% RH.

I do not proclaim to have an answer, just saying it may not be as simple a problem as we are being led to believe, it could be that there is some kind of chemical difference in 100LL from the fuel back in the day, and that’s aggravating it?

It didn’t use to be the issue it is today or I don’t remember it anyway, but then we didn’t have the internet and forums either, so information didn’t disseminate like it does now.

On edit, it seems I’m often misunderstood here, I am NOT saying don’t use DLC lifters, I believe you would be crazy not to if you could.

What I am saying is that in my opinion it will help, but I doubt it will be the absolute cure, but I certainly hope that I’m wrong

 

[MBDiagMan]

6 hours ago, N201MKTurbo said:

When I took my engine apart, it had no spalling on any tappet. There was a very small amount of micro spalling on one of the cam lobes. Would have easily made it to TBO. The engine had 1700 hours on it. 
 

I should go talk to the guys at the engine shop. They do hundreds of engines a year, mostly for the flight schools around here. I wonder if location makes a difference? We don’t have corrosion around here. Our atmosphere will actually dehydrate an engine.

Of course location makes a difference.  Arizona is a dry climate.  Florida would be the opposite.

[MBDiagMan]

5 hours ago, mike_elliott said:

I know you didnt, but it is common group think to have corrosion blamed on FL on this forum as you are well aware. Bottom line, corrosion in any state is bad. Corrosion in an engine is bad. Poor lubrication is bad, Poor metallurgy is bad.

Using Florida as an example of a climate with more corrosion than, say Arizona, is not a slam against Florida.  Florida is a beautiful state with great people.  Coincidentally on average there is much more humidity in Florida than in Arizona.  Humidity accelerates corrosion.  Nothing against Florida.