I am considering a camshaft lubrication modification for my IO-540, and wanted some opinions.

The mod involves drilling small oil galleries in the cam lobes, plus a few other tweaks. This makes pressurised oil flow from the main gallery down the centre of the camshaft and onto the surface of the cam lobes. They receive a fresh supply of cooled, filtered oil under pressure. It's an STC held by Aviation Power Supply but our engine is uncertified anyway. Apparently they have modified over 400 engines in NZ and Australia and never had a problem, almost every model of Lycoming is eligible.

Obviously, a standard Lycoming engine relies on splash lubrication, which is less consistent, takes longer to take full effect during a start, and comes from the hotter / dirtier unfiltered oil supply in the sump. Corrosion of the Lycoming camshaft is considered one of the few Achilles heels of this engine design, given the top mounted cam. The mod only costs about $380 US. This shop has my camshaft out of the engine anyways, so it's the best time for it.

So that's the sales pitch. Any thoughts?

Man that sounds like a great mod to me.

Also looked at this when building my 540. Came to the conclusion that it doesn't work at the most critical and hardest time on the cam and lifters: startup.

I guess one could argue as soon as your turn the starter, the oil pump will push some oil onto those cam lobes but the system would need to keep its prime.

There was some other mod that added little pre-oiler jets that are electrically controlled or something before you crank. Can't remember what it was called.

https://backcountrypilot.org/forum/lyco ... -stc-18993

We'd like a silver bulletin for cam problems, and on the surface, this is attractive.

Contact Ed Kollin at Camguard. I trust his expertise. I suspect he'll advise you to use his additive, run straight weight oils if suitable in your climate, and fly often.

A roller cam also looks like a viable option, but you'd have to buy a factory reman to get it. I'm not even sure it is the answer, just that Lycoming needed to appear to take action.

For that price I'd do it. It can't hurt.

That's pretty much the basis under which many STCs are approved. Not that they do any good, just that they convince the governing body that they won't do any harm.

I'm guessing that the oil hole in the cam is away from the lobe, so there's minimum pressure between the cam and the follower as the lifter passes over what is essentially a void in the cam.

I'm not sure that it helps the steel parts though, just the psychological health of the pilot. You want to do anything you can to help those parts that are known to cause considerable grief to your pocket book, yet the damage is thought to occur more when the engine is off for extended periods than when the engine is running.

For me, I feel better knowing the parts are in constant contact than there being an interruption on each cam revolution.

A roller cam gives me even more reassurance, but there can be issues with them too.

No facts, just my intuition, and it's lied to me before!

The frequent burning of avgas seems to be the cure for most of this issue...

Zzz wrote:Also looked at this when building my 540. Came to the conclusion that it doesn't work at the most critical and hardest time on the cam and lifters: startup.

I guess one could argue as soon as your turn the starter, the oil pump will push some oil onto those cam lobes but the system would need to keep its prime.

There was some other mod that added little pre-oiler jets that are electrically controlled or something before you crank. Can't remember what it was called.

https://backcountrypilot.org/forum/lyco ... -stc-18993

This can be addressed by having a starter button and separate mag switch. Crank, watch oil pressure come up, mags on. We got into this habit with an O290 powered Cub years ago. Not a Lycoming but engine guru Ronnie Smith advocates for this on the Rotax.

As noted above, sitting is going to be hard on them regardless. The Camguard is a good thing.

gbflyer wrote:...This can be addressed by having a starter button and separate mag switch. Crank, watch oil pressure come up, mags on. We got into this habit with an O290 powered Cub years ago. .....

I had that thought, but then realized that the engine is gonna go around a certain number of times before the oil pressure comes up--
whether the mags are switched on or off.
So I don't see the advantage to doing it with the mags off.

hotrod180 wrote:

gbflyer wrote:...This can be addressed by having a starter button and separate mag switch. Crank, watch oil pressure come up, mags on. We got into this habit with an O290 powered Cub years ago. .....

I had that thought, but then realized that the engine is gonna go around a certain number of times before the oil pressure comes up--
whether the mags are switched on or off.
So I don't see the advantage to doing it with the mags off.

Could be. I'm no expert.

I had a centre-lube cam stc on my cub before the rebuild and engine teardown. It was a new cam prior to the mod and was 4 years old at the time of rebuild with close to 600 hours on it. More in the 2 years I had owned it than the previous two. When I did the rebuild I sent the cam out to be inspected and reground if necessary and they said that it was bordering the limits and with the drilled stc they wouldnt touch it. Just a little food for thought. My IA also said that it was a good theory, but not many do it any longer because it doesnt really help they way it sounds like it should. So we did not do it on the new cam. Just fly it regularly and you wont have an issue.

AKGCBC wrote:I had a centre-lube cam stc on my cub before the rebuild and engine teardown. It was a new cam prior to the mod and was 4 years old at the time of rebuild with close to 600 hours on it. More in the 2 years I had owned it than the previous two. When I did the rebuild I sent the cam out to be inspected and reground if necessary and they said that it was bordering the limits and with the drilled stc they wouldnt touch it. Just a little food for thought. My IA also said that it was a good theory, but not many do it any longer because it doesnt really help they way it sounds like it should. So we did not do it on the new cam. Just fly it regularly and you wont have an issue.

Thanks - that is a great point of reference.

What did they think the cause of the wear was? Near limits at 600 hours is a nasty little surprise.

Battson wrote: I am considering a camshaft lubrication modification for my IO-540, and wanted some opinions. The mod involves drilling small oil galleries in the cam lobes, plus a few other tweaks.....

A lot of Lycoming cams seem to fail,
most probably due to a lack of use.
The cam corrodes, the followers scrape off the corrosion,
eventually they corrode / wear through the surface hardening
and that's when the cam starts coming apart.
Hopefully this failure is caught through screen/filter inspection and/or oil analysis,
but sometimes the engine fails in flight. Not good.

IMHO when you drill a hole in the cam lobe,
you are breaking through that surface hardening
and just giving that corrosion / erosion
a place to get a toe hold.
All for limited / undocumented benefit.

Camguard.

I wish we had better data on this. Seems like most is anecdotal and limited in scope.

The real question is whether the splash coverage on the cam lobes and lifter body faces is actually inadequate? Is any damage done during full oil pressurization? Or is it always a startup/dry face issue?

Oil gallery integral to the cam would help the former, an additive like Camguard that provides a lasting coating would help the latter.

Another option to protect Lycoming cams is an oil accumulator. It is basically a small tank between the oil cooler and the engine that retains some pressurized oil when you shut down. A solenoid valve releases that oil before you go through the start up sequence, providing protection at the most critical time. Here's a link to a discussion about them from the Vans community.
http://www.vansairforce.com/community/archive/index.php?t-100090.html

Flyhound wrote:Another option to protect Lycoming cams is an oil accumulator. It is basically a small tank between the oil cooler and the engine that retains some pressurized oil when you shut down. A solenoid valve releases that oil before you go through the start up sequence, providing protection at the most critical time. Here's a link to a discussion about them from the Vans community.
http://www.vansairforce.com/community/archive/index.php?t-100090.html

That's an interesting idea. Looks like a couple guys on VAF have added them. Appears to be 2 brands: Moroso and Accusump. I think this in combination with the drilled cam would make sense.

http://www.shopmoroso.com/eb/catalog/na ... =main.menu

https://www.cantonracingproducts.com/cg ... key=24-026

After careful consideration, I have decided not to install this modification for a number of reasons.

Mostly our plane seldom sits idle, and the cam problems seem to abound when planes aren't flown regularly enough. There are also some compliance related concerns, given the peculiarities of the NZ certification system.

Use Camguard and fly as often as possible.

I have read that multiviscocisy oils protect better against corrosion but I can't recall the source. May have been Mike Busch.

I'm reminded of the air taxi outfit that used to be on my airport.
Several C172's and a C206.
Every airplane flew every day.
They ran a number of engines to TBO with few problems,
using straight-weight Aeroshell W100 with no additives, no pre-heat, no spin-on filter.