Firewall Forward Centri-Lube Camshaft

[randallg]

Due to a damaged camshaft my engine is undergoing overhaul. It is a Lycoming IO-360A1B6D. I am considering the Firewall Forward Centri-Lube camshaft STC which provides internal lubrication to the cam lobes. Does anyone have an opinion about this? My AME is fairly conservative and recommends factory parts.

http://www.firewallforward.com/firewall ... 07_011.htm

[N2]

Personally if it were my engine I would go with the lubed cam STC. Firewall Forward has a decent reputation and I doubt they would be doing this STC if there wasn't some good reason!

Just one other tid-bit of info I would like to share with you seeing as how your getting ready to do your engine. When I was at Oshkosh a few years back I talked to every single engine builder I could find down there and not one recommended using a semi-synthetic oil. In fact they strongly urged me not to use it,(remember these are some of the biggest and most respected engine shops around I talked to)yet alot of AME's I talk to recommend it, except for the one I use now. He still prefers to use straight weight for aircraft that don't fly on a daily basis.So when you get your engine done you might want to investigate what type of oil you are going to run.

Makes sense does it not, supply oil directly to the cam....works for me!

(great photo's by the way!)

[Hornblower]

It certainly sounds like a good idea. I am an AME and am completely supportive of the use of PMA parts. I believe that for the most part the PMA parts are an improvement on the manufacturer’s parts and (with a few notable exceptions) offer good value and reliability. As for Lycoming parts, don’t get me started, since in my opinion they have been consciously degrading the quality of their products for over 30 years now. However there is always a risk.

I would tend to agree with N2 that the theory is sound. Keeping that in mind the biggest problem with Lycoming camshafts is corrosion to lobes and lifter bodies. What was your problem? If it was corrosion because your aircraft flys infrequently, or had been out of service for some period of time without being properly inhibited, better lubrication is unlikely to solve your problem. In this case more frequent use of the aircraft (at least once every two weeks) along with a heavier grade of oil (I agree with the rebuilders) and proper operation techniques, will be the solution.

[randallg]

N2 and Hornblower, thanks for the responses. Here is some more detail if anyone is interested, which was posted to cardinalflyers.com.

Subject: GAMIjectors - out of whack - problem solved

Here is an update on the problem I was having getting my Gamijectors tuned on my engine. As I posted in #3311 in September, I had done a lean test that indicated #2 was peaking at the lowest fuel flow and a spread of 0.7 gph. John-Paul at Gami said great, we`ll get you a leaner #2 and it was installed. Then the next lean test indicated that #2 had actually gotten a little worse, with a spread of 0.8 gph.

There followed some discussion in digest #3314 with Paul and George Braly that suggested investigating #2 for other problems such as induction leak or cam lobe wear. Well, I finally got it into the shop on Friday.

First thing the AME did was measure the intake valve lift. He compared #4 at 0.46 with #2 which was 0.25. So off came the cylinder and what do you know? The #2 lifter has failed in such a way as to make it pound against the cam lobe, which in turn is badly damaged. The camshaft is ruined and my engine goes to Progressive in Kamloops this week for teardown and repair.

This may explain a lot. Cylinders 1 and 2 share the same damaged cam lobe for the intake values, so I believe both those cylinders have been producing less power. CHT on #1 and #2 have always been significantly less than #3 and #4; I assumed this was because they got more airflow. The engine has always run smoothly.

This aircraft cruises at 130 knots or maybe slightly more. The previous owner thought this was normal, but it has concerned me ever since I started reading this digest and discovered most RG owners claim 140+ knots cruise, which of course is what the book says too. The flaps were badly out of rig, but fixing this made little difference. The other controls have been carefully re-rigged as well. Nothing has helped in a significant way. The only other thing that should cause this is a lack of power, but I always got full RPM and MP. Should have had the camshaft checked a long time ago...

While the engine is off this may be a good time to get the Firewall Forward Horsepower Plus STC. I`ve searched the digest and people seem to be pretty happy with it. My only concern is oil temperature; mine goes into the 220`s on a hot day, CHT`s are under 380. The FF oil cooler STC was installed this summer which helped a little but not much. The Vernatherm also came off on Friday and there is some visible damage where it seats. This will be machined and fixed. However, I`m not sure I want to put the FF pistons in before I have solved the oil temperature problem. This is a bit of a conundrum. Any suggestions?

Further to my post in #3354 regarding my destroyed camshaft and oil temperature problems, I have received some photos my mechanic took with his cell phone camera.

These show the damaged camshaft lobe:







These show where the vernatherm seats:

[randallg]

Further to my previous post, I have decided NOT to go for the Firewall Forward high compression piston STC, because of my oil temperature issue. I want to make sure that oil temps are normal after this overhaul. Their nifty camshaft is still an option and I am leaning towards it. I'm thinking of flying up to Kamloops to visit Progressive next week and have a close look at the engine, and talk to them about it.

[Hornblower]

Excellent research … good to see a private owner get the legwork done before spending money on a major rebuild.

It certainly looks like corrosion played a part in your premature cam failure, which is quite common on Lycoming engines flown infrequently.

Center-lube cam or not, breaking the new engine in well with nice gooey Aeroshell 100, followed by W100 for it’s remaining service life is better than using the 15w50. W 80 for really cold temps, and then only with good engine preheat, and warm-up techniques.

Leave the 15w50 for the engines that fly multiple flights every day. (my opinion)

[twistedoldwrench]

Yep on the corrossion problem- I like the AREOSHELL 15W50 after breaking in with Staight 100. My reasoning being a lot of wear and damage occurs during intial start up, and the thinner viscosity gets lube to the parts quicker. After that a proper warm up gets the viscosity up to were it needs to be for operation. Shell has a new line of 100 plus which has even more additives for the camshaft issues these engine are prone to have. My main point in posting is to say stay the hell away from that crap that comes in a blue container. In may experiance that brand "p" oil develops way more carbon deposits and sludge in an engine, and FWIW I've seen more premature engine removals with engines run on brand "P" than with the Aeroshell. I too have talked to many shops about this, and I think most would agree, in fact the old Lycoming manuals I have specifically don't recomend its use.

Food for thought and further discussions-opinions!!

[Ballsssssss]

Yep on the corrossion problem- I like the AREOSHELL 15W50 after breaking in with Staight 100. My reasoning being a lot of wear and damage occurs during intial start up, and the thinner viscosity gets lube to the parts quicker. After that a proper warm up gets the viscosity up to were it needs to be for operation. Shell has a new line of 100 plus which has even more additives for the camshaft issues these engine are prone to have. My main point in posting is to say stay the hell away from that crap that comes in a blue container. In may experiance that brand "p" oil develops way more carbon deposits and sludge in an engine, and FWIW I've seen more premature engine removals with engines run on brand "P" than with the Aeroshell. I too have talked to many shops about this, and I think most would agree, in fact the old Lycoming manuals I have specifically don't recomend its use.

Food for thought and further discussions-opinions!!

That's some good info about the brand "P". Thanks!

[Hedley]

Brand "p" (blue bottle) is preferred by many
operators because it is cheap, and can be used
as a break-in oil when you change a jug. I
don't run it.

For winter, I like the Aeroshell 15w50 to reduce
metal-to-metal damage during startup. It would
be nice if every start was perfectly pre-heated,
but in the real worth that doesn't always happen.

For the summer, though, Aeroshell 15w50 is
probably not your best choice. When it gets
hot, the Viscosity Improvers that give it that
magical SAE 50 weight break down, and you
are left with the very thin SAE 15 base stock.

For summer, I prefer the Aeroshell 100Wplus
which has the LW16072 which is an extreme
pressure additive required by AD for the infamous
"H2AD" engines used on the 1976-1980 C172's
which consumed lifters like they were going
out of style.

100Wplus is also cheaper than 15w50, and
also has the advantage that it won't run off
the cam lobes as fast as the thinner 15w50
when it's parked for an extended period of
time.

And that, I suspect is the real problem behind
the Lyc cam lobe spalling - (private) owners
parking their aircraft for extended period of
time without pickling them as per the service
instruction/letter.

Often what happens is some elderly owner
flies less and less, then finally dies. His estate
sells off the aircraft, but by then the damage
is done. 12 to 18 months of inactivity is
generally enough to kill a Lycoming cam lobe -
obviously depending upon temperature, humidity
and salt. The engine will start up and run and
pass the compression test, but it will produce
poor power.

I should mention that some people think that
Lyc cam lobe spalling can also be caused by
microscopic misalignment of the lifter and
the lobe, due to manufacturing tolerances
in the machining of the lifter cavity in the
clamshell, but I am somewhat dubious of
that. I might suspect that metallurgical
flaws in the camshaft (Lyc cranks, anyone?)
or surface-hardening treatment process
inconsistencies would be more to blame
than lifter misalignment.

[N2]

Just thought some might find this interesting, from the Piper Owners Society website.

Ron Wrote:
-------------------------------------------------------
> You do NOT want to use any automotive engine oils
> in an aircraft engine. The crankshaft and rod
> shell-type bearings in an aircraft engine are made
> from different alloys (containing silver) than an
> auto engine's bearings (no silver), and the
> organic zinc compounds that auto oils are loaded
> with, will attack the aircraft engine's bearings
> and leech out the silver and ruin them. You only
> want to use aircraft oils made for piston aircraft
> engines, and change the oil frequently or it will
> end up costing you a premature engine overhaul.
>

The only place you will find siler bearings is in some radial engine bearings. The sulfur in zinc dialkyldithiophosphate will attack silver and copper however there are inhibitors used to prevent that.


> Aircraft engine oils are contain ashless
> dispersant compounds that help to keep the
> tetraethyl lead combustions by-products (lead
> ash) in suspension in the oil, so they do not
> deposit into thick grey sludge in the nooks anc
> crannies inside the engine. Auto oils do not have
> this additive, since leaded auto gasoline has been
> completely removed from the US market for about a
> quarter of a century now.

There is about 3% polyamine "ashless" dispersant in aviation oils. There is about 5% in car oils and 9% in heavy duty diesel oils. It is the oxidized fuel components (from blow-by) called deposit precursors that that the dispersants bind to. The lead particles get caught in the carbon deposits and add thickness. The lead particles by themselves do not cause any problems.

The major problem with using auto oil is the metallic detergents. The FAA is concerned that aircraft engines burn some oil and that these metals will form metallic oxide hot spots in the combustion chamber. These deposits can cause preignition and serious engine damage.

>
> There are available on the market right now, two
> brands of premium semi-synthetic aircraft piston
> engine oils that are very good, and considered by
> most to the best that money can buy: Aeroshell
> 15W-50 and Exxon Elite 20W-50.

Aeroshell contains about 50% polyalphaolefin (PAO) and Elite contains 26% PAO. I cannot imagine a worse base stock for aviation use the PAO. Mobil AV1 was 100% PAO and had terrible problems with carbon deposits capturing the lead particles.
>
> There used to be a total synthetic aircraft oil on
> the market many years ago, but it was miserable at
> the task of lead ash handling, and many engines
> were ruined by the accumulation of the thick grey
> lead ash sludge in them.
>
> If you are concerned with the expense of frequent
> oil changes, then use Phillips 20W-50 XC
> mineral-based oil. It's much cheaper than those
> premium semi-synthetics, and will keep your
> engine lubed just as good and the engine will last
> just as long. All official aviation piston engine
> oils on the market today are very good oils, as
> long as you change them regularly to keep the
> engine clean inside. The premium semi-synthetics
> are probably a bit better if your engine sits in
> the hangar unflown a lot, as they have an
> anti-corrosion additive that helps reduce
> corrosion in engines that aren't run as
> frequently, but if you do fly frequently (at least
> every week or two), then the cheaper Phillips
> 20W-50 mineral oil is excellent, and the
> thriftiest choice of oil you can buy on the market
> today.
>
> Personally, I run Exxon Elite in my airplane these
> days, because it often sits in the hangar for 3 or
> 4 weeks in between flights, and the extra
> corrosion protection claimed by the manufacturer,
> and also reported by many users, makes me feel
> more comfortable, but back in the days when I was
> flying every week, I used Phillips to save money.
> My engine now has 1700 hours on it (it's an O-320)
> and compressions are still in the 70's and it runs
> great, does not burn or leak any oil, and I have
> no doubt it will easily make it to full 2000 hours
> TBO or beyond, mostly because I took good care of
> it and always changed my oil and filter on
> schedule or even earlier when it started looking
> "dirty" on the dipstick

I was the director of the engine laboratory and Exxon Research.
I performed the initial research on the Exxon Elite. Exxon ended copying the Aeroshell product for business reasons. I was disappointed in the Elite so when I left Exxon I created Camguard. It has 25 times the rust inhibitor that the Elite has, a deposit control package, and a vastly superior antiwear package.

Regards,

Ed


Edward Kollin
Technical Director
Aircraft Specialties Lubricants
http://www.aslcamguard.com