Tom's Engine is Fixed! Rotax 912 Complete Tear Down.
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- Опубликовано: 4 июн 2024
- Tom was having an issue with his rotax 912 where it would stop running around 5000 rpm. thinking it was a carburetor issue he decided he would install the edge-performance fuel injection system. Turns out that didn't fix the issue, so it was time to send the engine off to get fixed.
Mike at Stol Creek Aviation found the culprit.
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Развлечения
I was one of the floating valve comments on the last video. Lifters don't cause valve float, weak/broken valve springs do. If a valve spring floats enough, it can wipe out a cam lobe. I hope they checked the valves springs when they went through that engine, or this could very well happen again.
Exactly.
They were checked, the #1 cylinder, which the bad lobe controlled, were a bit weaker, coiincidence, or not?! They were replaced with new.
@tomrc. You are 100% correct. Lifters don’t cause valve float. Bad springs do or turning a higher rpm than the spring is designed to handle. The only other way to wear a cam down like that in that short amount of time is a finish issue between the cam and / or lifters or a hardness issue of the cam.
@@portnuefflyer If the reground cam has higher lift then standard springs might not be stiff enough.
Floated valves; 'lifters pumped up' not allowing valve to close...
I was taught it was the valve spring couldn't keep up with the rpm and momentum of the valve/pushrod.
I hope he tested his valve springs.
If he's got a weak one allowing 'bounce' that shiny new cam is gonna be short lived too.
You were taught right.
Watching you guys talking about this stuff makes me realise just how dumb I am!! Great video, keep them coming.
Kind of the same thing happened to mine probably 20 years ago in an 80 hp 912 UL. It just got to where it wouldn’t hardly get above 4500 RPMs I took it to Trevor Jacobson in West Monroe Louisiana thinking I had a carburetor or timing issue.
He was just spinning it over listening to it with the magnetos off just letting the motor spin and he told me I had a flat spot on the cam just by listening to it.
I was just thinking about this yesterday, for a new cam and installation total cost was $264.
Jonas, been holding my breath with great expectation to see you progressing with you plane. Please don't make me turn blue.
Trust all is well at your house.
Thanks for sharing.👍
⚘⚘ For your two girls. ♥️
Blessings.
A plane is on the horizon my man! :)
guys like Tom are full of super cool experience and wisdom. Love it.
My ears perked up soon as he said Prince Prop. After 1200hrs flying behind P-tips I agree. Great prop that can be custom manufactured for your exact specifications.
I want Tom and John Kangas around a campfire
I love his intelligence & wisdom!!!!!! What a treasured friend!!!❤❤❤❤❤❤
Let Tom know he’s loved!
Hal Stockman is a true treasure of knowledge, also loved in the aviation community!!!
Absolutely!!
Any video with Tom is a classic. Love to have coffee with him.
I'm so glad you guys finally made this video. I been waiting patiently to find out how it went. Congrats on getting the issue resolved Tom !
Amidst an ocean of scripted, over-produced YT videos, a couple of good guys talking airplanes is best.
Refreshing!
I unsubscribe from your videos long ago. Now I am back. So happy of how much you have changed. It sure had been a long journey but it has for all of us in life. Being a husband and a father has made you this amazing person that I am so glad to see. I truly enjoy your videos, they don't even need music! They are human warm videos that we all enjoy to watch. Thank you Jonas, and give my best to your family.
Flat tappet camshafts are typically work hardened during proper engine break in procedures. This is critical to lobe hardness and longevity.
The onboard fuel transfer pump is a great idea. I put one in my bird - fueling was always a hated task, but no more. I also use it to tranfer fuel from my aux tanks into the mains.
Love my E-Prop on my Aeroprakt A-32! As mentioned, start ups and shut downs on the 912 are much less of an event! Super smooth
I will say this, Hal is wrong valve float is a valve spring issue this is where the valve spring tension cannot sustain the RPM, this can be as simple as a harmonic in the system, overly tight valve guides, week structure in the pushrods, camshaft profile, and just over revving. A flattening of the power curve is common along with others like missing or popping in the intake exhaust. The common result to the engine is brinelling of the cam and lifters causing camshaft failure. Second issue could be that the breaking oil was deficient in Zinc a common problem in today's aftermarket camshafts.
@1960fl is actually 100% on this. The surface failure is most likely brinelling as a result of valve train float. Valve train float would most likely be a spring harmonics issue not ensuring the lifter stayed in contact with the lobe resulting in the lifter bouncing on the lobe, pounding it to death. I don't know the Rotax valve train intimately, but harmonics are generally overcome by using 2-spring or even 3-spring sets for each valve so differing frequencies, or dampers to spoil the frequencies. Changing cam grinds change accelleration rates, and changing lifters, valves etc change inertia, overheated or broken springs or remachined spring or valve seats of failing valve keepers or retainers reduce spring pressure, so this all effects the ability of the spring to control it all. Surface finishes, oil quality, debris in the engine, all add pain to a system not performing properly. Hal was right that it was valve train float not allowing the engine to rev, but this is because the cam was in a self destruction cycle. Hydraulic lifter pump-up usually results in burnt or bent valves when they don't close properly. I suggest at the very least use a new set of springs with your new cam.
Good morning from Minnesota!
You be surprised when you put EProp on I have one on my zenith 701 Rotax 912 uls I took off 7 kgs with old prop EProp weight was 2.5 kgs plus gain 7 knots ,easy starting less inertia they are great prop
Anytime valvetrain weight, cam specs or max rpm is changed it is crucial to have appropriate valve spring seat and open pressure. Also make sure springs don't bind or have too much clearance.
Spike knows what's up jhonas
Ha ha Tom talks a lot and knows enough to be dangerous. Ha ha. I also always keep old cam shafts on the ground next to the hanger. Ha ha. "I'll be on that like stink on @#%*." He has a way with words... A poet really.
That was very informative. Thank you for bringing us along.
Love these videos with Tom and Spike!
I always enjoy your videos no matter what it is about. Steve 28,000 hr Pilot.
Ducati motorcycles did away with valve springs years ago to eliminate valve float, the developed cam operated fingers that open and close the valves, they still use the desmodronic system today.
Very interesting, thanks for sharing.
well hot damn it was the cam . thanks for the update bud
Or floating valves due to weak springs caused the cam wear. If he didn’t replace the weak springs, we’ll find out.
You may want to try some zinc to your oil. It may help lube the lobes. I have seen this happen on small Hondas and clones.
Make sure you have Zinc in the oil.
Planes with Geographic Scenery in the background.
Rotax is making a killing yea . Just can't beat the confidence in flight . How cold is it at night,?
just want to say to old friend Tom! Hi from Mountain Mike (worked just uphill from you long ago).
Yo Mike!
Awesome... Nicely done... =)
Yes plane things again!!!!
My guess is Tempering and coating treatment of the cam shaft.
Same here...
What oil is he using? I think Rotax recommends like a premium motorcycle type oil or their own branded oil don't they? I think Shell has a light sport piston aircraft oil as well. Modern automotive oils have reduced ZDDP, zinc phosphorus, content in them because it's hard on catalytic converters and with roller lifters & followers they don't need as much either. ZDDP is a sacrifical extreme pressure additive used to protect the cam lifter interface. However too much zinc isn't good either, it has to be a balance. Some years ago we started having a lot of cam failures in classic cars, high performance engines and hot rods that used flat tappet cams like what the Rotax 900 series use. It was found that the automotive oil manufacturers had much reduced the zinc content in the oils to be the culprit. Diesel oils used to have a pretty high zinc content, but they have been reduced now as well.
If anybody knows how to figure it out it’d be Hal Stockman. It looks like the camshaft wasn’t properly heat/chill treated or wasn’t high enough in Cr content.
Or there are valve spring issues causing the valves to float, taking out the cam lobe in the process.
There seems to be troubles with automotive cam shafts also. My neighbor had a new camshaft last only a few minutes. There are many stories on RUclips about camshafts and lifters wearing out very quickly. I'm puzzled about this strange new problem.
Yes, lack of zinc in modern oils.
❤
Are you missing the lubrication of a non-ethanol fuel and wiping the cam lobes?
Go Simko!
What crane company does he run? I'm a crane operator and a student pilot looking to get into bush flying
Rotax engines are sensitive to prop weight; they have a limit called moment of inertia. I guess it is because of the gear box.
Hey Jonas, you could do that to your aircraft. OHH...... you still have NOT started DEFIANCE !!! When are you going to get on with it ?? We are all waiting !! Still waiting !! How long has it been now ??
I think about it a lot 🥹 hopefully sooner than later
"Thinking" and "doing" are very different ! Does Mike Patey think or do?
@@GerardMiles Damn dude! Where are your videos of your multiple plane builds? Give Jonas a break. He is not on this Earth to please you.
Hey, all done in good spirits. Jonas and his two stunning beautiful ladies would understand this. Just giving him a little "poke". No hard feelings here.
@@GerardMiles Good deal. It just came across as a bit harsh. Have a good night.
Why did he install fuel injection when the oil filter would have been full of metal? That seems really crazy to me.
Looks like a possible metallurgical issue.
Also lack of zinc and other important oil additives. We can all thank you know who.
@@totallyjonesin well, nàw, actually about 10+ years ago the zinc content was greatly reduced in modern automotive oils.
@@oneninerniner3427 In the late 70's early 80's we had a rash of scrubbed cams in GM pickup 350/400s. These were new under 5000 miles I was a dealer tech at the time. Dropping new crate engines in about one a week. They decided it was a combination of poor oil and the double valve springs. That is about the time the ecofreaks got a hold of the oil.
Id like to know where he found the fuel pump and QD'S
Summit Racing has a variety of fuel pumps, QD I think came from a marine outlet maybe.
I know I am going to get a lot of hate for saying this but you could not give me a Rotax . Wait, maybe for a go cart.
Or penicillin.
I'll never buy one, but you can give it to me and I'll give you some wood and a couple of flint stones.
We should go for automotive factoring standards in aviation motors. Honda and others can’t afford bad cam quality in 100.000 engines…
@@richardbieber9323 Viking A. Engines 140T plus E-Prop five blades
I put 2300 hours on the first one, in 12 years, totally trouble free, averaging less than 4 GPH on mogas, and that was only doing about half the recommended Rotax maintenance, that made me a believer.
Flyin out of God’s country. ID to WY…
Parking aircraft does that oil exposed. Rusty then nocks rust out...
He flies over 150 hours per year, keeps it in a stable temp hangar FWIW.
So I would guess maybe a detonation event did that against the valves...
Fake oil or oil pump or oil filter
Yeah that’s what Hal said. I should have put that in.
ຍິນດີຕ້ອນຮັບສູ່ປະເທດລາວ
you drove there in a car? why not fly