Rotax 503 Failure on My Hurricane Ultralight

As promised I am posting the reveal of why I went down. When I bought the plane the engine had been freshened up on the top end, but I think the crank is original. By the way the engine has a air shroud that was on it at the time of failure, but I now realize I didn't show it. I have been doing some research and of course the crank should have been gone through a long time ago. I know that I am being watched over and walking away from this is more than enough said to never do the top end of these engines without doing the crank.
As I finally thought it was the conrod bearing and that is tough one to predict. As I said the bottom end will be done with the top on all my engines. I mix @ 50:1 with AMSOIL Dominator.
Enjoy,
FBSC

[@tedheath9018]

In NZ we test the end play of the crank every 10 -15 hrs on these rotax 2 stroke engines.. Get two spark plugs smashout the ceramics, on one braze in a 3/16 male air fitting fit plastic hose to to it on the other end fit a big medical syringe. On the other spark plug braze or weld a piece of tube the ID diameter of your dial test gauge. Fit to engine suck and push on syringe on one cylinder other has dti which move up and down showing end play of the crank bearing. Swop around measure other cylinder. Known some 582s to go 1000 hrs but they will all fail. Your 503 looks like it was running too lean but that wont have anything to do with crank failure. Should have egt and cylinder temp gauges on 277 447 and 503

[@murrscottg]

Very interesting! Thanks for sharing!

[@FlyboySoCal]

Thanks for watching. Are you sure big daddy isn't watching? LOL

[@challenger2ultralightadventure]

I have a 503 on my Challenger 2 that I'm rebuilding. (posting videos under my name) The engine was fogged, but has sat for nearly 8 years now. It turned over easy, and the compression was perfect. However, I am concerned about corrosion on the bearings. I'll be taking that engine apart next weekend and find out what the situation is. Thanks for posting this, it is useful for someone like me. Cheers from Winnipeg.

[@FlyboySoCal]

My pleasure. FBSC

[@FlyboySoCal]

That is absolutely the right decision. Go baby go and Break it down. FBSC

[@dougnolen2163]

Recently was given (pretty much) 2 503"s and a Hawk Classic. will look for your videos

[@challenger2ultralightadventure]

@@dougnolen2163 I hope you enjoy them, and get something useful by watching them. They're a little amateur and unpolished, but I try.

[@caroltenge5147]

leave it alone and go fly the thing. Your worrying yourself into a corner.

[@cropduster48sady46]

Time got to it, and your right, hard to predect. When a rod does go on one of these, they go very quickly.

[@billcallahan9303]

Be glad it wasn't a 582. You'd really have a mess on your table. I've been flying 503s for 45 years. One engine failure. On 582s, five failures.

[@paper____]

The reason it seized is there was no shroud around the cylinders. You would of been better running the cowling & the fan. When you remove the fan there is a shroud that directs air across the cylinders. Rotax Rick

[@FlyboySoCal]

Rick, You would be correct if I did not have the heads shrouded. But I did. What I failed to do is show or state that the I had taken off the shroud before I made the first video when the engine was on the airframe. Thanks for the input. FBSC

[@billcallahan9303]

That's Mr. Rotax Rick of South Florida. He's overhauled at least 2, maybe 3 of my 503s. The last one done about 6 years ago. Still running! You want quality? See Rick.

[@russellhuston6481]

1st problem, wiseco bearings and pistons. Go with ceramic bearings throughout, Namura pistons/ring(s), oem gaskets. Break in 1st hour with castrol non synthetic oil. After break in use ipone at 40:1. Nothing will wear out till like 200 hours.

[@radioControlAddict]

try a 40:1 mixture it will stop a lot of problems

[@embededfabrication4482]

run the fuel air mix on the rich side and stop running at max power and they'll last forever, I dunno, when I ran my 583 in the mountains on the sled my jetting was only good for a window of about 2000 feet, if people are operating at altitudes not appropriate for the jetting then they're askin fer trouble maybe?

[@embededfabrication4482]

can you tell me the ID of a 503UL intake manifold if you have one lying around. I don't think my mikuni 34mm carbs like the UL muffler and the load from the prop, might have to get some 36mm carbs

[@FlyboySoCal]

Do you need the ID of the manifold side of the carbs?

[@ben91069]

just like a car engine though you could not hear a knocking connecting rod before it quit? You are lucky. I know those engines have uncaged needle bearings instead of babbit bearing like an auto engine. I am amazed that someone rebuilt the top end and didn't just rebuild the whole engine at the same time.

[@FlyboySoCal]

I will not let this type of situation bit me ever again. Thanks, FBSC

[@sonicapollo]

Leaking seal caused a lean condition or just general explode ery ?

[@FlyboySoCal]

That could be one of the reasons for the failure. My thoughts lean more towards the crank just had too many hours on it and and most likely bruised when the last top end failure occurred to the previous owner. Regardless my take away from all of this is to breakdown any used engine and thoroughly inspect or just rebuild the the entire engine. Thanks for the comment. FBSC

[@embededfabrication4482]

is that a 503UL ? it looks like you've got 4 hooks on the exhaust elbow ? I'm trying to figure out where to weld mine on

[@FlyboySoCal]

There are 3 loops per fitting joint. I will post a video that shows the final assembly. FBSC

[@embededfabrication4482]

@@FlyboySoCal did you measure the con rod to crank web distance with a feeler gauge on the failed crank to see how far it was worn?

[@FlyboySoCal]

@@embededfabrication4482 No I did not. That engine is long gone. Thanks

[@emanueldavila85]

How many hours do you think the engine had based on the logs?

[@FlyboySoCal]

Emanuel, I believe it was well over 350 hours, based on the wear of the cylinders and crank. I did not get any logs with the engine. But I do feel it was way over time to do the crank. My Bad!! FBSC

[@mcfast52]

The top of the piston is white, and that was running way too lean, it should be milk chocolate brown to dark chocolate brown, and leaded gasoline in a two-stroke it's only good for producing carbon deposits.

[@ben91069]

does AVGas have lead in it?

[@scottyb6765]

Interesting ! Just bad luck - I guess.

[@FlyboySoCal]

That will not happen again on my account. New crank for the 582. Damn right.

[@stanleybest8833]

2 cycles do that. Please just expect problems and don't put yourself in harm's way.

[@FlyboySoCal]

Will do.

[@harpomarx7777]

Do NOT walk while recording video .. the viewer gets dizzy.

[@performancecyclespecialtie6104]

If u knew is was leaking should have fixed it ! leaned out the engine not hard to prodict just stupidity !!

[@FlyboySoCal]

I did not open the engine until after the failure, which was a mistake that will not be repeated on my account. The engine was not running too lean and the spark plugs were burning nicely. I agree it would be foolish for me to fly knowing the engine was running lean. FBSC

[@avalanche9026]

Haa. At first I taught for a moment it’s a locomotive engine ?? The way you zoom in. Ha. To find out it’s under 12 inch the whole damn thing. People do have guts to take up that tremor engine ?? 2 cycle hmm. Bzzzzzzzz. Can’t listen that