Raptor 50SE rattle...DIAGNOSED!!! :-)

[Whirly-Girl]

I think it might be the main shaft bearing, but I've never heard this rattle before.

Here's what happened. I put my Raptor up on the shelf temporarily while building and flying my Bergen gasser for AP. It sat for about 5 months. (Ran it completely out of gas too.) When I put it back in the air, I looked over everything, lubed it up and flew. I noticed a rattle after a few flights, but it didn't do anything to performance...it just showed up during idle and initial spool up.

As I continued to fly, I noticed that sometimes the rattle would cause my engine to quit while I was carrying my machine to the flight line. I read on Raptor Technique that the common Raptor rattle is the clutch shoe bolts coming loose. I dropped the motor out and they are fine. Replaced all fuel line while I was at it. Rattle is still there.

I flew an AP job 2 days ago at a construction site and it was dusty. After a thorough cleaning at home, I went to take off today from pavement and I noticed an RPM change and a weird rattle, different from the other one that happens during idle; it was intermittent during spool up and then caused me to have to land. Upon landing and going to idle the engine wouldn't stay running. When we started it back up it would idle normally but the sound repeated on spool-up so we brought everything in for trouble shooting.

Now I have two rattles...one while the heli is idling and another while the head is spinning. The one I discovered today I think is main shaft bearings. I'm going to pull those out and check them here in a few minutes. The other "idling rattle" I haven't been able to track down, no matter what I try.

Could both the rattles be main shaft bearings?

What else can I check? :roll:

Thank you for your insight in advance.

[AZ ChopperCam]

check your belt tension. it is common for the belt to snag and rattle on spoolup if it's just a little loose.

also check your clutch as well as auto bearing.

[Alfred]

Check the mainbearing on the engine for rust.
Take the backplate off but don't remove the fan, it's just a visual inspection.

[Whirly-Girl]

We've pulled the engine and the main shaft. The engine has a little rust inside, only enough to slightly discolor the crankshaft and the inside of the crankcase. The main shaft bearings feel pretty solid too...

I was hoping to find a shredded bearing on the main shaft, no such luck.

The auto bearing looks good too, no dirt or rough spots.

I KNOW we're not the first ones to hear these noises on a Raptor! This thing only has about three gallons through it, max...still brand new.

We are frustrated, to say the least.

We're going to re-adjust the belt tension after putting it all back together and test fly it tomorrow, unless someone has another suggestion while we have it all torn down...

Thanks for your help.

Jeanette

[AZ ChopperCam]

also check your start shaft and one way bearing in the clutch. make sure the start shaft does not have any vertical play. if it does it can "hop" up and down and create a rattling sound.

[Alfred]

We've pulled the engine and the main shaft. The engine has a little rust inside, only enough to slightly discolor the crankshaft and the inside of the crankcase. The main shaft bearings feel pretty solid too...
Jeanette

Replace the main bearing, carefully using something like green scotchbrite clean the crankshaft.
Don't touch the casing, just run it nice and rich for the first tank.
This should flush out any micro particles left.
It's because the heli set there for that long without running, not the age of it that causes the problems.

[Janek]

To check the engine main bearing, you must remove the clutch/fan, and remove the crankshaft, then use a finger to "feel" the bearing. I'd lay bets that it'll be rough and the casing rusty.

Trying to check the bearing with the fan/clutch and crankshaft in place, will not detect a rough bearing, unless it's just about failed !

[Alfred]

My 1st suggestion was to establish if there was any visible rust without causing major dis-assembling.
Once rust was proven to go further.
I now would follow Janek's suggestion.
Me personally at this stage wouldn't even muck about and replace the bearing, no matter what.

[BarracudaHockey]

Check that the pinion bearing hasn't worn a grove in it as well, that can happen if the inner race isn't green locktited to the pinion.

[Wild Moose]

If that rattling sound is somewhat metallic, you may want to have a look at the clutch bell. I once heard a rattling raptor (V1) with what may be the same symptoms as yours and what we found was a blown Pinion (HMV1680) bearing.

There was some play between that bearing and the frameset (one could easily rotate the bearing's outer race) so we addressed that issue as well.

-Roger

[Whirly-Girl]

Engine: what I've found this morning...

I removed the clutch/fan assembly and am now holding the engine in one hand and wiggling the crankshaft in the other. There is almost a full 1mm of play in/out. I can see now where the clutch/fan assembly had to come off because those are screwed down until they seat against the engine bearing itself. :idea:

Now, how do I remove a crankshaft to feel the bearing itself with my finger??

Jeanette

[BarracudaHockey]

Take off the head and pull the sleeve out.

Slide the rod off the crank shaft and remove the piston and rod.

Pull the carb and gasket.

Heat it up in an oven to 250 or 300 degrees for about 10 minutes. You should be able to push the crank shaft out the back of the motor. Smack the back on a 2x4 and the bearing should fall right out if it doesn't come out on the crank shaft. Use a wood dowel from the back and push the front bearing out.

goto http://www.rc-bearings.com and order a set of ceramics from paul.

Put it all back together.

Also Mike has instructions on http://www.raptortechnique.com and paul has removal instructions on rc-bearings.com

[slow]

I'm willing to bet money on that the rattling you're hearing in idle and spool-up is the one-way bearing in the start shaft.

To check it, keep the machine at idle, and put your finger on the hex coupler where you insert your starter to stop it. If the noise changes, that's what needs to be replaced to fix that rattle..

/James

[Whirly-Girl]

:shock:

Holy cow! I get to put an RC motor in my oven?! HA HA HA!

Oh boy, this is starting to sound like a job for HUSBAND to take over!!!!!!!!!!!!!!!!!

Nuts...his website shows that he is on vacation until Jul 26th! I can't wait that long. I need this bird back in the air to take pictures.

slow: I already have the heli broken down into a bunch of pieces so I'll have to check that bearing another way. :dontknow

Jeanette

[slow]

Okay, if you've already got it in pieces, just insert the start shaft into the clutch and turn it. It should grip in one direction, and turn smoothly the other direction.

Hope you'll get it sorted.

/James

[Whirly-Girl]

It should grip in one direction, and turn smoothly the other direction.

Smooth as silk...and no vertical play with the start coupler/clutch bell.

One more thing eliminated while it is all torn down. :roll:

[flyinfool]

You do not need the oven, or to remove the carb, to get the crank out to be able to feel the front and rear bearings with your finger.
The crank should just push out the back once the cylinder liner and piston are removed as was mentioned above.
The crank having some play to slide in and out is normal, side to side play would be very bad.

Although there are a few people that have never had a problem, OS rear bearing have a earned reputation for short life. I have been using the stainless steel bearings from RC-bearings with good results of 3-4 times the bearing life.

A rattling noise is most likely a bad bearing somewhere, you just have to find it or them.

[BarracudaHockey]

You need the carb out to heat the casing which she will have to do to remove the bearing (well 99 percent of the time)

[Whirly-Girl]

I'm leaving the engine right where it is until my husband gets home in about an hour. I have too little engine experience to just start dismantling it beyond this point. I just don't have the know-how for this yet.

I'll post back with our results in a couple of hours. Thank you guys for giving me the leads on what to check and the patience to "talk me through this".

:noteworthy

[flyinfool]

Usually putting an engine in the oven is a job that can only be done/gotten away with, while the wife is out. :wink:

[BarracudaHockey]

My 4 year old ratted me out.

"Daddy was cooking the helicopter in the oven mom"

[Whirly-Girl]

:rolling

[littleman]

does the clutchbell move , i had the pinion wear, causing those symptoms. To me the most likely is the belt.
A.J.

[Whirly-Girl]

Okay, crankcase is in the oven! I stuck my finger in and rotated the rear bearing and I feel a gritty feeling as it rotates. Front bearing is smooth.

Do you guys replace them in sets regardless?

rc-bearings.com is on vacation until the 26th of July. Who has decent prices on bearings elsewhere? Is Tower Hobbies reasonable, $18.49 for rear...$14.49 for front.

Hey, does anyone have a spare set (ceramic from rc-bearings) they'll sell me?????

Jeanette

[Whirly-Girl]

Raptortechnique came through. I tried 225 degrees for 10 minutes...no worky. I tried 250 for 10 minutes, no worky...

Went to 350 for 15 minutes and they came right out!

I'll be replacing both and keeping the original front bearing as a backup.