Clunk Clunk Rattle Rattle

[Ron Babos]

One of the strangest things about the little A-65 is the amount of clunks and rattles that can be heard in side the cabin while flying. Most likely coming from the camshaft operation. Seems like no matter how may new parts are put in there, it will never go away.
How many of you have noticed this also?
Ron

[bernie]

did you upgrade to slick mags and not change the accessory gears ? it will run, make noise and metal. the previous owner of my chief went through that drill and ended up tearing down the engine to put the proper accesory mag drive gears in it. bernie

[mike newall]

I found this until I got ANR headsets and the noise went away

[Ron Babos]

bernie: The -8 uses the crank gear. It has the newer Bendix mags, and both the cam and crank gears were changed as the noise was there before rebuild. I now have a perfect set of cam and crank gears on the shelf, as I gained nothing with the new ones, except a thinner wallet. While at it, I put an new cam, lifters, hydraulic units. Dry tappet is set between .060-.075. After 38 hours there is no metal in the filter element. The first 5 hours had the normal junk, and since that it's quite clean.
Ron

[Nathan K. Hammond]

I've notced the same thing on my little 65. It makes the most noise for me at idle, or at least it's most noticeable. I always assumed it was either the impulse on the mags or the lifters smacking the cam. After 600 hrs and 9 years, it never made metal, lost compression, or got worse. I tried to pin point the noise a couple times, but never came up with anything definitive, and just started to accept the noise.

Theres a J3 with a 65, that really doesn't make much noise. So maybe it's just luck of the draw.

My dad has a Franklin powered Cub, and it's one of the quietest engines ever. No joke, when it's at cruise (2100 rpm) it makes the same amount of noise as my Cont. 65 at run up!

nkh

[shorty]

One of the strangest things about the little A-65 is the amount of clunks and rattles that can be heard in side the cabin while flying. Most likely coming from the camshaft operation. Seems like no matter how may new parts are put in there, it will never go away.
How many of you have noticed this also?
Ron

Hence th' name "air-knocker"

[Nathan K. Hammond]

HAHAHA !!

nkh

[Paul Agaliotis]

Had a noisy engine on a Cub, put up with it for about 500hrs. The Cub came apart for rebuild and the engine went on a Champ. Put up with the noise for another 300 hrs. Pulled a cylinder off for a oil leak at a hold down stud and found the center main bearing web cracked from stud to stud. Changed the case and all the excess noise went away. Paul

[Ron Babos]

Nathan: Thats it. Sounds like a dull impulse, which is impossible as it is disengaged by 300 rpm. The other sound that goes with it is the lobes to lifters contact. Mine is also most noticable at idle.

I did change the case at rebuild and the webs are ok. Seems like if it's flown for 1/2 hour -45 minutes the sound is almost gone, with a low wining sound coming from it. That sound I like. As soon as I land, it's back again.The Franklin engine uses helical gears and this will eliminate that straight tooth chatter that Continentals have.

You mentioned the J3 that makes very little noise. I have also noticed that some are quieter than others. I have been told that it's normal and even the 0-200s came out of the box with that sound

It just burns my ass to spend a ton of money, blue-print the stupid thing and rebuild it to a rediculously high standard and have my 30 year old Briggs and Straton lawn mower that has only had 2 oil changes in that time (I hate cutting grass) sound better. I also heard that early on, Lycon tore an engine appart twice to find out what it was, but didn't. The attribute it to piston slap. To me that's bs , as it would go away when the pistons warmed up.

Starting to like the ANR idea as the fix for the Continental clunk. Nothing else seemed to work. I have to wonder if possibly by installing Superiors and with the new valve springs, that it has amplified some of the noise from the cam?

Ron

[nowlen]

had an alon aircoupe(ercoupe) with a c90-14f and bendix mags. at idle the clunk/clank was the impulse coupling not disengaging. sold it and got a plane with the training wheel in the rear and i'm still learning
to land. the slick mags don't make the noise. bernie

[MikeB]

Ron,
Been following your thread for sometime and thinking about it. Any chance it could be a scored piston? Has it been in there from the beginning? Reason I mention it is my Cherokee had a slight thud/tap noise for some time which I just attributed to "normal" aircraft engine noise. Wound up being a scored piston. I used to hear the same noise on the old Cummins diesels when I worked in the truck shop. On those we'd just pull the oil pan off and look up from the bottom at the cylinder liner until we found it. One thing about aircraft engines is they're not so easy to troubleshoot with that big meat cleaver swinging around in front and the wind blowing all over you. Just a thought, you might try pulling the plugs and putting a 'bend a light' in the lower hole while looking into the cylinder from the top. I've seen scored pistons that still checked 70/80 as the rings were still good. Of course, if the piston is scored, but the cylinder is still good.....you'll see nothing useful.

[Ron Babos]

Mike: No scores. Never been able to find anything out of the ordinary with the parts. I'ts been apart 3 different times and all is well. The impulse kicks out at around 300 rpm. Tuned up my ears and started listening to other engines lately. It seems like all flat fours do it to some extent. Mine may be louder due to the fact that Superior valve springs may have more pressure than the older OEMs. Short of a rod coming out the side of the case, I will choose to ignor it, and call it normal. Let's face it , four straight tooth gears, with the sloppy clearances that Continental have with them are bound to do a bit of rattling in there. Then there's the uneven lifting and closing on the lobes of the cam. By that , I mean they are not evenly spaced around the circle causing the cam to be pressured from one side to the other in operation. My cam bores are minimum clearanced, so the cam can't be rattling in the case. Time to move on to the oleos. I'm sure that will be easy (not).
Ron