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**48fordnut** · 10-26-2006, 18:30

Re: A-65 Engine noise

try using a stethscope, or a short piece of broom handle.

**Pearson** · 10-26-2006, 18:46

Re: A-65 Engine noise

Ron,

The sound you are describing sounds similar to a rod knocking. In your posting you state, "From what I can tell its from the cam operation".

What causes you to think it is from the cam?

What oil pressure do you have at idle?

A wrist pin can cause a similar sound also. I have seen engines where the wrist pins are so tight it causes the piston skirt to slap the cylinder wall.

My engine makes noises, but it has done that since I bought it. I have been told that Continental engines are built "loose" so I just figured that was the way it is. Maybe you could fly it for awhile and send in an oil sample for analysis to get a general idea of whether anything is grinding itself to pieces.

**Ron Babos** · 10-26-2006, 19:20

Re: A-65 Engine noise

The oil pressure is 32 at idle at 180 degrees. Plunger is set to break at 40psi. It sorta sounds like a rod but the clearances are new. It has a filter on it and there is no metal in it after 120 hours. At 32 hours when I did a case change all the parts like pistons , pins etc were checked and all was well. In the 120 hours it has not gotten any louder than first startup. The only weird thing is that if I fly it for around 3/4 hour I can hardly hear a peep out of it as far as clunks and rattles. When I land and taxi it's there again. The best I can find for location is in the center of the case. Cam bores are a new .020 over at .0015-.002 clearance across the board. The lifter bodies are new from Aircraft Specialty Services. It made the same sound with the standard cam having the front bore near the limit of .006 clearance and a set of reginds.
Ron

**mgold** · 10-26-2006, 19:29

Re: A-65 Engine noise

What type of fuel and check the plugs. When hot no fuel build-up Just a thought.

**Ron Babos** · 10-26-2006, 19:44

Re: A-65 Engine noise

mgold: I'm running 100LL with MMO. Just checked the plugs as I recently installed Unison ure37by plugs. The Champions I took out were tan color and the 37bys are like out of the package with 40 hours on them. There is no indication of lean in the engine operation and asked around and found that others using this plug experienced the same (new out of box look). For what it's worth, never had one foul on a mag check. As far as the mag timing goes, it's slightly below 30 degrees. I'm putting it back as I lost 25 rpm indicated on the tach on climb out.
Ron

**supercub185** · 10-26-2006, 19:50

Re: A-65 Engine noise

All of em i have flown made the continental clunk.I think it is the characteristic of the engine.Espescially during acceleration.You may be hearing something different though,so get an old pilot to listen to it.The first t craft i bought scared the pee out of me,till an old timer said it was quieter than most he flew.Said they all made that noise or worse when new.

**mgold** · 10-26-2006, 20:22

Re: A-65 Engine noise

I run 100LL NO mo. use 40 champ. I have no noise . slick mags. In middle
of putting cowl bumps and shielded top plugs. I will be using 40s. Lots a luck.

**fearofpavement** · 10-26-2006, 20:31

Re: A-65 Engine noise

We just recently pulled an A-65 apart because of a nasty sounding clunk and clanking going on in the engine. Used a stethascope first, pulled the rocker covers, etc. Finally pulled off cylinders expecting to find something terrible inside. Found nothing out of the ordinary. Was certainly a sound that had me concerned but in retrospect i think it may just be a characteristic of the engine. This sound was very noticable when pulling the engine through but seemed to go away when running. It did seem to be more or less in the center of the engine. Guess that is where gremlins live... To describe the sound it was similar to what one would expect if someone assembled the engine and forgot to put the rod bearings in.

**supercub185** · 10-26-2006, 20:44

Re: A-65 Engine noise

It's pretty common knowledge they make noise.Like i say lot's of people call it the continental clunk.I have seen discussions on other sites and the concensus is they make a slight clunking.I even read somewhere what caused it,but have long forgotten.

**Guest** · 10-27-2006, 10:31

Re: A-65 Engine noise

Originally posted by Ron Babos View Post

Hi everyone. I have an A65 that has a clunking sound in it especially at low rpms. It is not the impulse. From what I can tell its from the cam operation. This engine has been apart twice for different reasons , like a case replacement . I has had reground lifter bodies , new lifter bodies, new hyraulic units (checked twice) and two different cams. Fresh gound crank, new bearings and a new set of Milleniums cylinders and pistons. Dry tappet clearance is around .060 average. It seems like no matter how many new parts I throw at it the sound is like it's built in. The best way to describe it is to put an impulse mag deep inside the engine at 1/4 volume. What burns me is some will make this sound as where other baffed out 65s are actually very quiet mechanically. Anyone heard this sound in there 65s or in others?
Ron

Hey Ron, here's a thought; if they are bendix mags inspect the impulse coupling per the service bullitens, maybe they are out of spec or not releasing?

Maybe you did that already.

Dave

**Guest** · 10-27-2006, 10:34

Re: A-65 Engine noise

Originally posted by fearofpavement View Post

We just recently pulled an A-65 apart because of a nasty sounding clunk and clanking going on in the engine. Used a stethascope first, pulled the rocker covers, etc. Finally pulled off cylinders expecting to find something terrible inside. Found nothing out of the ordinary. Was certainly a sound that had me concerned but in retrospect i think it may just be a characteristic of the engine. This sound was very noticable when pulling the engine through but seemed to go away when running. It did seem to be more or less in the center of the engine. Guess that is where gremlins live... To describe the sound it was similar to what one would expect if someone assembled the engine and forgot to put the rod bearings in.

Hey Fear,

wonder if the carbon on piston or something on cylinder upper are meeting when piston is at tdc? I saw that happen once.

Dave

**Ron Babos** · 10-27-2006, 14:24

Re: A-65 Engine noise

drude: Do have Bendix, but went for the new snap ring impulse. On a previous reply I was asked why I think it's from the cam. The lobe spacing on an opposed four banger is such that at one position the lobe if forced to a rappid over the center by another lobe. I think it's #4 exhaust. This can be heard when turning the engine over by hand. At the same time, there is a slight clunk at the crank and cam gear where the lash in the teeth can be heard from the lobe being forced over. On that note, I have new gears and the lash is at the minimum clearance of .009.
It's beginning to look like it may very well be all normal after all from reading some of the other posts. It is a new tollerance engine, with nothing left to throw at it for parts so I guess I just have to live with it.

Has anyone put a C-85/0200 spider on a 65 and found any extra takeoff rpms or is it one of those urban legand things?
Ron

**robbie** · 10-27-2006, 14:45

Re: A-65 Engine noise

Haven"t heard about the C85/0200 spider but I wouldn't think there's any differences or very very little. Flew the t-craft today, 25 years, 1000 hours and the cont knock still there. Don't hear it when pulling it thru, but when running there is that knock.
Ask a good "OLD" A&E too hear it. Bet you he say "Yep thats an A-65 for you".
Your engine sounds a lot tigher and newer than mine.

**Ron Babos** · 10-27-2006, 15:40

Re: A-65 Engine noise

robbie: It would seem being tight does little to make it quiet

One thing I didn't mention is that the 65 cam has little duration which will make the lobes of the cam smack the lifter a bit harder than the 85s and up. If you rock the prop back and forth in a certain area it will make a distinct clunk clacking sound. In my case on #4 cylinder. Could be something as stupid as having new valve springs amplifying the cam lobe flip over. All the small Contientals make the same sound when rocking the prop back and forth but only at about 1/2 the volume. When the engine was totally baffed out it was much quieter when doing that. I wonder if there is a conection here

Pay about 5k Canadian for new Milleniums and the extra noise is free

Ron

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A-65 Engine noise

A-65 Engine noise

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