Can someone explain what the cam chain rattling sounds like when the auto adjuster is not working properly?

My mechanic replaced my cam chain with a brand new one but I've been periodically hearing some sort of grinding noise from the bottom end of the engine. My first thought was that it was the cam chain adjuster not putting enough tension on the cam chain.

 

Cam chain noise comes from the top end. Get a big screw driver and hold the tip to the motor and the handle to your ear to pinpoint it a little better. The chain will make noise periodically, it does not mean that it is not working, it just has not made an adjustment yet.

 

Most of the cam chain noise I had was between 5000 and 6000 rpms, it was harder to hear as the bike wound out. It was clearly comming from just beneath the tank and a little forward.

 

Likewise. My chain noise came in around 5000 and ended around 6100 RPM. I didn't really hear it at other engine speeds.

However, the cam chain noise is a rapid ticking type of sound, not a grinding sound. Jhoffy, did you have the bottom end torn apart after your first 351 exploded? I won't jump the gun, but the engine/transmission may have sustained other damage that wasn't immediately noticed.

Can you describe the sound in better detail?

 

It sounds like a Robot passing a kidney stone.

 

Ears bleeding just thinking of it!

 

Any of y'all remember the guy who actually posted a video with audio here on the forum, and it actually sounded like the cam chain noise many of us have heard? I would have never thought you could effectively capture that on a vid, but his did. I can't remember that guy's name or find the vid.

Anyway, before installing Mark's tensioner, I had that knack, knack, knack metallic rattle at idle and then at that 5000 rpm range.

 

When you say "periodically," what do you mean? At certain rpms, more so when cold or warm, or at certain speeds or other conditions? Mine started at the classic 6,000 +/- rpm when cold, but lessened when warm. Progressed over time to a wider range of rpm and didn't go away when warm. You could also have a stock tensioner that is slipping between a couple teeth??

Krieger's adjuster is great. A reatively inexpensive way to determine if it is the cam chain if you can't be positive with the long screwdriver or mechanic's stethoscope.

Good luck!

 

Are you sure it's not debris from the civil war that went on inside your motor? Possibly something in the crank case?

 

Hi everyone,

The bottom end was completely rebuilt by a certified head mechanic along with the new top end. I told him everything that had happened and for him to keep a close eye out for anything that may be wrong. I even had him look at the clutch discs and such to make sure they were going to hold up for the 351 for a long time to come. I'm not so concerned that there is something wrong with the bike.

I first noticed it this morning off of a 50 degrees Fahrenheit cold start. As soon as the engine started, I heard what sounded like the initial noise of a Tractors PTO engaging. A high pitched, short "squelping" noise. Almost like a car that has a squeaky belt. The noise was there for probably 2-3 seconds and then went away. I don't have the best hearing, but from what I could tell it was coming from right where the clutch cable enters the engine above the foot peg in that area. From this point forward, it occurred periodically.

Naturally, I got off the bike to listen closer for the noise. I revved the bike up to try to instigate it to happen again. What I found was that it would only occur if I did revved the bike up quickly and then let off the gas. It would happen when the engine was decelerating. right before it came back to idle after being revved up.

I changed the oil for good measure to see if anything foreign came out of the drain and also check the oil filter and found nothing su****ious. Oil level was good prior to changing it as well. I've put about 100 miles on the bike since it was rebuilt so I think that if something major were to happen, it would have happened already.