What is this noise!? video...

[cmattina1]

So, this is a new engine to me, and it may have been sitting from anywhere from a few years to a few decade. Other than this noise, it seems to run quite well, burn little to no oil.

It's made this noise since the first time i started it. Have adjusted the valves and cam chain. Checked sump filter at about 1000km, and did not find any debris, though i did find some metal in the oil filter (somewhat normal?)

http://www.youtube.com/watch?v=9uGfMCNfcLs

I feel you can best hear the noise over the exhaust and tappets around 12second and 37 seconds..

 

[xjwmx]

I think I hear a loose cam chain in the mix. Did you adjust it? Don't get it too tight though.

 

[littlebill31]

It sounds like your cam chain tensioner is worn out. The actual piece that that the chain rubs against wears out and then the chain digs into the engine metal.

 

[cmattina1]

I've had it tight and loose, but I guess i'll experiment a bit more and go tighter on it... I usually do it while at idle... Should I hear the noise disappear as it gets to the right tightness?

littlebill, are you referring to the plastic guide? I understand that they made it out of plastic so that it will wear out before the chain does (breaks). if so, that means my chain is slowly being worn down and may simply snap one day....

 

[xjwmx]

^Try this; while it's idling loosen it until you definitely hear the chain. Then tighten it up to normal tightness, a couple mm movement of the pin, while listening.

 

[littlebill31]

Try what Xjwmx is refering to to make sure it's the tension. You'll hear a difference when you loosen the chain. You might also want to pull out the tensioner assembly and take a look at the end of the tensioner rod to see if it's worn out.

I know, it sounds weird to some, but I bought an engine, had a noise, pulled out the assembly and found out some idioso removed the rear tensioner and only the rod was pushing against it.
Might as well check though. It's easy enough to do.

 

[cmattina1]

okay, so the rod itself gets worn out

As in end of the rod as seen in this pic?

 

[littlebill31]

I'm guessing you have an old style tensioner because of the picture. I was refering to a newer style which pushes against the rear guide. There is a front guide and a rear guide. They can wear out. Also an old chain will cause a lot of noise and cannot be adjusted enough to remedy it. Thus, replacing the guide and/or chain is necessary. Which also means removing the engine and head.

Might want to put what year bike you have in your "signature" so members can get a better idea.

 

[TeeCat]

cmattina, like your bike, mine has had a similar noise for some time. I wondered, as well, about the chain guides, but when I changed my sump filter last season, I found no debris. Most recently (last week), I changed the upper filter in the Heiden cooler, and found only a trace amount of magnetic "dust", which I'm told is normal. I have my tensioner adjusted so the plunger moves in and out about 1mm when hot, and I seem to have a lot of thread left on the adjuster. Do you have thread (adjustability) left? I have an early type adjuster too.

It's perplexing, for sure. Those tensioners and guides give me heartburn fretting about them!

TC

 

[littlebill31]

Good point about the threads left TeeCat.

 

[cmattina1]

its a 78 bike with a 75 engine.

There is A LOT of thread left around an inch, give or take a 1/4"... or maybe that is not a lot...

 

[TeeCat]

Hmmm... my (un)educated guess would be that you're adjuster itself is okay and that the chain is not stretched inordinately. The puzzling thing for me is that both your bike and mine make that sort of "metallic hiss", but there is no apparent aluminum in the filters. I would think that even if the sump strainer is doing its job, you might still see some aluminum in the upper filter. Neither of us have. Hmmm.

TC

 

[littlebill31]

This is the typical tensioner for a '75

Which pushes against this

You can see the end I am talking about.

 

[TeeCat]

Bill, I thought the tensioner pushed against the roller (at least in a '73)...

and the guide (in the bottom pic you posted) was bolted to the front of the head and the frontmost part of the chain rode against it. I can't quite imagine how that works in a '75.

TC

 

[TeeCat]

Ah, '73s and '75s are different systems altogether... never mind...

 

[cmattina1]

thanks bill for the different pic. The rod pushes against the black "lever" which i believe is the plastic as oppose to the roller in my pic. I thought if I were to pull the housing out all i'll see is the rod and spring, as the tensioner is inside? So would i even be able to see if the end is worn or not? Regardless, i adjusted the tensioner again and there is 0 difference in sound regardless of how tight or loose I go....

Teecat, a metal hiss is a good description. And the big runs quite well too!

 

[littlebill31]

The rod pushes against the tensioner, into the chain. If you pull the rod assembly out, you can check the tip to see if, maybe, the chain wore thru the guide and is rubbing against the rod.
I'm just trying to narrow down soem possible causes.

 

[cmattina1]

oh, i see. good point. Thanks.

 

[cmattina1]

Well, pulled it out and it does not look like it has been rubbing against the chain at all... One thought i had, is when i put in the pamco, I didn't grease the rod. There was a youtube video where the guy greases it good, but i do not think it mentions it on pete's site...

 

[TeeCat]

Well, cmattina, at least you know that much. So that's one less thing you have to worry about.

Have you tried a mechanic's stethoscope? I have one but am almost afraid to tempt fate by listening for anything. Knowledge is power, but we can worry ourselves silly about these bikes.

TC