Sudden onset of a dreadful rattling noise

[Remi]

Hello everyone,

First of all, a big thank you to all the participants of this forum for the vast amount of information available here.

And now, here is my story, I am working on a 2006 Yamaha FZ6 that has been sitting for around two years (not entirely sure, but a long time), it had a few faults/faulty parts that I've already dealt with/replaced and I have successfully started it a number of times in the past few days for testing purposes. During the latest start earlier today the bike ran normally for a couple of minutes before a loud metal rattling noise appeared almost instantly, I killed the bike within a couple of seconds and my initial and current theory is that the CCT failed, I took it off and a short piece of metal wire fell out immediately before I even had the CCT fully out of the bike, I assume that it is part of the spring inside the CCT(?). I've already ordered a replacement CCT but I am not an expert by any means and this is a rather unusual project for me so I am very reluctant to proceed before consulting with someone of greater knowledge on the topic, so here I am. I guess I have a few questions, am I correct in assuming that a metal rattling noise is most likely cam chain related? is it normal for a CCT to fail so suddenly? (please consider the fact that the bike was sitting for a long time) what harm could have occurred from this sudden failure? is it possible that the cam chain jumped some teeth and wrecked the engine? what is the next logical step in resolving this issue?

Any help whatsoever is highly appreciated and thank you in advance.

Kind regards,
Remi

 

[agf]

Be patient Remi, there are a few very knowledgeable members that will log in in the next day or so and offer sage advice.
Wecome to the forum, and I'm sorry I can't do much more than that.

 

[TownsendsFJR1300]

Obviously, don't crank the engine anymore for now.

Pull the CCT and I suspect your correct-the spring came out. There's really nothing else (I can think of) that you describe. That is FIRST...

The earlier model CCT can / do fail, but usually not enough tension, rattling, NOT a "fall apart" failure..

Once that's confirmed, I'd pull the valve cover off, right side cam chain cover & check for any other visible damage- Maybe a guide, PU sensor, etc.

Remove the valve cover, check each valve (when NOT lifted-with clearance). Check spec's for any SUPER LOOSE.. **Any super loose valve would indicate a bent valve not fully seating**.

You'll later need access to the cam gears ALIGNMENT MARKS to line up with the crank at TDC when you get ready to re-assemble.

A member did a valve adjustment and was one tooth off with just the bike not running right- No damage, but that was just one tooth. Hopefully, you caught it in time.

Post back what you find, and do a search here, (if you don't have the shop manual), for re-setting cams to the crank..

**Note, if you have a leak down tester, you can check each cylinder (at TDC, compression stroke, valves closed and crankshaft held at TDC for leakage. For each cylinder, the chain doesn't even need to be on if that cylinder has the valves closed-BUT again, that piston must be locked up at TDC(OR it'll spin over with pressurized air)

 

[Remi]

Be patient Remi, there are a few very knowledgeable members that will log in in the next day or so and offer sage advice.
Wecome to the forum, and I'm sorry I can't do much more than that.

Cheers! I will be very patient about this so I don't mess anything up.

 

[Remi]

Thank you for the response TownsendsFJR1300, I will get to work and post the results later today.

Also, a small update, I took apart the CCT this morning and this is what I found.



The small piece at the top right is what fell out of the CCT as I was taking it out of the bike so it seems like I was right that the spring snapped but more importantly, have a look at the state of the rest of the spring, the bottom seems all mangled out of shape. I also noticed that the bolt at the tip of the CCT is heavily worn suggesting that the previous owner had been undoing it a lot. I'm not sure what to make of this other than the fact that the cam chain tension must have been a long running issue for him but he never fixed it. From the looks of it the tensioner can be adjusted manually with a flat head screwdriver which is what he must have been doing (and overdoing?), but I'm guessing that's not supposed to be necessary as these are meant to be automatic, am I right?

 

[TownsendsFJR1300]

They are automatic and don't need adjustment. I agree, with that buggered up head, that likely contributed to this failure..

I'd pull the valve cover(you need to anyway for re-setting the cams), and check clearances, hopefully not finding any super loose valves(bent)..

 

[Gary in NJ]

The ACCT can fail in such a manner if the cam chain has sufficient stretch, causing the CCT to over extend.

 

[Remi]

The ACCT can fail in such a manner if the cam chain has sufficient stretch, causing the CCT to over extend.

Uh oh... and how can I find out if this one's over stretched? I forgot to mention, the bike has 24,000 miles on it and the service history is... patchy.

 

[trepetti]

As for timing chain stretch, I replaced the one on my well-maintained 05 at 67,000 miles and although the original was a little longer, it was not nearly enough to cause a problem.

That being said, in your case I recommend an abundance of caution. Once you check for damage / valve clearance, replace the chain, the CCT and all 3 chain guides. It might be overkill, but spending the few extra $$ is better than hoping that broken CCT didn't cause any damage.

With only 24,000 miles on your bike, you should have a lot of life left in her.

 

[Remi]

I think I will take up that advice! I don't want to deal with a bigger mess down the road.

Another small update, I spent the afternoon taking the bike apart and I have found no visible damage whatsoever, everything looks as it should from what I can tell.

Also, does this look correct? Everything in sync?



Apologies for my ignorance, I am out of my comfort zone with this mess.

 

[Gary in NJ]

That looks like good alignment, especially since there’s no CCT installed. Are you placing tension on the chain with your finger? If that’s how you found them without having to retime them, you dodged a bullet

 

[Remi]

That looks like good alignment, especially since there’s not CCT installed. Are you placing tension on the Shaun with your finger? If that’s how you found them without having to retime them, you dodged a bullet

Yes, I found them this way but I screwed up initially because I turned the engine without putting pressure on the tensioner plate and skipped a tooth on the bottom bit so I had to undo that, put pressure on it and move in to the positions shown in the pictures.

 

[Remi]

I have finished the valve clearance check and yielded the following results:

All intake valves took 0.15 mm/0.006 inch comfortably but didn't like 0.18 mm/0.007 inch very much.

All exhaust valves took 0.25 mm/0.010 inch comfortably but didn't like 0.28 mm/0.011 inch very much.

According to my Haynes manual these measurements are "standard" and that "no adjustment is required"... so am I good or should I look what's underneath? Like shims and all that?

 

[TownsendsFJR1300]

Your #'s look good, go buy a lottery ticket..

With that said, the crank mark appears to off just slightly(see below pic).
When checking marks(and you seem to on them), the crank should FIRST, be dead nuts on.

-Then, chain taught, the exhaust cam
-Then, the chain taught, the intake cam
-All remaining slack to the rear (where the CCT would be.)

Also, I sent you a PM, might want to check messages.

 

[Remi]

Your #'s look good, go buy a lottery ticket..

With that said, the crank mark appears to off just slightly(see below pic).
When checking marks(and you seem to on them), the crank should FIRST, be dead nuts on.

-Then, chain taught, the exhaust cam
-Then, the chain taught, the intake cam
-All remaining slack to the rear (where the CCT would be.)

Also, I sent you a PM, might want to check messages.

View attachment 73722

Thank you, I will redo the check using this method.

 

[TownsendsFJR1300]

And ONLY turn the crankshaft forward or clockwise..

The Yamaha manual(I know you have a Haynes) is in-correct..

 

[Remi]

And ONLY turn the crankshaft forward or clockwise..

The Yamaha manual(I know you have a Haynes) is in-correct..

That is good to know, thank you, out of curiosity, what are the consequences of turning it counter clockwise?

 

[TownsendsFJR1300]

uh oh!!

 

[Remi]

uh oh!!

Big uh oh or just mild, watered down uh oh?

 

[TownsendsFJR1300]

If you spun it and nothing locked up/hit, you should be ok..

The engine turns / runs clockwise (looking from the right/starboard side) and the chain is taught from the crank, to the ex cam, then the intake cam. Slop is at the rear where the CCT takes that up.

ALL marks should line up or be super close(chain stretch would move marks off some). A full tooth off would be VERY noticeable with your marks..