rosscoe21

Dont know how to embed videos so here is the link.
[media]http://www.youtube.com/watch?v=iTTocG964ZM [/media]

rosscoe21

Hey I guess it worked.

j_raquet

My vote would be TCT. You could replace it or media blast the worm gear inside. I did that to mine and havent had any problems in 10k+ miles.

Good luck

rosscoe21

Thanks, I thought it sounded like the tct also. I have a buddy thats a tech at honda, I guess I'll have him order one.

Billman250

TCT 100%.

SpitfireS

So what is actually making this (950 rpm @ idle / 60 =~) 16 Hz noise?
If it's the chain rollers or chain links hitting something (a chain guide?) one would expect a higher frequency, no?
Or is the noise coming from the TCT itself?

Billman250

The noise is a result of a loose chain. A loose chain will form a bow on the non-tension side.

The bow will re-occur in each link as the chain turns. The bow is hitting the plastic chain guide, causing the noise.

Basically 16 or so bows per second are passing the guide.

SpitfireS

The cams are spinning at half the crank speed.
Ratio anti-backlash gears : central gear = 46:46 = 1:1
The central gear also has the timing chain sprocket.
That sprocket has 50 teeth.
Meaning the crank timing chain sprocket has 25 teeth.

This "picture" out of a service manual also shows the timing chain sprocket has 25 teeth.
(this is the block upside-down, the chain in the picture is the oil pump chain)
So far the math is IMO correct.


So 16 revs / sec x 25 sprocket teeth gives 400 chain rollers per second.
Every link has 2 rollers (*), 400/2 = 200 links / hits / second.
Even if every other, or every 3 links form a bow big enough to hit something you still don't get the 16 Hz.

Okay , if every 12 links form a bow you do.

12 chain links are ~ 12cm (4-2/3") long.
I don't have a chain here to measure exactly.

(*) I know its not wrong but also no right as 1 link shares 2 rollers with its neighbours.
That said: if 2 rollers have passed you have either seen: the end of 1 link and the beginning of another (a possible hit), or the beginning of 1 link (a possible hit) and the end of that same link.
That boils down to: 2 rollers = 1 "hittable" link.


Side note: that timing chain is spinning pretty fast.
The oil pump chain even faster!
And the oil pump itself is spinning like a gas turbine

Billman250

I don't know the exact frequency

but I do know for a fact where the rapid plastic wrapping sound originates.