Desperately Need Help - New Built Engine With Strange Sound.

[Ralph Wiggum]

Stock tension is effectively solid in operation as it ratchets out, Hydraulic pressure is only use to drive the tensioner piston out to the next ratchet tooth as the parts wear.

IE the tensioner doesn't "float" against Hydraulic pressure like a spring loaded belt tensioner does. If it did cam timing would change on engine accel/deccel.

[JETURBO]

But the stock item does allow almost a bounce against the guide I think ( hence the slack to skip a tooth and common enough )

If it was solid fixed the guide would wear out very quickly as the rpm will push the chain to all outer edges ( from how I see it )

Iirc it's a very similar set up to the standard idle belt tensioner and how that is "sprung" and allows for belt movement ( but correct tension )same but not same the belt gets unbalanced at around 3-4k then comes back into line

What brand are the new guides ?

Edited 18/09/15 05:06 AM by Womend Bellbat

[Ralph Wiggum]

The tensioner and moving guide are on the slack side of the chain. The Drive side of the chain is constantly running on the guide,the shape of the guide and the amount of oil in that area prevent excessive wear, not the tensioner movement.

RE the sneaky skip a tooth edit...chain stretch and engine acceleration/decel far faster then allowed for when they developed the system,not to mention the additional torque required to drive and subsequent wear from heavier valve springs is the reason. Not tensioner movement IMHO.

[JETURBO]

I honestly thought some hydraulic take up and then a limit would be there to prevent excess noise and to allow for inertia etc etc

The sound from that video definitely suggests something touching that front area...

[WTFWSAT]

A solid tensioner ?

So no hydraulic fluctuations......

I bet at a specific rpm your chain/guides have a harmonic spazz and the tensioner is passing that onto the timing chain cover and areas

Swop it out for a stock item ( its quick enough to do ) and see what happens

Yeah we've tried a stock tensioner. As well as pulling nylon bushes on the end of the tensioner to cushion any vibrations but it doesn't change the rpm range or pitch of the noise. The only thing that changes it slightly is letting tension off the chain until it's quite loose which makes the rpm range lower that the noise comes in at.

[arronm]

Have you tried 3000-3300 straight off a cold engine and then when it fully warmed up. Any change in noise or rpm??

[WTFWSAT]

Have you tried 3000-3300 straight off a cold engine and then when it fully warmed up. Any change in noise or rpm??

Yeah we have run it to operating temprature and it makes no difference to noise or rpm. It also doesn't change under load drive up hills etc.

[turbotrana]

First point of call for me are earphone thingamajig with the metal prong which will get you closer to where. Some good listening devices out there where you can position different place and switch between them.

Second point of call is I start cutting observation holes in things like rocker cover, timing cover. Might make the noise easier to locate.

[xr6tForMe]

I like turbotrana's post.

Even a long screwdriver with the tip against what you are listening to and the handle against your ear, works remarkably well for listening to specific places.

[xr6tForMe]

This info on resonance in chains may be of interest.

https://www.google.com.au/url?sa=t&source=web&rct=j&url=http://www.maplesoft.com/view.aspx%3FSF%3D5091/ford.pdf&ved=0CFAQFjANahUKEwiGwPztgcjIAhWBMZQKHfZRCAA&usg=AFQjCNEYf9tZuVVJ1ckHEhEKAy0PAAuMag