What is this for ? It has started to rattle

[PKFK]

See center of photo - this is a Yanmar 3ym30.

The silver colored screw has a metal sleeve over it and the metal sleeve seems loose and jingles at idle speed.

The screw seems to have a hole in it as well.

I don't want to go tightening it up without knowing what it does as it might be an adjustment for something on the engine. But the jingle of the loose sleeve is a new sound - an a bit troubling until I figure it out.

Any diesel heads out there that can advise ?

Thanks !

 

[nolasafari]

http://yanmar.com/product/marinepleasure/sailBoatPropulsion/operationmanual/YM_V2_21JAN09.pdf
This is a link to the manual.

I would start looking around page 88.

 

[PKFK]

Thanks for that link - but - I have the operator manual already and it does not identify that part unfortunately.

I did manage to find a service manual, and from what I can see there, it is a high limit adjustment for the throttle, with a warning in the service manual that adjustiing it will *void* the warranty ! (yikes)

So now I need to still figure out how to stop the sleeve around it from rattling......

 

[justsomeguy]

Depending on how hot it gets, some kind of shim?

 

[splax]

It appears the hole in the screw is for a lock wire. That is missing and the throttle may be out of adjustment. Have someone knowledgeable set the throttle high limit and install a lock wire, which should stop the rattle.

 

[nolasafari]

A little dab of of silicone glue will stop the rattle and is easily removed until you figure out the correct solution.

 

[Jake N Eggs]

It is probably a metal guard or anti tamper cover that is set over the locknut of the adjustment screw. It is hard to tell what holds it on. It could be the anti tamper lockwire that splax has suggested but it also looks like there is a clip that is pressed over the adjustment screw. If it wont lift up it probably doesn't need the lockwire. Try installing an o-ring over the large diameter and press it all the way down to where the movement is. It may also be possible to push down on the securing clip, if that is indeed what is there.

 

[nolasafari]

I looked at the one on my engine last night, it has no safety wire and is as loose as yours, so either yours is fine or both of ours are boroken.

 

[PKFK]

Ah-ha....nothing like getting a vitrual look at another engine to see what's up.

I suspect that this is in fact not "broken" then - and perhaps has just started to rattle due to the RPM of the engine.....I did notice that Idle is a bit slower (ie more vibration). If I nudge it up a tiny bit things smooth out and the sound stops coming from this part.

I will likely have a yanmar mechanic look things over this fall anyways, so I will also ask and report back if I get any more info.

Thanks everyone for the replies !

// Paul