high rpm metalic ticking or rattle

[cscheure]

150 yamaha , 1991, new onset noise only at 4000 rpm or higher, ideas or suggestions, actually 1994 150 txrs,metalic tapping sound definately tied to rpms, frequency increases with rpm, but just above 4000. est 400-500 hours on engine

[99yam40]

no idea what motor you have, or if it matters which one

150TLRP
150TXRP
L150TXRP
P150TLRP
P150TRP

[TownsendsFJR1300]

Description of the noise? Knocking, squeeling, banging, etc??? Something??

Can you post an audio / video with and W/O the cowl off?

Can you duplicate it in the water, with the cowl off and narrow down the area??

[99yam40]

on a motor that old , with all of the info provided.

my guess would be a piston/rod fixin to take a peek out the side
but it could be bad gas causing pre ignition maybe

[TownsendsFJR1300]

Sounds like some piston slap.

I don't think a compression or leakdown test will reveal anything but it certainly can't hurt. If a broken ring (not likely) etc, that would show up

If you have a stethescope, you maybe able to narrow it down to one piston. A screwdriver to your ear and each cylinder may work as well.

Unfortunately your trying to listen thru a water jacket and outer block, ie, very difficult.

Looking, checking for any excess play thru the exhaust may show something.

An engine that old, but I'd probably run it under 4K as its likely not worth the labor for a complete tear down..

More RPM's than that, you WILL find the issue (actually, it'll find you) and need a tow in.

If you dare to make a quick audio / video would likely help on our end..
http://www.boats.net/parts/search/Ya...TON/parts.html

[rodbolt17]

check the wrist pins for slop.
the old small wristpins sometimes gave way.
overpropping just hastened the failure.

[zenoahphobic]

"metallic sound" is all we have to go on at this stage. To me that suggest higher frequency sounds more commonly outside the engine mass itself maybe. Like something hitting or scrapping or even a grinding whirring sound. Look at all the stuff on the outside like flywheel, even perhaps your engine leg (oil will tell)