Ticking 200 OX66

[Buckwheat]

Well - new to this forum - I would appreciate any help - never owned a Yamaha outboard. PIcked up a used wellcraft with a 2003 200 OX66. Pretty loud ticking noise at idle and no wake speed. Cant hear it at higher RPM.

I keep reading about O2 sensor needing cleaning or replaced - or worse, like wrist pins and blown power head. Motor runs very strong and pushes the boat to almost 43 knots (5600 rpm) and gets great mileage when i keep her under 4000 rpm. put about 15 hours on her so far and it seems like a great motor. I think if the problem was serious, it would show up in the performance? Just interested in your thoughts. Compression even across all six holes. Other than the ticking, motor does not skip a beat. Thanks.

[ausnoelm]

I guess you need to determine where the ticking is coming from, it could just be something rubbing, but, if internal, then the ticking could well develop into a loud knocking, followed by a bang!

[Sequoiha]

the transfer tube under the O2 sensor is a common place for this ticking noise and its an easy repair, if its never been pulled and cleaned its time. I wouldnt bother cleaning the tube if it is ticking, needs to be replaced, do not spray any cleaning sprays in to the hole in the block, do not touch the end of the O2 sensor with your fingers, replace the gaskets, clean the whole block very well,

[rodbolt17]

clean and then test O2 sensor output voltage.
the other reason for ticking is the water pump retainer.
if the lock coller is not set correctly the driveshaft thrust bearing knocks in gear at low speeds.

[Buckwheat]

Thank you - very helpful - will have a tech look into this.

[CRAZY CHARLIE]

I had same and cured it by removing the O2 housing and removing what looks like a tiny silver dumbell/barbell. It was caked with carbon and there is a hole/passageway down the center of it that was clogged. Soaked it in Seafoam and picked away the carbon.Reassembled and the noise was gone. Pick up a gasket set for about $25 for reassembly.strange thing is that since I have performed this servicing ,the motor is Definetly using more fuel.I was told that the clogged part was making a lean burn condition which is not so good for the motors health long term.Charlie

[CRAZY CHARLIE]

BTW ,post back results ...Charlie

[99yam40]

you do realize this was a very old thread and good chance he has not been back here in 7 years

[CRAZY CHARLIE]

Nope,I didnt see that however Perhaps someone else can use this information.Charlie