250 xs Optimax

[sportsnutguy]

Sat I idled for at least 20 min after dropping it in and then shut it down for 5 min. When I went to restart it, it would turn over but would not start. Ball was completely flat. I switched tanks and it was fine and away I went. Fished a 8 hour bass tournament and it was fine all day. With an hour left I made a 2 mile run and I started hearing a slight knock. Shut it down and fished for a few minutes and decided to head to the ramp. No loss of power at all but on the way to the ramp…I heard it again. Got home and removed cowling to inspect. Nothing jumped out at me but I took this short video. Really dont want to start it again although I would like to do a compression test.
serial #1B765063

[sportsnutguy]

I took a 19 second video with my phone but it won’t upload

[JOE54]

drain gear oil look for metal particals, check compressor also for failing

[EuropeanAM]

You can't load videos to the forums. You CAN host it on Youtube and provide a link here, though.

Better get it checked- Joe's suggestions are spot-on.

[sportsnutguy]

well that explains it

[sportsnutguy]

I think the video is ready on YouTube

[EuropeanAM]

Can't really hear anything out of the ordinary in that video.

Definitely check the air compressor (pull belt, check for lateral or up-down movement in the pulley, make sure there is no "knock" at the bottom of the rotation/stroke, etc).

If no problem there, check gear lube.

[sportsnutguy]

I have a bad piston in the compressor. I’ll be looking tomorrow for a core that may have a good piston. Also considering having a piston made…waiting on prices. New compressor is $1100 so weighing my options. Any suggestions?

[JOE54]

yea inspect rails for debri from failed piston possible direct injector restriction risking powerhead failure that 1100 will be drop in the bucket, would not attempt to repair compressor , good luck

[EuropeanAM]

+1... Replace compressor as assembly (new) and replace return oil line filters as well.

Air supply hose, rails, all hoses and direct injectors should be cleaned and validated to make certain that no metal is present (and no damage is already done).

[sportsnutguy]

For the last two guys that responded today I appreciate the info. We have decided just to go with a brand new unit

[DewRonInc]

I have a bad piston in the compressor. I’ll be looking tomorrow for a core that may have a good piston. Also considering having a piston made…waiting on prices. New compressor is $1100 so weighing my options. Any suggestions?

Pro marine has a kit I found to be good, I took one apart and honed and rebuilt, worked like a champ, about to do another

[Savage]

Pro marine has a kit I found to be good, I took one apart and honed and rebuilt, worked like a champ, about to do another

Got a part number for that kit Ron?

[JOE54]

one i seen you have to use old crank , p/n 500

[Bob G.]

Got a part number for that kit Ron?

The reman kit is on page 132 of 288 of the Mercury catalog at Pro Marine.

I’d probably go with new.

[EuropeanAM]

one i seen you have to use old crank , p/n 500

And that component seems to be the weakest link... from what I've observed.

[JOE54]

^^^^^^^^^^+++++ another , i didnt want to say that, must be good to be you

[sportsnutguy]

I went with the new compressor and then the starboard side assembly diaphragm had to be replaced….which was done. Now it won’t pee at all, which it did prior to all of this. Merc mechanic is having a hell of a time finding the blockage. He ended up replacing the impeller and that didn’t work. Has flushed out 90% of the lines.

[SilverFox579]

Absolutely must find out why you have no telltale as it comes from the compressor. If no telltale there is no coolant flow through the compressor!

Has the compressor strainer been checked for blockage? When was water pump last serviced? Service is annually or 100hrs whichever comes first.

[EuropeanAM]

Compressor cooling circuit is very simple. Water supply comes through a strainer in the port side of the adapter plate, then routes to the air compressor.

Comes out of the compressor on the other side and goes to the telltale fitting.

So that's 4 points at which you could disconnect hoses to confirm water is (or is not) present... or access hoses/fittings to clean out any debris.