I hate 4 Strokes

[bullie]

I appreciate you guys. Lots of information here. I am on totally new ground with this one. I hope we can figure this one out.

Maybe I should organize the instructions you are giving me to make sure I don’t spend too much more time chasing my tail.
I have a new flywheel key in route and will check the tapers carefully before I reinstall. I will also drain some of the oil. The owner added too much.

What should I check with the timing belt?

[bullie]

I did find water in his fuel and had him replace it. Fresh fuel now.

[joesnuffy]

Their should be a key on the timing gear make sure its not sheared and timing of cam and crank are correct. I have noticed with water in fuel some stations in the keys had it some didn’t. If he gets his fuel at same station that might be an issue. If you can’t get it to run correctly you might try purchasing some fuel on your own higher octane and give it a whirl.

hope that helps,
Joe

[joesnuffy]

If you find timing off piston could have slapped the valves or a valve I would try a compression check once you know timing is correct and key isn’t sheered to make sure something didn’t possible get drawn into the engine and cause the flywheel key to semi sheer that would most likely lower compression on a cylinder.

Joe

[bullie]

joesnuffy, ok. Thanks. Are there 3 keys? Flywheel, drive pulley, and driven pulley?

What is the process of resetting the timing? I assume I will have to reset it after removing the timing gears.

[PugetSoundBoater]

quote Bullie:

joesnuffy, ok. Thanks. Are there 3 keys? Flywheel, drive pulley, and driven pulley?

What is the process of resetting the timing? I assume I will have to reset it after removing the timing gears.

I’m figuring you should not have to reset the timing once you replace the pulleys back on the shafts with the correct keys. Just don’t move the pulleys out of there original position and you should be good.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[fleetwin]

Don’t have any knowledge about these engines, but I know the cam timing must be verified or the engine will never run right…Do you have the proper service manual for this engine? The correct manual is absolutely necessary for clear set up instructions. I’m not sure just how your cam is driven. I guess I am used to the smaller 4 strokes where the cam belt is driven off the flywheel and comes out on top of the engine to the cam gear. Kind of sounds like this is not the case on your engine. If not, the cam gear is concealed inside the engine and driven off the crank.
The slightly damaged key you pictured would not affect timing all that much unfortunately, wish that was your problem though.
I’m hoping someone here is familiar with your engine and can give more concise instructions….For now, stick with the basics like Mumbles says, fresh fuel, proper oil level, and recheck compression once the flywheel is properly reinstalled.

[billw]

Here is a link to installing the timing belt on a Mercury 9.9. I am NOT SURE if this is a Tohatsu-based power head or a Yamaha based one; so use your own judgement. Where I work, we see very few small engines. If the picture looks like your motor, then it probably is the same thing, a Tohatsu based one.

http://www.boatinfo.no/lib/mercury/manu … .html#/122

Long live American manufacturing!

[joesnuffy]

I am guessing the timing keys won’t be sheered but verify the timing using the correct manual. Looking at the manual posted if its correct page 119. If timing verifies keys aren’t sheered and timing belt isn’t off by a 1 or 2 teeth. I also wanted to make sure you have about the same compression on both cylinders by verifying it with a compression gauge after you put flywheel back on to make sure of no internal damage just to rule that out or rule it in. I thought cam timing would be a good thing to check while you got the flywheel off waiting for a key. Also you may want to change the oil I was reading in manual posted that low oil pressure trips the computer/brain and won’t let engine run over 2000 rpms. If oil is diluted with fuel like mumbles said it could cause low oil pressure.

Hope that helps,
Joe

[bullie]

Ok. Waiting on the key now.

[Author]

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