Bad Reed Valve?

[rwheele]

I have a 91 40 HP 4 cylinder 2 stroke Merc. For about the last season or two it has had an internal rattle that has had me worried. Last time I ran it just as I was bringing it around to put it on the trailer it kind of coughed and quit. I winched it up and parked it for the winter.

Went to mess with it today and it runs but seemed to be flooding out the bottom carb and only hitting on two. First I checked the needle and seat and float level which seemed fine I could lower the float and gas flowed and raised the float and it stopped as it should. I checked the spark, which is strong, and even swapped the plugs to the top cylinders. I don't have a compression tester but both bottoms seem to match the top two. Then I noticed it was spitting out the bottom carb and holding your hand over it wasn't sucking but either seemed to have no suck or maybe even pushing air out a little. I

After finding this forum and reading a couple other posts I pulled all 4 plugs and the top carb definitely sucks and the bottom doesn't when you hold your hand over it. The carb is snug, I don't think it's sucking air between the carb and the block and I couldn't find any obvious places where it would have a vacuum leak.

Help

 

[GA_Boater]

Re: Bad Reed Valve?

Get a compression tester with free rental at an auto parts store and check compression to start. Reeds do fail, but way down on the list of suspects.

Welcome aboard!

 

[rwheele]

Re: Bad Reed Valve?

I will, but I bet my shade tree the two bottoms have the same compression as the top ones that run. My dad left me his calibrated thumb.

 

[racerone]

Re: Bad Reed Valve?

Remove the intake bypass covers ( if equipped with them ) and have a look at pistons and rings.----And do a compression test with a gauge.

 

[rwheele]

Re: Bad Reed Valve?

Just got back from Harbor Freight with a compression tester. Will report back tomorrow.

Thanks all.

 

[Faztbullet]

Re: Bad Reed Valve?

More likely bottom crankseal problem.....

 

[rwheele]

Re: Bad Reed Valve?

Been too rainy to work on it.

So if it's a crankseal how could I tell for sure and does it have to come apart?

I really love this boat and it has a lot of sentimental value, I will get it fixed one way or another. I'd love to repower it but I just don't have that kind of cash right now.

 

[carholme]

Re: Bad Reed Valve?

Do you have the s/n of your engine?

Gerry

 

[rwheele]

Turned out it dropped a Reed and ruined the block. I ordered a short block from Twin City Outboards (wwwtcoutboards.com) for 400$. John at Angler Marine in Pensacola, Fl swapped all my stuff and installed it for me. RUNS GREAT! I'd certainly recommend either place.