1992 90 HP V4: Odd Mid-Range Buzzing/Ticking Sound

[thegage]

At the end of last season my 1992 Johnson 90 HP V4 developed this sound between about 2500-4200 RPM that's a bit difficult to describe. It's a kind of loud buzzing sound with a bit of a tick in that is very evident over the sound of the engine. At the time the sound developed I found that the fuel outlet on the VRO pump was leaking a bit. Now, it wasn't pouring fuel into the engine compartment or anything, and I don't suspect a lean condition as I did a compression test after I fixed the pump and all four cylinders are within 5% of each other (100-105 psi cold), but there's this nagging suspicion that it may have contributed something. I'm not familiar enough with big old 2-strokes to diagnose the sound. Is it a bearing? One of the reed assemblies? Any insight would be appreciated.

John

 

[boobie]

Re: 1992 90 HP V4: Odd Mid-Range Buzzing/Ticking Sound

It could be a high tension leak on one of your plug wires or else you have the start of some lower unit probs. Take the hood off and run it and see if you can hear where to sound is coming from. If the sound goes away with the hood off, you may have a prob with the hood hitting something.

 

[thegage]

Re: 1992 90 HP V4: Odd Mid-Range Buzzing/Ticking Sound

Thanks for the input. Might be the lower end as I was getting some water into it last year before replacing seals, so another place to focus. From searching here it seems that a crankshaft head bearing might make this sort of noise. I can't get out on the water for a couple of days to have a listen.

John

 

[trendsetter240]

Re: 1992 90 HP V4: Odd Mid-Range Buzzing/Ticking Sound

I hate to say it but I think it's the top bearing in your lower unit. This bearing fails when there is not enough gearcase lube in thelower unit or the lube is saturated with water. Usually it's low gear case lube and not water as even with some water there is lubrication.

Do you hear the tick when the engine is runnning in neutral? If it only comes when in gear it's that bearing. Listen even at idles speeds in gear as it will be there but very quiet. Drain the lower unit and check the oil for water and metal shavings. The lower drain plug is magnetic and the metal shavings should stick to it. Otherwise run the lube through your fingers and feel for metal.

If it is that bearing you are on borrowed time and the gears will lock up if you keep running it.

Hope I'm wrong but I've seen this a few times. That unmistakeable ticking along with history of water in the gear case is a dead give away.

 

[thegage]

Re: 1992 90 HP V4: Odd Mid-Range Buzzing/Ticking Sound

It doesn't tick in neutral. I suspect I might be spending some time on ebay.

John

 

[boobie]

Re: 1992 90 HP V4: Odd Mid-Range Buzzing/Ticking Sound

Do some more troubleshooting before you start replacing parts !!

 

[thegage]

Re: 1992 90 HP V4: Odd Mid-Range Buzzing/Ticking Sound

Oh, I will. I can't get out on the water for a couple of days so I'm just spending spare time thinking about options.

John