Intermitent Clicking Noise

[irdir]

I've got a 1986 140hp Evinrude with VRO being used. Last time out, idling out of the no-wake zone, the no oil horn kept going off after every 5 min. of running it until I decided to pump the oil primer bulb once, then it went away. It ran flawlessly until we were putsing back in to the ramp and I heard a clicking noise coming from the engine. It sounded the same when I put my ear on either side of the motor. I thought that the engine was going to have to go for another rebuild because I ran it without oil. Went home to flush it out with the muffs and the noise was still there but was still unable to pinpoint where it was coming from. I figured that maybe it was the VRO clicking when it has air in the system.

Today I ran it again to see if it still made noise after sitting a little and sure enough it did. But, after it ran for like 10 minutes it decided to fade out and now it?s gone. I raised the idle up and back down to see if it would make a difference but it didn't. Then I put it in gear (the motor is in a test tank because I also wanted to set the idle speed) and it faded in and then back out again. Now I can't get it to come back. All I know is that it sounds like valve slap on a car, its coming from the power head, and it's now intermittent. Any ideas?

 

[mikesea]

Re: Intermitent Clicking Noise

I believe what you hear is the VRO going bad,If the VRO pump has never been changed ,It should be,there were upgrades over the yrs.You say the engine was rebuilt.In the shop I worked at,we always replaced the VRO pump IF the customer wanted to continue using VRO.Many earlier yr.engines converted back to oil gas mix due the many early probs.with VRO.In fact,OMC supplied a kit to change it back.Unlike engines like Yamaha,OMC mixed the oil with gas in the VRO,when the oil side of the VRO went out,you got gas ,no oil then the show was over.Yamaha,is oil injected after the carb and as the oil pump would wear it would over oil,causing engine to fog ,but didnt blow in the way OMC did.You could change over to mixing and save the cost of a few hundred bucks for a new VRO.Simply disconnect elec. connections,and oil line to vro.Be sure to mix oil with gas and prime the fuel lines with oil mixed gas

 

[irdir]

Re: Intermitent Clicking Noise

I tried to isolate the VRO from the engine and when i did i noticed that for sure the VRO pump is not making the noise. The ticking comes and goes at idle and a little higher in RPMs. If i run it out and then slow down to idle back in it'll click for a while and then just stop. Also, while it clicks it backfires and runs terrible. The plugs look good. One more thing, when it backfires it blows a blue cloud from the side of the carbs. I think the gasket on the intake manifold is bad but that doesn't explain the clicking. Maybe a bad reed? I got the intake manifold off and i'm gonna replace the gasket. How fast can i run the motor with the airbox off in neutral? Thanks.

 

[ezeke]

Re: Intermitent Clicking Noise

You might want to check the pulse limiter [check valve]. If it is black, it needs to be replaced with the blue and gold one. Regardless of upgrade, it needs to be cleaned periodically.

 

[R.Johnson]

Re: Intermitent Clicking Noise

If it were the VRO clicking, you would feel it if you put your hand on it. I don't see how a VRO would cause that backfire. Could it bee a spark snap you are hearing?

 

[irdir]

Re: Intermitent Clicking Noise

The check valve is blue and the VRO was changed by a previous owner to the 4-wire set up. I'll check the valve today for any junk in back of it. As for a spark snap, I don't think I’d be hearing it towards the bottom of the crankcase. That’s where it APPEARS to be coming from. From looking at that backfire I saw I’m leading to believe the gasket around the intake manifold went bad. One extra point I forgot to mention is that while we were fiddling around with it the "no oil" horn sounded. So that makes me think that if there is a leak, it's around the #4 cylinder port because that drives the VRO pump and then since it leaks it wouldn't pulse enough to drive enough oil in, causing an alarm. Hopefully i'm right otherwise i'll be very angry when I realize that this was a simple fix and I went all out, breaking gaskets and all that good stuff. lol

 

[irdir]

Re: Intermitent Clicking Noise

Bump