Mid-section Knocking! (See video)

[Tripp Halbert]

A video of the running engine can be viewed here on my Facebook page: https://www.facebook.com/video.php?v...15&pnref=story

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1995 115hp mercury 2+2

Note: the sound is most audible between seconds 25-35 and is kind of sporadic.

132 psi on all cylinders. Pushed on pistons at TDC, no play. rebuilt water pump. drive shaft good and solid, splines good.

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Observations:

-sound is mostly heard around 4k rpms and when coming of plane gradually. Cant hear it when the boat is loaded down.

-rpms sometimes "bounce" while on plane. max rpm is like 5700rpms?

-engine does not make this sound on hose at all- in gear or not. it does not make this sound in neutral either.

-lower unit had water intrusion until i replaced a seal. i found very small metal shards in it but very little of them.

-Have had stalling issues when trying to pull a skier but not when riding with 6 or 7 people around the river.

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Unrelated...maybe?

-keep hearing fuel line "click,click,click" when engine is at idle. (audible in my video near the end)

 

[Tripp Halbert]

bump...help please anyone recognize this sound?

 

[Bondo]

Ayuh,.... Donno's I heard it or not,....

What color are the spark plugs,..??
Possible detonation from a lean condition,..??

 

[Tripp Halbert]

Thanks for the feedback. Plugs look good. it was doing this when i ran 50:1 in tank with oil injection on top of that and also when i stepped down to 100:1 and now to straight gas in tank. during those i was making sure the injection system was functioning and it was definitely running rich and smoking, but still the sound was there.

Sorry about the poor audio but the sound is faint and hard to hear, but you can hear it between second 25 through around second 40 as it falls out of sync with the sound of the engine. It sounds like a loose piece pinging around??

 

[dunc333]

listened but not sure i could hear anything to dramatic i will listen again when i have less back ground noise cheers

 

[Tripp Halbert]

Okay. I will try to upload a better quality for you guys.

 

[Bondo]

Thanks for the feedback. Plugs look good. it was doing this when i ran 50:1 in tank with oil injection on top of that and also when i stepped down to 100:1 and now to straight gas in tank. during those i was making sure the injection system was functioning and it was definitely running rich and smoking, but still the sound was there.

Sorry about the poor audio but the sound is faint and hard to hear, but you can hear it between second 25 through around second 40 as it falls out of sync with the sound of the engine. It sounds like a loose piece pinging around??

Ayuh,.... Oil mixture don't really matter if the gas ain't gettin' to it, it'll detonate at high rpms, or high loads,....

Is there any Color to the plugs,..??

If they're white, 'n brand new lookin', that ain't such a good thing,.....

Ain't sayin' it is,... just sayin',....

The extra clear fuel filter says yer havin' fuel issues,....

 

[Tripp Halbert]

Oh okay I didn't know that, I will check them again and post back. Not trying to be a smart a$$, but What do you mean about the clear fuel? It's coming straight from the tank where the fuel is clear, no premix.

 

[Tripp Halbert]

No Title

Bondo

 

[Tripp Halbert]

Bump, anyone?

 

[Tripp Halbert]

hope this is a bit better quality, try this one guys.

 

[racerone]

Remove 20 / 25 bolts on the exhaust cover and have a look at the pistons and rings ( hot side ) of the motor.

 

[Tripp Halbert]

i gotcha, is there anything other applicable tests i could conduct before doing this? half of the bolts your talking about are rusted out and will probably break so i dont want to be dead in the water before running any other possible tests.

 

[Boat Doctor1]

ok my guess?? water in LU?? and all u did was replace a seal?????????????? DUHHHHH?? teardown complete lu & start looking @ all bearings & gearsets!1 Ant metal in lu oil when drained?? small fine ?? 1st guess its in that area. 2nd guess= possibly rod bearings - due to weak oil mix!! over time - somethings going to give if you keep running it!!

 

[Tripp Halbert]

Is there a replaceble bearing on the drive shaft in the foot (the one ur mentioning) cause that would definitely make sense