clicking noise at aggressive acceleration

[Joachim_Halse]

Hi folks,
my mercruiser alpha one 3.0 ltr mounted in a 1984 Wellcraft 180 bowrider is making a loud clicking sound when I put it to hard work, for example pulling the tube with two-three people on it out of the water, or pulling two small wakeboarders until the boat is on plane. As soon as the boat is on plane, the clicking stops. Or if I pull back a bit on the throttle and allow for a longer time to get out of the water the clicking also stops. When idling or cruising at a fixed speed there is no clicking. In other words, the engine clicking is related to aggressive acceleration at full throttle and seems to get worse with higher water resistance from towing. My question is, what can be causing this sound? I am not sure about the source location beyond somewhere in the engine compartment, since I dont like the idea of running full throttle and people on tube, while the whole backseat is flipped open... Am I over-burdening the engine or drive?
Thanks

 

[Grub54891]

First I would check for any loose alternator or PS brackets, The listen by the exhaust flapper area, and then move to the u-joints/ drive area. A good way to listen is to use a mechanics stethoscope, or a piece of hose held to your ear. I've even used a stick to listen to different areas of engines.

 

[Scott Danforth]

Clicking, or more of a rattling? Rattling is detonating which is your motor rating itself

 

[Joachim_Halse]

Thanks.
I'm ready to listen more carefully. But I have a few more uncertainties and questions:

Sounds are difficult to describe with words, and English is not my native language. No, I don't think this sound qualifies as rattling - "A rattling is a quick, often unsteady, burst of sounds. The sound of a rattlesnake is a good example of a rattling" (from www.vocabulary.com/dictionary/rattling). It is more distinct in that each click has a very short duration, occurring approximately once or twice per second, and with a high-pitched sound. More like the shutter sound of an older single-lens reflex camera.

I dont understand what you mean that my "motor is rating itself". Is it like my motor saying "I can take no more beating", or...?

The problem with locating the sound is that it is not so easy to reproduce the circumstances with high water resistance and full throttle, while having the whole back seat / motor cover flipped open to enable listening. I imagine the relatively loose insulation material will fly around, and the hinges of the back seat/motor cover might be damaged from the movements.

Is there a good place to look for a diagram describing the different engine parts of a Alpha One 3 ltr engine? I don't know where the "exhaust flapper area" is, nor the "PS brackets"...

I have found different serial numbers for both Stern Drive Unit, Engine Serial Number, Transom Serial Number, on the actual motor, which leads me to think that the stern drive is a "Alpha One Gen II", and the engine a "[FONT=&quot]3.0L/3.0LX ALPHA ONE ENGINE" (from looking up the numbers at boats.net).

Any help appreciated[/FONT]

 

[Bob79]

Try checking your timing.

 

[harleyman1975]

The sound could be a condition that is referred to as detonation caused by the ignition timing being too far advanced also referred to as pinging or a spark knock. this condition can be relieved by retarding the timing a couple of degrees or even by running a higher octane gasoline. Check your timing to be certain it is dead on. another possible cause is low oil pressure or a collapsing lifer. Check the oil level. Keep an eye on the oil pressure (min of 10 psi per 1000 rpms).

 

[Bondo]

I dont understand what you mean that my "motor is rating itself". Is it like my motor saying "I can take no more beating", or...?

Ayuh,..... Welcome Aboard,..... I don't wanta put words in Scotts mouth, but my guess is it's supposed to be Eating itself,....

Detonation is induced by many things, bad ignition timin' is one,...
But in boats, I think the most common cause is a Lean condition,....
Bad gas, Crap in the gas, water in the gas, 'n the effects all that has on the fuel pump, 'n carb,....

Detonation is often described as rattlin' like shakin' a coffee can fulla ball bearings,...

 

[Scott Danforth]

Damn auto correct on this @*!/!?_:#_ phone.

Bondo, feel free to put a word or two in my mouth - LOL

Rattling, or pinging or a bucket of marbles, or knocking are all ways to describe detonation

Detonation is your motor eating itself (caught the phone this time). Its early explosions while the piston is still traveling upward..... It has a detrimental effect on the surface of the piston spalling the surface until the piston has a hole in it. It also takes out bearings.

Now a clicking sound could be something loose, such as the damper bolts being loose or the coupling bolts.