Really strange sound on start up - Mercruiser 3.0

[gone_walkabouts]

Hi All,

Going boating tomorrow and hoping I can get an option on this strange sound when starting my Mercruiser 3.0. Video attached.

At first I thought it might be a wearing belt slipping under the load of the alternator on start - yet it seems to be coming from the back m/side of the engine . Thinking more starter motor now but hard to tell.

Engine performing fine once started , so assume it may not be internal issues.

Wondering if anyone has had a similar issue or has any idea on what test or area to focus on to diagnosis? It Make the noise if cold or warm and when battery fully charged.

A real croaking sound,

Thanks

 

[alldodge]

Don't know, might help to hear more then a couple seconds

 

[Grub54891]

Starter? not much to go on here.

 

[gone_walkabouts]

Yes unfortunately the video cuts out. The strange noise disappears shorty after it starts and shortly after the video ends.

 

[alldodge]

Might be the starter solenoid springing back disengaging

 

[Scott06]

Agreed sounds like starter

I would check there is no water In cylinder or does it turn over freely ? Otherwise starter is bad or maybe loose not allowing smooth retracting of gear

 

[Bt Doctur]

have to agree, a dry ,rusty bushing in the starter

 

[gone_walkabouts]

Thanks all - very helpful - so I assume new starter at a minimum. I do wonder if the issue is a symptom of a hydro lock situation beginning. The history on the risers and manifold are unknown, rust forming on the outside of the riser where it joins the manifold. Plan to inspect and replace gasket at minimum.

Is anyone able to give advice on how to determine if water is dripping into the cylinders? Moist spark plugs , would I see water in the oil ? I have a compression test tool also if that helps


I have attached another video of the sound that is clearer - it sounds like the starter motor teeth is slipping. Is the flywheel going backward normal ?

 

[Scott06]

Thanks all - very helpful - so I assume new starter at a minimum. I do wonder if the issue is a symptom of a hydro lock situation beginning. The history on the risers and manifold are unknown, rust forming on the outside of the riser where it joins the manifold. Plan to inspect and replace gasket at minimum.

Is anyone able to give advice on how to determine if water is dripping into the cylinders? Moist spark plugs , would I see water in the oil ? I have a compression test tool also if that helps


I have attached another video of the sound that is clearer - it sounds like the starter motor teeth is slipping. Is the flywheel going backward normal ?

Take the plugs out and turn it over if water come out spark plug holes. if flywheel is going backwards that is indicative of some pressure in cylinders

i dont think it would hydro lock that quickly as shown on video But easy to rule out

 

[Grub54891]

If the flywheel is just going backwards after shutdown that little bit, it's because the cylinder is coming up on compression with no spark. They all do that no problem.