Engine not starting – rapid vibration noise from the starter.

[moresparks]

Hi just wondered if I have a really serious problem that has developed over the winter and wondered if anyone can give some pointers.
At layup time .. everything all fine.
Just a standard 4 cylinder volvo petrol engine layed up according to the manual including fogging etc.
Come to start and hear a rapid vibration from the starter / solenoid but engine not turning over.

So far..
Replaced starter with brand new replacement.
Changed battery
Disconnected alternator and tilt pump.
Flywheel turns normally when turned over by crank nut on the front of the engine.
Same noise with spark plugs removed , flywheel turns over by hand as expected.
Propeller spins freely- i.e. not in gear.
I will check the relay circuit tomorrow but that looks ok at first test.
Just wondered if I have overlooked anything so any help would be appreciated.

 

[Croftie]

Sounds like a volt drop somewhere
Check all connections including -ve battery to engine/starter.

 

[gordmac]

The starter is turning but the engine isn't? Solenoid not moving the starter gear wheel into mesh?

 

[moresparks]

Hi - All sorted now..
Turns out to be a very intermittent high resistance cable in the starter / relay circuit - devil of a job to trace only by replacing cables one by one.
Thank you for your responses.

 

[Bilgediver]

Hi - All sorted now..
Turns out to be a very intermittent high resistance cable in the starter / relay circuit - devil of a job to trace only by replacing cables one by one.
Thank you for your responses.

I had a similar problem on a Mercruiser 3.0 TKS Petrol fitted to a club boat. Suspected a poor earth so took a jumper lead to the boat and clamped one end to the battery Neg. and the other end to the alternator bracket. Everything fine.

Visually the earth connection on the engine looked fine and well greased . Took it apart and polished up all the mating surfaces on several crimps etc greased and replaced. The surfaces appeared only slightly discoloured . At that terminal point the engine component was an aluminium elbow, the crimps were a mixture of steel and copper and the bolt stainless.Will be checking it again soon.