Engine Knock

[GRR]

I've just put the boat back in the water after an extended winter layup.
Fired up the engine (Volvo 431 Petrol) for the first time without ant problems EXCEPT there is a load clank from the back of the engine every 30 seconds or so, does not seem to vary with revs..

Any suggestion please

 

[sarabande]

definitely from the engine, rather than the gearbox or drive ?

Any change in oil pressures when it happens ?


Does it happen at tickover on neutral, or in drive only ? Ahead and/or astern ?

 

[GRR]

Happens in neutral, have not tried it in gear until I know if it is safe

Did not notice any change in oil pressure

 

[aquapower]

could be the drive plate or u/j as they are still turning when in neutral, has leg been off ? has gear cable been correctly adjusted ?

 

[GRR]

Apart from checking the oil and changing the anodes etc, the leg has not been touched.

It almost sounds like the starter motor trying to kick in.

 

[aquapower]

Then I think I would be checking the drive plate, gimbal bearing and the universal joints, unfortunatly you will prob need to come out of water and take drive off for a proper inspection

 

[GrowingLad]

Is the leg in the up or down position? Although I"ve got quite an old model leg, it's not too happy when the leg is raised right up or I'm running with high revs and turn to full lock.

There isn't a chance that you have a loose connection on either the starter motor or ignition key, if you think it sounds like the starter motor kicking in?
It's a nice simple thing to check and eliminate.

My knowledge or things like starter motors stops and installing them and connecting the right cables, but it you think it's the motor kicking in, when the engine is running, then perhpas something isn't quite right inside the motor and the vibrations of the engine are causing it to turn over (loose connection inside?) Maybe try tapping it with heavy screw driver handle etc and seeing if anything jumps to life when it shouldn't.

 

[Pendana]

You can check a suspect u/j by listening to the noise it makes (if any).
With engine running and in neutral, put full lock starboard to port, if it is particulary noisy on full lock than at mid-ships, the u/j needs seeing to.

Good luck

Eddie

 

[Mr Googler]

Is the leg in the up or down position? Although I"ve got quite an old model leg, it's not too happy when the leg is raised right up or I'm running with high revs and turn to full lock.

There isn't a chance that you have a loose connection on either the starter motor or ignition key, if you think it sounds like the starter motor kicking in?
It's a nice simple thing to check and eliminate.

My knowledge or things like starter motors stops and installing them and connecting the right cables, but it you think it's the motor kicking in, when the engine is running, then perhpas something isn't quite right inside the motor and the vibrations of the engine are causing it to turn over (loose connection inside?) Maybe try tapping it with heavy screw driver handle etc and seeing if anything jumps to life when it shouldn't.

I learnt at great cost to me the engine should not be run with the leg right up or in trailer position as the uj will bind and knacker it and/or the gimbal bearing!

 

[rafiki_]

If it is a new clank, which you have not been aware of before, then look for the simple things first. Has a bracket loosened? Is something touching the exhaust/engine hanging loosish.


If oil pressure OK, and engine runs OK, then does not sound too disastrous to me.

VolvoPaul is likely to be more helpful.

 

[oGaryo]

not something simple like the ignition key getting stuck in the start position or a short between run and start contacts under the dash?

 

[GRR]

not something simple like the ignition key getting stuck in the start position or a short between run and start contacts under the dash?

Checked that - also checked ignition on without the engine running