Yamaha F4 Outboard_Recoil Unit.

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Ian_Rob

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We were marooned on our boat last Friday because the pull start on our Yamaha F4 outboard wouldn‘t pull. By removing the recoil unit, turning the flywheel and re-fitting the unit, it pulled and started on the first attempt. Now that I am home, I will remove the recoil unit again and delve further into its workings but is there a likely cause of this problem?
 
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Ian_Rob said:
First thing I checked.…..
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Check that interlock for proper operation.

Only other thing ... wasn't hydro-locked with oil as a result of being laid down wrongly was it? .......... No the plug would have been oiled and it would not have started easily next day.

Be careful if you try doing anything to the recoil ... you really don't want to release the spring. Its like a caged tiger waiting for you to open the door!
 
VicS said:
Only other thing ... wasn't hydro-locked with oil as a result of being laid down wrongly was it? .......... No the plug would have been oiled and it would not have started easily next day.

Now that’s interesting. When I removed the recoil unit, the flywheel would only rotate in one direction so I removed the plug and did notice a dribble of oil from the plug socket and oil on the electrode which I cleaned off. When the spark plug was removed the flywheel moved easily in both directions.

What is hydro-locking exactly and what causes it?

The engine had been left, tilted-up, handle-down, on the back of my dinghy on my swinging mooring for the previous 36 hours whilst we went off to Weymouth. I wonder if being bounced around by wash from passing boats would cause an issue??

Be careful if you try doing anything to the recoil ... you really don't want to release the spring. Its like a caged tiger waiting for you to open the door!


My instinct told me it was best not to dissemble the recoil unit - pleased I didn’t

Thankyou.
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Ian_Rob said:
What is hydro-locking exactly and what causes it?
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Hydrolocking occurs when water, oil, fuel or any other incompressible fluid enters the combustion chamber in sufficient quantity to prevent the full upwards travel of the piston.

It sounds as though oil entered the combustion chamber. You will have to be careful how you leave your engine but it should be Ok simply tilted on the transom. Perhaps as you suggest being bounced around caused the trouble. Maybe not turned handle down would be better. Leave it straight and tighten the steering friction so that it wont turn on to its side

Better still lift it on board and store upright locked to a pad on the rail but at 27kg you might want to fit something like Plastimo's Cargo Boom to lift it.
 
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