Crusader 350 w/ Velvet Transmission: Locked up after brief shutdown

[Silver(ton)Surfer]

Hi everybody,

I left our slip yesterday to get gas (10-minute drive). Both engines fired right up and ran as smoothly and quietly as always.
When I tried to start the engines after getting gas, the starboard engine again fired right up. The port engine, however, didn't even turn over.

At first I thought the starter had died, as I sensed a burnt smell and it drew so many amps that the voltage collapsed to below 8 volts.
After I replaced the starter today, I however still have the same issue.

We have:
- 1986 Crusader 350, carbureted
- 1986 Velvet drive
What I already tried:
- Replaced starter
- Removed all spark plugs to eliminate hydrolock
- Removed v-belts to water pump and alternator to eliminate seized accessory
- Verified electrical system

Engine and transmission oil look clean and have recently been replaced.
I can also turn the prop shaft by hand.
When I try to start the engine, the starter makes a loud, powerful "clunk" as it engages. I see the crankshaft turn a tiny bit, but that's it.

If there was some type of internal failure I would have expect it to happen while the engine was running and that there would have likely been some noises first.

Any ideas? Frankly, I'm lost as this doesn't make any sense.

Oliver

 

[AllDodge]

When I try to start the engine, the starter makes a loud, powerful "clunk" as it engages. I see the crankshaft turn a tiny bit, but that's it.

If there was some type of internal failure I would have expect it to happen while the engine was running and that there would have likely been some noises first.

Check your motor oil level and color

 

[Silver(ton)Surfer]

Check your motor oil level and color

Clean, pretty clear, no funny smell.
I would also expect that if this was somehow wear / lubrication related we would have heard some unhealthy noises or seen rising temperatures first.

Neither was however the case. Everything seemed normal, we shut the engine down to get gas, tried to start if again and it was seized.

 

[AllDodge]

While it could be the motor or transmission which could lock the motor. The prop shaft turns easy so that leaves the motor.

Motor oil is clean "and note IT IS NOT high" on dipstick

Only thing left is the motor

 

[makomark]

...
as I sensed a burnt smell and it drew so many amps that the voltage collapsed to below 8 volts.
....

Is the amperage draw an assumption or was it measured?

...
What I already tried:

- Removed all spark plugs to eliminate hydrolock
...

Did you attempt to rotate the engine with the plugs removed?

...
I can also turn the prop shaft by hand.
...

As long as the velvet drive goes into Neutral, the prop shaft rotation is completely independent of the engine's situation.

Have you tried swapping starting batteries between the engines ?

I would also be inclined to make some voltage drop measurements across the battery cables...