Piston lock cad 42 possible causes

[Portofino]

Badly internally ( not really visible externally) corroded elbow .The spray ring holes are partially blocked and when stopped the sea water drips through back from new cracks + holes from the corrosion into the exhaust side of the turbo and through an open E valve , kinda siphons itself to fill the open cylinders .

@ Bruce It can’ t be leaky CAC unless theses are raw water cooled ? Says it’s salty and the close coolant levels have not changed .
Won’t be any backwards running either as after a back run the then progresses to Fwds would hydro lock it and bend a rod .
Aside I doubt the injection pump would run it backwards anyhow .

Another could be huge stern wash ( on the Rhone - barges etc ) temporarily altering the relative levels of the water in the horn / riser and turbo …..the open E valve senario .
He might not have been in the boat when this happened.Moored up etc .

 

[BruceK]

Yeah, the CAC is raw water cooled, but it also has a small drainage hole thats why I said it would need to be a big leak.
As for running backwards I thought it was a bit of a reach but I cant think of anything else that has raw water so close. As for your wash theory it is unlikely as the leg vents the exhaust and it has a rubber flap on the exit it to prevent this. I will happily take the exhaust bellows off below the elbow when the boat is in the water. None ever slops over even in the fast flow of the estuary. Corroded elbow is a possibility I imagine especially if the raw water system is pressurised because it's blocked, but if you have seen how the matrix fits, getting water to then squirt backwards and up would really have to be a one in a million chance. Unless the CAC is completely ruined it came in via exhaust and that involves a bit of sucking.

 

[Portofino]

Yeah, the CAC is raw water cooled, but it also has a small drainage hole thats why I said it would need to be a big leak.
As for running backwards I thought it was a bit of a reach but I cant think of anything else that has raw water so close. As for your wash theory it is unlikely as the leg vents the exhaust and it has a rubber flap on the exit it to prevent this. I will happily take the exhaust bellows off below the elbow when the boat is in the water. None ever slops over even in the fast flow of the estuary. Corroded elbow is a possibility I imagine especially if the raw water system is pressurised because it's blocked, but if you have seen how the matrix fits, getting water to then squirt backwards and up would really have to be a one in a million chance. Unless the CAC is completely ruined it came in via exhaust and that involves a bit of sucking.

We have very little to go on .That’s the issue with arm chair diagnostics.Some pics , many pics so a general state of the motors would be nice ,From another thread we know he’s bust a leg from a prop fouling incident and the boats marooned on the canal du midi / Rhone inland system.
No idea the state of maintenance? Theses mostly unbelievable issues are in my experience a result of a cascade of errors layered upon each other .
You and I are thinking one dimensional, it’s “ this “ based on the assumption the rest is ok .Like your “ flap “ valve .Is There one working on it ?

This boat saga has got legs .
Whoops see what I did there ?

 

[A_8]

@A_8 Oh you know that one too. We also had one that generated electricity for the farm house. If you didnt start it first go you were in deep trouble as you had spent all your weetabix. If that one kicked backwards the crank handle was long enough to remove your front teeth. Everyone was afraid of it. Crank handle to the
left

Indeed I do and very well. My dad had an 1939 oak 10m wooden boat with a 25hk 600rpm 2 stroke hot bulb engine which you started by pushing the flywheel back and forth and at the same time hitting the fuel pump and as compression got high enough it would start to self swing and eventually it would start spinning/running BUT it was random which way it would run so one had to shut the fuel and then hit the fuel pump again hoping it would turn the other way. I used this boat when I was around 20 yrs and before I could afford a sleep aboard boat on my own.
The engine was dead simple and I remember once sailing to Norway and the engine would not start as we approached the shore. Once moored we opened the cylinder head and found rust had eaten through from the cooling canals, put a screw in and the engine run perfect the rest of the season.

This is the exact model engine:

 

[gordmac]

I would suggest it is important to get the salt water out and the engine running to prevent any corrosion. Spin the engine on the starter with injectors out, put quite a lot of thin oil in, rotate a couple of revs by hand then spin on starter again. Put injectors in and run, you see heat to dry the internals and burn off the salt. This assumes it hasn't hydrauliced and bent a rod.