Re. engine explodedon first trip...

[stefan]

Today I close a deal on two fresh 122D:s, boat is up, old engines will be removed next week and replacement installed. Plug-and -play it should be. I wanted to post this as a few questions arose as to why an engine exploded. - The reason is most probably an injector failure. Maybe caused by water in the fuel. This turnes the injector to a torch melting the piston etc. Rare but not unknown they say. I will in every case begin to change the pre-filters every year in the future. I have a pair of fairly big filters on the engine room bulkhead with water separators along.
cheers

 

[MrCramp]

You often hear all these theories about water in fuel, but you don't often hear about the consequences. Will highlight the importance of water seperators. Thanks for the info.

 

[jfm]

Good news stefan. That was quick. Did you have to go to the ends of the earth to get the new engines or were they conveniently in Finland?

 

[tinkicker0]

Fuel erosion as it is known and yes it does break down the boundary layer on the piston crown.

If so, the crown will have patches that look granular in appearence.
Severe. long term cases will erode down to the piston pin eye with the result you describe.
However you should have noticed something amiss long before this point, smoke, silver dust in the water and on the stern of your boat, diesel smelling / rising oil levels in the sump and even heavy knocking.

Never known one to go in a matter of hours.

The old Bedford 466 and 500 motors were very prone to this malady.

 

[volvopaul]

I would say that if your engines have over 1000 hours then you should have had the injectors serviced before then, sounds like the nozzle has seized in the open position causing a term called hosing which the fuel is sprayed into the cylinder in a jet but not under pressure, not atomising the fuel hence it bore washes the oil off the rings and causes the piston to overheat and fail.

 

[stefan]

The diagnosis is exactly like you describe Paul. The nozzles were overhauled not long ago.
I found the replacement engines via a friend in Gothenburg. I can recommend the source, a company you find here: www.lskarlsson.se/ The owner Leif Karlsson has a house full of Diesel engines new, and old ones. Also D12s.