Mercruiser 4.2/ 200

tunafishhkg

Commodore
Joined
Oct 13, 2011
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Cape Cod MA/Hong Kong SAR
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35 Duffy
VM Motori, an Italian company engine that have little to no support. My friend has one on his eastern and I installed a drive shower assap when he got it. Not a lot of them around and he does not put many hrs on his but it does run good and simple to work on, just have to mail order a lot of the parts. I think like most high rev chain saw engines, any small problem can take it out so make sure to maintain and keep the SCA in the coolant checked.
 

Downeaster

1st Mate
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Sep 1, 2011
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Jonesport USA
Not sure if these are still badged Cummins or not but Cummins will drop these either this year or next. I wouldn't worry about parts if I already had one but I wouldn't be repowering with one now either.
 

BillD

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Sep 1, 2011
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Portsmouth NH.. Piscataqua and Merrimack Rivers
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27 H&H with Cummins QSB 5.9 480 power
Not sure if these are still badged Cummins or not but Cummins will drop these either this year or next. I wouldn't worry about parts if I already had one but I wouldn't be repowering with one now either.

the 4.2 "could be" a good example of the many reasons Cummins/Mercruiser have gone their separate ways.

200+ hp out of a 4.2 liter "lightweight" block with the slightest overload equals "poof".

Go over to boatdiesel forum, do a search on the 4.2 and read.
 

Pedlyr

Captain
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Aug 31, 2011
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Southern RI
Thanks for the replies gentlemen.

What I have gathered on these engines has been confusing to say the least, pretty much the same as mentioned.

They were designed by BMW Marine and built in Italy by VM, . VM was sold to Detroit Diesel and Mercruiser bought the line. They then put it on Cummins to take care of them. This arrangement is over in a year and a half so Mercruiser will be responsible. It is a "tunnel bore". Crankshaft is in the middle of the block. Mercruiser service manual is not accurate, and I am not sure Cummins has literature on this.

I have been "'working" on one of these in a boat we have bought. There is a terrible knock in one engine so I pulled all the covers.....you can't even adjust the valves. They are all tight as a drum too. 2 cylinders are not firing. Engine has liners and individual aluminum heads. But you can't adjust the valves. Like a lawn mower...or chain saw.

This should be fun.

P.S. The outdrives are toast. But I expected that.
 
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