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Thread Title:

Cummins Marine engines

Created On Wednesday April 28, 2010 16:09 Diesel Talk
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Note Wednesday April 28, 2010 16:09 View thread in raw text format
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I am fairly new to the diesel world and am finding I need to replace the engines in my sailboat. So this is going to be a great learning experience for me.

I have found a couple ex onan units that are Cummins 75 hp @ 3300 rpm. They have been marinized and a The oil sample sent said 3.9 on the bottles, I think I was told they were 4A2.3D's. 350~ hrs. At any rate, they were pulled from service 12 years ago, steam cleaned and put away. One oil sample came back with a B rating stating particles are from break in period and to watch. The other had water in the oil at 1% and could/would not be tested further.

Seller states that the water would be from the pressure wash when they were put away for storage 12 years ago. Oil was not changed or engine ran since.


1) Would water that entered the engine when it was pressure washed 12 years ago cause any damage to the unit? "just sitting there" at 1%?

2) What would the sitting for 12 years do to the oil etc? I had heard about the chemistry changing to be acidic and it eats the babbit bearing surfaces. Is this a valid concern? I know from gasoline systems that sitting can be as bad as using up.

3) What about bio diesel with these engines. Just read an article about a trawler that took on fuel in Nicaragua and they only sold biodiesel. It wreaked havoc with their tank seals and I am sure there will be challenges with the rubber parts in the engine too. Are these engines (1997 models) built biodiesel ready? Don't want that to happen to us.

Any and all advice is appreciated.


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Note Tuesday May 11, 2010 23:02 View thread in raw text format
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I would suggest that you offer the seller of these engines a bid based on the fact that they may need an overhaul.
You are correct in assuming that 12 years of sitting may not have done them a whole lot of good.
Much water could be present just from condensation.

Just looking at your post again, the model numbers you gave sound more like Volvo's, but the 3.9 on the bottle is the displacement of the 4 cylinder cummins.

On the plus side, Cummins are easy to work on, and parts are relatively cheap and widely available.

Beware of biodiesel. It is not state of the art, and a boat at sea is not a great place to carry out other people's fuel experiments.
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