Hi I'm new and I just bought a new/old stock Mercedes OM 617 to replace the Perkins 4-154 in my boat. The motor was Marinized by Nanni and I would guess built in late 80s or early 90s. (Guess!) I realize this may be a little outside the norm for this forum but I don't know where else to get info on this motor. The motor is obviously been sitting in a warehouse for many years. From what I can tell it has never been run. brand new.
I am concerned about damaging the motor when I start it the first time if I don't properly prep it and I've gotten a lot of "advice" regarding what to do to prevent dry start damage etc.
Anyone who has completely rebuilt one of these should have an idea of what I need to do.
Thanks
John

Gulfstar 50 Ketch
WV TDI 2012

Welcome.

I have not rebuilt any engine, but off the top off my head, use diesel break in oil (if that exists), rotate by hand a few times then bump it a few times as well.

Run for the allotted time with said oil, then use a diesel rated oil, my personal preference is Rotella T6.

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83 SD

84 CD

Thanks toomany,
any thoughts on pre lubricating the top end? I thought about using a couple teaspoons of marvel mistery oil .

On most new/rebuilt engines it is a good idea to pre-lubricate the engine by spinning the oil pump using a drill motor. Unfortunately I do not know how to do this on your engine, but hopefully someone has this info. Of course it would be ideal to run the engine on a stand to check for leaks, etc. before installation in your boat. Toomany's thoughts on rotating the engine by hand are good recommendations. You might contact Metric Motors in California for their advice (they are one of the premier rebuilders of Mercedes engines).

I definitely plan to run it on the stand forst. I will remove the old engine this week and spend a few weeks redoing the engine compartment (plumbing and rewiring etc) I still need to do a bit of work to get the new motor ready like setting up exhaust systems and completing cooling lines for raw water etc. I don't know how to spin the oil pump without cranking the engine. one guy suggested I fill the engine completely full of oil all the way to the filler cap then drain and refill to dipstick level. seems extreme. any thoughts on prepping the injector pump?

Where did you find such a rare gem?

Hahaha. I found this motor listed at a yacht surplus supply house in Southern California
Minniesyachtsurplus.com. The story is it had been purchased new buy a custome yacht builder and then sat on his warehouse shelf for years unused. When he died it ended up at Minnie's. I couldn't believe it until I saw it so I drove down and bought it onsite.

really depends on how it was stored.

If all entrances into the head past the valves were closed by some means (sealed), then don't sweat the upper end. I would be concerned simply because it has been stored by sea faring people and ultimately, that means it was kept near water many years (moisture everywhere) - it will find a way in. These liners will rust very quickly, there is no modern treatment coatings.

I would remove the valve cover to get an idea of what is going on, it will be the first big indicator. if it looks good ,coat it in oil.

Pressurizing the oil system is a great idea. no need to turn the engine. there is a direct access to the main oil galley from sump on the front of the engine. It is threaded and you could hook up any pressurized oil supply that suits you and is clean. Or just fill a reservoir of oil then pressurize with air.

main concerns:

lower end bearings with poor lubrication

injection pump needs to be filled with oil

valve train needs lubrication (and chain)

upper cylinder corrosion

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and if it's a turbo model.... make sure it spins freely and lube it by taking the supply off the top and pouring in some oil.

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Happy boating !! Please post follow ups with pictures after you get it installed. Good luck !!

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
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1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

All good advice and thanks for it. I will follow up with before and after pics although it will be a while as my schedule is tight so not much time to work on it.

If I were you, I would replace the front and rear seals while it is out... Although it is still technically "new", the rubber is not.

Dkr.

You want a boat to start. Keeping the glow system in good shape and running synthetic oil helps cold starts for anytime when it is cold enough to need the glows. Glow twice when really cold.

What shape is the boat in? What are your plans?

I think getting it running in the shop and seeing how it does would be my strategy. Much would be determined by how easy the access is once installed. Do check the valve adjustment first since you don't know anything except that it is new. Keep plenty of fuel filters onboard. Take extras if you'll be gone for long. Quality of fuel and filter clogging hasn't been a big problem here but it is the 1st thing to check when acceleration becomes a problem. Also, you want to install so that fuel has an acceptable place to go when you bleed the lines.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

On many sailboats that would be an issue. On my 32 footer, the engine would have to come out to do an OM617 style valve adjustment.

But OP has a Gulfstar 50! That's a big boat and probably has a spacious engine room below the centre cockpit (if it is that model) Probably quite a compact engine for a boat that size. Om617 is unlikely to be a turbo. Ones I checked out were 88HP.

New Transmission will probably be needed. Need to to ensure it can handle the power output and has correct reduction ratio so that engine runs at optimum rpm when turning prop at it's design rpm.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Graham
You are a genius! I have a nice engine room with plenty of room for this engine. It came with a new hurts gearbox so it's ready to go. I'm told this is rated for 85 hp so the 62 hp engine I'm replacing will result in a nice power increase