Mercedes 300D Marine Conversion

[bigshrimpin]

Does anyone know of a kit or shop that will convert one of these 5 cylinder diesels for marine use?

I have a Volvo AQ130C thats seen better days . . . I'd love to hear if anyone has had sucess putting this motor into a boat.

[gonzo]

Your outdrive is not designed for so much torque. It would be a waste to do the converison to have the drive fail.

[bigshrimpin]

I thought the Volvo 270 drives were pretty tough. Some folks have them hooked up to a V8's. The torque curve and HP seems to be on the same line as the Cummins/mercruiser 120

[Ike]

The 300D is a great engine. I drove one for many years. But I doubt anyone would have a kit or do conversions on these. The reason is simply cost. I had my 240D, predecessor to the 300D, (lost compression, needed an overhaul) go in the winter of 1986. The cost of an overhaul was about the same as buying a new engine. The was only a few hundred $ difference. I imagine the cost of converting one of these would be almost as much as buying a marine diesel (which mercedes makes by the way).

[hartley]

An interesting project if ever there was one , a couple of points come to mind
The 300d ,OM617 engine is rated 77HP at 4000rpm and around 120 ft /lbs of torque at 2400,as you can see it is not blessed with power or torque ,therefore your sterndrive unit will probably cope ,also a firm by the name of Lancing Marine in the UK had a marine conversion kit for this engine ,so it has all been done before ,although probably shaft driven .
But!!!! taking into account the engineering work involved,and also whether the 300D is a suitable engine is quite another matter ,although these engines ,with the correct coolant will run at 100C and over ,a 10 minute coolant boil will result in a cracked cylinder head or worse ,trust me ...
The coolant passages in these engines are incredibly small ( quick warm up )
So all in all,probably not a good way to go , a lot less headaches and easier on the pocket would be to rebuild your present engine .
How do i know all this ? I own a MB300D and have done so for fifteen years
But then thats just my opinion ....cheers

[gonzo]

If the torque is only 120ft/lb it won't overstress the drive.

[larper]

there is diferent models of OM617 engines with up to 123hp

http://en.wikipedia.org/wiki/Mercedes-Benz_OM617_engine

[hartley]

The MB OM617 engines at 125 hp are turbocharged engines ,not naturally aspirated . Good luck.

[ted655]

I have a '78 model 300D. It is in excellent shape. Aside from the cooling doubt, is there any other objection?
If a keel cool system of adequate+ size was used instead of raw water, would that take care of the marginal cooling issue?
As far as overhaul costs, I think anything marked "marine" is priced twice as much. Diesels are expensive, period.
My problem is finding a bellhousing adapter. Mercedes seems to not fit anything.
The 300 has a reputation as a reliable, tough little engine. The condition mine is in should give me good service for years (recreational use)., BUT.... if there is hidden troubles ahead, here is where I'd like to hear about them. Thanks,:D

[FAST FRED]

The big question would seem to be how hard will it be working?

77hp at 4000rpm , not a long life .

Say 30 hp , 2 gallons of fuel per hour and 2500rpm MAX , it should last well.

Even better at 1800 and 1,5gph.

FAST FRED

[fcfc]

http://www.dmv-bootsdiesel.de/Deutscher%20Index/Lieferprogramm/Ersatzteile.html
http://www.umruestteile.de/umruestteile/seite6.html
http://www.drinkwaard.com/ombouwsets.php4?op=select_motor
For what 's worth.

Edit : took a time to get the correct URLs.

[ted655]

Sadly, I no sprekin de deutz (close?). Yo say habla poko espanoil. My uncle is German but is 4 states away. I'll ask around but here in Cajun country it's doubtful.
I gather from pictures & the 5 words I managed, that these are conversion/ repair parts foe marinizws Mercedes.
Thanks for the hard work. I appreciate it!! I'll make it work somehow, FCFC.
Fast fred; I'm not sure how hard it will work. The purpose of the boat (24' X 8" big Jon) is to push our house barge (50' X 14' plywood hull) from place to place. Somedays would be long ones. Most days it will stay tied & idle. Sometimes with current & sometimes upriver against a 5-8 kt current.
All this is "slow", we are in no hurry down here. You are where you are at dusk & you tie up & go in da house. Tomorrow is another day.
So.... I'm thinking a 2:1 reduction gear turning a 20" 3 blade prop running a 2K rpm. IF that gives me the POWER I need to make headway. 2-6kts is plrnty fast for us.
But... I'm really relying on this forum to tell me what I need as I really know little about gears & props and how to juhhle the 3 components together.
I am very willing to sacrafice speed for power & longevity. I just wanna push the house around safely, so I'm all ears.

[FAST FRED]

Ted go on the


http://boatdiesel.com/index.cfm?RED=1B

Site and pay the $25. They have a calculator that will let you work with different gear ratios and prop sizes . Use 25 hp as the motors output and check with 3-1 gears and a bigger prop for slooo pushin.

FAST FRED

[ted655]

Good idea, thanks
Any opinions on transmissions? ZF/Hurth? Twin disk? BW?
I'm going to need a 10 degree down angle. I don't think everyone makes the dwn agl.
Hurth does but I've heard they are weak. BUT... what do I know. Any advice?

[FAST FRED]

Hurth are cheap , so just go a size or two UP for reliability.

Twin Disc should be available used, "Boats & Harbor?" or a good running takeout.ZF is a bitch for part$.

The engine may take 10deg down , so a cheaper tranny can be found.

FAST FRED

[ted655]

Thanks.
What is an opinion on the Borg Warners?

[hartley]

Ted655 ......You have a MB300D and wish to mate a marine gear to it ...riight? .Now first things first,is the MB manual or auto ,if manual no problems if auto may be problems ,you will have to obtain a manual flywheel from a wreck perhaps ,although manual 300D's are pretty scarce over here ,perhaps not the case where you are .also do not take it as given that the manual flywheel will bolt up to the crankshaft flange .....check first
Also you will find this exercise much easier if you use a borg warner gear ,now after all that ,and you wish to do this ,it is not all that difficult ....but you will have to have access to a lathe with a swing of at least 18 inches ( hobby lathes will not do ) or perhaps you know someone with such a lathe..If you get all this figured out and if you wish I will give you all the info you will need to complete the job ....cheers Hartley

[FAST FRED]

What is an opinion on the Borg Warners?

Great , cheaper than T-D and with 25 years of marine use , a used one might be findable.

FAST FRED

[Cleopatra23]

Wiseman of Stuttgart used to marinise these. He mated them to Borg Warner Vee drives so its all been done before. The power output of about 15HP per cylinder should not any give heat problems if the cooling system is OK. Best regards from David.

[Gary Gear, Ph.D]

I too am interested in replacing a pair of Mercruiser 470's with OM 617's. With fuel prices moving the way they are, diesel and bio diesel becomes much more attractive. The Merc. series 1 out drives can easily handle the torque and the RPM range of the OM 617 is very close to that of the 470.

Because this is a high reving diesel, ring and cyllinder wall life has never been particularly better than a gas counterpart. But it certainly is one of the engines of choice for bio conversions for some very sound reasons.

Mine is really a Lake Powell boat so long distance (60 miles between fuel stations) is common. Fuel effencicy is much more of an issue than speed. I'll be coming down from 340 HP combined to about 250 HP combined.

Anyone mated an OM617 to Merc. outdrive?

G

[sailinphelan]

Ted, I too am considering putting an MB (probably 300SD, dry stack) engine in my houseboat. Any progress with your conversion? Mine had a 302 Ford driving a Volvo/Penta dual prop stern drive.

I did once make a conversion plate to put a Chrysler slant-6 into a 1960 Land Rover; it still runs by the way, 15 years later.

PJ