Mercedes 300D Marine Conversion

B

bigshrimpin

New Member
Joined
Nov 24, 2004
Messages
4
Reaction score
0
Location
Davis, CA
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.
 
Your outdrive is not designed for so much torque. It would be a waste to do the converison to have the drive fail.
 
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
 
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).
 
mb 300d marine conversion

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
 
If the torque is only 120ft/lb it won't overstress the drive.
 
MB300D marine conversion

The MB OM617 engines at 125 hp are turbocharged engines ,not naturally aspirated . Good luck.
 
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
 
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
 
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.
 
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
 
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?
 
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 ***** for part$.

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

FAST FRED
 
You must log in or register to reply here.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making any potentially dangerous or financial decision, always employ and consult appropriate professionals. Your circumstances or experience may be different.

    • Similar threads

    J
    Marinizing a Mercedes 240D Engine??
    2
    Replies
    15
    Views
    11,986
    jfreemanTMN
    J
    Back
    Top