Mercruiser 1.7 Diesel Replacement

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Canon18

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Hi all,

I’m looking to replace a goosed Mercruiser 1.7 120 diesel and was wondering if there are any better/more reliable alternatives with similar power and weight that can be hooked up to the Mercruiser drive leg?

I believe the early VP D3’s were also problematic so probably not a lot gained there. I know Yanmar did a 125hp around the same time but not sure if this is compatible with an outdrive? I should mention that it will be fitted in a 6m RIB.

Any advice appreciated.
 
The Yanmar I was thinking of is a 4jh3-dte. I should have also mentioned that replacing the existing engine like for like is also an option but I know this model was prone to faults and I want to protect myself as much as possible. Also note that the existing engine self destructed under the previous owners ‘care’ so any new engine will be better maintained.
 
Hi, can’t help with your enquiry but I have the same engine. If you’re getting rid of it I’d be interested in taking the wiring loom, unfortunately ours has been burnt out.

Send me a private message (PM) if you can help. Thanks.
 
FWIW, I believe that yanmar diesels were often mated to Mercruiser drives. Might make the yanmar an easy fit.
 
anecdotal evidence suggests many of the marine conversions involving road engines and marinising conversions can be problematical.
Some pretty high reving units have been used giving rather frantic engine cruising RPM despite prop pitch mods.
Try not to get involved with oddball engines requiring extensive modifications ?
 
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Excellent, many thanks for everyone’s input - on the hunt for a good replacement Merc now to keep things as simple as possible and just get out on the water!
 
Known to be problematic these 1.7s. Loads fail and aren’t really up to the task of the marine world. Great on fuel and pretty powerful wee things when they are working.
I suppose the answer might lie in what the boat is, how much it’s worth and where you use it.
It’s likely the financial outlay of a new diesel of any type may not tally up with the value of the boat ? The wee Merc 3.0 petrols are cheap to buy, reliable and almost as economical. Just that petrol is dearer than red diesel. Extra 15hp too. Will mate up to the drive too. Might need to check gear ratio though. Or re prop.
 
I have read that a lot of issues with this unit relate to a couple of common factors.

Firstly the wastegate in the turbo seizes shut and this in turn causes a high egt and damages one of the pistons (always the same one - #3 iirc). This leads to the engine failure. I believe that there was an exhaust blanket used which exacerbated things but apart from that there is no cure other than modifying engine bay baffles to reduce the salty air getting to the engine.

Secondly, the units compact size and weight attracted users who previously used petrol units and were used to wringing the neck out of them, this is too much for the little Isuzu unit.
 
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