New engine or start tinkering?

Andrew E said:
Out of interest, roughy how much are we talking about for a new engine (Bukh DV20) to replace the MD7A, including fitting and any changes to the propshaft. A new Beta would be my preferred choice, but they’re extremely expensive, perhaps 60% to 70% the value of my boat, so probably a no no unless I win the lottery.
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A new Bukh will be way more expensive than a Beta. IIRC a Bukh DV24 (they don't make 20s any more - basically same motor, more go) is £8k or so. A Beta about half of that, or perhaps less. The fitting is another few £k, for either, comprising quite a lot of labour (I'm guessing unlikely you'll be wanting to dos it yourself), and quite few parts (some may perhaps be reused, but likely few if any given the different age/size of the motors you're talking about).

I know very little about marine engines, but some of the above posters most certainly do know what they're talking about. It doesn't sound like your engine is on its last legs, and you've got some relatively simple, practical things to try.

It's proved reliable all season. If all else fails, buy yourself a clothes peg and some dark glasses!;)
 
I swapped an old md7a out for a beta 14. In my case the engine was very rusty due to the wood above it being rotten and allowing water through constantly. It had failed twice in service and parts were getting scarce and expensive.

It cost the price of the engine again for all the other "stuff" you need. The beta will need a bigger seacock. The prop, shaft, seal, cutless bearing, etc will all need to change. Exhaust exit hole size and location may need changing and if it doesn't you still may need a new water trap.

The other problem is that when you start doing "new" then you'll want "new" everything so as to be sure your going to get 10+ years reliable and worry free service.

I'm glad I did the engine change, it has taken a fair amount of worry out of a day on the water.
 
"If it ain't broke, don't fix it" is a commonly read concept that is guaranteed to result in big problems. In machinery maintenance this is known as 'breakdown repair' and will always result in non-availability at the most crucial moment according to Sod's Law. The modern maintenance philosophy is 'condition based maintenance', requiring condition monitoring. This can be as basic as listening to the engine, measuring tappet clearances, checking oil and coolant levels, belt tightness, etc.

In the OP's case he has observed the condition, smoke from the exhaust at all operational times. Now something needs to be done. If injectors are left for some time with a misshapen spray pattern the result can be considerably more serious than smoke, ranging from a scrap injector nozzle to a burnt out piston or even, pushing this a bit further, a wrecked engine. As ever, address the simplest points first, pulling the injectors and having them serviced is quite cheap, the four in my BMC were £100 including new seals, pressure testing and spray pattern assessment. If that does not bring about the hoped-for result it may then be necessary to go further.
 
vyv_cox said:
"If it ain't broke, don't fix it" is a commonly read concept that is guaranteed to result in big problems. In machinery maintenance this is known as 'breakdown repair' and will always result in non-availability at the most crucial moment according to Sod's Law. The modern maintenance philosophy is 'condition based maintenance', requiring condition monitoring. This can be as basic as listening to the engine, measuring tappet clearances, checking oil and coolant levels, belt tightness, etc.

In the OP's case he has observed the condition, smoke from the exhaust at all operational times. Now something needs to be done. If injectors are left for some time with a misshapen spray pattern the result can be considerably more serious than smoke, ranging from a scrap injector nozzle to a burnt out piston or even, pushing this a bit further, a wrecked engine. As ever, address the simplest points first, pulling the injectors and having them serviced is quite cheap, the four in my BMC were £100 including new seals, pressure testing and spray pattern assessment. If that does not bring about the hoped-for result it may then be necessary to go further.
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I do respect Viv's comment above but to some extent I still stand by my "if it ain't broke, don't fix it" however there may be merit in having the injectors serviced BUT, before you start, check the manual, if the head has copper sleeves sealed with an "O" if these are disturbed, a special tool is required to fit new ones.

I had major problems starting my Volvo MD2B and was assured by the local Volvo expert that it was the injectors. He removed them and had them cleaned and refitted, result, I was about £250 out of pocket and not one bit of difference in ease of starting.

Going on to the rest of the engine, if you want to strip it, you are looking at £250 for gaskets, As far as any other parts are concerned, you need to check with Marinepartseurope.com as most mechanical items are out of production. I think you can get main bearings etc but think a set is about £350. You could think about pulling out the pistons and honing the bores and fit new rings if they can be sourced, again, do some research before you even think about putting a spanner on the engine.

Sorry to be such a grouch about your engine but bitter experience with my Volvo led me to the conclusion that when I first had problems, I should have dumped the heap of "Green Death" and bought a new Perkins Perama, it would have been cheaper,
.
 
As has been said by numerous people above, step 1 is to get your injectors tested and cleaned.

If you still have white smoke, it could also possibly be pump timing (not sure what sort of pump that engine has and how you time it), but if you have slightly retarded ignition it will blow white smoke (especially when cold).

Next option to look at if injectors are good and timing is right is the injector pump.

Do the injectors first though, it's about 80% likely to be the problem.
 
vyv_cox said:
"If it ain't broke, don't fix it" is a commonly read concept that is guaranteed to result in big problems. In machinery maintenance this is known as 'breakdown repair' and will always result in non-availability at the most crucial moment according to Sod's Law. The modern maintenance philosophy is 'condition based maintenance', requiring condition monitoring. This can be as basic as listening to the engine, measuring tappet clearances, checking oil and coolant levels, belt tightness, etc.

In the OP's case he has observed the condition, smoke from the exhaust at all operational times. Now something needs to be done. If injectors are left for some time with a misshapen spray pattern the result can be considerably more serious than smoke, ranging from a scrap injector nozzle to a burnt out piston or even, pushing this a bit further, a wrecked engine. As ever, address the simplest points first, pulling the injectors and having them serviced is quite cheap, the four in my BMC were £100 including new seals, pressure testing and spray pattern assessment. If that does not bring about the hoped-for result it may then be necessary to go further.
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This is first class advice.
 
prv said:
Ok. I haven't needed a mechanic so have no first-hand recommendations, but I know lots of people sing the praises of VolvoPaul

On the bright side, when there's little wind you're unlikely to blow into anything at any great speed :)

Pete
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That may well be true, in a marina or some other fairly tame environment, but I would worry about being set onto rocks by a tidal current, when there is a swell running to bounce you up and down nicely on it, as happened the training ship Astrid a couple of years ago, outside Kinsale:)
Regarding the substantive matter; I would recommend that the OP takes out the engine, buys the workshop manual, and reconditions it himself, if he has the relevant skills or skilled friends.
 
Spirit of Glenans said:
That may well be true, in a marina or some other fairly tame environment, but I would worry about being set onto rocks by a tidal current
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In that sort of situation, unless you were passing very close to the rocks to begin with, you should have room to anchor.

It's true that in some parts of the world (Channel Islands spring to mind, especially the reefs north of Herm) you might well be close to rocks with a strong tide - and the holding probably isn't reliable even if you did get the hook down in time. But fortunately around here (where the OP is) things are a little more benign.

Pete
 
The Solent area is benign in some ways, but there are a lot of places I would not want an unreliable motor.
E.g. crossing the Brambles channel
Portsmouth Harbour entrance
Bembridge
etc etc.
Not trusting the motor seriously cramps your boating .
 
I had exactly the same dilemma two years ago. My old Bukh needed a refurb more of ancillaries and engine mounts, fuel system etc. The engine always started but not right away but apart from that run like a dream. The engine was no where near powerful enough and that was the key for me replacing it in the end.
 
Andrew E said:
starts first time and runs pretty well apart from alot of white exhaust smoke. She hasn’t missed a beat
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robertj said:
I had exactly the same dilemma two years ago. My old Bukh needed a refurb more of ancillaries and engine mounts, fuel system etc. The engine always started but not right away but apart from that run like a dream. The engine was no where near powerful enough
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Exactly the same dilemma? Apart from his starts first time, yours doesn't; his smokes, you don't mention that; your ancillaries and mounts need refurbishing, he doesn't mention that; yours wasn't powerful enough, he doesn't mention that. :rolleyes:
 
From recent experience I would advise that you check out the cost of spares before you start tinkering.
This spring I spent several hundred pounds on bits for a Yanmar 2GM [head gasket, injector overhaul etc.] before deciding to stop digging the hole and go for a new Beta.
It was the old story of "perhaps it just needs a new...... ... then it will be OK".
 
Rough cost for bits if available
Rings £150
Bearing set £350
Gaskets £250
Misc £250
Pistons N/A
OS pistons N/A
If there is ovality in the bores new rings will not bed in. Honing will not help.
You could spend £1000 and make engine worse.
I stripped down a MD2B and fitted new rings and honed bore. Engine was a bstrd to start at first after rebuid and had to use a hot air gun into the air inlets to get in running. Had to leave it running for a day under load at the pontoons to try and bed in rings.
Your MD7A is about 40 years old and has a finite life due to internal rust.
Save your money and buy a 4 or 6 hp outboard as an aux.

PS Rebuilt a Ford 1.6 diesel and found out after it was in bits that I could not get the special single use Torque to Yield bolts for big ends. Eventually used special high performance bolts from Burtons designed for Cosworth engines.

Moral, check avaiabilty before starting.
 
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