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Thread: Options for a Volvo MD5a

  1. #1
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    Default Options for a Volvo MD5a

    Hi,

    I have a mid-1970s Albin 7.9 with an 8ish horsepower Volvo MD5a one-cylinder water-cooled engine. The mechanic at my boatyard (in NH) told me that he can turn the engine over without releasing the decompress lever, and because of that the engine isn't safe for sea and he no longer wishes to work on it.

    So, these seem to be my options:
    1. pull the engine and add an outboard.
    2. find someone to rebuild the engine.
    3. buy a new Beta 14.
    4. scrounge the interwebs for a rebuilt Volvo.
    5. sail engineless.
    6. something outside the box like an electric motor and batteries.


    As far as I can tell, there is no good choice. 1 is bad, because the engine is in the bow so the trim would be thrown way off, and the transom is small. 2 is bad because I can't find anyone in NH to do it as yet. 3 is bad because I bet I could buy a much nicer boat with a decent diesel for the price of a Beta. 4 sounds unlikely. 5 is bad because the boat is on Great Bay in NH and the currents are crazy. 6 is bad because the boat lives on a mooring, so charging is an issue.

    Any advice????!?

  2. #2
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    Default Re: Options for a Volvo MD5a

    I built a yacht with a Volvo MD5 in her back in 1984, It is now a very old engine, if its that worn that you can turn it over without the decompressor it is proper knackered. At the least it will need new rings more likely a new piston & cylinder liner, If its been raw water cooled i would expect the waterways to be getting very thin & a cylinder head or block failure will be not far off. Parts availability will be not good & the cost of parts will be eye wateringingly high. On the plus side you may bet a bi of money back breaking it for parts.
    Your mechanic is right, its reached the end of the line. If you can afford it fit a Beta, I have a Beta 16 in my current boat, lighter smoother & reliable.

  3. #3
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    Default Re: Options for a Volvo MD5a

    Alternative? Plenty of Maxi 77 and Albins here in Sweden with the same engines with not a lot of hours on them and used in non salt water. You could easily buy one of those for the price of a Beta. Shipping is currently cheap, sale of your current boat should cover the costs, or take next year off and deliver it yourself. I can keep my eyes open for one if you would rather ship just the engine. Are you running a leg or shaft?

  4. #4
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    Default Re: Options for a Volvo MD5a

    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

  5. #5
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    Default Re: Options for a Volvo MD5a

    Quickly now, to the China Diesel thread. . .
    Simpler is better, except when complicated looks really cool.

  6. #6
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    Default Re: Options for a Volvo MD5a

    Anything can within reason be rebuilt . I'd definitely go for option 2. Volvo prices aren't any more eyewatering than Yamaha or anyone else really, particularly as you are not rebuilding a twin turbo V8.
    single cylinder. even if it needs new piston, mains and rod bearings, rebore or sleeve, etc., its a small engine and simple to work on.

    IF, as suggested , you have internal corrosion and or its been rebuilt before, and you are running out of tolerances, thats different, but I should think you could have that out of the boat and in a shop in a couple of hours and even do the stripping and assembly yourself, you can show the bits to a pro, and if it is beyond repair, highly unlikely, well its out of the boat now and you would have had to do that anyway….it will be a great way to learn. Leave the machining to the machinists,ok. but you don't have to find a marine engineer, this is standard stuff for any mechanic who doesn't just do oil changes on Civics.

  7. #7
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    Default Re: Options for a Volvo MD5a

    I would investigate repairing it. It may be as simple as a valve adjustment. Those are a very robust little engine, designed for the task.
    You might talk to some "different" mechanics and get more opinions.

    (I have repaired and rebuilt a number of marine engines and have yet to find a worn out bore, there just isn't enough dirt out at sea. You could be surprised that decarbonizing, a quick valve job and some new rings might do it.)
    Changing engines will be an event. Aside from the engine itself there will be concerns with the shaft and couplings, a propeller, controls, plumbing and fitting the engine beds etc. are some of the more obvious challenges.

  8. #8
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    Default Re: Options for a Volvo MD5a

    That's such a small and simple motor. Not much more complicated than a lawn mower. I would definitely look into rebuilding before any of the other options. First thing you should do is sign up for a membership on boatdiesel.com. It's the best $25 you will ever spend on maintenance for that motor. That will give you access to manuals, people who can help diagnose problems, the ability to find a good mechanic in the NH area, ads for parts or motors - everything.
    - Chris

    Any single boat project will always expand to encompass the set of all possible boat projects.

    Life is short. Go boating now!

  9. #9
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    Default Re: Options for a Volvo MD5a

    If you are on freshwater or its freshwater cooled fine have a go at rebuilding it.
    But if its had seawater running through it you are on a hiding to nothing. In our club every single person i know who has rebuilt an engine has ended up replacing it anyway within a few short years. All regreted spending out on the rebuild. A small marine diesel has a designed lifespan, once it gets to 30 years its on borrowed time.

  10. #10
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    Default

    Get a can of ether.


    Sent from my iPhone using Tapatalk

  11. #11
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    Default

    Get a real compression test in psi, not a "oh if I can turn it over by hand" test,.
    Those old Volvo engines have massive flywheels.
    #1 should be what can you afford?
    #2 what do you really want?
    Denise, Bristol PA, retired from HVAC business, & boat restoration and building

  12. #12
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    Default Re: Options for a Volvo MD5a

    Thanks to all for the comments! I will definitely get a second opinion as the next step. I definitely don't want to sink a ton of money into a forty-year old salt water cooled diesel, but if I can get a few more years out of it that would be great. It has been run in salt water its whole life.

    I'm pretty sure that an outboard will not work for me because although the Albin is small at 26 feet, the diesel lives in the forepeak on this boat and replacing it with an outboard would change the trim a lot.

    I do like the idea of replacing with a less-worn or rebuilt md5a. Anyone know of one out there?!?!

  13. #13
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    Default Re: Options for a Volvo MD5a

    Might try this guy:

    https://maine.craigslist.org/bpo/d/u...674003443.html

    There's also this:

    https://providence.craigslist.org/bp...682114095.html

    Doesn't solve the compression problem but might be useful if you need other parts.
    - Chris

    Any single boat project will always expand to encompass the set of all possible boat projects.

    Life is short. Go boating now!

  14. #14
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    Default Re: Options for a Volvo MD5a

    Another thought….was it running recently, soon before the mechanic's comment about spinning the motor by hand? Maybe just take the rocker box off and check the valves and the decompressor mechanism, see nothing is stuck open… could be all it needs is a head job.

  15. #15
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    Default Re: Options for a Volvo MD5a

    I agree with get a real compression test and be inclined to find another mechanic to do it. I could turn over my MD2 15hp by hand but it wasn't easy with full compression. I normally hand started it with the compression released only on one cyl and could turn it over (with effort) quickly that way. When it bumped 2-3 times I hit the other compression lever and it started. That engine was strong and propelled a 24k lb cutter and not a worn out POS. These are simple engines to rebuild...as long as the block is good.

  16. #16
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    Default Re: Options for a Volvo MD5a

    There are some reports that the exhaust valve on that engine is subject to pitting and corrosion. This could be the whole problem.
    (It is good practice to stop the engine and turn it by hand until it is on the compression stroke. This insures both valves are closed to the atmosphere. In particular the exhaust valve which has the cooling water discharge right there next to it)

    If I was closer you could easily talk me into "rebuilding" or repairing that engine. They were designed and alloyed to be raw water cooled and there "should be" plenty of metal left.
    They are really engineered to last darn near forever, and should run many thousands of hours with proper care. I recently brought an MD17 (3 cyl) back from the dead that had been sunk for over a month. It was siezed up solid. I was able to go through it without even buying head gaskets, I used them over again! The other gaskets were either reused or just cut out of gasket paper. (The only thing "fussy" is the governor/high pressure fuel pump. There are some small parts and critical adjustments and I wouldn't recommend an amateur go in there)

  17. #17
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    Default Re: Options for a Volvo MD5a

    I can turn over my 10 hp yanmar diesel by hand without pulling the lever. That means nothing.

    This is a dead-simple engine. If it really is low on compression, pull the top off and lap the valves. If that doesn't do it, pull the bottom off and replace the piston rings. Maybe some new bearings while you have it open.

    One saturday once you have it on the bench and you have a new engine. Really, you can do it. Just don't take apart the governor or fuel pump or injector, as Canoeyawl says.

  18. #18
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    Default Re: Options for a Volvo MD5a

    seems we all pretty much agree that no.2 is the way to go, but I can't see a sub 10hp outboard really affecting the trim ...what can it weigh, 35 kgs 80 lbs more or less ..? even my 40hp fourstroke only weighs 85 Kg or so.

  19. #19
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    Default Re: Options for a Volvo MD5a

    How does it start and run???????? Are you satisfied with the performance?

    I don't know why he would call it "not safe". Unreliable maybe, but not safe safe(?), only in the sense that it may not be there if you need it. However if it has never let you down before, just because you may now know something about it that you didn't know before doesn't change the engine or its reliability.
    And you are in a sailboat, .... aren't you?

    I realize this line of thought doesn't work for everyone, ...... that's how I would look at it.

  20. #20
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    Default Re: Options for a Volvo MD5a

    Sleep with one eye open.

  21. #21
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    Default Re: Options for a Volvo MD5a

    Im gonna guess the valves need adjustment... and if its not that the rings are stuck...

    These are much cheaper than replacement.... Isn't there a small diesel mechanic anywhere up there? Maybe put it in your truck and drive to maine?
    There is a joy in madness, that only mad men know. -Nieztsche

  22. #22
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    Default Re: Options for a Volvo MD5a

    I know this is an old thread, but here is a used on Craigslist:

    https://reading.craigslist.org/bpo/d...398993492.html

  23. #23
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    Default Re: Options for a Volvo MD5a

    Figure there is merit to what the mechanic said - for your own peace of mind, repair, rebuild (if practical based on parts availability - I don't know this engine) or find a "running take out" as replacement. Changing to a different diesel would likely raise mechanical, pipe/tube, control cable, and electrical interconnect issues - death of a thousand cuts. Changing to gasoline would add more items to the issue list.

    Engine you have is suitable to the task, just needs work, right? IMHO, for this case, more radical solutions considered less work or more economical seldom work out that way.

    Regards.

  24. #24
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    Default Re: Options for a Volvo MD5a

    Quote Originally Posted by v10builder1 View Post
    Figure there is merit to what the mechanic said - for your own peace of mind, repair, rebuild (if practical based on parts availability - I don't know this engine) or find a "running take out" as replacement. Changing to a different diesel would likely raise mechanical, pipe/tube, control cable, and electrical interconnect issues - death of a thousand cuts. Changing to gasoline would add more items to the issue list.

    Engine you have is suitable to the task, just needs work, right? IMHO, for this case, more radical solutions considered less work or more economical seldom work out that way.

    Regards.
    I'm thinking that as the original post was in 2018, he's done whatever he was going to do!
    There is nothing quite as permanent as a good temporary repair.

  25. #25
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    Default Re: Options for a Volvo MD5a

    Where in heck did this come from??? I originally came to this forum looking for info for a Volvo-Penta Md5a? I still have the motor and still hope to use someday.. Blast from the past or what!!!!

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