Volvo MD7 (?) How maintainable in the medium term?

Topcat47

Topcat47

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I'm looking at a boat with a nicely maintained and clean looking MD7 17hp twin engine. "Official" spares are scarce, how about "Pattern Parts? I had a MD1b around 12 years ago but it was replaced when I was unable to source, a head gasket or an exhaust manifold. This looks to be around the same vintage.
 
You will have the same problems. Declining supplies of spares as the number of engines in use falls. Be prepared to replace it, although it could go on for years. Guess it depends on how willing you are to risk that it will keep going without any significant failures, and perhaps whether the boat is "good" enough to justify (for you) the expenditure of a new engine.
 
I've had experience with an even older MD1 and found that some spares including head gaskets and piston rings are still readily available. You'd be struggling with things like pushrods and pistons though. It's easy enough to make paper gasket out of old charts or Kellogg packets, I'm told.
 
ghostlymoron said:
I've had experience with an even older MD1 and found that some spares including head gaskets and piston rings are still readily available. You'd be struggling with things like pushrods and pistons though. It's easy enough to make paper gasket out of old charts or Kellogg packets, I'm told.
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Hi ghostly, where can I get head gaskets? My 1971 MD3B is still going strong, but she will need some in the future, thanks LD
 
I'm currently looking for a pair of injectors for my MD7A but used ones are as rare as hens teeth and new Bosch ones are £350 each which makes the engine unviable really.
 
Parts are still available, there are alot to my surprise actually. Key part seem to be good for parts and any parts you cant find, fuel hoses ect. you can have made or make yourself for not much money at all.
Major parts will however be stupidly expensive as are all volvo parts.
If in okay condition it will run forever if maintained.
Mine was fully rebuilt in 2007 and I will only replace it if it majorly goes tits up as the new engines arn't much different.
You will find alot of people who love these engines I have and I must admit I do like the durability I cant imagine a modern engine lasting 30years and still be in as good condition as some of these
 
Not just the engine which may be a problem, wait until the gearbox packs up. Many years ago I was quoted as much for a new gearbox as an engine + gearbox of another make. Cone clutches were IIRC around £350 each at the time.
 
MengWalton said:
You will find alot of people who love these engines I have and I must admit I do like the durability I cant imagine a modern engine lasting 30years and still be in as good condition as some of these
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Just not so. Modern engines, mostly now freshwater cooled will way outlast these old seawater cooled engines. The basic engines are lifed to typically 8000 hours which is over 50 years average yacht auxiliary usage. Most old engines die because of long term coolant related issues arising from running cool and the use of seawater in the cast iron blocks, heads and often gearboxes.
 
I don't know about that Tranona. There's something about old engineering that makes for longevity. For instance, there are loads of Seagull engines still doing sterling service and freely available on eBay. I like the simple, robust construction from this era. Mostly the corrosion due to direct cooling isn't terminal because of the sheer thickness of metal.
 
ghostlymoron said:
I don't know about that Tranona. There's something about old engineering that makes for longevity. For instance, there are loads of Seagull engines still doing sterling service and freely available on eBay. I like the simple, robust construction from this era. Mostly the corrosion due to direct cooling isn't terminal because of the sheer thickness of metal.
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There are also many that have rotted away. While the oily mechanicals are generally robust, the big enemy (as I pointed out) is salt water (and neglect). No point in having good bores and bearings if the waterways are full of crud and the engine overheats, blows a head gasket, sludges up with oil or cokes up with carbon and unburned fuel because of inefficient running.

Engines from the boom years of 1970s and 80s are now regularly replaced as owners give up the unequal task of keeping them running.

Sound reasons why Volvo stopped making their own engines at the end of the 1980s. The advent of the robust small Japanese industrial engines offered far better long term prospects.
 
Tranona said:
The advent of the robust small Japanese industrial engines offered far better long term prospects.
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In theory you're right but in practice?. These engines are in the main designed for running at constant revs for long periods, driving generators and hydraulic pumps in small plant. They're not designed for the treatment many boat engines get, short cool run periods, motor sailing at low revs, left standing for months on end in winter and intermittent summer use, etc.
 
GrahamM376 said:
In theory you're right but in practice?. These engines are in the main designed for running at constant revs for long periods, driving generators and hydraulic pumps in small plant. They're not designed for the treatment many boat engines get, short cool run periods, motor sailing at low revs, left standing for months on end in winter and intermittent summer use, etc.
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Well The Volvo Perkins 20x0 series and the Kubota based Betas and various Mitsubishi engines have been on the market for over 25 years now and there does not seem to be a rash of premature failures. Having run a Volvo 2030 for 3500 hours without a single problem (on a charter boat in Greece) and it was running just the same when I sold it as it was when new. Nothing done to it except for changing oil and filters.

Those base engines are used in a huge range of industrial and agricultural applications - diggers, dump trucks, tractors, air conditioners, generators, cranes, cherry pickers etc, much of which endure far more abuse than yacht engines. So not just constant revs applications.

As for intermittent use, they are much more tolerant as unlike the old style engines the salt water never gets near the base engine, and the environment in a modern boat is usually dry and clean. You don't often see oily, salt corroded engines in modern boats.
 
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