Diesel Engine Maintenance

Chris Murray · 18 August 2003, 21:39

My last boat had a 5.7 ltr V8 Volvo (275HP). It had a monster Holley 4 barrel carburettor (not very fuel-efficient, by today's standards) and did around 2.25 nautical miles per gallon (imperial).

It was kept in the water 100 miles from home and in general, I would probably take it out one in three visits, spending the rest of the time maintaining either the boat or its engine. I don't want to spend nearly so much time with my new boat (when I get it) with my head buried in the engine!

One of the more expensive tasks (which I had to contract out to a marine engineer) was to replace the exhaust manifolds. This required the engine to be removed from the boat, which proved quite an expensive process.

Now I shall get to the point!

How much maintenance would be associated with a diesel engine (say 300HP)? Presumably, it would have similar exhaust manifolds that are sea water cooled? Does fresh water cool the block? If not, what is its life-expectancy?

Bearing in mind that some of the modern outboards can have the block cooling channels flushed out in situ - which should presumably increase longevity of the engine - do any such facilities exist on modern diesel engines?

Any experiences or comments about maintenance in general would be most appreciated.

Thank you!

Regards,

Chris.

gavin · 18 August 2003, 21:51

Diesels are an absolute pleasure to maintain, you will have maintaince issues with them but with a modern marine diesel,it will be designed to be looked after.Depending on the type of engine, some use fresh water cooling from a tank, others use seawater, however zinc anode inserts are inserted to corrode first and clearly marked, inspect these first and perodically to avoid expensive corrosion problems,diesels are all about fuel supply, and a good power source to turn over these higher compression ratioed motors, and heat the cyls before the fuel is injected into them.You generally have higher torque lower revs, better fuel consumption , and fewer electricial components to give trouble,but to make it a viable purchase, you need to be doing the engine hours to offset the higher initial cost of the purchase,

Chris Murray · 20 August 2003, 20:55

Thanks Gavin!

I've just seen that Volvo has come out with a new 310HP 6 cylinder diesel, designed from scratch for the marine environment. There are even a couple of new sterndrives to choose from. The author of the piece on these engines, Tony Jones of Motor Boat & Yachting, appears to suggest that it might eventually be capable of developing something in excess of 350HP.

I was going to include a picture, but I am not sure about the copyright position, so I decided against it!

I appreciate that this info is likely to be of little value to you, as you already have a good engine, but I guess it doesn't stop us wanting to know "what else is out there" !

Any idea why most diesel RIBs seem to use Yanmar engines? Is it because there was no real alternative - until now?

Regards,

Chris.

Richard B · 20 August 2003, 21:59

Quote:

Originally posted by Chris Murray
Any idea why most diesel RIBs seem to use Yanmar engines?

this same question was asked on YBW.com some while ago, but the opposite way round... Let me explain:

The question was "Why is Volvo the most popular 1st choice for standard manufacturer fit engines?" Now, bear in mind that the considered manufacturer base was high volume, high value hard boats. Also, most people on YBW.com seem pretty cheesed off with Volvo spares prices, and their complete lack of positive customer service. The most unchallenged answer was: "Volvo allow dealers to pay for the engines when the boat's sold to the customer if the builder meets his targets" which obviously helps the builder with his cash flow. Just a bit! Now, relate this to the low volume production of Diesel engined RIBs - are Volvo going to be interested in targeting the RIB builders on the same scale as Jeanneau, Sealine, etc? Make your own mind up! So maybe the reason is marketing rather than technical??

You might get a broader sample of responses on YBW on a theme of "best diesel engine" or "Volvo versus Yanmar" But then none of them will have taken a Yamaha 240hp engine all the way around the world. And isn't the Yanmar 300 a 24valve version of the Yamaha engine?

Pete7 · 21 August 2003, 09:10

Chris, when I bought my Pacific (fitted with marinised 4.2L Ford 200 hp engine by Mermaid) I went along to do their one day engine maintenance course at £85 including large engine manuals. Can only say it was brilliant. They taught the 8 ppl on cse on the very engines we have in our boats. I now have no quarms in doing routine maintenance, changing an injector or timing the pump etc. I know some of the other engine manufacturers do similar courses, which should be considered essential. I hope the 4 cylinder diesel will require little attention other than good routine maintenance and regular checks to catch any problems early.

The Mermaid is fresh water cooled and being a ford block means I can buy filters etc anywhere. You might like to know Mermaid do have a very nice 300 hp 6 cylinder ford block. I think your problem might be the large number of different options for engines and drives now available and selecting the right package.

http://www.mermaid-marine.co.uk/

Pete

Alan Priddy · 21 August 2003, 15:50

Whats maintenance? a good unit goes on for ever. Alan P

Pete7 · 22 August 2003, 07:56

Alan, I normally carry out maintenance so my boat doesn't sink,

but you are right a good unit goes on for ever. Think mine is 22 years old.

Pete

Julian · 22 August 2003, 13:49

Our Yanmar 300 is serviced once a year and thats about all thats needed on them, runs beautifully all year round , the only thing i do to the engine is winterize it and thats it. Cheap to run and service.

Julian

Chris Murray · 23 August 2003, 08:31

Thanks Guys!

I have just received my advance tickets for Southampton. I shall certainly have a look at Yanmar, Yamaha and Mermaid.

What a shame I shan't be buying my new boat for a little while. Still, with help from your good selves, at least I should be able to get all the right kit first time, rather than learn by my own mistakes!

Best wishes,

Chris.

DepSol · 23 August 2003, 11:11

Quote:

Originally posted by Alan Priddy
Whats maintenance? a good unit goes on for ever. Alan P

As long as it is fed the right ingredients

Dom