Update May 2024,
Mixing elbow replaced, engine serviced.
Numerous spares now aboard.
UPDATE Feb 2024- Jack at MRC had a go at the engine, changing its fluids -and removing and inspecting the exhaust elbow. A new elbow and timing belt have been sent.
ORIGINAL POST
Our Ovni came with its original Volvo-Penta MD22E BT engine. These have a good reputation for reliability and durability, if not parts cost. This engine was also sold as a Perkins Prima M50, and, in turbo form, powered the Rover Montego Saloon. Many parts are common to these engines, and others, and as is often the case, non-marine channels provide more reasonable prices.
The engine had had some work done in the Canaries prior to crossing the Atlantic, but I cannot locate the invoice. It does not appear to have been properly laid up During the sea trial, the engine started easily and ran without smoking, but the survey reports it will only reach 2450 RPM (vs 2650 or more) at WOT, though at over 8+kts. It may be overpropped; the feathering Max-prop is adjustable for pitch. There was some minor vibration also noted. It was also noted that the stuffing box seal was leaking a bit, but it was not "burped" and greased as it should have been. Kind of like caring for an infant.
It is configured with a raw water strainer easily accessible and well above the waterline in the companionway. Fuel filtration is handled by a vetus 40 micron filter/separator, and the OEM 18 micron unit mounted on the block. Pretty good setup really. .
What isn't so good is the belt-driven overhead-cam design which means that valve adjustment requires special tools and shims and is a far more involved process than that the screw-type adjusters in simpler engines with gear driven cams located lower in the engine block. The price of sophistication. My old Yamaha 850 had two chain-driven overhead cams I hated doing the shim-in-bucket valves.
The shop manual is readily available online, and the boat also came with some spares. I have not yet found a parts manual, but parts can be searched here, in their very slick online database..
The fuel tanks were cleaned in Brazil, in 2020 I believe. I doubt stabilizer or boicide were added when the boat was laid up.
So, it requires a full service, and a laying in of spares.. I'll also replace the mounts and stuffing box/seal and cutlass bearing just to know I have a reliable baseline. In the interest of time I may hire a mechanic in Curacao to do this work.
Mounts may be as follows: PER2634C202 - Mount, M50 4.108 CUSHYFLOAT.
A thorough service leaves the mixing elbow, alternator, water pump, fuel pump, and starter as potential failure points in extended use.
The boat came with some spares and will require some more.
Draft list of required spares.
Part numbers are:
Timing Belt: Gates 5190 ~£25
Idler: INA 532008810 ~£50
Tensioner: INA 531009910 ~£40
Water pump: Perkins U5MW0085 (minor modification needed)
Engine Mounts
The engine is a single overhead camshaft design with an alloy head so you will get to know how to change drive belts and set the timing for reasons explained further down the list.
Usually these engines were wired as "above ground" or insulated earth so the starter, alternator and senders are dual pole, adding a new level of difficulty to troubleshooting faults
The water pump">raw water pump is camshaft driven at the top rear of the engine and they leak as most impeller pumps do.... but directly onto the gearbox. Some were fitted with a little tray and drain hose to stop the saltwater damage. The bigger problem is the drive tang that connects the pump to the camshaft and unless the alignment of the pump to the cambox is perfect, both the tang and the pump shaft wear out ( way worse than the 4-108 tang)
The exhaust mixer elbow will not be easy to live with and they fail fairly quickly, especially the little bolt on bit at the injection point. Oh, also harder to plumb in a sensible vent loop too because of that little part.
It can be hard to get the injectors to seat properly. Because it's an alloy head they avoided the possibility of damage from over torquing the injectors by using a spring bridge so the spring , not the bolts hold the injectors on the sealing washer.... always anneal the washers if you pull the injectors.
The coolant circulating pump seems to last pretty well BUT if it does leak it's about half a day's work to replace it. All the timing sprockets have to come off to get that sucker out and you need a damned good puller for the injector pump sprocket.
Finally..... the valve clearances are remarkably labour intensive to adjust and the camshaft has to be removed to get the settings right by adding or removing expensive spacers to the valve stems. Special tools are needed to hold the cam when the cambox lid is off but the good news is that once set properly, those clearances are good till the next valve grind.
So that's all the troublesome bits that I can think.... of and the good news is the injector pump. It's a Bosch VE and it really leaves the old 4-108 distributor pump for dead, self priming, good electric shutdown and it sits close to the manual lift pump on the cambox.
I hope this helps with your decision .. they are good engines.
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