"Axel,
From the sounds of t
"Axel,
From the sounds of things, you personally will not want to touch anything on this engine but the dipstick, check the fresh water level and verify the strainer is not clogged. You need a competent mechanic (or time and desire to become one ... which is not very difficult).
The M50 design is different from probably any automotive engine you have ever seen, as it is NOT grounded (unless someone has altered it's original wiring). If you give your auto mechanic the service manual for the M50 and ask him to take a careful look at the engine wiring diagram, with particular attention to the grounding circuit ... it should only take a minute or 2 before he is scratching his head in puzzlement. The M50, as originally wired is grounded ONLY when 1 of the Start, Stop or Glow Plug buttons are depressed. As for your stop 'button' problem, the actual source of the problem is probably in the engine compartment. There are 3 relays on the aft port side of the engine near the valve cover(? by memory). One for each of the afore mentioned buttons. These are quite close to the raw water pump and hoses and generally also in the path of salt water flung around by the prop shaft
if there is a slight leak in the shaft seal or stuffing box. Check the operation of the relays and the wiring between them and the stop button. Ultimately there is a plunger that blocks fuel on or near the injection pump that the relay operates. As a stop gap or in an emergency, there is a mechanical lever on the injector pump that will allow you to stop the engine (can be reached from the front of motor on port side top).
If your mechanic is afraid of touching the timing belt when he changes the aux belt (alternator, engine driven compressor, whatever) run far and fast to get another mechanic. The timing belt is (better be!) behind a cover that needs to be removed, the aux belt(s) are plainly visible from the front of the engine.
The aux belt change (required in your case) should take someone with any level of experience on any auto engine, a max of 20 minutes ... I can change mine in 3 mins.
The Timing belt will take a couple of hours, will probably require an impact wrench to loosen the tensioner (needs to be replaced with the belt). The fresh water pump should also be replaced at this time ... anything else is foolish. See notes below about replacement interval (2000 hours or 6-8? years). You will want to rent special perkins tools from (among others) Transatlantic Diesel, Virginia USA. Buy the water pump, timing belt and tensioner ONLY from someone that will rent you the special tools. They are merely some pins (by memory) that lock down the top and bottom halves of the motor, and could be fabricated earily if you have the dimensions, but it is plain stupid to attempt to change/tension the timing belt without these locator pins.
If you are going to be the 'engineer' on a passage of any length, you need to become more educated on diesel engines and in particular your M50. There are books by Calder (I think) and others that will give you easy to understand troubleshooting. You will also need to buy a perkins M50 Service Manual (maybe $100 US from any Perkins distributor or Transatlantic Diesel if you don't want to hunt). You will NOT be saving money to skip this ... your chosen mechanic will need it, and in your spare time voyaging, you can read it for entertainment;~)
The age and hours on the engine REQUIRE that you change the timing belt if you don't have proof that it was done at around 2000 miles and in the last 6-8 years or so. Timing belts can can go bad in time with NO hours. If the time belt breaks on passage, you are done using you motor. On 'interference' engines (and I don't think the M50 is) breaking a timing belt will cost potentially thousands dollars of unnecessary repair (bent vales and punctured pistons). In fact the only way to cost effectively fix a 'valve crashed' older engine is to do a complete overhaul (if you are intending on keeping long term)."