Saturday, 17 June 2017

Propulsion Machinery - Final mechanical post for now, I promise

This will be the last of the posts I have done about Enfys' machinery - until something else goes rusty or falls off! 

I had to get the engine up to replace a very rusty sump-oil-drain tube and whilst the motor was up out of the bilge I tacked a few other jobs. Having no facilities or need to remove the engine completely from the boat I devised a pair of 'A' frames that stood on the side decks with a strongback between them, over the engine. From this I slung a basic chain hoist with a 500kg capacity (the Beta 20 has a stated weight of 105kg). After disconnecting the engine's pipes, cables and wires and spending a whole afternoon unbolting the rusty clamp coupling and getting the mounting screws out the engine was ready to lift.
The engine was lifted up and turned through 90degrees and placed on blocks that spanned the cockpit floor frames.
Lifting engine

Engine now reasonably accessible
The sump oil was drained and the after a bit of a struggle the rusty elbow and pipe was persuaded to part company with the sump.  New parts were obtained from Beta marine and elsewhere to renew these and also the flexible engine mounts.
Now, I have to say that in my opinion, none of these parts is really suitable for use in a damp salty marine environment; the drain hose is a standard industrial hydraulic hose and the crimped ferrule was just crumbling. Three of the four flexible mounts were totally 'minty'. I found that they were of Italian manufacture and are most commonly fitted to air compressors; made of pressed mild steel and cad plated. To try and prolong the life of the replacements I painted them thoroughly with zinc-rich primer and a few coats of machine enamel.
Rotten sump oil drain connection

Beta engine mounts disintegrating in the marine environment
The whole lot of rusty engine parts were cleaned, treated and painted in some 'Carmine Red' enamel to match the supplier's original spec before being reassembled.

New engine mounted loosely fitted
Whilst the engine was accessible I fitted the Beta-supplied (and very expensive) 'upgrade' of the poly-vee auxiliary belt and pulleys to rid her of the curse of the 'black-dust' and tri-annual re-tensioning of the original 'V' belt. I stripped the alternator again to clean the belt dust from its innards.
Front of motor caked in belt dust - a well-know problem with these early Beta engines

New parts obtained and ready for fitting

Poly-vee kit fitted. A chunk had to be ground off the raw-water pump to let the belt pass.
Whilst the engine was out the bilges were cleaned and painted and the prop shaft was withdrawn to enable replacement of the outboard 'cutless' bearing. The propeller shaft was found to be worn and we were concerned at how badly the propeller had been corroding.
Bilges cleaned...
....and painted.
Badly pitted prop, and worn shaft
The 'cutless' bearing was chopped up and pulled out and the housing polished inside with emery on my electric drill. A new sleeve was pressed in as shown...
Method of getting the old 'cutless' out
Winding in a new bearing sleeve

New 'cutless' in place
A new shaft and propeller had been ordered and reeling from the cost I was determined to find out what was wrong with the existing galvanic (cathodic) protection (or lack of it!).
Enfys has a pair of zinc anodes bolted back-to-back through her sternpost that appeared to be connected to the outboard bearing housing. Inboard there was a wire connected between the stuffing box and engine's gearbox.
I made some continuity checks and found that although there was a circuit between the anodes and outer bearing there was no circuit through the stern-tube - it was open circuit, which was quite a surprise! This fact, coupled with the fact that the cable between stuffer and engine was also O/C and that there is an insulating flexible member in the propeller shaft coupling meant that the prop had probably been fizzing away merrily.
What I did to mitigate this was to fit a 'new' anode to the hull with through-hull studs (more holes in the planking.. arrgggh!) which was connected to the stuffing box and engine by new cables. At the prop shaft coupling a stiff copper wire bridges the flexible member. Now, checking continuity the propeller and shaft are all bonded to the anode.
Something odd - sterntube is corroding inside shaft log/sternpost - no continuity to the outboard end, too.
New zinc 'pear' anode fitted to hull

Connecting wires fitted to studs - backing pads will be needed at a later date.

Cable clamped to stuffer with a jubilee clip

Bonding wire connected to gearbox - flexi coupling was also bridged.
Engine back in place, lined-up and coupled
Engine back in place
 The lifting frame was rebuilt and the engine lowered back into place and carefully re-aligned with the shaft coupling.
Another job that I did whilst the shaft was out was to renew the stuffing box packing. A horrible fiddly job that required kneeling in the bilges - but I'm glad I've done it as the annoying drip from the gland has now gone!

The 'plumbing' and wiring was all re-connected, fuel tank refitted and filled, fuel pumped and system bled, batteries switched on, water hose laid on and she started and runs!

Thursday, 23 March 2017

Engine Work 2

Here is the second of a few non-Finesse specific posts but as a practical boat owner who does all their own repairs and maintenance I thought I would share on the blog..

On re-commissioning Enfys last season we discovered that the engine's alternator was not charging. A quick check of engine wiring loom and controls revealed that the alternator was receiving its excitation voltage but the output was dead.
N-D Alternator - Loose wire protruding from rear cover is a direct connection to one phase
of the AC windings and provides a pulse-train for the tachometer

I removed the alternator and took it home.  Usefully (not) the engine mariniser had sprayed paint all over the data plate making it illegible so it took a bit of detective work to find out that the alternator is a 'Nippon-Denso' with an output of 40A.  It was the internal voltage regulator that had failed - there was no visible damage or corrosion - it just decided to stop working after the winter lay-up. I must say how poorly and cheaply-made this machine is; not really suitable for the marine environment, in my opinion. Pricing up a replacement showed that it was not cheap to buy though... despite being the same as used on plant-based Kubota engines.
The regulator is the module on the left with a heatsink on its back.

Regulator assembly

After a couple of attempts a correct replacement regulator was sourced from an auto-electrical parts supplier and the machine was re-assembled and tested on the bench by spinning it with my electric drill. Whilst in the vice I blew copious amounts of black dust, from the 'V' belt, out of the machine's internals.
Connected up for test. My 'test' battery is a little tired.

Thursday, 9 March 2017

Engine Work 1

Not unique to a Finesse but Enfys' engine is a 20hp Beta based on a 3-Cyl Kubota industrial engine.  Sometime prior to our purchase of the yacht there had been a water leak at the raw water outlet at the back of the engine probably caused by a poorly-fitted hose. This would have been typical of the shoddy standard of this particular engine installation that was noticeable elsewhere too.
The exhaust outlet was heavily corroded and I noticed a crack had appeared in it - time for replacement.
Finally got the old elbow off leaving three broken bolts in situ.

The fixing bolts were M8 mild steel and might as well have been made of chocolate as three of them sheared off as soon as I put the spanner onto them. After a bit of sawing and hacking I got the elbow off.

Remains of the elbow after my hacksaw had done its stuff

The reason why the corrosion was so bad soon became apparent; the heat exchanger and elbow are made of aluminium alloy and were jointed by a copper-faced gasket.. doh!

Copper faced gasket had been used on original assembly

I had to remove the whole heat exchanger from the engine and put it on the bench to tackle the removal of the broken bolts.  It was assumed that these would need to be drilled out and the trashed holes would need to be 'Helicoiled', however, to my surprise I got all four out and cleaned up the blind holes with a tap. A new elbow and joint gasket were sourced from Beta Marine - the new gasket was fibre. Instead of using new bolts I 'Locktighted' M8 threaded studs into the holes in the casting and bolted it up with nuts and washers - hopefully making it easier to remove next time.

Studs fitted once mating face had been cleaned up

New elbow fitted to heat exchanger

Next post will cover another corroded pipe and fittings on this engine...