Cevema's old Yanmar YSE 12

Cevema joined me shod with a Yanmar YSM12 single horizontal. When I bought her I was concerned that a 12hp engine would not be man enough to fight the lively tides in the Bristol Channel. During the first year's sailing it did better than I expected and even allowed me to tow a Trapper 500 back into Burnham on Sea against a head wind and foul tide. When hard pressed for any period of time, however, she used to expel oil into the bilge. Exactly where it came from I have no idea, but it was clearly not a sign of good health. I was going to get another YSM12 rebuild it, and swop them over, but the cost and time implications put me off especially considering that at the end I would still have a twenty year old engine for which parts are not going to get any easier to source. I talked to the bank who seemed keen to invest in a new engine. As I was dipping my hand so deeply in Mr Lloyds TSB's pocket I figured that I may as well go up to twenty horses and started the task of picking a new engine. I spent hours measuring the engine bay and collecting drawings from the manufacturers. Most of the engines were of similar sizes for given output. Only Volvo, however, offered a gearbox with an 8° down angled output shaft at no extra cost. Using the Cosine rule (yes ‘o’ level maths still helps!) I determined that this would give me an extra 4 inches at the front of the engine which would be valuable when it came to servicing and maintenance and also allows the engine to sit flatter which can’t be a bad thing. The 2GM20 was tempting but wouldn’t have been as smooth or quiet as the Volvo and used raw water cooling. Although Volvo have a name for expensive spares, in truth, I think all the marine engine manufacturers reef one severley for spares; from bitter experience I know the cost of Yanmar spares. So the decision was made to buy a Volvo MD2020 from R K Marine. Graham there was very helpful and has given me a lot of advice not to mention a good show discount. Whilst I am very practical and have an engineering apprenticeship behind me, I have no experience of playing with marine diesels so needed guidance which has always be forthcoming from R K Marine.

Having craned Cevema out the first step was to remove the old engine. The initial plan was to have the engine craned out but when I had all the engine mounts and services disconnected, the crane driver went on holiday. I decided to have a go with the main sheet hanging from the boom. This worked surprisingly well with the help of a man mountain who was in the yard working on his long keeler.

from this pic you can see the position of the old bearers

The original engine bearers were a very strange affair with two sets offset and at strange angles. Extra long jig saw blades and a lot of foul language and indiscriminate use of an angle grinder finally expelled these from the hull. The next problem was to decide where to put the new bearers.

jig made to line up bearers with prop shaft

From the Volvo Penta website I downloaded the drawings for the engine and from these made a wooden ‘footprint’ of the new engine to which I bolted the shaft coupling. As the 8° down angle from the gearbox was critical I enlisted the help of my furniture maker friend to ensure the accuracy of this part. This ‘jig’ was then fitted to the prop shaft which gave me the final position for the bearers which I made from 3” x 2” oak and glassed in using West System epoxy.

positioning the new bearers with the jig

Between the original bearers was a ‘bridge’ which kept any fluid leaks from the engine out of the main but shallow bilges under the saloon sole. This had to be cut away to clear the new sump and moved forward by around six inches. I had to carefully cut the saloon sole boards to fit around this new protrusion. The original sea cock was also in the wrong place. I tried to remove the strainer but is was not being moved. I cut it down with the Dremmel and screwed a stop-end on it. I fitted a new bronze 3/4”BSP strainer and sea cock. Apparently with fresh water cooling one required a bigger strainer/sea cock. (This can all be seen in the pic of the engine installed at the end)

On the Yanmar engine the lift pump was on the port side and the exhaust exited on the starboard; the Volvo naturally works the other way around. The original silencer was a stainless box which I replaced with a plastic model from Vetus as I am assured that these are quieter.

new Vetus silencer roughly in position

I sandwiched it between the port wall of the engine bay and a piece of board I glassed in. The original filter/watertrap was attached to the port hand wall of the engine bay in such a manner that filter changing was virtually impossible. I put a new CAV model on the opposite wall near the front of the bay where it is easily accessible.

new primary filter diesel filter

I fitted a syphon break in the back of a cubby hole in the heads as this was sufficiently high above the water line and unobtrusive without being impossible to get at should that prove necessary at any time. This was to be connected between the freshwater pump outlet and the heat exchanger inlet. Whilst there was no engine in the bay, it occurred to me that there was a lot of wasted space behind the engine so I decided to fabricate a stainless steel tank to fit in this space; but I will write a separate article about that later.

new home made diesel tank in position

The new control panel was slightly bigger than the Yanmar item so once the old one was removed I cut the aperture out larger with my faithful Dremmel. When I first bought the Dremmel I was very disappointed with it; but it is great for cutting out fibre glass with a bit which looks like a cross between a drill, router bit and a burr. It also comes with a mini barrel sander bit, which is very useful working on boats. Whilst I have a good collection of good quality hole saws, I don’t have every size under the sun and the little barrel sander is great for carefully opening up holes. The little abrasive cut-off wheels are too delicate for most jobs but are often the only way to cut something buried deeply in a boat. Cutting off the excess thread from the bronze skin fitting/strainer was a perfect example; I had to cut it off neatly so that I could still screw on a stop end, but being so close to the hull, bearers etc I couldn't get a saw in. I got through at least half a dozen discs and used some choice language but there seemed no other way to do the job, so the Dremmel should be applauded for doing the job at all. It is possible that there are other cutting discs available should one be prepared to search for them. I bedded in the panel with plenty of Sikaflex.

new panel installed

The panel has only four screws securing it; I would have preferred to see more. There is only one connection to be made to the engine via a fat loom with large multi plugs either end, the only other electrical connection to be made is from the engine to earth and positive feed from the battery changeover switch.

The old engine had the diesel return from the injectors routed straight back to the secondary filter, but Volvo insist that it must go back to the tank, so provision had to be made for a return pipe. All the diesel lines wanted to be 6mm copper; the marine purveyors of such material call for the parting of huge sums of money, but a local heating supplier supplied the tube and fittings at a fraction of the cost.

engine mounts attached to bearers as per Volvo Penta drawing

I drilled my jig for the engine mountings as per the drawing down loaded from the Volvo Penta web site, and slipped it onto the prop shaft. From this I drilled the bearers and attached the mounts from the engine with coach screws; whilst I could make rough measurements from the engine re the position of these mounts, I was really putting huge faith in the drawing downloaded.

With all the services now in place and the flexi-coupling sat loosely on the shaft it was time to find out how good the info on the drawing was. Predictably the crane driver had decided to take another holiday so the lift had to be done with the mainsheet and boom again. With the help of another yottie the new lump was hoisted up and swung into place; he lowered the engine down and I pushed it into place. This was very difficult, partly because the supporting rope was unable to go back as far into the engine bay as the engine needed to. On the second attempt I managed to locate the mounts in their requisite holes and heaved a huge sigh of relief. I bolted up the flexi-coupling and set about aligning the engine with the shaft. This is done by measuring the gap between a specific bolt head (painted red) and the body of the coupling at different positions of rotation of the shaft with feeler gauges. The engine is wound up or down on the mountings to get the alignment perfect. With more space this would have been easier than expected but when one is jammed into the rear of the engine bay having entered head first down through a ‘too small’ aperture from the cockpit locker, it is pretty tricky. Connecting the big ‘flexible’ exhaust pipe was very difficult but was finally achieved with a great deal of discomfort and foul oaths. The main problem was the short distance from the engine outlet to the silencer and the bends required. Connecting up the gearbox and throttle linkages to the morse control was fairly straight forward. I bled the feeds from both tanks and connected up the diesel feed and return. The various water pipes were fitted as were the electrical connections.

The new Volvo Penta MD2020 finally in place

To test the engine I fitted a hose pipe in place of the sea water. The engine was reluctant to start but I later discovered that this was because unlike the Yanmar it doesn’t like plenty of throttle for starting. The electronic rev counter/hour meter had to be programmed for the engine before it would work; this involved my sitting in the quarter berth poking the back with a pin whilst the current bride shouted out the contents of the display.

The new engine encroaches a little further into the cabin and so required an extension to the engine cover, which was completed by my friend the furniture maker. Although the MD2020 is a bigger multi-cylinder, I now have far better access to all the parts of the engine I am likely to want to get at.

The extended engine cover

The new engine required a righthand prop and I was persuaded to go for a three bladed 15” x 10” bronze prop which I got from T Norris, saving more than my membership fee with the discount gained from showing my membership card. I had fitted a button anode to the ‘P’ bracket, last year, which had been eaten away quite badly. I went to the chandlers to buy a replacement only to be asked for £10.40. An outrage I think you’ll agree; so I cast some new ones up myself using an old float chamber as a mould.

She is now back in the water and the engine starts easily and is very smooth and quiet. The extra horses make her really fly across the oggin. The only down-side is that the prop walk is quite a bit worse, but I’ll have to learn to live with it.

A Volvo agent has now to look at the installation for warranty purposes and I will write a review of the product at a later date as and when I find out how good it is.

Ralph Ferrand