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December 2008. Original Volvo Penta MD2B (25 h.p.) with MS reverse gear (reduction ratio 1.91:1)

original Volvo Pentra diesel

Here is a picture of the original diesel. We were able to start the engine with a help of the ether spray (the weather was quite cold that day). The former owner claimed that it had been overhauled last year and the transmission had been rebuilt. The wiring harness was waiting for a short circuit and a fire in my opinion.

I am thinking of replacing it with a new Volvo Penta D1-30 with MS15L transmission (reduction ratio 2.63/2.96) or Yanmar 3YM20 with a KM2P-1 transmission (reduction ratio 3.22/3.06 or 2.62/3.06) (fwd/rvs).

removing volvo

March 2009. New Yanmar 3YM30 engine

Niemiec Marine repowered Moowind with the new little 30hp Yanmar. It is shorter than Volvo but fattier. Its port side sits very close to the cockpit wall. I would need to remove an alternator in order to get to a starter, for example.

Prop and shaft

A propeller shaft alignment was a major concern because the original Volvo had the shaft positioned below the engine mounts plane and Yanmar has it above by about an inch or so. Hence, the engine must sit lower on its bed. Redoing the bed liners by cutting the embedded metal rails out of the molded fibreglass, and then trimming the mold and glassing in the new metal plates would have been a major expensive refit. Therefore, the new spiffy tall Yanmar mounts were replaced with not so shinny old style short mounts. The matter was of course, not in their brightness but in a weight distribution and a vibration compensation. The new Yanmar has two 150 kg mounts on one diagonal and two 75 kg mounts on the other diagonal. The old style mounts are designed to support equal weight. I wonder if I will be able to detect an increased vibration level because of that?

I had prepared the old Volvo for removal by disconnecting all wires, hoses and a shaft coupler. Next morning after the shrink-wrap was cut, the engine did not want to go through its hatch. Chris from Niemiec Marine had to also remove an exhaust manifold and an alternator and then tilt the engine almost vertically with a pulley.

Once the engine was out, I cleaned its compartment and painted with two coats of Interlux bilge enamel. Thanks god the weather was warm and dry over this first weekend in March for a paint to set properly. I also repaired the hole in a cockpit floor made for the Edson pedestal that I had discarded to make more room in the cockpit.

new engine

From contacting multiple marines, I knew that I couldn't get away with keeping the original shaft and prop. The shaft would be too short for Yanmar and the prop would spin in the wrong direction! Moreover, the prop size and pitch should match the new engine's RPM and the transmission gear's reduction ratio. Niemiec used some software to calculate the the prop and came up with 14R10.

The cutless bearing was worn out and I wanted to have dripless shaft seal instead of a traditional stuffing box. Niemiec suggested to use a mechanical shaft seal known as PSS. The original bearing was cut along its length for easy removal from the stern tube. The new Johnson cutless bearing BALE (1"x1 1/2"x4") made by Duramax Marine was compression installed and secured with two set screws on the stern tube outside the hull. It turned out to be half inch longer than the tube, so the excess was cut out.

From Cadler's book I understand that mechanical seals if fail result in rapid flooding but otherwise are perfect and can tolerate shaft misalignment, shaft defects and require no maintenance besides replacing a rubber compression sleeve every five years or so and a couple of o-rings. They have a nipple for optional water lubrication, which is mostly useful on power boats due to high shaft RPM when water can be sucked out of the stern tube during an acceleration.

The new shaft was measured and sent out for cutting and keying. What was a surprise when it came back cut a quarter inch shorter than measured! Now what? Through it away and order another one? It would be an expense for Niemiec Marine, probably. One idea was to use a drive saver that is a strong rubber ring that sits in between an engine and a shaft. No, that didn't work because the drive saver was too sick (1" instead of needed 1/4") What worked for the marine and made me a bit unhappy was cutting out 1/4" of the cutless bearing along with the stern tube.

waterlift muffler

The engine short mixing elbow was replaced with a tall one. Niemiec did the job, it was part of their repowering project. It connects to a water lift muffler.

Fuel system

I replaced the fuel copper tubing with the fuel hoses and Chris from Niemiec Marine fabricated two new fittings to accept them. He also had to cut two new stainless pipes for the fuel supply and return lines that go inside the tank to replace the original copper ones. Volvo engine did not have the return line but the tank had a line connected to a manual pump for removing water from its bottom. This now became the return line and the pump was discarded. It had been broken anyway.

The fuel filling hose was made of water tubing. The deck fitting was unusual size 1 1/4", likely metric, the same as the other end on the tank. I had to buy the entire hose box, 12 feet, because of non-standard size instead of necessary 8 feet. Nobody wanted to cut it.

Yanmar came with its own water separation filter. I just needed to mount it. I also added the fuel shut-off valve ahead of the filter.

I have also replaced the tank's vent hose that goes to a pushpit's pipe end below the deck. Not sure if this is the right way to do because water can get in.

raw water strainer
Cooling and exhaust systems

I plumbed the engine's raw water intake to a new Groco bronze ball valve screwed to a new through-hull with a strainer. Another strainer made by Groco and looking similar to a fuel water separator, is seated in-line and is accessible for a periodic cleaning through a companion way's top removable step.

I installed the vented loop between the engine raw water exit and the exhaust elbow mixer, which goes to a fibreglass water lift muffler that I mounted on a glazed plastic lumber platform behind and above the PSS. From the muffler the same 2" heavy-duty exhaust hose makes a loop and goes to a starboard side through-hull, which also had to be replaced because of its size.

expansion tank

I put the coolant expansion tank in the cockpit locker, next to the raw water vented loop.

Shifter and throttle

The original Volvo engine had its shifter and throttle on the Edson pedestal. Since the pedestal is gone, I had to order a new shifter and a throttle. I decided to go with a single lever one for safety and convenience reasons.

The mechanism is fully adjustable for right/left hand and for push/pull gear/throttle operations. It can also be oriented to accommodate the cable incoming direction: forward or aft. It has a safety switch that prevents starting an engine in gear. The throttle can be disengaged from the gear by pulling out a handle.


August 2010. Niemiec cheated!

It was the second year of cruising in the Caribbean when the exhaust mixing elbow just fell off! It got loose a few months after the Niemiec completed their repowering project. As you know, they installed a riser in between the cylinder block and the mixing elbow. The riser did not have the matching thread, so Niemiec just ground off the threads of the cylinder block and the elbow and insulated the entire assembly with the tape, most likely to hide their cheating. When it got loose, I just put two clamps around the insulation tape but it did not last long. I was in St. Lucia when it completely fell off. Luckilly, I was idling at the anchorage in Rodney Bay and did not flood the engine.

I sent Niemiec Marine two emails and received no response. This tells me that those guys are not interested in keeping good relations with their customer who paid them quite a lot of money.


This is the third fault made by Niemiec Marine that I discovered so far. The other two were the rudder fairing that also fell off a month after the job had been done and the bilge pump and the switch, both got loose because there were no washers used, just the machine crews.


I had to fix it myself with what I could find in Rodney Bay area on St. Lucia. Not much, I should say.

I had to further tune the thread on the exhaust elbow with a file to better match the one on the riser. They have 1/16" difference, by the way. Then I purchased new fibreglass insulating tape and epoxy putty suitable for up to 150° C. This of course may be not enough when the engine is running on high RPM. I also embedded two clamps in the putty, just in case it fails, the elbow will not fall off right away. I tested it on low 1800 rpm and I could still touch the riser with a bare hand. I applied putty in the evening and started the motor next day to heat treat the epoxy. It was supposed to cure to the product that could have withstood even more higher temperature. I hope it will.

As a side note, while searching the internet for a fix to my problem, I found that the exhaust riser did corrode and was supposed to be replaced every four years or so. Well, if my new connection last for another three years, I'd be happy.

October 2011. Lip-seal failure on a sea-water pump

I was on my way from Spain to Gibraltor and just left the fuel station in Cartagena when I heard no sound of water spitted through the exhaust. The sea-water leakage from the pump caused the complete damage to belt. If it were unnoticed, the engine would die from overheating. I was lucky that I had a spare belt and in Gibraltor I was able to get the new lip-seal.

November 2012. The second primary fuel filter.

Fuel contamination is apparently such a huge problem in tropics that having a second ready-to-go fuel filter in place is a must! So I added two tees, two valves and another Racor R20P fuel assembly. Now if the first filter gets clogged, switching to the second one will take just a few seconds rather than 30 to 40 minutes - that what it takes to replace a filter in the ocean and it is quite a messy job to do when it's rough there.

November 2012. New bearings and lip-seal for sea-water pump.

At the same time I had to replace not just the lip-seal but also the bearings for the sea-water pump. I got a spare pump because in an emergency its not easy to replace them.

June 2014. New starter solenoid

Genuine Hitachi relay failed not far from Faial (Azores) in my third Atlantic crossing. There with a difficulty I was able to find similar model, Cargo, made in China starter solenoid. It was bigger than mine, which was actually good and it had the mounting holes that matched the Yanmar engine. I paid 33 euro for it, not cheap. I had to change the terminals of the triggering wires because they were too small and with a round file slightly enlarge the terminals of the starter wires.

October 2014. It failed again!

The Chinese relay did not last long. In 4 months I had to replace it again! In Gibtaltor it cost me 72 euro! It was different one, made in Italy rather than China. Will see how long it lasts.

October 2015. New mixing elbow and riser pipe

I wrote in my sailing log in July of 2016 that Yanmar lost its RPM due to the clogged mixing elbow.

Yanmar recommends cleaning it every year but I only did it once after the first year. It was more or less clean. Because the riser pipe was not made correctly, I had hard time disassembling the whole thing (see above).

People say that the mixing elbow should be replaced every five years because of corrosion. 7 years passed but the elbow was still strong without any signs of forming holes. I had to hit it very hard with a hammer when I was cleaning it in July. I wanted to solve the cleaning problem though and along with a new mixing elbow I ordered a new riser pipe. The later is somewhat special in a sense that it has different concentric threads on its ends and hence, it is not that easy or even possible to make them with ordinary tools.

Now everything is back in order. I decided to not thermoinsulate the riser pipe in order to reduce corrosion.