Review: Yanmar 4LV 195 Marine Engine

Yanmar 4LV 195 Marine Engine Review

Released in 2017, the 4LV series was designed for yachts over 15m and for smaller planing- hulled cruisers. The range comprises the 150, 170 and 195 which develop maximum power at 3,500rpm and the 230 and 250 revving out to 3,800.

All models are based on the Toyota 2.8L turbo intercooled direct injection diesel. The engines are compact and have clever features reflecting over 100 years of Yanmar engineering. All are available with hydraulic multi-clutch gear boxes with either an eight degree down-angle at the output flange and three different reduction ratios or a 12 degree V-drive having four sets of ratios.

For twin installations combined with a bow thruster, Yanmar also offers its JC20 joystick control for precise low-speed handling.

THE NITTY GRITTY

The four cylinder 4LV has high pressure common rail fuel injection with electronic engine management. Unlike mechanically injected engines, the injection timing is variable, enabling the engine to operate over a wide range of rpm without fear of cylinder wall glazing under light loads.

The trouble with mechanical injection is that with fixed timing, usually around the peak torque zone, the timing is running too advanced below this and too retarded above. At low rpm, the advanced timing results in an oversupply of fuel, which can wash lubricating oil from the cylinder walls. Combined with low loads at low rpm, and there’s insufficient combustion pressure on the piston rings to prevent blow by of combustion chamber gases down to the sump, diluting the oil and reducing its ability to effectively lubricate the engine under higher loads.

Electronic injection won’t prevent this light-load blow by but less fuel being injected under these conditions will reduce it significantly, especially as the control module varies the injection pressure as well.

In the past, Yanmar specified maximum engine outputs using a fuel density of 860 grams per litre. This was fine for Japan and Europe but like the US, Australia has always suffered low density distillate of 840 grams per litre. It doesn’t seem like much, but the lower density meant that in the US and Oz the engines were down on power from what was quoted in the tech sheets. However, perhaps from exposure to the US market, Yanmar now stipulates maximum outputs based on 840 grams per litre, so we’re finally getting a true idea of engine output in Oz.

To prevent any impurities clogging the fine injector passages Yanmar recommends fitting a RACOR 500MA water-separating fuel filter before the final filter on the engine. High injection pressures demand the cleanest fuel possible to reduce injector nozzle blockage.

Yanmar even goes as far as specifying three brands of fuel hose, all of which have fluorine-contained rubber or FKM to prevent fuel permeation and possible fuel seepage.

Like all modern Toyota diesels, the 4LV has a camshaft belt drive; providing the belt is replaced every 800 to 1000 running hours, it shouldn’t break. In line with Toyota’s concept that prevention is better than a cure is the fact that the oil sump capacity with filter is a massive 8.5L with a range of 2.5L from the lower to upper sump oil dipstick level. Having such a large sump capacity ensures the oil retains its lubricating properties longer. Even the standard down-angle gearbox has an oil capacity of 2.0L and the V-Drive box 5.4L, so the 4LV is over-engineered where it counts.

Yanmar recommends using an SAE15W40 oil for temperate to tropical operating conditions with API (American Petroleum Institute) service categories of CD, CF, CF-4, C1 or C1-4. Unusually, the hydraulic gearboxes need a mono grade SAE30 oil, whereas most others require a Dexron-type oil and mechanical boxes SAE80/90. Being the nerd I am, I’d suggest oil and filter changes every 100 to 200 running hours and every six months, as turbo intercooled diesels hate running dirty oil.

As the 2.8 base engine was clearly designed for right-hand drive Hilux models made in Thailand (the world’s largest user of one tonne utes), the oil filter and sump oil dipstick are on the starboard side just below the exhaust manifold, with the air intake manifold on the port side. The filter is mounted upright at a slight angle so replacing it needs to be done quickly to prevent oil dribbling down the cylinder block. I learned to do this PDQ in my 1975 and 1980 Corollas. Fortunately, my 1999 Corolla has a side-mounted filter and I reckon Toyota should have also mounted the filter this way on its 2.8. 

Heat exchanger cooling is standard with raw water cooling for the gearboxes. The coolant capacity is a massive 18L, ensuring plenty of capacity in tropical conditions. The drain plug is located on the starboard side also, so if mounting the 2.8 in twin installations provision would need to be made to access the starboard side of the starboard engine. Fortunately, the final oil filter is mounted near the forward end of the engine to port.

Standard is a 12 volt 130-amp voltage regulated alternator mounted at rocker cover level with the 12-volt 2.0kW starter motor level with the top of the engine mounting feet. The alternator alone weighs 5.3kg and is rated to provide up to 14.7 volts of battery charging capability with a minimum output of 71 amps and operating rpm of 1300 to 1800, meaning that even at WOT the alternator won’t be over-stressed.

Complete with the KMH50A-3 down-angle gearbox, the 4LV is 1,151 mm long, 761 wide and 772 mm high, while with the KMH50V-3 V-drive box the dimensions are 1,152 x 832 x 858 mm.

Gear ratio choices for the 50A-3 box range from 1.67:1 ahead and astern to 2.43:1.
For planing hulls, I suggest the 2.13:1 ratio with prop rpm of 1,643 and for yachts the 2.43:1 ratio providing there’s sufficient space to swing the prop. The 50V-3 box has ratios from 1.22:1 ahead and astern to 2.47:1 and again for planing hulls the 2.08:1 ratio should do. Unless mounted in performance hulls, the prop rpm should be no higher than 1,700 or propulsion efficiency will be dramatically reduced.

THE WRAP

With its maximum torque of 495 Newton Metres from 2,000 to 2,600rpm, the 4LV 195 would make a good re-power choice for a Bertram 28 in twin installations and be lighter into the bargain. The old 260hp, 5.7L V8 petrol engines normally fitted to the 28 developed a similar amount of torque at slightly higher rpm so planing performance should be similar, losing out slightly at the top end. With a shaft angle of around 12 degrees the 4LV 195 would only need to be angled up four degrees at its forward end, which should eliminate raising the engine boxes by much to handle the higher in line four. However, because the 4LV 195 develops significantly more torque than its Hilux counterpart, the engine needs careful propping to ensure under normal loading it reaches slightly above its designed Wide Open Throttle rpm.

Yanmar has been smart in using the 2.8L Toyota base engine, just as it’s done with the 4.2L Landcruiser 100-series engine. Parts are readily available from Power Equipment (the national Yanmar distributor) and Toyota dealers around Oz and currently Power Equipment has the 4LV 195 in stock. Oh what a…

Google Yanmar Marine Engines, click on Find a Dealer, enter the type of dealer (marine), your region and postcode to locate your nearest dealer.

PERFORMANCE AND FUEL CONSUMPTION

Note rapid torque rise from 1000 to 2000rpm and that 80 percent of maximum torque is still available at WOT.

Quick specs

YANMAR 4LV 195
Engine Type Four-cylinder direct injection turbo inter cooled diesel
Rated BHP/MHP* 191.7/194.4 at 3,500rpm
Max Torque 495 NM at 2,000 to 2,600rpm
Displacement 2,755cc
Bore x Stroke 92 x 103.6mm

Dry Weights w/Gearbox
4LV/KMH50A-3 388kg
4LV/KMH50V-3 411kg

*Brake horsepower/metric horsepower or PS

This review was originally published in issue #508 of Trade-a-Boat magazine. Subscribe today for all the latest boat news, reviews and travel inspiration.