Tohatsu M18E2S outboard motor review

The Tohatsu 18 outboard created a niche market for itself upon its Australian release back in 1982 because it delivered almost the same performance of a 20hp outboard motor, but with a weight not much greater than a 15hp engine.

The current Tohatsu M18E2 outboard model has been in production since 1998, and over the years the 18 has become incredibly popular with not only recreational anglers, but also with commercial net fisherman due to its legendary reliability. In fact, I’ve tested four of these engines (three for extended periods) since 1989 and not one of them has let me down!

Designed more for commercial usage, the M18E2 has the traditional side-gearshift with all-electrical connections, like the stop button in the lower cowl. There’s an auxiliary cooling-water intake under the antiventilation-plate in addition to the main intakes above the gearcase torpedo. Six trim positions are provided, with one shallow-water drive-setting and a full tilt lock.


When my mate Kim asked me about a suitable engine for replacing the unreliable 15 that came with her early ‘80s 3.8m Savage Snipe tinny, I recommended she buy an M18E2. While the 246cc Yamaha 15F was an option, it’s better suited for tinnies to 3.7m, and it doesn’t have the torque to power for a hull the size of the Snipe when carrying three adults and fishing tackle.

She also needed an engine with a piston displacement of less than 300cc for easy manual starting, and the engine needed to have relatively low exhaust emission levels despite being a carbie two-stroke. The Snipe simply didn’t have the buoyancy aft to handle the weight of a 15 or 20 four-stroke on its shortshaft transom, nor could Kim afford the initial purchase price.

In September Kim bought a Tohatsu M18E2 from a local dealer and from September to November we ran in the engine following Tohatsu’s guidelines using semi-synthetic Valvoline TC-W3 oil as recommended by Lakeside Marine, the Australian Tohatsu distributor.

During the first ten hours, short bursts of WOT operation are allowed but extended trolling periods are not. The engine rev range should also be varied every ten minutes, but kept mainly above 4000rpm. This break-in procedure with occasional full load allows the piston rings to bed-in correctly. After the first ten hours the engine can be operated at any speed, and for any length of time.


Throughout the running-in and performance testing, Kim’s Tohatsu always started first pull, hot or cold. Once running on the normal 50:1 fuel/oil mix, it emitted oil smoke only on cold starting.

Spinning the standard 9.1in pitch Tohatsu alloy prop and pushing a total of 350kg (including Kim, myself and tons of fishing tackle) the 18 trolled us at 3.3kmh (1.8kts) and 700rpm using 0.8lt/h with relatively low vibration levels for a big twin. We planed cleanly at 19.7kmh (10.6kts) and 3500rpm on the third trim hole, and at 4000rpm we cruised quietly at 23.9kmh (12.9kts) using 3.9lt/h. However, due to the Snipe’s long deep keel the prop ventilated excessively through anything but wide turns.

Opening out the throttle from 4000rpm delivered instant acceleration and by the end of the first two hours the 18 reached 5700rpm. By 12 hours it had freed up and reached 5800rpm at WOT, averaging 38.9kmh (21kts) using 8.3lt/h, with the usual raucous exhaust note of a carbie two-stroke due to carbie induction roar.

The Tohatsu M18E2S outboard motor averaged 15kmh (8.1kts) using 3.3lt/h over a “loop” of normal cruising that included ten percent WOT operation. This is only 22 per cent more than a 15F under the same conditions but pushing 295kg on my 3.6m Sea Al Super Skua dinghy. By comparison, a 262cc Mercury 15 on the same hull used an equal amount of fuel as the Tohatsu.

After 15 hours of saltwater leg/lower immersion no corrosion was apparent anywhere on the 18. Powerhead access is also excellent, with the carbie, spark plugs and bowl-type fuel filter easily reached. Lakeside Marine recommends servicing the 18 every 50 hours, or six months after the initial ten hour/one month service, and the waterpump impeller should be replaced every 100 hours or annually.


The OEDA 1 Star-rated Tohatsu M18E2S outboard motor has combined hydrocarbon, oxides of nitrogen and carbon monoxide emissions of 443.8g per kW/h, 33 per cent lower than the loopcharged 1 Star 15F, and 48 per cent less than the crossflow 0 Star Merc 15. The M18E2 has a three year warranty for recreational usage.


Engine type

Loopcharged premix two-stroke outboard


Two in-line

Prop HP at rpm

17.7 at 5500

WOT rpm range

5200 to 5800

Piston displacement


Bore x stroke (mm)

60 x 52

Ignition system

CD w/mechanical advance

Charging circuit

6amp w/o voltage regulation

Break-in period

10 hrs on 25:1

Fuel type



25lt plastic remote tank

Oil type

Valvoline TC-W3

Fuel/oil ratio


Gear ratio


Transom height




Rec. price


Spare alloy propeller price


Servicing costs*

Year one $290; Year two etc. $210

* As per manufacturer’s recommended schedule excluding parts. All prices current as of December 2009. Prop and servicing prices from Bill’s Outboards and More, Weston NSW, phone (02) 4936 1013.