Review: Beta 150 marine engine

By: Andrew Norton

Presented by
  • Trade-A-Boat

The Beta 150 marine diesel is ideal for repowering older trawler yachts.

Review: Beta 150 marine engine
There are loads of boats on the water like the Island Gypsy 32 and 36, Grand Banks 32 and 36, and the Clipper 34 — crying out for a repower with an engine like the Beta 150.

Way back in 1983 I had a pleasant little sideline delivering Island Gypsy trawler yachts from Sydney Harbour to Bobbin Head on Cowan Waters, an offshoot of the Hawkesbury River, for Harvey Halvorsen. The models ranged from 9.8 to 11m and were mostly powered by the old 120hp Ford Lehman straight-six diesel. One of the 11m boats had twin 120s, but this was overkill and resulted in a top speed of only 11kts, whereas a single 120 gave a comfortable 8kts.

The naturally aspirated 120 motor was a damned reliable engine and only reached around 2500rpm, so with regular maintenance would last a lifetime. Another popular engine of the period was the naturally aspirated 5.8lt Perkins 6-354 which developed 120hp at 2500rpm.

But engines wear out and as these two 120s are long gone with spares becoming increasingly rare, what’s a suitable replacement engine?


Beta Marine 150

A while back UK marine engine mariniser specialist Beta Marine released its direct injection 6.7lt 150, based on an Iveco engine for ease of accessing spares worldwide. This engine develops 147bhp at a lazy 2800rpm, so it can give an old trawler yacht a new lease on life with a bit more power and torque when needed.

Cummins also uses the Iveco 6.7 as the base for its QSB6.7 which in electronically-managed turbo-aftercooled form can develop up to 543bhp at 3300rpm, so the Beta 150 is incredibly under-stressed. But it still complies with the EU Recreational Craft Directive for exhaust emission levels and is much cleaner running than the direct injection 120.

Although the starter motor on the Beta 150 marine diesel is located just above the engine bearers the alternator is mounted high up just beneath the heat exchanger overflow tank. The engine is set up with a water lock for injection of seawater directly into the exhaust elbow to reduce the possibility of water flooding back into the engine.

Individual covers are fitted to access the valve rockers to adjust clearance and the fuel injectors are easily serviced. To port is an air cleaner with replaceable element and the fuel/water separator. No shroud is fitted over the V-belt or pulleys for the alternator and freshwater circulating pump, as Beta obviously reckons who would be stupid enough to stick their fingers into a moving belt? That’s my type of logic!

Sensibly Beta Marine fits a sump oil evacuation pump that draws in oil from the aft end of the sump. This means that with an engine slightly inclined, as it would be in a normal installation, all of the old oil should be able to be removed – nothing worse than adding fresh oil to remaining sludge in the sump. However the oil filter is mounted almost upright, so when changing it you’d have to be damned quick to prevent oil from dribbling down the block. Mounting it sideways may have been a better idea but at least it’s easy to access and replace.


Boat engines

More boat engine reviews

Find marine engines for sale.



Beta doesn’t mention the oil viscosity or change intervals but I recommend a specific mineral-based diesel oil with an SAE rating of 15W40. I’d change the oil and filter every 100 to 200 running hours or annually, depending on how infrequently the engine is used. Naturally aspirated diesels don’t "stress" their oil as much as turbocharged engines but clean oil is one surefire way of extending engine longevity.

Beta also doesn’t give details of the reduction gear ratios but I presume the standard ratio would be 2:1 through the hydraulic gearbox. At least the dimensions are reasonably compact with an overall length including box of 1381mm, 574mm from engine bearers to sump oil filler cap or 910mm overall and a width of 756mm.


The Trade-a-Boat verdict

It’s good to see that an engine like the Beta 150 marine diesel still exists. There are plenty of older trawler yachts around just crying out for a repower. Boats like the Island Gypsy 32 and 36, Grand Banks 32 and 36, and the Clipper 34 which always needed more power than the standard four-cylinder Ford 80 fitted, an engine similar to the naturally aspirated 3.9lt Perkins 4-236.

These old trawler yachts are all about the voyage rather than racing to an anchorage. And when you do (eventually) get to your destination their hard-chine hulls provide a level of stability not found in round bilge cruisers. With the cleaner running of the 150 your passengers sitting outside won’t vomit everywhere in following seas from the diesel fumes as was the case with the old Fords. I know this well from being very handy with a mop and bucket when taking potential owners for a run!

Contact Graham at Beta Diesel Australia on or phone (02) 9525 1878.

Visit for more information.


Beta Marine 150 diesel performance













































* Minimum and maximum continuous cruising rpm. As this engine has mechanical fuel injection with fixed timing it must be "worked" to prevent possible cylinder bore glazing from fuel over-supply below the maximum torque band. Trial data supplied by the author.


Beta 150 marine engine specs

TYPE Naturally aspirated straight-six four-stroke diesel marine engine

RATED BHP/MHP* 147.5/149.6 at 2800rpm

MAX TORQUE 455Nm at 1800rpm


BORE X STROKE 107 x 124mm

WEIGHT 680kg (dry w/gearbox)

*Brake horsepower/Metric horsepower


See the full version of this review in Trade-A-Boat #466, August / September 2015. Why not subscribe today?


Want the latest stories delivered straight to your inbox? Sign up for the free TradeBoats e-newsletter.