Diesel Two Stroke

[Ski in NC]

Nothing wrong with low oil pressure at hot idle on a DD. It freaks a lot of people out, especially those used to gassers.

Remember that the con rods are drilled to carry oil to the piston cooling nozzles on the tip of the rod. Constantly spraying the underside of the piston (on trunk pistons). On two piece cross-head pistons (turbo versions) the piston has a semi-closed volume fed by the rod that fills the chamber and "shakes it" to cool the crown.

There is a lot of oil diverted to cooling the pistons, and that means low pressure at idle.

Some seem to have bigger pumps, probably just to get customers to quit complaining about it.

If I see hot idle oil pressure at 500rpm at 5-10psi, I don't even blink. Should be 35-40 at hot cruise rpm of 1500-1800.

Nothing wrong with a "chirp" from oil press alarm when shifting. At least you know the alarm is working!!

And DD's run oil HOT. Folks wonder why I wear jeans doing a summer DD test run. Rub a bare leg against a 230F oil filter and you are getting blisters!!

You can idle these things down to usually 500rpm with a good governor and careful setting of the governor/buffer screw. But with some combos of big prop and certain gears (that shift quick), if set too low will stall. I set them so at hot idle I can go from fwd straight to rev and if it stalls, set it up a bit higher. In a maneuver, when operator needs to go straight from fwd to rev it usually is a situation where you don't want a stall!!

Old Allison hydraulic gears were great on not stalling. Nice slow clutch engagement gave the engine a chance to recover. But one complain about that, too.

 

[Lepke]

I was working at Uniflyte in the early 70’s when these guys were being made. Don’t remember the bullet prof feature but it was probably there ... I just don’t remember it.

When I worked at Washington Iron Works in South Seattle

Uniflight's PBRs weren't bullet proof. Most rounds went all the way thru the hull unless they hit an engine.
I use to run a Washington Diesel in a salmon packer, rigged for tuna. 6 gallons an hour @ 9 knots, in an 85'x18'x9' hull, maybe 150 tons. Wa Diesels were made by Washington Iron Works until the cheap war surplus engines drove away the business. The engine was a forerunner and similar to DDs mechanical injector, except all the injectors, rockers, and linkage was exposed and had to be oiled manually. The engine looked a little like an Atlas, but much heavier built. Atlas died about the same time, too.

 

[dwiggl]

Lepke, Did you do your training on Mayer Island? Used to see those Bad Little Boats doing exercises in the bay decades ago.

 

[Lepke]

Lepke, Did you do your training on Mayer Island? Used to see those Bad Little Boats doing exercises in the bay decades ago.

There was a shooting range in San Pablo Bay where the .50 cal had enough room to shoot without killing some homeowner. Otherwise we trained north of Grizzly Bay in Montezuma and Suisun sloughs. There we had adapters for shooting blanks and a number of training simulators for grenades, mortars, and artillery. There was a Quonset Hut base camp and a "friendly village" that housed our enemy. At night we defended the base perimeter and days did patrol and boat searches. It was common to see the boats going between the training areas.

I suppose it was a decent exposure to the job, caring for the boats and weapons, but it didn't relate well to what I experienced.