It’s quite an engine, but...
QWe are a charity restoring a boat which was fitted with a Ford-based Thornycroft engine and BorgWarner Velvetdrive gearbox. Firstly, what are the two drain pipes (marked A and B in the first picture) for? They come out into a union and are a very thin tube going down in to drip tray. A comes out of the injector pump and B from the side of cylinder head.
Secondly, in the side of the engine there’s a wooden plug (marked C) which goes into a hole with a dog in the bottom. If it were a petrol engine I would have said a distributor drive. What is it?
We think this is a hydraulic drive because you can turn the outlet flange without the engine turning. We know it needs an oil cooler and assume it goes to the two sockets (marked A and B in the second picture). Does this cooler normally go in the external water feed before the engine oil cooler and engine heat exchanger? Or are there air radiator coolers?
Finally, does it matter whether the prop rotation is left or right as long as the gear lever is mounted the correct way?
ATONY REPLIES: Regarding the engine: pipe A is a drain for the injector pump cam box. This box should be filled with engine oil to lubricate the pump cams and roller followers, but when the pump wears, fuel can leak down into the cam box. This causes excess wear but shows itself by weeping from that drain.
Pipe B seems to be the injector leak-off pipe and should run back to the fuel tank. If you take the rocker cover off I think that you will see a thin pipe connecting all the injectors that links to this pipe.
I suspect the hole marked C used to house a mechanical rev counter drive (in which case I would use an electric rev counter driven from an alternator W terminal instead), or it may have driven an exhauster, air compressor or hydraulic pump. Make up a simple plate and gasket to seal the hole.
Regarding the gearbox: this is a hydraulic box, not a hydraulic drive. It requires Dexron automatic transmission/power steering fluid. I think the same oil goes into the reduction box.
If it is raw water cooled, the oil cooler water supply is usually fitted into the pipe between the inlet strainer and the raw water pump. If this is a keel cooled dry exhaust engine, the gearbox oil cooler is fitted into the return from the keel-cooler so the heat exchanger is fed by the coolest water possible.
On the internet, www.bf494.co.uk/assets/ VelvetDriveInstallationManual.pdf shows where the oil cooler connects to the gearbox. It seems that A is one of the connections but B, the yellow cap, looks more like the gearbox breather to me.
I would advise against running it in reverse because it is likely to cause excessive wear. Try to get the correct handed propeller. Normally the operating lever moves forward for ahead gear.