Engine Check Out

[Duke 7184]

Finally after 13 months my boat is headed back into the water. During her time on the hard the engine was only run long enough to siphon antifreeze through the cooling system. Now I want to check out / service the engine before the yard puts her back in the water.

The engine is a Yanmar 3GMD. This model doesn't have a heat exchanger just raw water cooling. My question is this: Should I be concerned about using pressurized water,(from a hose) applied to the input side of the raw water pump while I'm checking things out?

Once I know the engine runs satisfactorly, I'll wait until she is back in the water to complete the maintenance.
Duke

[sailingdog]

Very unlikely, but it depends on how the water is going to get into the cooling system and how high the water pressure is. If you're not using a strong mechanical fitting to attach the water supply to the through-hull, I doubt that you will generate enough water pressure to damage the cooling system.

If your marina has very high water pressure*, and you've screwed the hose into the through-hull or used some other very secure method to attach the hose to the through hull, you might have a problem. However, I think it is far more likely that a hose or hose clamp would give than the metal inside the cooling system... but YMMV.

*At my previous house, the water came in at almost 110 PSI, and we needed a pressure regulator added to the water system to prevent it from damaging the pipes and fixtures. Normally, water systems are at about 60 PSI IIRC.

[Duke 7184]

SD,
I thought about using a 5 gal. bucket inside the boat; using a buddy to keep the water at an appropiate level and allowing the raw water pump to draw form the bucket using a seperate line.

I don't care much for this idea because it adds so much clutter around the engine where I need all the space I can get.
Duke

[sailingdog]

It also can cause problems if you're clumsy and knock the bucket over... besides, that isn't really going to tell you if everything is in good working order, which using an adapter to the thru-hull will... like you raw water strainer, and such... if you have an obstruction in the raw water lines, better to find out about it now, than when you're in the water IMHO.

[Omatako]

Sorry to be contradictory but it is better to find some way of allowing the raw water pump to draw it's own water. If you use pressure to push water into the system the cooling system will work even if the impeller is shagged because the water will flow past the spinning impeller under pressure.

Better to find some way of creating an artificial "pond" to draw from like a toilet plunger head pushed up against the hull over the intake skin fitting, connected to a hose which is inserted into a bucket which is filled from the hose and which is held at about the same level as the skin fitting (gasp)

That way you'll sort of simulate the same conditions your engine will be confronted with when in the water.

Hope this makes some sense.
Andre

[sailingdog]

Andre-

A very good point...but often more difficult for the person to rig up than a hose connected to the through hull fitting.