How screwed am I?

[B3R7R4M-H34]

Originally Posted by billknny

WAIT A MINUTE! You say you are going to close the "exhaust system seacock." What people are talking about is the cooling water INTAKE seacock. If that's what you mean, then OK.

It's a bit unusual to have a seacock on the exhaust, but it is sometimes done. Cranking the engine with the exhaust blocked in is a BAD idea...

That's what I meant. It's a closed coolant system ( yanmar 3mgf). The seawater seacock is for cooling the exhaust.

[waterman46]

Originally Posted by B3R7R4M-H34

That's what I meant. It's a closed coolant system ( yanmar 3mgf). The seawater seacock is for cooling the exhaust.

Seawater usually cools more than just the exhaust. Fresh water + antifreeze in your closed system is almost always cooled in a seawater/coolant water heat exchanger. Seawater from the seacock is first pumped through the heat exchanger then same raw water is then dumped into the exhaust just outside and below the exhaust manifold. Some installations also use the same raw water circuit to cool oil and transmission fluids.

[hzcruiser]

Originally Posted by billgewater

[...]
The sudden development in 4 stroke outboard motors came about (I believe) largely from legislation in California related to pollution. Suddenly everyone could actually make 4 stroke outboard motors. With road vehicles the [...]

Wait until they release the new 6 stroke engines! They should be even more economical to run.

[CFS Klopas]

It took 3, 15 second sessions to get my Yanmar 2GM to start last time. I take it I should have closed the raw water intake after the first attempt?

[transmitterdan]

Originally Posted by CFS Klopas

It took 3, 15 second sessions to get my Yanmar 2GM to start last time. I take it I should have closed the raw water intake after the first attempt?

Yes, unless your exhaust drains directly overboard. But if the engine exhaust is below water line and has a lift type muffler you can destroy the engine by continually cranking. If possible have another crew manning the seacock and open it when the engine fires.

[hellosailor]

B3-
"and kept cranking the engine"
Beware! Starter motors are "high impulse power" motors. They are designed, intentionally, with near-zero clearance between the rotor and stator coils because in only 10-15 seconds they don't get terribly overloaded. But in 60 seconds they get hot enough to make contact and "sandpaper" each other, leading to permanent damage and failure to come.

The specs will vary by your equipment, but a rule of thumb is 20-30 seconds of cranking, 15-20 MINUTES of cooling off before you crank any more. Yeah, it can be that extreme if you want the starter to really last for the long term.

[transmitterdan]

BTW, if you read the thread this far, every user manual for a marine engine warns about cranking extended periods with the sea cock open. It also gives instruction on the maximum cranking time for the starter and the required cool down periods between extended cranking attempts.

[Jim Cate]

Originally Posted by transmitterdan

BTW, if you read the thread this far, every user manual for a marine engine warns about cranking extended periods with the sea cock open. It also gives instruction on the maximum cranking time for the starter and the required cool down periods between extended cranking attempts.

Not so, Dan! No mention of either factor in the manual for my Nanni 43 hp, vintage 1989.

But the generic advice is pretty good universally, I think!

Jim

[transmitterdan]

Originally Posted by Jim Cate

Not so, Dan! No mention of either factor in the manual for my Nanni 43 hp, vintage 1989.



But the generic advice is pretty good universally, I think!



Jim

Jim,

Is the manual for a “marinized” Nanni or just the manual for the base tractor engine?

[Jim Cate]

Originally Posted by transmitterdan

Jim,

Is the manual for a “marinized” Nanni or just the manual for the base tractor engine?

It is t he manual that comes with the Nanni, is published by them and refers to many aspects of marine usage.

Jim

[skipgundlach]

If you have a 4-154, you should have an external water pump, with the belt forward of the alternator belt.

I remove the belt to preserve the impeller on the RWPump whenever I want to do extensive cranking - even to merely bleed. No water in, no water to overflow the muffler or other mischief

You escaped this time, but next time it will be simple to avoid...

[thereefgeek]

I'm confused. I had no idea that PERKO made fuel filters, but good on ya for replacing (whatever the heck it was) with a proper RACOR fuel/water sep.

[kungfoo]

I know I'm a bit late to the party on this and you already have your answer, but I think that Nigel Calder's "Marine Diesel Engines" covers this exact case.

I've been pretty happy with that book, and generally has good debugging steps included.