cooling system

[jfgln]

Today I looked at a boat for sale which was powered by a Merc 5.7 with Alpha one drive. The owner ran the engine in the driveway with ear muffs on the drive, but it also had a thru hull fitting that was tied into the cooling system. It was also connected to the hose with a toilet plunger looking device to the hull. The engine compartment was tight, so I couldn't see how this water line was connected to the back of the engine.

I have seen this kind of set up on inboard engines, but never on an I/O. Have you ever seen a set up like this? Why would it be done?

 

[Don S]

Re: cooling system

Yes, usually it's done on engines that have the Full Closed Cooling System installed. the raw water pump is in the drive on the Alpha I drives, but isn't big enough to handle the extra cooling requiered by the full system. So a larger engine mounted pump is installed for engine cooling. The raw water pump in the drive is kept to keep some cooling water flowing through the drive. That is why both have to have water. Otherwise the impellers in the drive pump would destroyed.

 

[jfgln]

Re: cooling system

When you say Full Closed Cooling System this includes the exhaust manifolds? I didn't see the extra water pump(maybe I missed it) the hose from the thru hull went to the back of the engine. I couldn't see what it was connected to.

Thanks for the info,

Jeff

 

[Don S]

Re: cooling system

When you say Full Closed Cooling System this includes the exhaust manifolds?

Yes, manifolds and engine.

I couldn't see what it was connected to.

I can't see it either, and that is what we need to know. So I guess it's up to you to tell us what it goes to.

 

[Dunaruna]

Re: cooling system

Don, many years ago you had a very pretty crystal ball. Is it broken?

 

[Don S]

Re: cooling system

Yes Aldo, it got overworked and cracked