Mariner 2.5 impeller

[Daydreamer]

Thought about it for a bit and decided its in too good a condition to scrap, it would be disrespectful.

Removed the leg which came off easily and didn't disturb the crankcase in the least, the waterpipe fitting is now obvious. A phonecall suggests that the pipe might be available or as Lakesailor says it should be repairable, even if it is made of brass .

But.

I now realise that I don't understand how outboards work. The cooling water is pumped though the head and then I assume it is ejected with the exhaust gases down the leg into the wide oceans. So how does the tell tale work or have I missed something really rather significant here?

 

[VicS]

So how does the tell tale work or have I missed something really rather significant here?

I don't know the intimate details of the engine in question but I think you will find that the telltale is a small bleed off the cooling system part way round the engine. Its purpose is to indicate that the pump is working and cooling water is reaching the engine.
It does not necessarily indicate that cooling water is flowing around the engine as it should because the cooling channels could be blocked after the point at which the tell tale is tapped off.
It is, therefore, a good idea to check that some water is also blown out of the exhaust relief port(s) in the leg.

 

[Daydreamer]

Thanks again for the reply.

Closer examination shows no waterway to the telltale but there is a small hole through the leg to the outer plastic cover so it would seem unlikely that there would be much of a jet of water at slow speeds (I have only tank tested it).
And although the impeller needs replacing it is far from defunct and I am coming to the conclusion that there was actually nothing wrong with it............

 

[VicS]

Closer examination shows no waterway to the telltale

What is connected to the telltale then?
Are you sure the connection to it is not blocked?

Are you sure you are looking at a telltale?
If its a telltale there must be a connection from the cooling system to it. If there isn't it's not a telltale!

.

 

[Daydreamer]

Are you sure you are looking at a telltale?
.

No

 

[Rigger Mortice]

A small rubber tube, about 50mm long, 4 or 5 mm in diameter , sticking out from the engine. Starboard side, near the fuel tap. It comes from under the engine out through the plastic cover.

 

[Lakesailor]

This is the telltale on my Tohatsu (very similar, if not the same as the Yam)
It is a small elbow tapped into the water jacket around the cylinder. Water coming from it tells you that water is getting at least that far around the engine.

 

[Daydreamer]

How very intriguing. There are distinct similarities but that pipe nor any of the casting bosses are present on mine.

I've found so far, four suggested makers names for this outboard and I am fairly confident that the date of manufacture is 1986. They seem to have been introduced in the early seventies.

What I rather casually assumed to be the telltale is this cover (item 24 driveshaft housing). It has a small hole underneath which links to a hole in the driveshaft housing. I now wonder if this may be an air bleed into the exhaust gases but it certainly has no direct waterway connection.

 

[VicS]

Item 24 is the cover over the exhaust back pressure relief port. Just a hole ( or holes) into the top of the leg.

You should see exhaust gas blowing from there together with a little water. It may be no more than a few drops or even just a fine mist

What is the serial number of the engine. That should help us pin the model down. Then with luck we can find the exploded diagrams for it..

If it is a Mariner it should also be possible to down load an owners manual.

can you also tell us the country of manufacture USA, Japan, Belgium ???

You sure it is a 2.5 ? I dont find a 2.5 listed for Mariner before 1990. Then there are European made ones and USA made ones.

Before 1990 I find 2hp Japanese made engines.

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