No cooling!!!

[elsie1]

Can anyone help. I have A johnson 20hp seahorse outboard. I ve just recently changed the impellor and all has been OK for an hour or so of running. However I now get no water up at the thermostat and there seems to be engine exhaust pressure coming in to the water outlet of the thermostat housing, I've been scratching my head all day. All water ways are clear and the pump works but when I put it all back together, no water!! has anyone got any ideas.

Cheers

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[tugboat]

I'm not familiar with your particular engine but if you had to drop the leg to access the water pump it is possible you didn't get the pump discharge pipe correctly reconnected to the head. Engines I have worked on this has been a real fiddle. Maybe your engine has a different setup but it's worth a look?

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[VicS]

This sounds exactly like the problem I had with a smaller Evinrude.
<A target="_blank" HREF=http://www.ybw.com/cgi-bin/forums/showthreaded.pl?Cat=&Board=pbo&Number=504445&page=&view=&sb=&o=&vc=1#Post504445>see here</A> for the thread a few weeks ago on the subject and my reply.

If there is no water flow then exhaust gasses will find their way back from the leg via the water ways in the cylider head to the thermostat housing. So that is not necessarily indicating another major problem like a blown cylider head gasket.

Do let us know what is causing the problem when you have solved it.

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[VicS]

Oh sorry that was you.

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[elsie1]

Thanks for your replies. yes I'm afraid I ve had a few problems with cooling on this engine. first problem turned out to be the keyway in the impellor worn. The pump would run for a minute before the shaft started turning inside the impellor. quickest way out of this problem was to turn the impellor upsidedown therefore exposing a new part of the brass bush to the key. this latest problem occured only after servicing the pump. I've looked at the point were the pipe disapears into the head and all looks OK. I've also blown water up the pipe and it comes out at the stat OK. thanks for the vote of confidence regarding the head gasket that did worry me a bit. I'll keep at it and let you know when I get a result.

Cheers


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[VicS]

I did later wonder about the keying of the impeller on to the shaft. Are you sure this really is now ok. You have eliminated the possibility of blockages in the engine cooling passages including the inlet pipe if you have connected a hose to the bottom end of it and got a flow all the way through so you are back to looking at the water pump and the connection between it and the pipe. I think maybe the worn keyway is an area for concern any way. There have also been instances of the rubber part of the impeller becoming detached from the central bush.

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[Jools_of_Top_Cat]

Not knowing this model and not trying to teach you to suck eggs, but are you absolutley sure you have the impellor blades in the right direction?

Just a thought

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk>

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[VicS]

I've often wondered about getting the impeller blades set correctly on re-assembly although I have always endeavoured to do so. Surely even if they are wrong it would pump a bit, and I wonder if it would sort itself out anyway.

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[Dave1258]

Assuming the impellor blades are of the std rubber type, then they would 'flip over' should you install it against the direction of rotation, check the gasket for conformity with the original one removed. Dave.


<hr width=100% size=1> A man should have two things in life, a boat and a wife willing to let him have one.