Over heating problem

[Darol Wester]

On a 2005 Merc, 25 HP, I got into some weeds and cut down on the water at the telltale. I've inspected the pump housing and impeller. I've had the exhaust manifold off, blew air in all the waterways. Had the head cover off and all is clean as a whistle. Yet, when I run it, the top cylinder runs too hot to touch very long and the bottom one is very cool. This is a new motor with only 2 hours on it. Any ideas?

 

[Darol Wester]

Re: Over heating problem

Nobody??? Is it characteristic for the top cylinder to run hotter? I'll accept any ideas here. Thanks.

 

[CharlieB]

Re: Over heating problem

The difference in temp between the two is so small that you shouldn't be able to notice an obvious difference.

'05' 4 stroke?

Either way, you have either a misplaced flow diverter in the block alongside the cylinder

OR

a head gasket leaking cylder pressure into the cooling system, preventing complete water flow up to and around the top cyl.

Get it in and see if it can be covered under warranty

OR

pull the head and check for straightness

 

[Darol Wester]

Re: Over heating problem

Sorry....2 stroke. It is headed for the shop. I'm better than 2 hours drive from the shop so I'm always trying to fix it if I can. Thanks Charlie.

 

[emckelvy]

Re: Over heating problem

Did you by chance check the thermostat?

 

[TheOzzieMechanic]

Re: Over heating problem

Should not cause one cylinder to run hotter than the other. (the thermostat that is). Actually dont think they still run a thermostat that year model. 25 2 stroke don't have a head gasket so thats out! What is the tell tail output like and does it flow straight away. Tell me more I am interested. How hot did it get originallly.

 

[Darol Wester]

Re: Over heating problem

It does have a cylinder head (block cover) gasket and there is a thermostat that seems to works fine.

The telltale isn't like all the other outboards I've used. It's more of a strong dribble than the straight squirt. It does increase some when the thermostat opens. They tell me at the dealer that this years model has this characteristics. ???

I don't believe it got very hot.

 

[TheOzzieMechanic]

Re: Over heating problem

This may not be the same model I am thinking about can you give me a s/n and i will check the service manual tomorrow. The us built 25 didnt have a cyclinder head, only a block cover gasket. However the rebaged Tohatsu (detune 30 hp engine) will have a head gasket. One way of telling which engine you have is dose it have the fwd rvs on the tiller handle or is it a side shift engine????

 

[Darol Wester]

Re: Over heating problem

SN# 1B178199 Model # M1025312DD

When I bought this motor it didn't have a side shift or tiller. They had to install the tiller components. Now it's forward/reverse via the tiller.