Is there a water bypass on my '66 18hp?

[samo_ott]

When I start it up cold should water be coming out the back? The thermostat should be closed so I would think not then? So is there a bypass? And if so is there any mechanism in there that needs maintenance? thx

 

[tashasdaddy]

Re: Is there a water bypass on my '66 18hp?

yes it has a relief slot in the tstat and there is a by pass. but they don't pump a lot of water, and is usually more mist than stream, and sometimes evaporated by heat of exhaust.

 

[F_R]

Re: Is there a water bypass on my '66 18hp?

I believe there are actually two water routes through the powerhead. The thermostat only blocks one of the routes. The other is wide open all the time, so water does flow all the time. Periodic water pump inspection and/or replacement is your best protection against disaster. Once it overheats and fries, it is too late.

 

[samo_ott]

Re: Is there a water bypass on my '66 18hp?

While that makes a bit of sense does this mean the engine warms up unevenly? The cooler side has constant water flow and no water regulation and the other side heats up quickly to the designated operating temp stamped on the thermostat and stays around there?

 

[F_R]

Re: Is there a water bypass on my '66 18hp?

Yeah, that's about it. They have to keep the exhaust area cool or that would overheat in a flash.

 

[Chinewalker]

Re: Is there a water bypass on my '66 18hp?

Yes, the thermostat only regulates the water running around the cylinders themselves. It is the cylinders where the running temperature being held in a more constant state helps efficiency. The other pathway runs through the exhaust cover where keeping an even temperature is less critical, so it flows constantly.
- Scott