Cool Running Engine

[Unregistered]

The engine in my 1976 Tartan 27, just purchased last year, runs at almost exactly 100F. I've tried a new thermostat and it now runs at about 103F (well, we're moving in the right direction!). The block is a warm, but you can easily hold your hand on it indefinetly without discomfort. So I don't think that it's the gauge.

I noticed that the 90deg elbow fitting in the thermostat housing that accepts the bypass water hose has a very small orifice in it. Should there be one, and if so how big should the opening be? My theory is that the restriction is forcing most of the pressure developed by the water pump to run through the block and up against the thermostat, pushing it open. Perhaps a previous owner was having overheating problems and put this fitting in to cool things down.

BTW, the cool temps have created carbon build-up issues with the exhaust riser. Just had to rebuild one a couple of weeks ago because of an overheat.

[Don Moyer]

Hello,

Your assumption regarding the by-pass hose restriction is correct. Removing the restriction will no doubt raise your temperature somewhat. However, given your very low temperature, you may find that your thermostat is not closing completely, in which case your temperature may still be a bit on the cool side.

In any case, the first step is to remove the restriction and see where your temperature stabilizes.

Don