Broken Thermostat a problem?

I pulled the thermostats on my motor and noticed that one had actually "sprung" I guess you could say...the post had actually popped to the side of the cross bar so it could no longer close. <br />I guess this would be like having no thermostat at all.<br />I'm replacing them anyway, but other than not running as efficiently as it could when cold, is there really any problem running an engine this way... or for that matter with no thermostats at all?

Re: Broken Thermostat a problem?

DrBob.... (Thermostat Purpose)<br /><br />Many engines are considered high performance engines and demand a thermostat(s), but many smaller hp engines also require a thermostat for the following reason.<br /><br />The pistons actually distort/twist off round when running. The thermostat is required to keep the outer wall surrounding the steel cylinder, and the cylinder wall itself at a temperture to compensate for the distortion.<br /><br />With the thermostat removed, the difference in temperture between the inside the cylinder and the water jacket quickly reaches a point whereas (in effect) you have a oblong piston running up and down a round cylinder or vice versa.<br /><br />Bottom line is without the thermostat, the piston and cylinder wall could be damaged in a short period of time.

Re: Broken Thermostat a problem?

This is something I learned here at iboats.com myself.<br />I asked the same question, and got a reply that made more sense than anything else. If the engine maker could save the 5 buk per unit cost by omitting the tstat, there wouldn't be one. They chose to leave install them.

Re: Broken Thermostat a problem?

Thanks Joe and 12Footer.<br />Joe, please don't take this as a disagreement, I'm a novice, and am interested in learning as much as I can. If I understand you right, the distortion would occur at a relatively low temp, correct? Once the tstats open (at 143 degrees in my case)isn't it similar to running without them at all? (although I realise the flow rate would be less with them)Or am I missing something?

Re: Broken Thermostat a problem?

I was buying some parts for my 9.8 Mercury and the parts salesman at the boat shop said outboards in California don't have thermostats (I assume he was talking about smaller maybe older outboards because I would think a 225 HP OPTI would have a t-stat).<br />I checked my 1980 25 HP Johnson and sure enough there isn't a t-stat or even the housing for one. The 82' Mercury 9.8 I have has one so I assume its from some other state. <br />I guess needing a t-stat depends on your climate and how sophisticated your outboard is.