T-Stat for 61 E-rude 40 HP?

[brokengine]

My Lark III has been running hot after running full throttle >5 min. It's not the water intake(not clogged) and the impeller is realatively new. I'm assuming if it were the the water pump itself it would overheat faster than it is- so I guess my t-stat is the next spot to look. But the Seloc manual has little information about t-stats. I could use some help with how to test it,service it, find it, etc. Thanks. Also -I've got a 62 Lark IV 40 HP for parts.

 

[Paul Moir]

Re: T-Stat for 61 E-rude 40 HP?

Brokeengine - Yeah, you would think these engines don't even have a thermostat the way that Seloc covers them. Have a look on page 3-49 for a good blow-up of the thermostat assembly. The thermostat itself is the 3rd item down (discounting that screw) just below the thermostat cover gasket.<br />Testing: Look for evidence of crudding, corrosion and sticking. Place in pot of water on the stove and heat it. Using a meat thermometer test the tempurature, you should see it open around 140°F.<br />Service: Buy a new one. Iboats sells them pretty cheap. Napa autoparts has them as well. So does your local Johnny/Rude dealer.<br /><br />Your problem may be related to the spring and plug affair below the thermostat. That's supposed to open up by water pressure at higher rpms and allow more cooling water to flow through. Make sure it's not stuck.<br /><br />Do not force the cover bolts (ie, break them). If they're stuck try penetrating oil and heat from a propane torch. If you've got one, an impact screwdriver is the tool for this job.<br /><br />Hope this helps!

 

[brokengine]

Re: T-Stat for 61 E-rude 40 HP?

Thanks for the help. I got the screws off fine but when I looked inside there is no thermostat. There is the sleeve with the ball under it which feels spring-loaded and working fine. Should there be a thermostat there because my 62 model was the same way? Thanks.

 

[Paul Moir]

Re: T-Stat for 61 E-rude 40 HP?

Yes, there should be a thermostat - the 35hp got there's in '58, and the 40s always had them. Some people 'fix' overheating problems by removing them, thinking they're unnecessary. Perhaps the local old time OMC mechanic is one of them.<br />Try testing the engine with the thermostat cover off. Is there a good gush of water?

 

[68wetboat]

Re: T-Stat for 61 E-rude 40 HP?

broke, I found that my piston casing had a hole in it....i guess the exhaust or something heated up and just made a pinhole alot bigger.....welded it back and checked for t-stat......WASNT THERE<br /><br />casing, spring, and valve were there though...so no water was flowing at all through piston casings. I've got a 68 Johnson and the set up works as follows: thermostat pushes a valve down when temp is above *** degrees(140 or so)....but if all parts are there..i.e. spring, casing, valve but no thermostat, the valve will block water flow to the cylinders and BAD THINGS WILL HAPPEN.<br /><br />my advice, don't even run your motor till your sure that water is flowing through the thermostat housing...and make sure that the thermostat does work.

 

[brokengine]

Re: T-Stat for 61 E-rude 40 HP?

I'm getting a good gush of water with the thermostat cover off. That pressure should be enough to open the spring loaded plug which is under where the t-stat should be. Can anyone help me with my next step; Do i simply put a new t-stat in and run it? And if it was getting constant water before and running hot, what will the t-stat change? Thanks for all the help.