Motor too hot? small leak at t-stat cover

[rick_l]

Re: Motor too hot? small leak at t-stat cover

I have always been told that unless you are a duck hunter or you are using the motor in cold weather, you can leave the thermostat out. It will make a differenece in the amount of water that is circulated throught fthe block. Need to fix the gasket though.

 

[OptsyEagle]

Re: Motor too hot? small leak at t-stat cover

I would say your problem must be with the thermostat or a blockage (which is what the t-stat does when your engine starts to run too cool. It shuts down the water).

I would try it without the T-stat to see if it overheats and at the same time I would test the T-stat. The T-stats for my 1961 Johnson 5.5Hp and 1975 9.9 Hp Evinrude (same t-stat for both) will start to open at almost exactly 140 F and be fully open at 150 F. I tested them by simply putting them into a pot of water on my stove and heating up the water and measuring the temperature as the t-stat started to open and close. I would then remove it from the stove and go back and forth and I was very impressed with how accurately it opened and closed at the same temperatures all the time.

With this in mind I know that when my engine starts up, my T-stat is closed. As it reaches 140 F it slowly starts to open and if my engine ever gets to 150F it would be open completely. However, my suspicion is that the T-stat probably never fully opens or closes while my engine is running. I believe what happens is that as the engine warms up and the T-stat opens more, the increased water flow cools the engine down and the T-stat starts to close again and then the engine warms up and this process continues on until I shut her down.

My point is to answer your question of what temperature your motor should run at. I know mine stays at almost exactly 145F +/-5F (at the t-stat position) after warm up and until I shut her down. At this temperature I can put my hand on the powerhead, but I am kind of glad when I remove it. This temperature on the hand, however, results in no swearing or profanity of any kind. Where I am sure with another 20 or 30 degrees, that would not be the case.

I hope that helps and good luck to you.

 

[OptsyEagle]

Re: Motor too hot? small leak at t-stat cover

When I said you could run it without the T-stat, that was simply to test if your problem was coming from the t-stat. If it is, then simply change the t-stat.

Do not run it continuoulsy without the t-stat. Not only would that result in accelerated fouling of your spark plugs but would increase the carbon build up in your motor and on your piston rings, etc. It would seriously reduce the life expectancy on that motor.

 

[1730V]

Re: Motor too hot? small leak at t-stat cover

I have always been told that unless you are a duck hunter or you are using the motor in cold weather, you can leave the thermostat out. It will make a differenece in the amount of water that is circulated throught fthe block.

Bad idea. The stat is there for a reason. It insures that the engine heats evenly keeping round things round (pistons, rod journals, etc.) and flat things flat (heads, blocks, etc).

I have found blockage, under the powerhead, on 4's and 6's.

The powerhead is easy to remove.

 

[gnarbrah]

Re: Motor too hot? small leak at t-stat cover

hmmmm, lots of food for thought. Here's what I'm thinking, I'll pull the thermostat and do the stove test (I'm replacing the gasket anyway so I'll have it in hand) I'm thinking the thermostat is probably good, its brand new as of 2 weeks ago. Stove should let me know. That should lead me to the wonderful world of blockage......

I've blown compressed air up the pick up tube and wherever I could with the thermostat out (I'll do that agin when I pull the thermostat for good measure) I've also poured water into the thermostat area and it found its way out the bottom leg (where its "peeing" in the videos) without any trouble. The grommets looked good on the pickup tube when I put the lower unit back on and the old impeller was still all there so theres no pieces of it hiding anywhere. Question is, where should I look for any other types of blockage and how do I rectify?

Thanks again for everyones input, I'll know everything about these little motors before long!