Overheating lawnmowers

What type of fuel are you using?

Is this a 10 year old murray with a newer 6.5 hp engine?

Did the overheating happen with the "old" motor on the mower?

Just from the limited information I have from your post and not being able to be onsite to troubleshoot your mower, it sounds like something in the mower portion is causing an extra load on the motor, causing it to operate beyond spec which may be causing it to overheat. I suspect this because you mentioned overheating with your old motor as well.

Have you had your blade sharpened and rebalanced lately?
 
You talk about taking it apart and cleaning, it overheating and "freezing???" up, what does that mean??????

Freezing up?? What do you have to take apart and clean?

From your talk about full throttle and hurting your hands, we can all assume you have a bent blade or shaft, of a blade that is badly out of balance, but to help you, we will need clearer info.
 
shurguywutt said:
What type of fuel are you using?

Is this a 10 year old murray with a newer 6.5 hp engine?

Did the overheating happen with the "old" motor on the mower?

Just from the limited information I have from your post and not being able to be onsite to troubleshoot your mower, it sounds like something in the mower portion is causing an extra load on the motor, causing it to operate beyond spec which may be causing it to overheat. I suspect this because you mentioned overheating with your old motor as well.

Have you had your blade sharpened and rebalanced lately?
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Gas with ethanol (and a stabilizer additive), I haven't looked for ethanol free gas, but I'm sure that somewhere around here will have it.

This is a 15 year old murray with a 15 year old 6.5 hp engine. The previous machine may have also been a Murray, but it was a briggs and stratton engine with 4.5 hp (if I am remembering right). I was hoping that the larger engine would have more capacity for absorbing and dissipating heat.

I have not had the blade sharpened and rebalanced. I can give that a try and see if that helps.
 
Fish said:
You talk about taking it apart and cleaning, it overheating and "freezing???" up, what does that mean??????

Freezing up?? What do you have to take apart and clean?
Click to expand...

On the previous machine, there was a problem with the air filter housing which meant I had to clean out the carb fairly regularly. With both machines after about 90 minutes or so of use it would stop and the cord wouldn't pull and the blade wouldn't turn. I diagnosed that as the piston freezing in the cylinder due to overheating. If I didn't want to wait a day for everything to cool down, I could spray some penetrating oil into the cylinder through the spark plug hole and work the blade back and forth after it had a chance to work its magic. It could just be that more time helped it cool to where it would move, the spray may not have been needed.

From your talk about full throttle and hurting your hands, we can all assume you have a bent blade or shaft, of a blade that is badly out of balance, but to help you, we will need clearer info.
Click to expand...

It sounds like my next step is sharpening and balancing of the blade.
 
I read in reply #7 you have been adjusting the screw. A lean engine will run hot.

Run wide open throttle, give it plenty of fuel, new air filter, clean shroud and there is no reason for it to run hot.
 
philnotfil said:
Gas with ethanol (and a stabilizer additive), I haven't looked for ethanol free gas, but I'm sure that somewhere around here will have it.

This is a 15 year old murray with a 15 year old 6.5 hp engine. The previous machine may have also been a Murray, but it was a briggs and stratton engine with 4.5 hp (if I am remembering right). I was hoping that the larger engine would have more capacity for absorbing and dissipating heat.

I have not had the blade sharpened and rebalanced. I can give that a try and see if that helps.
Click to expand...

If you have not had the blade sharpened/balanced in 15 years that could be your problem.

Does your mower vibrate a lot?

This can be a telling sign that the blade needs to be balanced/sharpened or replaced depending on its condition.
 
If the engine has truly seized, and you have broken it free, it won't last long at all. The only way I can imagine that you haven't
had anything real violent happen yet is your running at slow speeds. If this is the case, time for a new mower.
 
Fish said:
If the engine has truly seized, and you have broken it free, it won't last long at all. The only way I can imagine that you haven't
had anything real violent happen yet is your running at slow speeds. If this is the case, time for a new mower.
Click to expand...

Agreed.
 
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