Riding Mower Engine Overheating

[Rick'sToro8-32]

I have a Brigg's and Stratton 8 HP on my 30 year old Toro 8-32 riding mower.

It has been overheating after about 45 minutes and before I am finished mowing, and konking out. When it cools down I start it back up and finish mowing.

Does anyone have any idea what might be causing this situation?

Thank you.

 

[ILENGINE]

Give us a model number information so we can see what engine you are attempting to repair. When the engine quits do you still have spark. Are you sure there isn't a mouse nest in the engine causing overheating.

 

[Rick'sToro8-32]

Thanks.

B & S 8HP at 3600 r/min
Synchro-Balanced

Model: 191707

Type: 2161-01

Code: 87042712


It just did it again, I popped out the spark plug and turned it over and could see I am getting good spark. There is no sign of debris under the cowling, I actually put a new electronic ignition in it not long ago, it was clean then. I don't think there is a nest or grass there.

I'm not sure what a vapor lock in the gas line is really, but that is what has popped into my mind as I consider this.

This problem has been going on for the past couple years, it is to the point where I need to fix it now.

Thank you.

 

[gainestruk]

Next time it does it spray a little starting fluid or pour a thimble full of gas down throat of carburetor to see if it's a fuel delivery problem, if it starts its something in fuel system, just be very careful engine is hot !

Speaking of hot what is it doing other than shutting off to make you think it's overheated ?

 

[Rick'sToro8-32]

It only does this on hot summer days for one thing. In the spring and fall when air temps are cold there is no problem.

Also, when I was young I worked at a cemetery and drove a commercial Ferris mower. It was known for getting hot, and the temp gauge agreed, and quitting and then after it cooled down it would run again--just like my little mower.

When an engine overheats it has a certain smell (like the Ferris), and you can almost feel that the engine is too hot from the heat that radiates off the engine. That's how mine is when it quits it just smells too hot and when you pull up the seat it is noticably hotter than it is when it is running fine.

 

[SeniorCitizen]

Pull the shroud and look for blockage rather than just thinking it's clean.

I had a mouse build a nest over night while 3 cats slept close to the food bowl within 20 feet. I could see it on top of the flywheel when checking the oil level but they aren't always visible. Cleaned it out and same thing happened the next night. Cleaned it again and sent 3 cats to cat heaven. English Blue blood lines and I'm sure some have won blue ribbons at cat shows somewhere but worthless as mousers.

 

[gainestruk]

If engine is running lean that can cause heat, make sure your air filter is clean.
Hopefully someone else can think of something and jump in.

 

[SeniorCitizen]

I'm not up to date on engines that a timing light can't be used on but it seems like if a flywheel key was sheared or partially sheared it would advance the timing which would possibly cause over heating.

To check timing on a mower engine i always held my thumb on the plug hole and watched the spark. If my thumb is blown from the hole at the same instant I see spark it be close enough.

 

[Rick'sToro8-32]

The comment on timing makes sense. And, when I had the spark plug out today it was very clean and light/white colored, I think that means it is running lean, so maybe that is an issue.

 

[motoman]

A person can not tell how hot something is. It requires a gauge which is not expensive. If you can obtain expected engine temperatures from some source (not likely) you can use an infra red gun or a heat probe furnished with a $50 DVM to take readings around the engine...cylinder fins, head. Or you can buy some temperature crayons at a welding supply house. But the best for AC engines is an oil temp gauge because as the oil goes so goes the engine. I start my fan on my oil cooler When oil temp climbs to 280F- which is very often when mowing here in summer. And using the craftsman 3 bin baggers will quickly push the oil temp to 300F as the damp grass weight increases. The ignition modules on the Intek I have sits on thick cast iron seats which helps keep the modules below failure range of 180F-240F. But I would imagine heat is more of factor on lawnmowers with smaller metal mass.(almost done)

You can easily find and mark true TDC and put a ref mark on your machine. Then hook up an inductive pickup style auto timing light. I did this . You may have to work in a darkened area to see the weak strobe the ignition module puts out. Mine was a faint reddish flash. But it is probably easier to check flywheel key first. Finding TDC is probably not worth the effort if you can avoid it .