I have a toro timcutter 42" zero turn that I recently purchased used. It has the 16 HP Briggs and Stratton Engine. It runs great however when the deck is engaged and I'm mowing forward it seems as though I'm losing power. In higher grass sometimes it almost stalls out. When I come back to neutral the RPMS go back to normal. Any advice on this issue? Thanks in advance.

 

It is possible that the engine is simply running out of power. You may need to raise the mower deck or cut a narrower path when in heavy grass. I have a 25hp gas tractor swinging a 54" deck and it too can be really bogged down in heavy grass.

It's also possible that your engine is getting worn out and no longer developing full power. A compression and leak down test could help confirm. It would also tell if you have another problem like a blown head gasket which some Briggs V-twins are prone to.

 

Thanks for the advice! What would be the best way to go about doing this? Is there any way to DIY?

 

How old is the mower or how much use do you think it's had? It's hard for someone to wear out an engine in a couple years mowing their own, one yard. Does the engine surge, blow smoke or do anything else that makes you think it's not running properly?

 

I searched the model number and I believe it was manufactured 04-06. The guy I bought it from mowed his lawn and few neighbors lawns. He had owned the mower for 3 years. I only use it residential. Never any smoke or surgages. When the deck is on and I drive forward you can notice the power loss even when you're not cutting any grass. Uphill it does the same thing but only when the deck is engaged.

 

Is the engine actually slowing down, or are the blades slowing down but the engine still running?

 

The engine is slowing which also makes the blades slow down. But the main cause for the problem is probably the engine

 

Ok so far I have changed the plugs che ked the governor and those look good. I did do a compression test and its reading 50. What should the compression be at that seemx a bit low to me.

 

You are probably seeing the compression release affecting your compression test. A leak down test is generally more reliable. With it the crank is held with the cylinder TDC and air is fed into the cylinder at a fixed rate. The pressure reading then can tell you how well everything is sealing. If the pressure is low you can listen for the sound of escaping air and narrow problems down to piston or valves.

How did the old spark plugs look?

 

Plug looked good wasn't any oil on it but it was pretty clean. Could anything with the mower deck itself be causing this problem? I mowed with it again today and it almost stalled out a few times in thicker grass. This grass is cut once a week so it should handle it with no problems. I did replace the seat and needle in the carb a few weeks ago because the needle was bad so the carb should be all clear. I asked my neighbor who's worked on a few of my past machines and he's not able to come up with a solution either. Thanks

 

It could be engine problems, deck problems, or it could even be blade problems. If you have mulching blades on and you're in thick grass, it can stall just about any mower. Do the blades turn freely? Does it have mulching blades?

 

Dull blades can also consume more power as can the mulching blades Cheese mentioned. Also don't forget that the engine has to carry you around the yard. If you're big/heavy and/or having to mow while traveling uphill it will consume more power.

You keep mentioning thick grass. It is possible that you machine simply does not have enough power to cut a full swath of thick grass. 16 gas hp with a 42" deck is not a huge amount of power. You may have to cut your grass more often, drive more slowly through the thick areas or cut a narrower path.

 

Here's an update of my situation as of today. I dropped the deck and the old blades were very worn so new ones were put on. I checked ked all the pulleys and they are all in working order. While I had the deck off I drove the mower up a small hill at my neighbors. Uphill I still noticed the engine was losing power. Deck was put back on and it did cut a little better but was still losing some power. I'm sure in the engine itself now. Should the leak down test be the next step? How is this usually done? Any other ideas? Thanks again for the help guys!

 

What engine is on this? Briggs made a lot of 16 hp engines. Single or twin cylinder?

 

It is a single cylinder engine

 

Look at the choke linkage. Is it returning all the way to open the choke after you start it?

 

I did check that and it's operating as it should. The throttle was checked as well and is also fully functional.

 

Hey guys any other suggestions of what else I could try to solve this problem? Mowed again today very slowly. Hoping to find a solution without replacing the engine. Thanks again!

Kyle

 

I've seen a few of these wipe the camshaft lobes off, and the valves open very little. When they get bad, they have very little power and usually get to the point where they won't even rev up to full throttle without popping and running badly. You could check the valve operation and see if the move much while you turn the engine.

 

Here's an update for everyone that has helped with suggestions. I've been very busy and finally was able to work on the mower the other day. My neighbor and I removed the engine and split the case and sure enough one of the lobes on the cam is worn almost perfectly round. I've ordered the replacement part already. We did notice that the timing marks were not lined up and even when turned manually the marks would never lineup even close. I would think this would cause the engine to run poorly which it was doing. Is there something we're missing with marks not being lines up? When we get the new camshaft we plan on lining the marks up as they should be. I will try and upload of picture of the old one and how it was positioned.