Outdoor Power Equipment and Small Engines - uneven cut

I have a lawn tractor 12 horse briggs , murray model, five speed.

When i mow in 3rd. gear it leaves a line of uncut grass right in the middle of cut path but if i mow in 1st. or 2nd it will cut all the way.
what causes this.

Check your blades. It could be that your blades are so dull that going to fast and they will not cut. But they will cut if you are going slower.

it happens even if i have new blades and sharp ones, i used to be able to use 3rd. and cut just fine.

could it be that the belts need adjusted tighter.

If you suspect any slipping of the belts, than you are absolutly right.

I'm gonna have to check things on it better and see what happens. I need to have the blades sharpend anyway and see if i can make alittle adjustment and see what happens.
thanks term, at least i have the ability to wack that grass down and get me alittle time to fix things since i found the shed.
Also i didn't even know i owned a 53 mercury in the back yard,lol.
( man the grass grows fast and high around here,lol.)

Wade:
Check to see if the deck is level. The front tip of the blade should not be any more then 1/4" lower then the back tip of the blade. If the blades are to low in the front it will look like it not cutting in the middle. Good luck.

Rogerh

thanks

Are you using OEM blades or aftermarket? Standard cut or mulchers? Give us your frame ID #'s so we can help you better.

I'm using regular blades non mulchers

What do you mean by frame id's
the model number of the mower?

I checked the deck height and it all seems pretty close to level by my measurement and all the the connections seem good and straight.

Hello: wade1

I checked the deck height and it all seems pretty close to level by my measurement and all the the connections seem good and straight.
Alternate possible aspects missing. Ground speed. Which may alter cutting ability as indicated prior. As can ground surface conditions and deck movement cause uneven cutting.

As the tractor increases in speeds, chassis movements occur and change. More so over rough ground surfaces. Which are not noticed at reduced or slower speeds.

If all underdeck parts appear level and firmly in place as is the decks supports, ground condition may be part of the problem when speeds increase.

May not be a blade problem, pulley problem, speed problem or ground surface condition, etc. Check the deck supports too.

May be looking in all the wrong places & at the wrong parts, etc.

"My Two Cents."

Regards & Good Luck. Sharp Advice.
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I'll check some more when the rain stops,lol.
I used to be able to cut in third speed, my yard is alittle big for second speed and it feels like forever at that speed.
My yard is uneven but it hasn't changed since i used to be able to cut it.

But i do remember replacing a blade once with a store bought one but it was the same lenght. But that shouldn't matter would it since it cuts fine at a slower speed.hmmm

Yes, to the model number of mower. These are, as I referred to them, the frame ID #'s. It sounds to me that you are using inexpensive, aftermarket blades. Based on my experience at our shop, do away with these and buy yourself genuine Murray blades. Murray blades too are inexpensive but you can be assured that they will fit up as intended. If after installing these and you still have trouble, it is remotely possible that the two quills may have shifted, thereby increasing the space between them. Post back with the model # and I can provide you with OEM blade part #'s as well as get a better idea of your deck layout.

hey puey61, here's the info you asked for...
the actual mower is called a Sentinel ( made by murray ? )
model # g3912010
12 hp /39 inch cut
code 6034 ( don't know what thats for)