my 49 cub started knocking yesterday while pushing some gravel with the front blade, the knock is mechanical and seems related to engine rpm,but it stopped knocking after about 2 minutes, thats the only time it has done it except last year while pushing some snow, knocked about 2 minutes and stopped it, nothing seems to be wrong with the tractor, it has good oil pressure no fluids mixed anywhere and it doesnt do it today, any ideas? id rather fix something now, than in the middle of mowing season which is where this cub makes me money
- Thread starter ericlb
- Start date
Janicholson
Well-known Member
Most knocks that go away are carbon deposits that break free and get pinched in a squish area of the combustion chamber. This can be very disconcerting, but is usually not fatal to the engine. If it uses a little oil, a synthetic oil might reduce deposits some. Removing the head and cleaning the chambers might be a preventive step that is not too difficult. Jim
thanks guys,this had me going, as you would think either is knocks, or it doesn't, it doesn't fix itself, this little cub has been a good one since ive owned it and i use it mainly as a mowing tractor for the more maintained areas, i did have a blade full of gravel,and she was grunting a little, it may well have been carbon deposits breaking loose, time will tell, if it does it again i may have to pull the head and have a look
fixerupper
Well-known Member
Had a little screw that holds the choke plate on a 630 Deere come loose and get sucked into a combustion chamber. It really made that big piston knock for a few minutes till it went out through a valve. Just shows how a very small item like a small screw or piece of carbon can create a serious noise. Jim
teddy52food
Well-known Member
Give it a good dose of ATF & let it set for a few days. The longer the better.
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