Lawn Mower Blade Bolt Stuck
I know the feeling, FRUSTRATION!!! but we'll get it figured out. The blade bolt can be stuck for a few different reasons, usually it's a combination of rust and over-tightening.
The easiest way to remove a stuck blade bolt is with an impact tool, they make the whole job look easy.
Other Options include:
- Use Tool Leverage
- Hammer & Chisel
You may not have an impact, so I'll show you a few different options. Some of these options may not suit you, it'll depend on what tools you have access too.
Best to don a pair of work gloves, stuck bolts usually means slipping tools.
The impact tool is designed for this job.
Over-tightening The Bolt
Blade Bolt Torque
Mower blade bolts should be torqued to spec, these bolts are usually over-tightened and when you add corrosion, removing can be a headache.
L/H or R/H
A l/h threaded bolt loosens to the right. (left bolt in pic)
A r/h thread loosens to the left. This is the most common type thread. (right bolt in pic)
Removing A Rounded Bolt
The bolt on the right has a rounded head, this kind of damage happens when a tool slips on a bolt head, or corrosion deforms it.
Getting the bolt out presents a challange.
Imperial or Metric
Some mowers will have metric bolts and using imperial sockets and wrenches on them can cause damage. Easily done.
Tools You'll Need
Most stuck bolts won't need all these tools, but some do.
Removing The Bolt
For safety, lets remove the plug wire and turn off the gas.
Turn the mower over with the carburettor side facing up, stops gas leaking on the floor.
Remove any rust.
Spray front and rear of the bolt and give it some time to soak in.
By far the preferred way to remove a bolt.
An Impact gun hammers the bolt as well as twisting it, this loosens the corrosion between the threads.
An impact tool will remove the bolt in seconds and you won't need to lock the blade.
But if the bolt head is rounded, the impact tool is no use. You'll need a different solution.
If you are not using an impact tool we'll need to use a piece of timber to lock the blade against the body.
Longer timber is better than shorter. Cut a length to suits.
Select a socket (12 point preferably) and check the fit.
Turn the Ratchet left to loosen.
Using a breaker bar, or if you don't have improvise with your ratchet and some pipe.
Pushing down on the pipe will give you leverage, and this will give you the power you need to break it loose.
Just be sure the socket is a good fit, and it stays on the bolt head when your applying force.
Turn the Wrench left to loosen.
If you don't have a ratchet and breaker bar, try 2 interlocked wrench's for extra leverage, or use a hammer to shock the bolt.
If it still won't budge, try tightening it slightly, this often helps, odd I know!
Try striking two hammers, while one is placed against the bolt head, this can help break loose any corrosion on the threads.
If the head of the bolt is rounded, move on to next solution.
If your bolt head is rounded, try a vice grips.
Get it as tight as you can, and try hitting it to the left sharply with a hammer.
Not all vice grips are the same, for this application you'll need a flat jawed set. (seen in the bottom of the last pic)
Check out this post on Vice-grips tools.
This method is pretty effective, but you'll need a new bolt, sharp metal working chisel and a heavy hammer.
With the chisel and hammer, take a side ways and downward aim at the bolt, we'r attempting to loosen it by turning it left.
This will require good aim, so now's a good time for those gloves.
Ordinarily I'll tell you to get some heat on the bolt, the reason I haven't introduced it earlier is because it comes with the risk of damaging the crankshaft nylon seal, which would cause the engine to leak oil.
The risk of this is fairly small, once you direct the flame and only use a small amount of heat.
We'r not going to redden the bolt, just going to heat it up. Maybe 2 minutes with a butane torch directed at the bolt.
You can now try heat with any combination of the above methods. Heat is very successful at helping move stuck bolts.
This method will obviously require a welder, when I get a really stubborn bolt with a rounded head, I take a new bolt and weld it to it.
This gives me a not so pretty but a clean bolt head to work with.
This solution has never failed me yet.
You'll need to replace the bolt. Blade bolts have a fine thread, they are a specialised bolt so getting one in the hardware store isn't advisable.
Finally, you'll have to move your timber to lock the blade in the other direction and torque your new bolt to spec.
Check out this post to see why it's important to torque your blade bolt.
Spindle turns when removing the blades? The easiest way to prevent the blade from turning while loosening the blade bolt, is to use a large block of wood to lock the blade against the mowing deck.
Lawn mower blade bolt direction? Turn the mower on its side, carburettor side up, turn the blade bolt to the left (anticlockwise) to loosen.