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jdvmax

@rr.com

Briggs motor on Sensation mower hard to pull enough to start

I have a Sensation mower with a 4 HP Briggs engine. It has sit idle for many years after I had used it and broke off the blade from the spindle when I hit a piece of carpet outside. The blade was/is fine but the bolts on the spindle broke off. It is very difficult to pull the starter cord to get it started now. It does pull but not far and I can't get enough speed built up in the pulls to get it turned over. The things I have tried are as follows:

I have taken off the starter cover and the engine does spin easily with a wrench turning the bolt on top.

I have taken out the spark plug and the starter pulls easily without the plug in.

I have tried spraying starting fluid in the spark plug hole and in the carb but it does not start.

I have heated up the plug with a torch to clear away deposits on the plug.

I have checked the engine brake mechanism and it is not binding the engine.

The engine does have oil and I have put new gas in the gas tank.

I have also now removed the top bolt fixture on top of the flywheel so that I could see if the key was sheared off and the flywheel was displaced (because I understand that might affect the timing and cause kickback) and the key looks perfectly fine and is centered in the slot.

To clarify the pull on the cord, I can pull the chord out the whole way, but it is hard to pull and I cannot do it fast enough to generate enough speed to get the mower to fire (I assume).

If anyone has any suggestions, I would greatly appreciate them, THANK YOU.


Doctor Olds
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1970 442 W30
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The impact could have damaged the engine internally or you may have bent the crankshaft.


shdesigns
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Stone Mountain, GA
reply to jdvmax
A bent crank would make it tight and is not worth repairing. If you broke the blade, it probably bent the crank.

There is also a compression release on these small engines that may have gotten stuck.


Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
reply to jdvmax
Did you remount the blade? An engine can be started without it but it's not easily done.


Jack_in_VA
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join:2007-11-26
North, VA
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Reviews:
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reply to shdesigns
said by shdesigns:

A bent crank would make it tight and is not worth repairing. If you broke the blade, it probably bent the crank.

There is also a compression release on these small engines that may have gotten stuck.

He said the engine spins freely so I doubt if the crank is bent.


mityfowl
Premium
join:2000-11-06
Dallas, TX
reply to jdvmax
If it was a real old Briggs I doubt if you bent the crank shaft.

That said it has to be over 20 years old to be a good Briggs.

You bent the crank. It's toast.


leibold
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Sunnyvale, CA
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reply to jdvmax
In the list of the things you did already I'm missing one of the most obvious items for an engine that sat unused for a long time: cleaning the carburetor and checking that gas reaches the combustion chamber.

Chances are that it is so obvious you just didn't mention it but otherwise it is one more thing to do/check.
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jdvmax

@rr.com
reply to mityfowl
I haven't remounted the blade as of yet. I expect to be able to by drilling and tapping the bolt holes on the spindle and then threading in new bolts. The engine does spin freely (with the expected compression pauses of course) when I use a box end wrench. But when I put the starter back on top and pull the cord it is hard, not impossible, but difficult to pull fast enough. The starter cord does pull ok when not attached to the mower.


jdvmax

@rr.com
reply to Jack_in_VA
I haven't remounted the blade as of yet. I expect to be able to by drilling and tapping the bolt holes on the spindle and then threading in new bolts. The engine does spin freely (with the expected compression pauses of course) when I use a box end wrench. But when I put the starter back on top and pull the cord it is hard, not impossible, but difficult to pull fast enough. The starter cord does pull ok when not attached to the mower.


jdvmax

@rr.com
reply to mityfowl
I tilted the mower on its side and pulled the starter chord and as I watch the spindle turn on the shaft, it does not wobble or spin at all funny. It appears true. As I said, I can pull the starter chord out the whole way, but not easily enough and quick enough to get it started (if it did fire, which I do not know as of yet, but do expect it would). I am strong enough to pull it hard, believe me.


Jack_in_VA
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North, VA
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reply to jdvmax
said by jdvmax :

I haven't remounted the blade as of yet. I expect to be able to by drilling and tapping the bolt holes on the spindle and then threading in new bolts. The engine does spin freely (with the expected compression pauses of course) when I use a box end wrench. But when I put the starter back on top and pull the cord it is hard, not impossible, but difficult to pull fast enough. The starter cord does pull ok when not attached to the mower.

Keep in mind the blade acts as a giant flywheel when you pull the starter. No wonder you can't get it started. Fix the blade mount and put it back on then try to start it.

Why don't you just buy a new spindle mount? It's easier than trying to drill out the old broken off bolts.


Msradell
P.E.
Premium
join:2008-12-25
Louisville, KY
reply to jdvmax
As mentioned earlier by another poster, did you thoroughly clean the carburetor? Sitting idle for a long period of time will cause the gasoline in the carburetor to become tar and it will never run until cleaned out! Reinstalling the blade (also mentioned by others) will also make it much easier to start.


jdvmax

@rr.com
reply to Jack_in_VA
I did not realize that Thanks, I will try to get blade back on..


jdvmax

@rr.com
reply to leibold
I haven't actually cleaned the carb. I guess I was 'trying' to avoid that if possible, because I haven't done it before. I did put new gas in. I will attempt to clean it. Can I ask though if that would cause the symptoms I am seeing with the pull start? It doesn't seem like it would. It only seems that the tarred up carb might keep it from getting enough gas to start, if I could pull the starter chord sufficiently.


Jack_in_VA
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North, VA
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Reviews:
·Millenicom
said by jdvmax :

I haven't actually cleaned the carb. I guess I was 'trying' to avoid that if possible, because I haven't done it before. I did put new gas in. I will attempt to clean it. Can I ask though if that would cause the symptoms I am seeing with the pull start? It doesn't seem like it would. It only seems that the tarred up carb might keep it from getting enough gas to start, if I could pull the starter chord sufficiently.

It is not likely to start without a blade. I think you are just wasting your time until you address the blade.


mityfowl
Premium
join:2000-11-06
Dallas, TX
reply to jdvmax
said by jdvmax :

I haven't actually cleaned the carb. I guess I was 'trying' to avoid that if possible, because I haven't done it before. I did put new gas in. I will attempt to clean it. Can I ask though if that would cause the symptoms I am seeing with the pull start? It doesn't seem like it would. It only seems that the tarred up carb might keep it from getting enough gas to start, if I could pull the starter chord sufficiently.

Man you have to do the most basic things.

Then get back with us.


jdvmax

@rr.com
reply to jdvmax
I am trying to remove the spindle that remains on this mower so that I can either replace it or tap and die some new threads in it. The problem is, I cannot see a way to remove it. There are no apparent set screws or bolts that hold it to the shaft of the mower. Does anyone know if this spindle (I wish I could attach a photo here, but do not see a way to do so) could just be threaded onto the shaft?

This is a Sensation Commercial mower, probably bought around '85 and is a very heavy duty mower that was my father's and one which I would like to get going again, because it has been used very little. I unfortunately broke off the blade from the spindle years ago. Thanks for your help.


shdesigns
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Stone Mountain, GA
Usually they are very hard to get off. I always have to use a pulley puller and a bit of heat.


pike
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Washington, DC
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1 recommendation

reply to jdvmax
Click for full size
Click for full size
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said by jdvmax :

I wish I could attach a photo here, but do not see a way to do so



Jack_in_VA
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North, VA
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Reviews:
·Millenicom
reply to jdvmax
said by jdvmax :

I am trying to remove the spindle that remains on this mower so that I can either replace it or tap and die some new threads in it. The problem is, I cannot see a way to remove it. There are no apparent set screws or bolts that hold it to the shaft of the mower. Does anyone know if this spindle (I wish I could attach a photo here, but do not see a way to do so) could just be threaded onto the shaft?

It's a press fit. You will need a gear puller.


54067323

join:2012-09-25
Tuscaloosa, AL
reply to jdvmax
said by jdvmax :

I am trying to remove the spindle that remains on this mower so that I can either replace it or tap and die some new threads in it.

Do you have a model number for the engine? If so I might be able to find you a disassembly diagram.



Doctor Olds
I Need A Remedy For What's Ailing Me.
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join:2001-04-19
1970 442 W30
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reply to pike
said by pike:

said by jdvmax :

I wish I could attach a photo here, but do not see a way to do so

Or this!

»Site FAQ »How do I post attachments and screenshots?
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OregonBob

join:2008-10-14
Klamath Falls, OR
reply to jdvmax
I hit a rock one time and it sheared the key on the flywheel which put the motor out of time. I had to pull the flywheel off and replace the key between the flywheel and crankshaft.


Jack_in_VA
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North, VA
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said by OregonBob:

I hit a rock one time and it sheared the key on the flywheel which put the motor out of time. I had to pull the flywheel off and replace the key between the flywheel and crankshaft.

Woodruff keys are not that hard to shear on the flywheel or shaft blade mount. Fairly easy to fix though.