Mini engine parts broke this time

J

JimP2014

Well-Known Member
So a few nights ago I was merely cutting the lawn and then all of a sudden the engine just quit. So I decided to take off the valve cover, and pretty much found all this stuff. Not positive I think the rest of the engine's okay. I have bent push rods before this is the first time ever broke the rocker arm stud. The only thing I found that I thought was unusual is the stud for the rocker arm It requires a 10 mm deep socket and I think the torque is around 10 ft lb I was under the impression it was a 3/8 in deep socket but that socket was too small. I couldn't find where the size is printed but it seems it would have to be a 7/16 in deep socket that would work.

Does anyone know if this is 10 mm for the actual hex nut?

Thanks,
Jim
 

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JimP2014 said:
So a few nights ago I was merely cutting the lawn and then all of a sudden the engine just quit. So I decided to take off the valve cover, and pretty much found all this stuff. Not positive I think the rest of the engine's okay. I have bent push rods before this is the first time ever broke the rocker arm stud. The only thing I found that I thought was unusual is the stud for the rocker arm It requires a 10 mm deep socket and I think the torque is around 10 ft lb I was under the impression it was a 3/8 in deep socket but that socket was too small. I couldn't find where the size is printed but it seems it would have to be a 7/16 in deep socket that would work.

Does anyone know if this is 10 mm for the actual hex nut?

Thanks,
Jim
Click to expand...
I should have mentioned that is the intake push rod and on this machine it's on the bottom most people think it's up near the carburetor which would be up top.
 
JimP2014 said:
So a few nights ago I was merely cutting the lawn and then all of a sudden the engine just quit. So I decided to take off the valve cover, and pretty much found all this stuff. Not positive I think the rest of the engine's okay. I have bent push rods before this is the first time ever broke the rocker arm stud. The only thing I found that I thought was unusual is the stud for the rocker arm It requires a 10 mm deep socket and I think the torque is around 10 ft lb I was under the impression it was a 3/8 in deep socket but that socket was too small. I couldn't find where the size is printed but it seems it would have to be a 7/16 in deep socket that would work.

Does anyone know if this is 10 mm for the actual hex nut?

Thanks,
Jim
Click to expand...
Hello J.,

Looks like a 10mm to me.

You will need the at least the rocker stud, pushrod and pushrod guide plate.

Use the numbers on the valve cover to find what you need on Parts Tree.

There are lots of videos online about how to properly adjust the valve lash clearance.

You will need the proper bit to loosen the lock screw in the center of the adjuster barrel nut, then the broken piece of the stud will unscrew easily.
 
Auto Doc's said:
Hello J.,

Looks like a 10mm to me.

You will need the at least the rocker stud, pushrod and pushrod guide plate.

Use the numbers on the valve cover to find what you need on Parts Tree.

There are lots of videos online about how to properly adjust the valve lash clearance.

You will need the proper bit to loosen the lock screw in the center of the adjuster barrel nut, then the broken piece of the stud will unscrew easily.
Click to expand...
Yeah I don't know why it says Mini okay thanks for your info you know that black plastic you can't just buy it you have to buy the guide plate but it's only like $7 or $8 so I have that and then the rocker arm stud and then it comes with that barrel hex nut plus that little torx screw I've had this thing apart maybe a hundred times I just never ordered any of that stuff before but But the push rods actually have brand new including the aluminum one for the intake I don't know since you did respond like why would it just break after 30 minutes of use like I can put everything back together and then it breaks again the engine's probably 15 years old I wonder if that rocker arm stud broke because it's just old and I'm hoping when I install a new one and go through all the hassle putting everything together it doesn't break again after 30 minutes I don't know why it broke that's the problem but thanks for your help I just don't understand why Briggs& Stratton and it seems like they mix SAE and then metric.

Jim
 
StarTech said:
No engine numbers to work from...But thinking you got a seized intake valve on your hands.
Click to expand...
When you say a seized intake does that mean it's far more serious than I believe because right now I'm hoping to just repair the broken parts + from my perspective it's going to fix everything you're saying it could be more problems?
 
JimP2014 said:
When you say a seized intake does that mean it's far more serious than I believe because right now I'm hoping to just repair the broken parts + from my perspective it's going to fix everything you're saying it could be more problems?
Click to expand...
31P677-0804-B1 there might be some additional characters after this but it didn't copy correctly and that's for the engine so it's a 19.5 horsepower Briggs& Stratton OHV engine
 
Hello J.,

These studs often fail from metal fatigue. They flex (microscopically) hundreds of thousands of times when and engine is running. Along with that comes heating expansion and cooling contraction which all metals have to endure.

It would be a good idea to check the valve guide for raising up out of the head too far, because that would also cause a repeat failure.

If the guide is raised up, it is due to repeat overheating, and the head will need to be replaced.

Briggs & Stratton 31P677-0804-B1 - Briggs & Stratton Vertical Engine Cylinder Head, Gasket Set-Valve, Intake Manifold, Valves Parts Lookup and Diagrams | PartsTree

Find genuine OEM replacement parts and diagrams for the Cylinder Head, Gasket Set-Valve, Intake Manifold, Valves for the Briggs & Stratton 31P677-0804-B1 - Briggs & Stratton Vertical Engine
www.partstree.com www.partstree.com
 
Last edited:
Auto Doc's said:
Hello J.,

These studs often fail from metal fatigue. They flex (microscopically) hundreds of thousands of times when and engine is running. Along with that comes heating expansion and cooling contraction which all metals have to endure.

It would be a good idea to check the valve guide for raising up out of the head too far, because that would also cause a repeat failure.

If the guide is raised up, it is due to repeat overheating, and the head will need to be replaced.

Briggs & Stratton 31P677-0804-B1 - Briggs & Stratton Vertical Engine Cylinder Head, Gasket Set-Valve, Intake Manifold, Valves Parts Lookup and Diagrams | PartsTree

Find genuine OEM replacement parts and diagrams for the Cylinder Head, Gasket Set-Valve, Intake Manifold, Valves for the Briggs & Stratton 31P677-0804-B1 - Briggs & Stratton Vertical Engine
www.partstree.com www.partstree.com
Click to expand...
Thanks very much for telling me this I got that valve guide plate ordered also.
 
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