22 HP Briggs & Stratton won't start.

[Mauston]

I have a 22.5 HP Briggs & Stratton model # 331877 Type 2371 G5 that the starter won't turn past compression. Following are symptoms and thing I have checked and tried.
1. The starter will turn the engine until the compression stroke but stops at compression.
2. With the plug out the starter spins the engine fine.
3. With the plug out and my finger over the plug hole the starter will not turn through compression.
4. The battery is fully charged.
5. I have jumped with a charger and also a car battery.
6. I have checked wiring, connections and solenoid and they are ok.
7. Have connected Car battery Neg. directly to engine ground and Pos. directly to starter.
8. I replaced starter with a new one.
9. Removed flywheel to insure key was not damaged.
10. Checked rocker arm adjustment to confirm they are in spec.
11. Removed belt to insure no drag on engine.
12. Can turn engine through compression with the palm of my hand on the flywheel screen.
13. I have been working on this for several days. Actually got it to turn over once and it started and ran fine but would not turn over again after shutting it off.
14. Checked valves, push rods. Also there is no carbon on piston.

I am out of ideas and it's about to drive me to drink. Any thoughts will be much appreciated.

 

[Mikel1]

When you were checking the valves was the compression release working?

 

[Mauston]

When you were checking the valves was the compression release working?

Not sure what that is. How do i check?

 

[Mikel1]

The compression release pushes one of the valves off it's seat to relieve compression. With rocker cover off turn by hand(CW) watching the valves, one should lift off it's seat if its working. Understanding 4 stroke operation makes this easier to understand.

 

[Mauston]

Not sure what that is. How do i check?

I have goggled the compression release so i know what is does and basically how it works. I don't know how to determine if it is working and how to repair if it is not.

 

[Mauston]

The compression release pushes one of the valves off it's seat to relieve compression. With rocker cover off turn by hand(CW) and see if it's working.

When I turn over by hand the cylinder holds compression so i assume the release is not working. I guess I have to disassemble the engine to check and repair??

 

[Mikel1]

I added more information to above post.
I would make certain this is your problem before tearing it down. Not sure if you fully understand.
It is on the cam.

 

[bertsmobile1]

This symptom is typical of excessive vlave lash.
This defeats the decompression.
To check if it is working remove the rocker covers
Rotate the engine and watch the rockers depressing the valves
The inlet valve opens near top dead center ( piston closest to the head ).
Then just around bottom dead center it will close and stay closed till the piston is almost at the top again where it will open a tiny amount to let a little of the charge out.
You can see it and if you are truning the engine over by hand in quiet place you can also hear it, sort of a sigh.

Because it is a very small amount of movement it the space between the ralve & rocker is bigger than the amount the valve opens, it won't open.

 

[BlazNT]

This symptom is typical of excessive vlave lash.
This defeats the decompression.
To check if it is working remove the rocker covers
Rotate the engine and watch the rockers depressing the valves
The inlet valve opens near top dead center ( piston closest to the head ).
Then just around bottom dead center it will close and stay closed till the piston is almost at the top again where it will open a tiny amount to let a little of the charge out.
You can see it and if you are truning the engine over by hand in quiet place you can also hear it, sort of a sigh.

Because it is a very small amount of movement it the space between the ralve & rocker is bigger than the amount the valve opens, it won't open.

What he is elegantly saying is check your valve lash again.
Intake valve clearance will be between 0.003" - 0.005" (0.08 - 0.13 mm).
Exhaust valve clearance will be between 0.005" - 0.007" (0.13 - 0.18 mm)

 

[bertsmobile1]

Well not quite.
He is visually checking for decompression, or audiably if you like.
Valve lash can be correct but cam can be work or decompression unit could be broken.
Numbers tend to confuse people but we can all look & listen.
Right now the engine is not starting so we are in diagnosis mode, eliminating things one at a time.