20HP Briggs & Stratton won't turn over completely

[bushjd]

I have an Ariens tractor ~ 3 years old with 20 HP B&S Model 331777 1372 B1. Recently we used it for a few hours of yard work with several starts and stops of the engine. Ran fine all the time, always has. Upon a restart attempt it would not turn over. Starter was engaging but would not turn over the motor. I thought perhaps battery was low on charge. Put the charger on it and it went to trickle within a few minutes. Following restart attempt unsuccessful. Jumped the 12V battery with the car. No luck.

Began troubleshooting and repairs as follows:
* Replaced the starter
* Replaced the starter solenoid
* Had battery tested with positive results
* Checked, cleaned, and tested all wiring connections and grounds
* Neighbor has same tractor, so I borrowed the starter, solenoid, and battery from it
* Jumped directly from battery to starter
* Jumped directly from car battery to starter.

Nothing has worked! Until I pulled the spark plug. Engine cranks fine. Do I have a valve train problem? Damage or out of adjustment? Upon at least 3 cold engine start attempts it has turned over successfully but with labor, but enough to start and it has run fine. Immediate restart attempts are always unsuccessful. Any helpful suggestions are greatly appreciated!

Thanks,
Jason

 

[Rivets]

I would check the valve clearance. This manual might help you.

http://dl.dropbox.com/u/12502267/B&S Service Manuals/04_272147VanguardSingleCylinderOHVAirCooled.pdf

 

[tloc3385]

I have an Ariens tractor ~ 3 years old with 20 HP B&S Model 331777 1372 B1. Recently we used it for a few hours of yard work with several starts and stops of the engine. Ran fine all the time, always has. Upon a restart attempt it would not turn over. Starter was engaging but would not turn over the motor. I thought perhaps battery was low on charge. Put the charger on it and it went to trickle within a few minutes. Following restart attempt unsuccessful. Jumped the 12V battery with the car. No luck.

Began troubleshooting and repairs as follows:
* Replaced the starter
* Replaced the starter solenoid
* Had battery tested with positive results
* Checked, cleaned, and tested all wiring connections and grounds
* Neighbor has same tractor, so I borrowed the starter, solenoid, and battery from it
* Jumped directly from battery to starter
* Jumped directly from car battery to starter.

Nothing has worked! Until I pulled the spark plug. Engine cranks fine. Do I have a valve train problem? Damage or out of adjustment? Upon at least 3 cold engine start attempts it has turned over successfully but with labor, but enough to start and it has run fine. Immediate restart attempts are always unsuccessful. Any helpful suggestions are greatly appreciated!

Thanks,
Jason

Check your valves most likely they need adjusted you'll need a feeler gauge the exhaust should be .005 of an inch and the intake should be .003 of an inch. Since you pulled your plug and out and the motor turns fine its a compression issue for sure. It could also be a cam problem but start with the valves. Also make site no oil is getting above the piston it can cause hydrolocking. Those are just some ideas off the top of my head. If you need help with the valve adjustment let me know.

 

[bushjd]

Thanks for the help so far. Any tips for the valve adjustment will be greatly appreciated.

Is there a compression release on this motor that could be faulty?

Thanks!
Jason

 

[tloc3385]

Thanks for the help so far. Any tips for the valve adjustment will be greatly appreciated.

Is there a compression release on this motor that could be faulty?

Thanks!
Jason

Is it an ohv motor or internal this procedure is for ohv you need to start by pulling the plug and setting your piston a 1/4" past top dead center you can do that by using a dowel rod our something similar and feeling your piston to tdc and making a mark on the rod then measure a1/4" above that mark make another mark and spin the flywheel until the new mark meets where the old mark was. Then find your rocker arms and valves they be secured with a nut with a torx screw in the center on each one loosen the torx then the nut insert a feeler gauge between the rocker arm and valve then tighten the nut until the feeler moves back and forth but is snug then hold the nut and tighten the locking screw. The exhaust should be .005 of an inch and the intake .003 of an inch. I believe the compression release on the motor is on the cam itself so start with the valves then move to the cam.

 

[bushjd]

This is an OHV motor. Valves were adjusted to .003 for intake and .005 for exhaust at 1/4" past TDC. No difference. I could not detect any motion with the intake valve a partial turn after closure, so I'm guessing the compression release is done. What next, new cam???

Thanks for the help,
Jason

 

[tloc3385]

This is an OHV motor. Valves were adjusted to .003 for intake and .005 for exhaust at 1/4" past TDC. No difference. I could not detect any motion with the intake valve a partial turn after closure, so I'm guessing the compression release is done. What next, new cam???

Thanks for the help,
Jason

Check to make sure ur pushrods are seated properly or one may be broken pull your plug and with the valve cover off turn the motor over and watch ur valves u should see them both compress Pretty deep if that all checks out then its time to look at the cam check the lobes and the spring compression release on the cam it may just be gummed up u can try cleaning it. You can get to the cam by just taking the bottom off the motor i just has to replace mine due to a worn exhaust lobe. Check your lifters to make sure they're not stuck.

 

[jdz]

I have an old Huskee mower with a 20 horse Briggs and it has the exact same symptoms as Jason's does, but mine is not an OHV engine. Any suggestions for repairing it?

Thanks,
Aron

 

[tloc3385]

I have an old Huskee mower with a 20 horse Briggs and it has the exact same symptoms as Jason's does, but mine is not an OHV engine. Any suggestions for repairing it?

Thanks,
u wanna check the same things start by pulling the plug and see if the mower turns over also watch the spark plug hole as you turn it over see if any fluid comes out. If the motor turns over but no liquid comes out you need to check your valves or cam. Internal valves can be adjusted. Its difficult to explain in words but go to youtube and search lawn mower internal valve adjustment. If your mower doesnt turn over when you have the plug pulled then the motor is siezed. If fluid comes out check your head gasket most likely needs replaced and its letting oil get above your piston.

 

[motoman]

tloc , welcome, I like your approach. motoman