Too much compression?

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familyman121712

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I have a poulan pro riding mower with a briggs and Stratton 19hp ohv engine. The battery us fully charged, the starter is brand new, I've checked the valve lash and made sure they are moving. Compression still stops the crank. Any ideas?
 
most likely its a engine with the known Automatic Compression release failure... you should see the intake valve bump open on the compression stroke if you remove the valve cover and rotate the engine by hand,
also post the engine Model and Type numbers, they are stamped into the valve cover.
 
Second the ACR failure. Quite common. Camshafts are currently on back order. They had an ETA 07/15/2021 but that has passed and no camshafts yet.
 
Scrubcadet10 said:
most likely its a engine with the known Automatic Compression release failure... you should see the intake valve bump open on the compression stroke if you remove the valve cover and rotate the engine by hand,
also post the engine Model and Type numbers, they are stamped into the valve cover.
Click to expand...
 
Model # 33r877. Type # 0009 g1. Can you go a little more in depth on the acr? Ive never heard of it, but I'm not really a small engine guy.
 
familyman121712 said:
Model # 33r877. Type # 0009 g1. Can you go a little more in depth on the acr? Ive never heard of it, but I'm not really a small engine guy.
Click to expand...
It consist of a weight, and return spring and a rod that bumps the intake valve off slightly just before TDC to drop the compression down when cranking to assist the starter to turn the engine over. It then moves out of the way to allow full compression while running. The problem is the weight breaks off and will end up in the bottom of the engine sump and without it working the compression is too high for the starter to crank the engine past compression stroke.

Very known common problem and I have personally been waiting on a backordered camshaft since April for a customers mower.
 

Results

www.briggsandstratton.com www.briggsandstratton.com
Your valve clearance is on top left of page 10 in Operators Manual posted above. Intake valve .003-.005 / Exhaust valve .005- .007. I myself would set intake valve lash at .004 & exhaust valve lash at .006.
Don't give up yet, watch video above for proper valve adjustment procedure.
 
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ILENGINE said:
It consist of a weight, and return spring and a rod that bumps the intake valve off slightly just before TDC to drop the compression down when cranking to assist the starter to turn the engine over. It then moves out of the way to allow full compression while running. The problem is the weight breaks off and will end up in the bottom of the engine sump and without it working the compression is too high for the starter to crank the engine past compression stroke.

Very known common problem and I have personally been waiting on a backordered camshaft since April for a customers mower.
Click to expand...
Crap. That does sound exactly like what its doing.
 
IL, I think I see why the ACRs are failing and it is a design problem. Even when the ACR is fully retracted the pin is still loose enough to be constantly bump by the tappet rocking the pin until it breaks off sending the ACR weight flying across the engine. It is just like you bending a piece until it breaks. And sometimes it takes out the governor while at it along other damage. The last two I did use aftermarket camshafts ACR had damage the governor too. THe next to last one actually snag the cylinder a little, lucky it was just a nick.
 
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