Briggs ELS 725 Exhaust Pushrod Issue

davbell22602

davbell22602

Lawn Addict
446677
0470-E1
050310YG

Sears GT5000 917.276310 48in cut gear drive

Got this on trade earlier this year in the spring. Diagnosed it last year in of having 3 of 4 pushrods missing and the 4th one was bent. Plus oil leak also. Recently split crankcase and found loose crankcase bolt which is probably why it leaked oil. Found bent steel pushrod inside the crankcase but the other 2 are missing in action. Replaced all 4 pushrods and crankcase gasket. Set the valves to .005 on the compression stroke 1/4 turn past TDC as manual says too for each cylinder. When exhaust pushrod is in cylinder #2 the engine goes into a bind and bends it. Engine will roll over just fine by hand when its not in there. Exhaust valve will open by hand when using the rocker arm to open it. It will not open the exhaust valve with rocker arm instead it bends the pushrod. I set to .005 on loose side this last time when it bent the 2nd exhaust pushrod on cylinder #2. Timing marks are lined up inside the crankcase. Is it possible to have a bent exhaust valve in the guide?


Here's pics of the bent pushrods found tearing this engine.

IMG_20140623_175459_137_zpsx7l6p7rn.jpg


IMG_20140623_194155_594_zpspeyvwmzx.jpg



Here's pics of the cylinderhead from cylinder #2 where it keeps bending pushrods.


IMG_20140704_101413_989_zps6mq9wczf.jpg


IMG_20140704_101426_607_zpstbkzmgy3.jpg
 
The one closest to the gear looks squirrelly, can you take some better pics of the lobe tip?
 
Fish said:
The one closest to the gear looks squirrelly, can you take some better pics of the lobe tip?
Click to expand...

I can get better pics but both exhaust valve lobes are borderline of the reject size of needing a camshaft. Intake lobes are 1.235 and exhaust are 1.225.
 
Check the location of the guide itself. When overheated, the exhaust valve guide will sometimes move. Sometimes it moves toward the head, holding the valve open, causing that cylinder to not fire. If the guide moves the other way, it will interfere with the rocker and cause the pushrod to bend. gregjo1948
 
gregjo1948 said:
Check the location of the guide itself. When overheated, the exhaust valve guide will sometimes move. Sometimes it moves toward the head, holding the valve open, causing that cylinder to not fire. If the guide moves the other way, it will interfere with the rocker and cause the pushrod to bend. gregjo1948
Click to expand...

Guide didnt move.
 
You must log in or register to reply here.
Back
Top