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Harlanhuls · Aug 14, 2009, 06:10 AM

This engine has a compression release and I think it is stuck open. I am not familiar with the release mechanism, a separate valve? Any help appreciated.

crigby · Aug 14, 2009, 07:05 PM

Hi,
No the compression relief, commonly called an ACR, is built into the camshaft on the exhaust lobe/side. It is not separate and does not usually stick, except in the non-working mode.
The problem is something holding a valve open, loose spark plug, or something worse.
Peace,
Clarke

Urho · Aug 16, 2009, 07:55 PM

Take the head off the engine and see if the valves are opening and closing as they should.

crigby · Aug 17, 2009, 08:22 AM

Hi,
If it is OHV as many of the engines of this HP are now; then it is just the removal of the rocker cover.
Peace,
Clarke

460racer · May 28, 2012, 10:32 PM

I had the same problem with a V-Twin 16 hp. One valve on each cylinder was stuck closed. So, when the cam attempted to push the valves open the push rods popped out. One was badly bent and the other was okay. First I got the loose push rods out so I would not mess them up. Then I sprayed some carb cleaner on the valve stem and used a socket extension with the flat end against the end of the valve and I tapped the other end with a hammer with increasing strength until the valve began to move in to about 3/8" or so. Then I used a large screwdriver under the valve retiner (top of valve) between the spring coils and wedged against the head and pried the valve back closed. I did this about four times and each time the valve moved easier until I could push it in with pressure with my finger and it returned closed with it's spring prerssure. I sprayed the valves with carb cleaner each time before driving the valve in. The springs are pretty weak and easily pushed in. Don't push in the valves that still have their push rods in place because the push rods will drop out of the rocker arm pocket and you will have to put them back in. Then I used some small forceps and patience to put the push rods in place. Gently drop the push rods in their approximate position. With a flash light you can see the tiny lower pocket the push rod tip must go into. Then hold the top part of the push rod with forceps and push in the valve and rocker arm with one finger until the push rod end can be guided under the rocker and into it's push rod pocket. It is delicate work. Then, once the push rods are in place pull off the spark plug wires so the engine won't start and crank the engine over while watching the valve operation a few times. If everything looks okay put it together and start it up. I am sure a Briggs mechanic has another solution for this problem but it worked for me. From now on I'm going to add a little Mystery Oil to my oil and gas to try to keep the guides from gumming up.

460racer · May 29, 2012, 11:36 AM

I forgot to mention that before I tapped the stuck valves in I pulled the spark plugs and looked with a flash light to make sure the piston was well down in the cylinder. Also, the lash on the new push rod seemed loose compared to the others so I tightened it up about .010 with a 13mm open end wrench to loosen the lock nut and an allen wrench to screw in the push rod pocket. I don't know what the correct lash is but it seems to be about .020.

460racer · May 29, 2012, 03:22 PM

Okay, I've been to the Briggs parts store again for a rocker cover gasket. In the discussion with the parts guy about my problem, he brought up an additional tid bit of information about the push rods on this engine.. . The exhaust pushrod is aluminum (steel tips) and the intake pushrod is all steel. In my case the intake valves were stuck likely due to some old gas and associated varnishing. My engine is in a pressure washer and I don't use it much and I didn't put any preservative additive in it for storage. So the old gas has been in it all winter. My bad.