Long story short. Had some problems with my riding mower, B&S 31q777-0036. I took the sump cover off to inspect and see what all the noise was about. I didn't find much majorly wrong in this area, but I found a few extra parts laying in the case. From what I can tell they are the compression release mechanism. I cannot find anything that shows exactly how these parts should be reassembled. Seems like the motor would work without these parts, but I'm not a B&S engineer. Can someone point me in the direction of good documents on the compression release mechanism? Or make an experienced statement as to if I should or should not reassemble the motor without them?
compression release mechanism
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It's not uncommon for the compression release assembly to break off the camshaft, especially on these late engines. It's not repairable, and not worth screwing with. Just order a new camshaft and case gasket, and be done. You can get the part numbers by looking the engine up at the website of one of the MTF sponsor's, and ordering from them too........www.midwestmowerpro.com
Without the compression release, the starter will not be able to spin the engine over, and it'll look and sound like you have either a dead battery, or a failed starter. So the compression release, and correctly adjusted valves, are mandatory.
Without the compression release, the starter will not be able to spin the engine over, and it'll look and sound like you have either a dead battery, or a failed starter. So the compression release, and correctly adjusted valves, are mandatory.
Yeah, it had those battery and starter symptoms since last season. From the looks of the half-moon shaped piece it was broken for a while and had been banging around in the crank case for some time. Well I did say long story short and my real problems came from the carburetor’s valve throttle which had broken loose and got sucked into the cylinder. So the gaskets have been on their way. I just ordered the cam, but I have a feeling that I still have one part that is not a component of the compression release mechanism. It is a small disc. Smooth on one side and has a round concaved impression on the other side. I can’t seem to find a good rebuild document on this specific design or an exploded view that shows detail on the compression release mechanism. If anyone has a link to something more specific and detailed for this motor I’d appreciate it.
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Post a photo of the mystery part and we can identify it.
You're going to want to take this engine completely apart if you sucked something down the intake. The piston, valves, and cylinder head may have damage. No sense in doing it half-way and wasting time and money to build a rotary grenade.
The disk you are talking about may be a head broken off a valve lifter.
You're going to want to take this engine completely apart if you sucked something down the intake. The piston, valves, and cylinder head may have damage. No sense in doing it half-way and wasting time and money to build a rotary grenade.
The disk you are talking about may be a head broken off a valve lifter.
I'm on the road now; I'll post a photo when I get home. I've already torn down the entire motor and everything is intact. It might be a key of some kind or it is part of the release mechanism I just don't know.
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That, looks like the valve lash cap, one or both of the valves should have a recess where the cap should fit over the stem, and contact the rocker. Ive seen it where one valve had it, and one didnt..and where both had it. The recess in the keeper is the tell-tale, it slides right in.
That is it. I have not disassembled the valves completely yet so I had not considered it to be part of the head. I did take the valve cover off. I guess it was all the pieces of the compression release mechanism that I found lying around threw me off. I want to say I would have realized what it was when I got further into the rebuild, but now I'm sure to get that sucker back into place where it belongs. Thanks Red-85-z51!!!
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