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Discussion Starter #1
Hello all, Jim from CT here. I have an Ariens deluxe 30 snowblower and could use some direction here. Left outside for the night, with tarp on top. Turned choke knob to choke position, started right up. Upon moving the choke back to "run", the very bottom of the choke shaft broke off, so I do not know what position it remained in while I drove it around the house and into my basement. Upon getting it to the basement door, engine stalled. Tried restarting but could not pull rope very far, way too much compression. Removed spark plug, pulled rope about 12 times, put plug back in, still very hard to pull. Brought into basement, removed valve cover to find one bent push rod and one broken push rod. Also a stuck exhaust valve. Freed up exhaust valve this morning { although it moves freely, it does not go as far down as the intake valve, is this normal?}. Removed bent and broken push rods, put spark plug back in and pulled rope to see if it was still hard to pull, and it was. What could be causing this, and why would both push rods get damaged in the first place? Just changed oil before last storm and it ran just fine.
 

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Sounds like the valves contacted the piston to bend the pushrods. The exhaust valve may have a bent shaft preventing it from returning into the guide. The exhaust valve does not need to open as far as the inlet but I don't know the engine specs. Did you check the spark plug that it did not break and deposit some material on the piston that then contacted the valves?

The engine probably has a decompression valve that works automatically and now it may be stuck closed so you are working against the full engine compression.

Good luck.
 

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Discussion Starter #3
Spark plug looks fine, not broken. I'm assuming I'll have to pull the head in order to find out if the exhaust valve is bent?
 

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Discussion Starter #4
Just spoke with someone at B&S, described what happened and they seem to think my cylinder head got too hot and I need to replace the head.
 

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Strange. The Briggs engine has a geared cam shaft so valve to piston contact should not be possible unless gear slipped or possibly rocker arm failed with valve open were running engine piston slammed into the valve. You would think the valve spring would retract the valve. Is it still under warranty? Hopefully your piston is not damaged. I would pull the head.
 

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Discussion Starter #6
considering what a head would cost, plus 2 push rods and whatever other unseen damage is inside, i'm probably better off replacing the entire engine. By the time I get done with parts and labor at the local shop it would probably far exceed the neighborood of $425.00 which I think the replacement engines cost.
 

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Discussion Starter #8
I don't think so. I have both pieces of the broken choke shaft, which is plastic. Can't think of anything else that could have gone in there. Not even sure how or why this happenned, I always maintained it well and kept the oil changed. Only thing different I did with the last oil change is put in 5/30 instead of 10/30 due to colder weather here.
 

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I have heard of this happening on OHV engines with a lot of hours that never had a valve adjustment. The valves get looser and looser until eventually the pushrod pops out from under it and gets bent. You would expect only one pushrod though, unless the first one hit the second one somehow.

As for being harder to pull with both of them removed that would be because the camshaft has a compression release which holds the exhaust valve slightly open during slow RPMs to assist with starting. With no pushrod it isn't pushing up on the valve.
 

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Discussion Starter #11
One thing I noticed after I removed the muffler, I peeked into the exhaust hole when the exhaust valve was still stuck. The valve shaft appeared to be sitting low or off center. I took a block of wood and a hammer and gently tapped on top of the exhaust valve/spring from the top and whatever I did seemed to loosen it and correct the valve shaft position. strange, I would not think a machine that has been used only 4 seasons would need a valve adjustment. I guess I will pull the head, have nothing to lose at this point.
 

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If you're not up to the challenge of tearing down and or overhauling the old engine and you have a shop replace it ask for the old one back and put it up in Craigslist. It might make you a few $$ and someone who's only paying for parts might get a deal at the same time.

I think Classiccat might have something with the question of your engine eating a part from the broken choke mechanism. That would make more sense then the other ideas brought up so far. No matter what, need to do some tear down to find out.
 

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One thing I noticed after I removed the muffler, I peeked into the exhaust hole when the exhaust valve was still stuck. The valve shaft appeared to be sitting low or off center. I took a block of wood and a hammer and gently tapped on top of the exhaust valve/spring from the top and whatever I did seemed to loosen it and correct the valve shaft position. strange, I would not think a machine that has been used only 4 seasons would need a valve adjustment. I guess I will pull the head, have nothing to lose at this point.
True. A 4 year old machine has no warranty and if you are lucky maybe all it will need is a replacement head. Hopefully the piston was not damaged. Post some pictures of what you find.
 

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Discussion Starter #14
Makes sense, but like I said, there are only 2 parts to the choke- the plastic choke shaft which no broken pieces fell in, as I have both of them, and the metal flap that closes/ opens, which I have and can't fit in there anyway.
 

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You don't mess around there pmgnut!

Looking at this (and flipping through a briggs service manual), I think Shyrp may be on to something. When one became unseated, can the rocker for the unseated valve swing-over and jam the other one causing it to break?

while the head is off, hit that with some seafoam to decarb..and look for discoloration...to see if it did indeed overheat. May as well remove the valves as well and clean them up.
 

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A bit off topic, any guides or info on doing a valve adjustment on these things?

Quite familiar with the process on motorcycles. Some use a locknut screw design, higher performance engines use shim under bucket which is a royal pita as it involves camshaft removal.

Good luck to the OP.
 

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Discussion Starter #19
So after I clean everything up, is it necessary to replace the head gasket? Seems to be in very good shape. No nicks, cuts, etc. Not too familiar with adjusting rockers though after I get the new push rods back in. Does it look like any major damage here? One thing with the rockers, and I should have taken pics before I took them off- each one is a different color. One silver one and one is a bit on the bronze colored side. Which goes where?
 
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