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.

 

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?

 

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.

 

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.

 

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.

 

did your engine "ingest" something when your choke broke?

 

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.

 

+ 1 on removing the head.

I've never cracked-open a Briggs OHV however I can imagine that trying to force a bent valve through the valve guides will cause more wear/damage. Will the valve(s) have to be cut-out?

 

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.

 

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.

Yep, we used to see this a lot on those engines. The compression release is also notorious for falling off the camshaft.

Yes you can reuse the headgasket if it came off in one piece. It's an air cooled engine so worst case it will leak around the head and have low compression. I've reused them on my personal equipment before with no issues, I just wont do it on a customers machine.

When you put it back together set the valve clearance to 0.003"

 

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.

 

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.

 

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.

 

Just yanked the head, pics of piston head, valves, springs and another picture of piston after cleaning up a bit.

 

Valves move up and down freely when I apply pressure...

 

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.

 

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.

 

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?

 

My Tecumseh engined Craftsman is 10 years old and has a large number of hours on it. I have never checked the valve clearance, so don't feel bad.

You should use a new head gasket and get the torque settings for the head nuts/bolts. Since you had to knock the exhaust valve to free it then it was probably seized in the valve guide and Shryp has the explanation for that. You will need to check the valve guides for carbon buildup or scoring.

The rocker part numbers may be different but the parts guy will advise you of that.

The valve adjustments may be specific to your particular engine, so you need specific advice on that.

The overheated head would have the effect of warping it. A machine shop can check for that, and should also check the cylinder for warpage. The machine shop can check the valve guides for damage with proper size and can replace or bore them if oversize valve stems are available.

Your idea of a new engine is worth considering.

Good luck.

 

Check to make sure the valve guides are in the correct position. I know on some lawn equip. they have had some problems.

 

People will tell you that you have to replace the head gasket anytime you remove the head. If it were mine I would just clean it up and put it back together. Worse case is you find out the engine is running great now, but has a small leak and you take it back off and replace the gasket later on.

For the colors I don't remember which is which, but I think it does matter. Maybe if you give us the engine your machine has we can figure it out. Is it a Briggs?

 

Really appreciate all the help, you guys are great. Here is a picture of the valve guides. Guide on the right in the first pcture is the exhaust side. It appears to be higher than the intake guide. Is that normal? Also if you look underneath { in other picture}, valve guide is not sitting flush with bottom. Maybe this is why I can't push the exhaust valve as far down as the intake valve? If you look underneath the head, looks as if it got forced up a bit?

 

As Shryp already stated, a new head is the proper way to repair your engine. I have heard of people resetting the guide to proper height and using a center punch to stake the aluminum around the guide. Staking is a method of forcing the material around the guide and holding it tighter in position. This could be a short or forever type of repair, I don't know. Here is a LINK to the Briggs OHV service manual. Page 96 deals with the valve guides. I do know that some Briggs use steel and aluminum push rods. If you have this type, aluminum is the intake and steel is for the exhaust. I hope this helps.

 

I have read that Briggs did have issues with valve guides popping out of blocks and the only "proper" fix was to buy a new head. I am not sure which engines that applies to though. I am also not sure what they should look like. Never had one of those apart myself.

 

The issue with the broken choke and the subsequent engine damage seems, to me, a little more than merely coincidental. Unfortunately, a head removal is about the only sure way to know what's going on.

 

After some further research on my engine I've discovered that it is no longer in production and has been replaced with model# 21M314-0128-F1, but this replacement engine has a different alternator { 1.5 amp DC }, while my engine has a 60W AC. Can I still use this replacement model on my ariens deluxe 30? The only thing on it as far as electrical goes is a headlight. No heated grips and no electronic auger chute control.

 

It's not exact but 1 amp will usually drive about 18 watts. You need to see how many watts the headlight is rated at to know for sure.

 

Watch this. I believe this is your engine.