Bent push rods - is this B&S engine toast?

Messages
2,352
Location
Southwest Virginia
I have a Husqvarna lawn tractor with a B&S 24 HP Intek-V Twin engine that I bought seven years ago and use to mow about one acre. Last week it ran fine and when I was done cutting I parked it in the shed. Yesterday it started right up and seemed to be running at full speed, but was making a consistent pow/putting sound, not as loud as backfiring. I ran it for maybe 30 seconds and then shut it down to search for mouse nests. After clearing some mouse debris I started it again and it made the same sound. Thinking it might go away if warmed up I ran it for a few minutes, but the sound persisted and I shut it down to investigate. I am not a mechanic, and only removed the top cover and air filter but could find nothing unusual, so I cranked it again. This time it would not start and I noticed it was puffing air out of the air inlet where the air filter mounts. Suspecting valves I removed the valve covers and found one push rod had fallen out of place and was severely bent. The other push rod from the same cylinder was intact but also bent, just not as bad (see photo). I then pushed on each of the four valve stems (two cylinders) to see if one was stuck and three of them depressed at least a good half inch. The fourth valve that had the severely bend push rod would only depress about a quarter of an inch and hit metal. I rotated the engine by hand several times but that valve always stopped against metal at about a quarter inch. The only metal in the cylinder I could think of is the piston, but it shouldn't be that close to the valve. One item of note. I had rented this house for 19 months and the lady tennant cut the lawn with this tractor for two seasons. She left last December and when I went to start cutting the lawn in April I found the oil level was just touching the tip of the dipstick. She apparently never checked or added oil. I filled the crankcase for that first cut, and then changed the oil and filter for subsequent cuts. I cut seven times so far before it went kaput yesterday. Any ideas as to what caused this and how severe of a problem it is? It ran fine when parked and simply sat for a week in the shed. I suspect that simply replacing the push rods will not fix it.

TS0_5935cs5.jpg
 
Messages
22,693
Location
Apple Valley, California
Same thing happened to my bos'ss wood splitter. The gas gummed up the valves in the guides. I took the springs off and sprayed carb cleaner down the guides until the valves were free. Got new push rods and all is well.
 

CT8

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15,392
Location
Idaho
Straighten the push rods out as straight as possible and reinstall and see how the engine runs ,go from there.
 
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18,195
Location
NH
Originally Posted by CT8
Straighten the push rods out as straight as possible and reinstall and see how the engine runs ,go from there.
I like that idea, nothing to lose at this point. Although the one valve that is hitting something... any chance you can borescope it? Any chance it may have injested an acorn? That would explain a lot. I don't think the oil level being low matters--if it was running great after adding oil, and fine this season so far, then it might be a lark. Latent damage maybe, but I don't think it's related. JMHO.
 
Messages
1,524
Location
FL
Originally Posted by Chris142
Same thing happened to my bos'ss wood splitter. The gas gummed up the valves in the guides. I took the springs off and sprayed carb cleaner down the guides until the valves were free. Got new push rods and all is well.
^This is why your valve is stuck.
 
Messages
1,106
Location
Northern, NY
Some B&S engines have a tendency to have the valve seat fall out of the head, which can cause what you have witnessed. Head gaskets are pretty cheap for those engines, take the head off and see what is going on. If the valve seat has fallen out, you can likely "stake" it back in place with a hammer and punch.
 

JTK

Messages
13,521
Location
Buffalo, NY
Like Rob_Roy said, I'd pull the effected head before i tried anything else. Sorry if I missed it, but did you try to actuate the valves by hand? Do they move?
 

Tom NJ

Thread starter
Messages
2,352
Location
Southwest Virginia
Originally Posted by JTK
Sorry if I missed it, but did you try to actuate the valves by hand? Do they move?
Yes three of the valves depressed easily by hand for at least a half inch, while the valve that had the bent pushrod would only depress about a quarter inch before hitting something metal. I am going to try tapping that valve stem with a hammer to see if I can unstick it, but I suspect that a seat or guide fell into the cylinder as others noted above.
 
Messages
119
Location
Maryland
Originally Posted by super20dan
do not buy any tractor with the twin inteck -its junk. nothing but problems
My Dad bought an MTD in 1995 from Hechingers that had a Briggs 18HP V-Twin. At the end of its 13th year it did the same thing as the OP's, and this machine had the proper oil changes. I always checked the oil level before each use.
 

Tom NJ

Thread starter
Messages
2,352
Location
Southwest Virginia
So I tapped the stuck valve lightly with a hammer and it freed right up. I then straightened the push rods in a vice and installed them and adjusted the valves. Unfortunately I apparently left the ignition switch on the other day so the battery is dead, and I did not have jumper cables with me, so I couldn't start the engine. I am charging the battery overnight and will try it tomorrow. The stuck valve did depress about a quarter of a inch before this repair and then stopped against something hard. I'm not sure if my tapping it free simply unstuck it, or possibly pushed a dislodged valve seat into the combustion chamber. The engine did turn freely by hand after this repair and I did not hear anything rattling, so fingers crossed.
 
Messages
157
Location
VA
Hopefully you got lucky, the Intek's as stated are not known for their reliability and do have some issues especially with their valves as you have found out but the manufacturer really doesn't matter as their lower end stuff seem to all be about the same quality and the Kohler Courage has it's own issues as well.
 

Tom NJ

Thread starter
Messages
2,352
Location
Southwest Virginia
Success - the engine started right up and ran fine! grin2 Of course there is still the open question of what caused that valve to stick in the first place, and without that answer it may happen again. The valve with the severely bent push rod was hitting something hard when I pushed it in my hand, felt metallic, and the other push rod for that cylinder was also bent, just not nearly as much. Deposits from the gas or oil do not seem very likely as this engine has only seen Top Tier non-ethanol gas and Mobil 1 EP oil, plus it gets a dose of Techron once a year. I added a cup of naphthenic solvent (MMO) to the oil and another to the gas just in case deposits are a factor. Thanks to all for your advice and counsel!
 
Messages
944
Location
AR
upgrade your fuel filter! - just put a big see-through automotive in-line filter on it. B&S Inteks are notorius for fuel contamination problems!!!! I put one on my 21hp Intek when I got it and it sits outside - since 2001 - only replaced battery twice. ~500hrs so far *AND check & adjust your valve lash!
 
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Tom NJ

Thread starter
Messages
2,352
Location
Southwest Virginia
Many thanks to Brian123 who PMed me this link to a video on bent push rods. Bent Push Rods The video makes clear that my problem was a valve guide that lifted out. I tapped it back in but am not sure if it will stay in. If not I'll have to replace the head. For now the engine starts and runs fine.
 
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