12 thoughts on “Displaced Valve Guide = Damage to V Twin Briggs

  1. wats a causes a lawnmower motor to rev up and down then die then wait a few secs then ajust carb mixture screw and it will run for a min then rev pu and down then die

  2. Had the same problem three years ago and pushed the guide back in (using a socket & being careful not to hit stem) after cleaning with carb cleaner & applying J & B weld to the circumference. I also dented both sides of aluminum around guide. Well this year it happened again to the other cylinder's exhaust valve. Time to go get some more J & B weld. Husqvarna yth2148 els 21 hp. Briggs&Stratton 40h777 400000 series. I believe problem was due to cutting very high grass which strained the engine.

  3. I had the exact same problem with B&S 446677 engine. I complained to B & S and they sent me two new heads for free. This is a design flaw in this engine and they know it.

  4. First off I have about zero experience with small engines but with a lot of research and a lot of videos on here, I was able to take my B&S 21hp motor apart find the problem and seemingly fix it. It turns out that I had this exact same issue with my Husqvarna 21hp 48in model 385787. I just held the spring down with my figure and tapped the sleeve back into place with a smooth hammer.

  5. I did the same thing to this engine when it happened the first time. Unfortunately it is not a lasting repair. Within a couple months the same issue happened again to the same valve. I replaced the cylinder head assembly and the owner is still using the mower years later.

  6. Interestingly enough, I thought maybe my buddy's mower I'm looking at now may have this problem but both of the guides are where they should be and yet he has a bent pushrod. Strange!

  7. if the valve guide is pushed up clean it as best you can (or push it up with a same diameter socket)  coat it with red lock-tite , and carefully push it back down flush with the the top of valve guide rim.. (make sure you have valve in the guide before doing this to avoid damaging the edge of the guide.  Then peen around the edge around the guide. IF the bottom is flush with the bottom of the guide support , peen it also (some are and some are not flush) Between the locktite and the peening it will not move again (mine has been fine for 3 years-  BIG yard-over 2 acers- and you have nothing to loose,, cost to replace a new one (head and all) ebay $84.00

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