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dhoadley

Intake valve woes

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dhoadley

This isn't exactly tractor related, but it is small engine repair. Non-running 5hp B&S from a walk-behind leaf blower, popped off the head to find the intake valve seat loose in the block. It's unbroken, but has wallowed out about a 1/32" where its supposed to press in. Is there a repair, like gluing it back in with JB Weld, or is the engine trash?XX( Thanx guys, my education continues.....Dave

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BLT

Common thing on aluminum Briggs engines. If you can let the valve center the seat, you can peen the seat back dowm. If you have more than .005" clearance between seat and block couter bore, the block is scrap. You have nothinbg to lose.

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dhoadley
quote:Originally posted by BLT

Common thing on aluminum Briggs engines. If you can let the valve center the seat, you can peen the seat back dowm. If you have more than .005" clearance between seat and block couter bore, the block is scrap. You have nothinbg to lose.


id="quote">
id="quote">I think its more than .005". I'll try it anyway and if that doesn't do it, I'll try JB. It's scrap anyway, I might as well experiment. Thanx, Dave

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JimDk

Dave,

I fixed an 8 hp alum. engine from a A/C Homesteader several years ago.

I made a hold down bolt 1/4" x appropriate length to go through the guide. Take a flat washer slightly larger dia. than the seat, depress the center to somewhat resemble the angle of the valve seat. Add a washer and nut on the guide end, and tighten. With that much clearance, I would use JB, and quickly stake/peen the aluminum before the JB cures. Good luck.

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HubbardRA

Remove the seat, then inside the bore where it sits, use a center punch and make about 6 or 8 small punch marks around the inside of that bore. When you punch a point into the metal it forces metal outward. These small mounds of outward metal will tighten the bore and then the seat can be driven back in tightly.

I think I would coat that area with JB weld before driving the seat back in. That way you would have both the upset metal points and the JB Weld holding the seat in.

This is essentially an internal staking, but it works better and holds tigher than just staking the seat around the outside.

I have used the punch technique on loose wheel bearing races many times and never had an adverse function from one of them. This is an old blacksmith trick that my father-in-law taught me many years ago before he passed away. You cannot easily make the hole smaller, but you can make the hole function as if it is smaller, and in most cases this is all that is needed.

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