# B&S 12 hp Valve Seat Fell Out



## dlmcmurr (Jun 20, 2005)

I ran out of gas. When I refueled, my Briggs 12 hp had no compression. Upon tearing it down, I found the intake valve seat loose around the valve stem. I'm not familiar with replacing a seat. If I only drive the old seat back into place, will I buy any time? Although the engine/mower are not great, I was hoping to get a couple of more years out of it. I might be able to find a guy to take the mower as is, replace the seat, and give it back to me to reassemble. Thanks for any help. David


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## bugman (Aug 12, 2004)

yeah it'll have to be replaced, it fell out for a reason, it might've not had a good hold in there, it may come out again and you'll end up the same way, and probablly keep on doing it until its replaced correctly.


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## repair_guy (May 9, 2004)

*B&S 12hp Valce Seat Fell Out*

Hi David.With all due restect to what the other members has told you,I have rearly had to replace a valve seat when it comes out and I'v been doing small engine repair for 30 some odd years.

Valve seats is heard,just clean it up and clean the hole it goes in.Tap it back in(bottom it out) and with a pin punch and hammer ping all the way around it,ping a mark at 12 and 6 o'clock at first to hold it from moving.Then ping a dimple at every hour.That will hold it in and I've never had one to come back out.You might have to run a valve seat grinder around it and re-lap the valve in.It sounds like a lot of trouble ... but it's worth it as high as parts & laber is these days.


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## scrench (Dec 8, 2004)

do as repair guy said and you will be good to go


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## Bunky (Jun 21, 2005)

I'll have to try the pin punch method described above if I ever have a seat fall out again.

In the past I've had an intake valve seat pop out and made a tool on a lathe to tap it back in without removing the valve. Hand cycling the engine I was able to get the valve to hold in the valve seat at the correct location and then used my tool to tap in the seat. It would fall out about every two mowings (2 hours each session). So I picked up some high temperature locktite for valve seats. The locktite made the repair last one-half season and counting.


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