My nephew popped a valve seat out on his lawn mower (while it was running) and he wants me to try to put it back in. Ive never done it. Whats the best way to do it at home? I was gonna just freeze it and try to knock it back in with a rubber hammer. Will that work?
If it fell out once, it will come out again. It needs to be bored a bit oversize, new seat gets frozen, head gets warmed up. I would call it a machine shop job, if you want it to last.
If it's a low-stakes lawnmower engine i would just grind a little void into the outside diameter of the seat near the top in 2 or 3 places and then stake the metal of the head with a punch so it smooshes into those voids. That may (MAY!) retain the seat, but to get it to transfer heat to the head properly so you don't chunk the valve you may need to use something under it like a thin film of jb weld or other type of epoxy that won't liquify at high temps. They make special goop for this on real ($) engines but it's pricey.
I am not afraid to suggest some serious rigging on a messed up lawnmower engine!
Pretty much since it fell out, most likely it won't stay in again. Machine shop work wouldn't really be worth the cost. Vigo's idea is worth a shot, but my Dad and I have done similar, would fail again after a while.
“Adhere” that thing back in. Find the bestest glue crap you can. If it fails, get a new mower.
You can drive the seat back in with a drift made for the task then stake the area around the valve seat. Chances are good the seat will need to be re-ground to give a seal.
If the engine is OHV, get another head. Why did the seat fall out-is there a mouse nest in the cooling system?
In reply to ChasH :
No idea. I dont know what kind of mower it is but im guessing its not valuable. Definitely not worth having an engine shop fix this head. They are young and just got married, im trying to do a patch up to get them back up and running. I plan to tell him it most likely wont last, but maybe it will buy him some time to find parts or find another cheap mower.
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