Hi, I have a 99 sears garden tractor with a 19.5 hp B&S motor. My
problem is the valve seats came loose on the right side of the motor.
(I have heard this could happen from overheating due to grass
clippings caught in the heat shield)
Sears will only send someone out to fix it for $100 and I have heard
that the fix is NEW MOTOR, which I will not do.
I replaced the valve seats with new ones and used loctite valve seat
glue/compound. The intake is holding but the exhaust still comes
Does anyone know a fix for this, I saw no 'oversized valve seat' in
the sears database. How about peening? (I am not sure what that
entails or even if it pertains to this problem). I thought about
drilling 2 small holes in the valve seat and trying to find some roll
pins to hammer in to kinda hold it in the block (valve seats on the
B&S are in the block, not the removable head.)
Anyone have any ideas?
Thanks in Advance!!!!
the books i have that show installing valve seats show that you heat up
the head in an oven and put the valve seats in a freezer and then they
fit in pretty tight.... dont thing you would need any glue or loctite to
do this.... matter of fact if you do need loctite then you ahve a
problem as the seats are too small.. before you give sears $100.00 take
the mower to a lawnmower shop and see what they can do.. probably alot
cheaper and surer than sears....
If you can put in a new valve seat by hand, then I assure you the seat is
too small. Normally this can only be done by packing the new seat in dry
ice and leaving it there for perhaps an hour. Meantime, clean the seat
area (the hole you will put the seat in) very very clean - not one speck of
anything. Then heat the block with a torch (not a little propane torch).
When the block is hot, using forceps, remove the new seat from the ice and
insert it into the block. It should drop in reasonably since it has shrunk
from being cold. Make sure it is in correctly, and then leave it alone.
As the temperatures stabilize, the seat will expand and the only way to get
it out is to use a chisel and break it.
No need to use any adhesive of any kind. Hope this helps. Bob
I think you are missing the point. He said he valve seats are loose. The only
fix is an oversize seat. Any good machine shop can install an oversized seat
for you, it's a very easy job. Even though Sears doen't offer one they are
Sorry for the confusion, but its $100 for the service call, and I am
pretty sure the fix is a new engine. I wont spend $100 for someone to
tell me I need a new engine I won't buy, since my next one wont be a
The original valve seats, once loosened reamed out the holes and now
won't seat since the holes are waaaaay to big. I put new ones in with
adhesive, but they did not stay. I will try that forum mentioned
Thanks for all the replys!
The problem you had with Loctite is that the exhaust valves do some
incredible major temperatures.
Beyond that, I'm not all that sure what the answer is -- peening sounds
possible. Or shim with something (aluminum foil?) and bang them in. Just
thinking out loud. Two part epoxy not likely to work.
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