Peening Valve Seat on 13HP Briggs repair.

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Hi, im in the process of "fixing" this mid 90's 13HP briggs I/C engine.

Original problem was the intake valve seat was completely lose holding the intake valve open. Took them motor apart lined the seat back up, a couple friendly taps later and i thought i home free.
Ran perfect till i shut it down after it cooled i went to start it but the seat held the valve open again. So i tried this "peening", and while it runs just not as good as before now it kinda chugs most of the time, and with the perfect throttle placement can get it to smooth out, but put a load on it, or up / down the throttle and back to chugging. Did this peening cause the valve or the seat to become out of round? What should my next step be?

Heres what im working with.
Precise engine repair: http://www.perr.com/tip7.html

IMG_20131002_162541_zpscccef5f3.jpg

IMG_20131002_162550_zps57b01268.jpg


Thank you very much!
 
I think a few larger peens would have worked better than the many small ones. I am guessing your valve seat is not sitting flat anymore. You could test by filling the intake port with a liquid while the valve is closed and see if any leaks past.
 
Originally Posted By: Christopher Hussey
I think a few larger peens would have worked better than the many small ones. I am guessing your valve seat is not sitting flat anymore. You could test by filling the intake port with a liquid while the valve is closed and see if any leaks past.


+1

I'm wondering if you could try reseating your valves with some valve grinding compound or if you "over peened" and would need a new valve seat to make it work. It might be easier to simply replace the valve seat and start with a fresh surface.
 
A good automotive machine shop may be able to help by installing a over sized seat.
B&S probably doesn't make one but other small engines used in motorcycles and such use them also and there are a lot of sizes available, if not they can make one out of stellite or similar.

I don't know much about it but i know they need to heat the block or head and cool the seat to install it properly, just pressing it doesn't work well.
I think your seat shifted when you peened it.

This is an interesting thread.

http://www.practicalmachinist.com/vb/general-archive/need-advise-making-valve-seat-91194/
 
Looks like a woodpecker had at it at this point. LOL! That's how you learn though SL2.

Like said, that seat is going to have to be replaced and peened in 2-3 spots.
 
I`m with Trav on this one RE: seat shifted.

Also: typical peening only needs 4, in criss-cross fashion so as to secure the valve seat. Too much isn`t necessary IMHO.

Q.
 
1st, you might try lapping the valve & seat. You will need lapping compound and a lapping tool (a stick with a suction cup on the end). You will need to remove the valve spring when you do this. Make sure you check/adjust the valve clearance when you are done. Adjusting the valve clearance involves grinding a TINY bit of metal off the end of the valve stem a little bit at a time and rechecking it.
2nd, if lapping the valve & seat doesn't work, you will need to have the valve seat ground. ANY B&S authorized dealer can do this for you, they are required to have the tools to do this.

Whenever I have had to peen-in a valve seat I always grind the seat, lap the valve to the seat, and adjust the valve clearance. This is the correct way to do this repair. I have done hundreds of these over the years.
 
unless it's a machining/manufacturing defect, most common cause of B&S (or any flathead air-cooled engines of OPE or even moped varieties), valve seat falls off due to engine overheating (aluminium expands more than stellite(valve seat material).

Q.
 
Originally Posted By: Quest
unless it's a machining/manufacturing defect, most common cause of B&S (or any flathead air-cooled engines of OPE or even moped varieties), valve seat falls off due to engine overheating (aluminium expands more than stellite(valve seat material).
Q.

BINGO!

The four main causes of overheating are;
1. A plugged cooling system.
2. The engine being enclosed in shrouding that doesn't allow adequate air circulation.
3. Overloading the engine and running it in an overloaded condition for an extended period.
4. Sucking air and running lean. This was/is a VERY common problem on this B&S engine series (and many other B&S engine models). The throttle shafts wear out and the engine sucks air. Not only does the shaft wear out, but the the hole in the carburetor that it goes through also wears out. This problem occurs much sooner when the air filter hasn't been serviced properly or replaced in a timely fashion. Most shops will only recommend a carburetor replacement because that is the B&S recommended repair. Over the years I have figured out how to fix this problem. I have found brass bushings (valve guide bushings) that are appropriately sized, I ream/drill out the worn throttle shaft hole in the carburetor, press in the brass bushing (using Locktite sealant on it), and install a new throttle shaft. This is NOT an approved B&S repair, but I have had excellent luck doing these.
 
Originally Posted By: Quest
unless it's a machining/manufacturing defect, most common cause of B&S (or any flathead air-cooled engines of OPE or even moped varieties), valve seat falls off due to engine overheating (aluminium expands more than stellite(valve seat material).

Q.


In the OPs other thread he stated that there was a mouse nest in the motor.

That was way over kill on the peening. More damage was probably done than good. Need to start over and replace the seat and the valve.
 
that seating surface does not look straight enough to match the valve, let alone seal on compression. new seat, try and get it positively fixed without ruining the surroundings, lap it to match valve, adjust clearance.
If it was running good prior to this "hit" then that should do it.

If you think it is firmly in place and are tired of the project, maybe a rough lapping will reduce leakage enough for you to run it ok. But you need to check clearance after that too.
 
UPDATE! Its COMPLETELY fixed!

After using the Valve Grinding Compound, the clearance was off so bad it would not start. Thats when it really hit me!, The valve lash this whole time. The intake valve was so tight i could not get a .001 gauge in-between! I remove the valve, and grind off about .006, but while i have it all apart again i decide to wire brush the pistontop, valves, and head, rinse in fuel and dry to a like new aluminum color then reinstall everything.

I fire it up, and it starts right up! no hiccups, smooth as glass, no puffing, throttle response is spot on, power is up a good 30%. It even spins the blades much faster & my 45 min old mix of 1QT 10W40 and a few Oz's of SAE30, 20W50 and 5W30 no longer smells of fuel, but im still goign to change it to a 0W40.

Now i only have to fix a few flywheel teeth! DO i have to replace the whole flywheel? thanks as always!
 
Good job SL2!
The way that the seat is peened-in, it will NEVER come out again.
Just use a quality brand of heavy duty SAE30 motor oil in the engine. I recommend PYB. Alternatively, you can use a synthetic 10W-30, but you will need to check/add oil more often.
Are you sure that your problem is with the ring gear and not the starter drive? I have seen MANY bad starter drives over the years but I can't say that I have seen more than a few ring gears with broken teeth (almost always caused by someone who didn't know how to remove the flywheel properly). The ring gear is not available as a separate item, if it is broken you will have to replace the flywheel.
 
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if there are only very few bad teeth you may have someone weld on some material and then file it to look like the rest of the teeth.
 
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