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I have been "gifted" an old Briggs and Stratton engine in a Craftsman walk behind string trimmer. It is an L Head motor. It was run w/o oil and fried the engine (oil was ugly), and now it won't start.

I'm about to tear it apart to rebuild it but was looking for advice on what is likely the culprit and what I should be replacing. I'm assuming the tappets got worn down so the valves aren't opening and possibly the camshaft is worn out as well. Should I replace the valves as well? Anything else to consider?

Also, I can't find the engine model number anywhere..It is not where the B&S site says to locate them. It is an old engine (probably 20 years old) but hardly run, so almost like new.. except for the fried part.

Any thoughts and ideas are greatly appreciated.

-g

Being an old L head the model number should be above the spark plug stamped into the metal. I have seen some there the numbers where on the side of the housing. Or if it has a shelter outcropping above the muffler the numbers will be stamped there.

Now for the meat and potatoes part of the problem. In good likelihood the only things that is not damaged is the valves, and tappets. I am sure the crankshaft had aluminum transfer from the rod. Possibly the rod and the camshaft are broke. And maybe the block itself may be damaged, past the normal aluminum transfer between the cylinder and the piston and the galling of the piston and cylinder walls. So basically the engine may be past repair, and will require a shiny new engine.

Yeah, that's about it. You could replace all the moving parts, but you could also get an old engine that hasn't been fried and rebuild that without taking a chance the block is ruined.

ILENGINE said:

Being an old L head the model number should be above the spark plug stamped into the metal. I have seen some there the numbers where on the side of the housing. Or if it has a shelter outcropping above the muffler the numbers will be stamped there.

Now for the meat and potatoes part of the problem. In good likelihood the only things that is not damaged is the valves, and tappets. I am sure the crankshaft had aluminum transfer from the rod. Possibly the rod and the camshaft are broke. And maybe the block itself may be damaged, past the normal aluminum transfer between the cylinder and the piston and the galling of the piston and cylinder walls. So basically the engine may be past repair, and will require a shiny new engine.

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Thanks for the reply. There seems to be no area above the spark plug to have anything stamped. Right above the muffler, there is a number but it doesn't seem to match the model numbers I've been seeing. The stamped numbers are 8069 22:04 D15. However, when I search the model number under Sear's Parts Direct it shows the motor as being 120k02. It's confusing.. I just want to make sure I don't buy the wrong parts.

I was afraid of how many meat and potatoes there would be. I don't really need this trimmer, but it is nice to have. It's really only worth keeping if I can fix it w/o too much money being put into it. I guess I'll just have to open it and see what it looks like inside.

The Briggs 12xxxx engines are good. I have 3 mowers currently with those engines. But I wouldn't spend any $ on internals for any of them. I had a 12S912 on a PW. Needed a camshaft, gov-oil slinger and whole gasket set - well north of $100. Around here, a 12xxxx mower with a dirty carb is $0-$20.

dougand3 said:

The Briggs 12xxxx engines are good. I have 3 mowers currently with those engines. But I wouldn't spend any $ on internals for any of them. I had a 12S912 on a PW. Needed a camshaft, gov-oil slinger and whole gasket set - well north of $100. Around here, a 12xxxx mower with a dirty carb is $0-$20.

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Good point. I'll see if I can find a replacement engine around here... Tho they probably won't be anywhere that cheap around here.