Small engine mechanical help

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pricefarm

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I have a scag mower with a Briggs and Stratton engine with 1300 hours on it. It started leaking oil around the crankcase and around the governor. I replaced the crankcase gasket and the seal around the governor. I cleaned all the oil off the engine. Now there's oil leaking around one of the heads. I can remove the oil dip stick and it will blow oil out. So Iam sure the head gasket is blowed. I have never replaced head gaskets before. How hard of a job would it be and what other problems might be wrong ? Just wondering if I should continue to fix problems on this engine or maybe replace it?
 

dun

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Replacing head gasket is easy. It's all the crap you have to take off and put back on that is the PITA. Some where on internet it should have the torqueing sequence and values.
 

Atimm693

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Shroud, intake/carb, and exhaust have to come off. Can be tough or easy depending on the configuration of your mower.

If the pushrods are different, the aluminum one goes on the intake valve. Make sure you set the valve clearance right. Some are very sensitive and will not start if set too loose.

It would be wise to get a service manual for that engine. It'll have the torque sequences and valve lash specs.

I'd do both while it's apart. The gaskets are cheap. Clean the heads and block with some fine emery cloth on a piece of glass, or anything that's really flat.
 

dun

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Personally, If I was going to go through the effort of a head gasket after what else you've done I would either do a full rebuild or buy a crate replacement
 

bbirder

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dun":3jvgt50y said:
Personally, If I was going to go through the effort of a head gasket after what else you've done I would either do a full rebuild or buy a crate replacement
+1
 

greybeard

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"I can remove the oil dip stick and it will blow oil out. So Iam sure the head gasket is blowed."

Usually, on a briggs and scrap iron engine, that means the rings are worn all to heck or even a small hole in piston.
 
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pricefarm

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dun":2l08yllm said:
Personally, If I was going to go through the effort of a head gasket after what else you've done I would either do a full rebuild or buy a crate replacement

Yes Iam thinking about just replacing engine with 1300 hours I think it's probably time to just replace. New engine runs around $1000
 

Atimm693

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greybeard":1uao3gz0 said:
"I can remove the oil dip stick and it will blow oil out. So Iam sure the head gasket is blowed."

Usually, on a briggs and scrap iron engine, that means the rings are worn all to heck or even a small hole in piston.

Briggs OHVs are notorious for blowing head gaskets. The primary symptom is oil consumption, crankcase pressure blows it into the intake through the PCV.
 

papavillars

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I would not replace it with a B&S.I favor Kawasaki ,Honda or Kohler. I used to love the Kohler, but my commercial mowers came with Kawasaki. I have not had any problems with them. My new ZTR came with a Kohler , hope they are still great motors.
 

Nesikep

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On engines with only 1 or 2 cylinders oil blowing out the dipstick is not a sign of something wrong, as the piston goes up and down it's changing the crankcase volume and that's what's blowing oil out... on engines with more cylinders there's usually always one piston going up while one is going down so that doesn't happen.
 

True Grit Farms

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Nesikep":3a1vj2lz said:
On engines with only 1 or 2 cylinders oil blowing out the dipstick is not a sign of something wrong, as the piston goes up and down it's changing the crankcase volume and that's what's blowing oil out... on engines with more cylinders there's usually always one piston going up while one is going down so that doesn't happen.

So why doesn't a 1 or 2 cylinder engine blow oil when it's new? This is the first time I've heard that one. A single cylinder Kubota generator doesn't blow the dipstick out till they get wore out.
 

greybeard

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True Grit Farms":j999g2yh said:
Nesikep":j999g2yh said:
On engines with only 1 or 2 cylinders oil blowing out the dipstick is not a sign of something wrong, as the piston goes up and down it's changing the crankcase volume and that's what's blowing oil out... on engines with more cylinders there's usually always one piston going up while one is going down so that doesn't happen.

So why doesn't a 1 or 2 cylinder engine blow oil when it's new? This is the first time I've heard that one. A single cylinder Kubota generator doesn't blow the dipstick out till they get wore out.
Because an engine in good mechanical shape only produces slight changes in crankcase pressure + or - when running. A worn out engine (rings and cylinder wall) allows combustion pressure to leak by the rings and into the crankcase--combustion pressure is a lot higher than just the cranking pressure you get when doing a compression test due to the expanding gasses of combustion. Good rings, no scored cyl wall, good valve guides hold the combustion pressure on top of the piston where it is supposed to be so it can do it's work. Worn crap allows some of that pressure into the crankcase, and does it at a time when the piston is on it's way down, which shrinks the total volume of the crankcase.
 

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