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B112_son

12 HP Briggs smoking

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B112_son

I have a B112with the original 12hp Briggs. I have noticed this winter upon initial start up everything is fine. Put it gear and once under load starts smoking like crazy. However, after the engine warms up say after 10 min no more smoking at all and everything seems to be good. I should state it does not smoke when cold if not under load.

I have read many people having trouble with head bolts due to the extreme cold as well as intake bolts. My initial thought was one of the bolts for the intake because I noticed in the fall one of the bolts is stripped. At some point a helicoil was used but when I took it apart to clean it did not snug up as much as I would've liked. But still ran fine in the fall.

Yesterday the smoke appeared to be more blue. I haven't had a chance to do much more investigating lately.

I'm hoping it's a loose bolt causing a gasket to leak. What do you guys think? I'm hoping it's not a head gasket.

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powerking_one

I would venture to say that you have a broken piston ring(s) causing this (first assuming the oil level is correct and the crankcase beather is OK/good). This can be a common failure if the engine has had an overheated life due to clogged cooling fins on the block and head (mouse condos under the blower housing). Doubtful is it a head gasket or head bolt issue.

Tom (PK)

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trowel
quote:Originally posted by B112_son

That's not exactly the news I was hoping for. Why would the smoke clear up when the engine warms up though?


id="quote">
id="quote">Could be,..Broken rings when hot expends sealing the bore.Watch the oil, it will tell you after a 3 hour run.

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B112_son

I'll have to check the oil again today. I haven't checked it the last 2 times I used it.

Makes sense with things expanding. I've never been in an engine and I know the bore would have to be checked but since it runs good when hot is it possible I would just need to clean and re-ring?

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trowel

Depends, broken rings tend to score the bore and usually always require a good hone or rebore job leading to OS piston and rings.

After removing the head turn engine to BDC, you can see if cylinder wall has scoring and/or glazing, top of bore (cylinder deck) feel if there is a lip, if so then rebore is needed.

Clean top of piston, if has number # 10 or # 20 stamped on the top then it was rebored before, if no number then it is STD size.

The valve seats should be checked also while head is off.

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trowel

Depends, broken rings tend to score the bore and usually always require a good hone or rebore job leading to OS piston and rings.

If normal wear then simple re-ring would be fine but check a few things first :

After removing the head turn engine to BDC, you can see if cylinder wall has scoring and/or glazing, top of bore (cylinder deck) feel if there is a lip, if so then rebore is needed.

Clean top of piston, if has number # 10 or # 20 stamped on the top then it was rebored before, if no number then it is STD size.

The valve seats should be checked also while head is off.

Also check the crank shaft to rod lash, while turning over the engine back and forth with a rocking motion at BDC while pushing down on the top of the piston with your other hand.

If clicking is heard or excessive play is felt then you may need a OS rod and have the crank ground.

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