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15.5 Briggs I/C issues

Posted by mschramm none (My Page) on
Wed, Aug 6, 14 at 17:13

Just picked up a 2009 Bolens lawn tractor at garage sale recently and have had a few issues with the engine. (Which I expected...) it's started up and ran fine drive it around the yard about 15 minutes, parked it and told myself that was a good deal! The next day in an attempt to mow, it ran about 10 minutes max when it lost almost all power in the engine. I checked the oil, which was about a quart over full, and also noticed oil in the breather before the carb. I did a little research online and ended up replacing the head gasket as we'll as an oil change. Put everything back together and the black smoke had stopped but the engine sounds horrible when I move the throttle higher than idle...this is where I am stuck now. The engine is a briggs 15.5HP model number 31A607 Type 0741 B2. Any help would be appreciated so I can now again!!


Follow-Up Postings:

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RE: 15.5 Briggs I/C issues

"....I checked the oil, which was about a quart over full...."

Head gaskets don't cause that.
Leaking needle& seat assemblies in carburetors do.


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RE: 15.5 Briggs I/C issues

OP - ditto Bill's comments plus suggest you chk for raw fuel in crankcase oil. A simple way is to pull dipstick and smell residual oil on stick for the smell of gasoline.
If present, immediately drain/replace crankcase oil/filter and get fuel sys problem repaired before running engine again as crankcase oil diluted by raw fuel loses much of it's lubricating properties, allowing accelerated engine wear/damage.


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RE: 15.5 Briggs I/C issues

Black smoke is from running rich. Probably from excess fuel from the carb leaking in. Never hurts to install a $7 fuel shut off valve between the gas tank and the fuel filter.

Also, if you can describe "engine sounds horrible" a little better. Is it missing, stalling, smoking, revving? Sounds like my wife when I forget her birthday. Horrible can encompass a lot of different things.

This post was edited by optsyeagle on Thu, Aug 7, 14 at 16:07


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RE: 15.5 Briggs I/C issues

The "horrible" noise sounds like a very loud knocking


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RE: 15.5 Briggs I/C issues

I suspect that is the Counter Balance Bearings. No practical fix if it is that and eventually it will knock a hole in the block when it breaks. Probably been run a bunch with gas in the oil. Probably why it was at a garage sale.

Walt Conner


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RE: 15.5 Briggs I/C issues

I'd change the oil and adjust the mixture on the carb.


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