# B&S 12 hp engine hard to start



## MGW (Sep 10, 2005)

I have a lawn tractor with a Briggs and Stratton 12 hp model 281707 engine. The engine is hard starting when cold. It chugs for a bit until it gets going. Sometimes it chugs and stalls. After the engine is warm it starts ok. The gas is fresh. The choke seems to be working ok. I tried starting fluid thinking it was a carburetor problem. The starting fluid didn't help. The air cleaner is clean. New sparkplug. The compression is low when the engine sits 30-45 psi.
After the engine has been running the compression goes to 80 psi. I squirted oil in the cylinder and the compression went to 80 psi when cold. After addin the oil the engine started fine two times, when I cut the grass. On the third time the engine was hard to start again and the compression was low. This occured over a couple of weeks. I'm thinking head gasket. Is there any way to tell for sure before I take the engine apart? Or do you think I may have another problem?


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## MGW (Sep 10, 2005)

Sorry I click on the wrong Forum

:drunk:


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## blaake (Apr 7, 2006)

ill by it give me a price


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## certifiedtech (Jun 30, 2006)

This post was intentionally remove by "certifiedtech"


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## certifiedtech (Jun 30, 2006)

Sound like the valve clearance is off causing a compression leak.
Remove valve cover/crankcase breather (behind carb,). Remove spark plug and set the engine to "top dead center" With the piston at the top and both valves closed. With a feeler gauge measure the distance between the valve stems and lifters 
(Intake "min 5" "max 7" use 6)

(Exhaust "min 9" "max 11" use 10)

In other words

Intake 6
Exhaust 10

Most likely you`ll need a valve job.


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## scrench (Dec 8, 2004)

you can set them with one valve open all the way , if the intake valve is all the way open set the exaust, when the exaust is all the way open set the intake . if you just find top dead center on the piston there is a chance it wont be on the compression stroke , you want the flat side of the cam ! it dont sound to me like the engine needs a complete valve job just yett . is the throttle shaft in the carburator tight? did the engine smoke like a house on fire ? with compression that low dry , then that much wet that would indicate a ring sealing problem the cylinder wall might be scored . valves could verry well be the problem , but the compression should not jump up that much with wet dry test if it was the valves , how much oil did you put in the combustion chamber ?


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## mowerman (Nov 2, 2006)

the valves just need to be adjusted that will involve pulling head and valve cover this has been my experiance


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## jeep4me (Jan 22, 2008)

Try checking the head bolts to see if they are snug. Sometimes this can cause a loss of compression and/or eratic engine operation.


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## oscaryu1 (Mar 25, 2007)

Look for:

1) Loose head bolts
2) Loose spark plug
3) Blown gasket/broken gasket
4) Incorrect valve clearance
5) Worn rings


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## engine man (Mar 25, 2006)

how much you want for the engine?


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## glenjudy (Aug 26, 2006)

engine man said:


> how much you want for the engine?


It may be too late, the original post is a couple of years old.
thanks,


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## RC10GT1980 (Aug 23, 2005)

well than lol
hummmmmmmmmmmmm................


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