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Briggs 17.5 Hp Vertical Won't Rotate Past Tdc


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#1 New.Canadian.DB.Owner OFFLINE  

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Posted May 15, 2014 - 07:28 PM

I am working on a Briggs 17.5 hp vertical shaft, OHV, single cylinder engine.  It won't rotate past TDC with the spark plug in.  With it out or with a compression tester installed (150 psi), it will spin all day long.  I have gapped the valves (.008 intake & .013 exhaust).  I have pulled the head and removed the carbon.  The battery is fully charged.  It is a physical stoppage, as in it take strength to manually rotate it past TDC.  It is as if it has built up to much pressure in the cylinder.  If you can get it started, it runs fine.  What am I missing?



#2 EricFromPa ONLINE  

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Posted May 15, 2014 - 08:44 PM

Set the valve lash on BOTH valves to .004-.006 if it seems to run a bit hot like that set the intake only to .004-.006 and the exhaust to .006-.008.

 

It should crank over very easy now and start.

 

Check your engine oil for gasoline.You will be able to smell it on the dipstick.If you do smell gas change the oil before starting.The Floats in those carbs have a very bad habit of sticking.I've had dozens of OHV briggs come in with they're entire block filled with gasoline.

 

Head gaskets also like to blow on these engines between the push rod galley and the cylinder bore.If the head gasket is blown it will leak oil into the cylinder and cause higher than normal compression at start up and Smoking especially when the front of the engine is facing down hill.

 

Do not jump start it off of a Car or truck those little starters burn up really quick.If you hurt the starter by trying to jump start,it will still spin the engine over but it will not have much torque.

 

Those cheap $40 made in china starters on Ebay are not as heavy as the original ones and they will only last for a couple of years if your lucky.The correct replacement starter costs $90+ so don't try to jump start it.


Edited by EricFromPa, May 15, 2014 - 08:51 PM.

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#3 New.Canadian.DB.Owner OFFLINE  

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Posted May 16, 2014 - 03:34 PM

That fixed.  Went to ink amend my manual, only to notice that the manual is in metric, not standard.  Mis-read the units & numbers.  (0.08mm & 0.13mm)  






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