# need some opinions



## jetrail (Dec 7, 2005)

ok i bought a few broke returns this week , 2 troy bilt mowers , w/ the briggs 6.75 hp motor , one was ran flat out of oil and even though the piston moves as in the connecting rod is intact it has no compression , well the other one it the one that gets me , it will start run for maybe 3 minutes then die , and when you check the compression it reads like 15-20 , so could it be the rings or valves , it doesn't smoke , runs clear , a little chatter in the engine , but will only run for a few minutes then dies and won't start back up . i thought it could be the valves , but didn't know if it might be the rings either , any advice is appreciated , 
thanks 
jay


----------



## bugman (Aug 12, 2004)

Is it a over head valve engine or side valve? I don't think its the rings...


----------



## rake60 (Oct 13, 2005)

jetrail
A leakdown tester may be a good investmant for you. 
You can get one from Briggs for about $170 or you can make your own.
The attached picture is one I made myself for less than $20 All it really does is
pressurize the cylinder to pinpoint leakage. You set the piston at 
Top Dead Center on the compression stroke and lock it in that position with
a clamp. Then isolate the breather from the carb. Pressurize the cylinder. It
doesn't take much air 30PSI is sufficent. Then listen. If you hear air escaping
around the head, the head gasket is leaking. Air from the carb means the intake
valve is leaking. From the muffler would be the exhaust valve and from the 
breather or oil fill means it's going past the rings. If you don't have a 
compressor a portable air tank will do for an air supply.
If your interested in building one I posted the rough skech I used to make
mine.


----------



## scrench (Dec 8, 2004)

dry test wet test works too


----------



## jetrail (Dec 7, 2005)

its not a overhead valve , i haven't had time to take it appart , but im planning on it tonite or tomorrow , i hope it is something simple like a head gasket ect , but my gt feeling is a broken ring or cracked piston


----------

