# suspect valves - what's my psi?



## MikeJ (Oct 16, 2004)

I've found some great info here and elsewhere that's led me to believe my valves are bad in my Tecumseh HSSK50 snowblower engine, but I have no clue what my compression should be. Tecumseh's manuals and web site are useless. Anyone have a clue what the PSI should be or where I could look to find out?

Thanks much.


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## bugman (Aug 12, 2004)

you could just use an automotive psi or compression tester. now if you take by hand turn the flywheel until it gets hard to turn and holds it it might not be your valves. it could be they aren't seating if it doesn't, you could take off the head and see if they seat any at all. it could be just that the combustion chamber needs cleaning do that by hand real good put it back together then get it going and spray carb cleaner in it. this cleans the intake valve and exhaust. the carbon build up make it hard to start and if real bad will fill the place behind the valves causing them to leak.


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## MikeJ (Oct 16, 2004)

*you might be right - i'll let ya know*

You were totally right dude--thanks a million.

The problem, btw, was sputtering and backfiring. Brand new carb too. I still dunno what official compression I should be getting but I got 30 on my first pull, then 60, and 90 after a few more--that seemed solid so I took your advice on the cleanout.

New plug, sprayed carb cleaner in the plug hole, ran it and sprayed carb cleaner in as it ran--cleared up my sputtering and backfiring problems almost completely. Still think I might open the head for a real cleanout and new gasket but I'm ready for some snow now


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## bugman (Aug 12, 2004)

great :thumbsup:


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## Fl Flash (May 1, 2003)

Compression spec for the 5 hp Briggs is 100-125 lbs warm. Its not very helpful though, I prefer using cylinder leakage for diagnosis.
Lock the piston at top dead center on the compression stroke, using an adapter and regulated air pressure ( 100 psi ) pressurize the cylinder. If you can hear air leakage at the crankcase vent you have a ring/cylinder sealing issue. If you hear air escaping out the carb or exhaust you have valve problems. Hope thats helpful.


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