# Briggs & Stratton - bad rings, breather, or other?



## Motor Hugger (Jul 24, 2005)

Hi, great forum - I'm glad I found this place. I've got a 6.5 hp Briggs & Stratton Intek-powered lawn mower, 4 years old. The engine quite suddenly began having problems this summer. It burns oil like mad to leave a haze of bluish white smoke hanging over the yard after a few passes. Starting is nearly impossible, and sometimes the engine "catches" and rips the starter cord out of my hands, but strong pulling gets it to turn over. Only starter fluid and marathon pulling will start this engine. Motor oil covers the inside of the air filter and the air intake. 

First I checked the compression by turning the engine over with the starter cord; ~20 PSI dry (very bottom of compression gauge scale), and ~35 PSI wet. I figured this low compression is the problem, but I've read that compression testing these small engines is difficult and unreliable, and it doesn't help that I cannot find the compression specs for this engine anywhere. I also tried holding my thumb over the spark plug opening while hand cranking the engine, and the pressure seems to bleed on the upstroke, and I feel a vacuum on the downstroke. I can even hear what sounds like air squeezing past the rings.

I checked the breather valve as well. Blowing and sucking on it (not what you're thinking) revealed a functional diaphragm, letting air pass easily while flapping shut with the least bit of suction. A 0.45" feeler gauge wasn't even close to slipping between the diaphragm and the valve body. The tube connecting the breather to the intake housing is also clear. Is this a thorough test of the breather? 

The cylinder head and valve cover both seem secure, but I haven't removed them to check for a bad head gasket. Rather than do any major work on this engine, I prefer to buy a new one. I found a Honda GCV160 cheap, and it only cost a bit more than doing a ring job on this BS engine, since I'd have to buy the tools for compressing rings. I've no experience on replacing/adjusting valves, so without help such a repair is out of the question. 

So, is low compression is the problem? What else could I do to pinpoint the problem? Thanks in advance for your help. Sorry about the long posting but I didn't want to leave anything out.


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## bugman (Aug 12, 2004)

well, the low compression may come from it having a compression release for starting easy, that and the ripping outta the hands part leaves me to think the valves are in fact outta adjustment, you say oil in the filter.....bad breather. also keep a check on the oil anyway, when they use oil like that, they get low, and that does cause a ring problem.


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