Honda GX670

[Art Dotson]

I'm new here and I'm looking for some guidance.

I have a Honda GX670 motor on a sawmill that is stored outside year round. It is usually covered with a tarp to keep the weather out, however last winter the tarp was blown partly off and while replacing it, it caught on the hose connecting the air filter to the carburetor. The hose got turned upward and funneled snow melt or rain down into the motor. BAD LUCK. I cleared the water from the crankcase and cylinders and added new oil and filter. The motor turned over and started seemingly without issues. It ran a little rough initially but smoothed out quickly and seemed to run fine. Next day I went to use it and it wouldn't turn over. Checking things I found that the crankcase and cylinders were full of gasoline. I'm thinking the float stuck open and it siphoned itself full over night. I cleared all of the gas and added new oil and filter and added a fuel shutoff valve inline for safety's sake. It started and ran OK, a bit rich it seemed. I was able to saw a couple of logs with only a few backfires. Next day I went to saw again and managed a couple of cuts with no problems till I got to a tough spot in the log and the governor opened and I got a lot of smoke out the exhaust. That cleared and I tried it again and again when the governor opened I got lots of smoke. I shut it down and noticed a lot of oil residue in the exhaust system. I'm about to tear into this to see what's amiss and would like some ideas on things to look for to indicate what may have happened. I'm guessing some of the water froze solid at some point and either cracked something or displaced a gasket or seal. What do you people think?

[StarTech]

It really depends on how much, where and how long the water stayed in the engine. Personally I would go ahead and pull the head and see what damages lay there first.

[Deere2me]

Before ya tear into it, I would ( and usually do) run a leakdown test first, If you have access to a leakdown tester. It really gives you a good idea what your up against. Just GOOGLE leakdown test.

[bobodu]

Gee....I guess two of us wasted time answering the same question in the other forum....

[Art Dotson]

Ran compression & leakdown tests with good results on both. Pulled the carb looking for physical damage from ice forming but found none. Fuel cut valve was gummed up, explains the siphoning if the float valve was open and the float bowl was pretty dirty. Still puzzling over the oil smoke. Looks like maybe some came up the crankcase vent hose. No PCV valve that I can see and oil level is only to full line. Going to check the fuel pump for damage tomorrow. What might cause oil to come up the vent tube? Or possibly through the fuel pump?

[bgsengine]

Ran compression & leakdown tests with good results on both. Pulled the carb looking for physical damage from ice forming but found none. Fuel cut valve was gummed up, explains the siphoning if the float valve was open and the float bowl was pretty dirty. Still puzzling over the oil smoke. Looks like maybe some came up the crankcase vent hose. No PCV valve that I can see and oil level is only to full line. Going to check the fuel pump for damage tomorrow. What might cause oil to come up the vent tube? Or possibly through the fuel pump?

Smell the oil , make sure it isn't fuel contaminated. Oil coming out breather (and it DOES have a PCV - on small engines it is called the breather) usually caused by faulty breather (typically a reed valve in valve cover) or over-pressurization of crankcase from combustion blow-by, blown head gasket, excessive oil level (often caused by fuel leak into oil via carb or fuel pump)

[Art Dotson]

I think I have solved the dilemma. Everything I've checked came out good (except for some dirt and grime here and there). I'm waiting now on some carb gaskets to go back together with everything. I have surmised that when the crankcase flooded with siphoned gasoline that it flooded the breather chamber with an oil/gas mix and higher RPM's managed to suck that up to the carburetor and down the throat. If I had continued to run it, it probably would have cleared on its own, but a fast shutdown seemed like the thing to do at the time. I want to thank everyone that responded to this post on here. At the very least you helped confirm my line of thinking on solving this problem and as a result I have saved hundreds of dollars. Other than time I'll end up spending about $50.00 +/-. A new motor runs anywhere from $900 - $1500. Dodged a bullet on this one! Thanks everybody!!

Art