OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines Honda GXV140

Hi, having a bit of a problem with my honda. It is a clean up job right from the start after living in a shed for the past 4 years not going. Started with the usual, strip down clean carby, fuel tank & line, check valve settings, new oil,air filter etc. Got it going and after about 1 minute of running started smoking. Went to take off carby to check clean again noticed oil in front of carby and plastic part where air filter sits, had a look up breather hose, oil. Have gone through other cases such as this checking the ventilation compartment and oil drain hole, all good, took head off to check head gasket, had to change it, put it all back together, still smoking and getting oil through breather hose. Could it be the rings even though there is no movement in piston from side to side, ( had a quick check when i had the head off). Any help appriciated Paul.

Hi paul.foot, a compression test could tell if the rings are low, worn rings can be the result of this as well I would check the top crankshalf oil seal is not pushed in too far or loose due to drying out after sitting for a long period. In the ventilation area check the wire filter is clean and again the ventilation hole is clear.

Paul, you can't judge the condition of rings by whether the piston moves from side to side. A compression test should show you whether the compression rings are leaking - they rarely do on Hondas, but if they did, blow-by could cause oil to be blown through the PCV system into the breather pipe. Eventually the oil rings wear out, but that causes blue smoke from the exhaust, not oil in the breather pipe.

If there is oil in the breather pipe, one possibility is that the mower has been tipped over, which fills the PCV compartment with oil, and often the breather pipe as well.

Hi Grumpy and Roebuck, have done a compressionand, 115 psi which I think is good. Top crankshaft oil seal is still intact and tight no movement at all. Have rechecked the ventilation compartment and wire filter and hole,all clear. I put about 5ml of oil into filter area and was able to see it drain through ventilation hole, done this 3 times just to be sure.

If your decompressor is working, 115 psi is normal. Honda specifies 85 to 121 psi. Hondas can be very tired and still show normal compression pressures.

Is the PCV disk (see brown disk in yellow circle, in the picture below) in good condition? Be sure it is not stuck either open or closed, and it is not worn right through in the center:



If the disk valve is working properly, it sounds as if you may have to check the piston ring gaps.

Hi Grumpy have sent a quick photo showing disk valve. (In the second photo the divot in the valve isnt as big as it seems, its the way the photo came out.) It came off easy, didnt feel as if was stuck. Seems to be in good order. How can you tell if its stuck open or closed without taking plate off. What would be involved in checking the piston ring gaps.

Is it possible that it may have to much oil . When checking oil level the dipstick does not get screwed back in while checking but screwed back in when finished oil level check is right.
I thought it was worth a mention just in case it was over-filled and it could save having to pull it apart.
I also take the hose off the aircleaner when I've had this problem so I don't have to keep cleaning the carby of oil and to monitor the amount oil spitting out till it stops and then reconnect the hose to airfilter once the problem stops but I don't know if this is recommended by others.

This needs to be emphasised. Honda dipstick oil level checking is the opposite to Briggs & Stratton. BTW, Honda has used this consistently for all of their engines [car, motorcycle and industrial/garden] since the 1960's at least.

Honda procedure is: unscrew and wipe dipstick, then briefly rest on top of its housing. Withdraw and check level.

Briggs procedure: Withdraw or unscrew dipstick, wipe, then screw back in or fully insert. Withdraw and check level.

That's much better , thankyou gadge.

That information about how to check the Honda dipstick is correct of course. Also, as Rob said, if the sump is grossly overfilled it could cause substantial amounts of oil to pass through the disk valve into the valve compartment. If that happens, some of it will get into the breather hose, and the normal gas pulses in the hose will blow it into the carburetor's air intake. So, check the oil level before concluding that the ring gaps have to be checked.

Unfortunately Paul, to check the ring gaps you have to take the engine off the mower, remove the cylinder head and crankcase cover, then remove the connecting rod, complete with piston and rings. Then you remove the piston rings from the piston and put them one at a time, into the cylinder bore, 1 cm down from the top, ensuring they are square to the bore by pushing them into that position with the top of the piston. Then you use feeler gauges to measure the gap in the piston ring. When you get to that point (and you should only go there if the oil level is correct in the sump, of course) we can talk about how worn the rings are, and what to do about it.

If the disk valve were stuck closed, high pressures would eventually (depending on how worn the piston rings were) develop in the crankcase, and most likely oil would be forced past one or more of the crankcase gaskets, possibly blowing the gasket while doing so. If the valve were stuck open, there would be more oil than normal in the PCV valve compartment all the time, and this would result in there always being some oil in the breather hose. Your symptoms seem to be a decent fit for a stuck-open PCV valve, which is why I suggested you check for that.

The amount of wear on your valve disk is normal for a Honda that has just about worn out its piston rings.

Hi Grumpy,Gadga and Roebuck, thanks for that. The oil level is correct, about 1 mm over top of criss cross part on dipstick. What i might do is drop the oil and clean sump out again, depending on how dirty the oil is of course. ( probably didnt clean it out properly the first time )
When you said this part Grumpy :The amount of wear on your valve disk is normal for a Honda that has just about worn out its piston rings: that virtually means that the rings are due to be changed, but should they knowing that it has good compression?

Paul, I've dismantled a number of Hondas that smoked, and tested the compression on most of them. In all cases where I tested the compression, it was still in line with the middle of the specified range in the workshop manual. One of those engines had been abused for years, and was so worn that the only parts I didn't throw away were the external parts, plus the fasteners.

I must add that all of those engines were old enough to still have cast iron oil rings. In recent years Honda has switched to chromed steel rail oil rings similar to those in cars, so it now takes a bit longer for the real oil burning to start, but the second ring, the oil scraper, is still cast iron, not chromed, and it wears out as quickly as ever.

Your Honda emits oil smoke, and has modest quantities of oil in the breather pipe. It does not seem to have anything wrong with it except that it smokes and has oil in the pipe. If it looks like a duck, quacks like a duck, smells like a duck, and walks like a duck, it's probably a duck.

Hi Grumpy, thanks for my duck. Havent had a chance to get onto the mower yet, had a few other jobs come in hopefully get back to it tomorrow arvo. Not to stressed if it doesnt stop smoking, only cost me $15, just trying to spruce it up for my dad, he's getting a bit old to be pushing a mower so i thought i'd get one to drag him around,it being a 2 speed. I'll let you know how i go tomorrow. Thanks Grumpy.

Sounds good, Paul. To me, opening up a Honda is a more formal process than, say, a Briggs, just like working on a Leggo project is more formal than a bent-and-twisted-tin child's toy. I tend to do it more carefully and respectfully, and find much less cause for irritation. I'm a very slow mechanic, but if there were nothing else wrong with it, re-ringing a Honda engine would take me about 2 hours once it was out of the mower and on the bench. That would include a test run. Be sure you do not fit the cheap aftermarket rings that are not chromed and have a cast iron oil ring - they work properly but last less than half as long as the good ones. If you buy good aftermarket rings (chromed top ring, chromed steel rail oil rings) they will probably cost less than half what you'd pay for Honda rings, and as far as I can tell, are just as good. I suggest you send a PM to roebuck about this.

Hi Grumpy, will do as you suggest, will get abck to you asap. (hopefully it wont be to long). Thanks Paul.

Hi Grumpy and Roebuck,sorry it has taken so long, been busy. Have gotten new rings ( thanks Roebuck ) fitted them and reassembled the motor, double checking everything as I went. Gave the motor a coulpe of easy pulls just to make sure it all felt good, 1 quick pull and off it went no smoke to been seen anywere, but a bit of coughing. What now!! You guessed it, dirty fuel. Being as careful as i was i grabbed the wrong fuel container, needless to say I had to flushed out fuel tank,line and carby, put it back together, one pull and its running like a brand new mower. Thanks again Grumpy and Roebuck, much appriciated. Thank you to Gadge, all information and/or help appriciated.

Thanks for reporting back, Paul - threads aren't much use in the archives unless they have a successful conclusion, proving that the problem was actually found and fixed.

I'll close the thread.