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DMKNLD

K321 breather blow by under heavy load

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DMKNLD

Since my 7114 K321 rebuild, probably 100 hrs on it now, I get a small amount of white smoke out of the breather, only when it is under heavy load, ie tall grass when I'm mowing uphill and the governor kicks in. I use maybe 1/2 a pint of straight 30 oil every 8 hrs or so of mowing. I do add an ounce per gallon of Seafoam into the fuel as a stabilizer. The oil dipstick is new so it shouldn't have a crankcase air leaks that would cause breather blow by. Any ideas?

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OkieGT

The rings may have not seated yet, just a guess with such limited info. Did you align the piston and rings correctly? Was the cylinder bored, how much? What size rings and piston did you use? All things we must know in order to be of help.

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powerking_one

If you have 100 hours on this engine since the "rebuild", that should be way more than needed for the customary 10 hrs or so needed to seat new rings. Using that much oil suggests the cylinder is out of round/tapered out of spec. Was the cylinder mic'd for these dimension service limits before the "rebuild"? What were the ring end-gaps upon reassembly?

Tom(PK)

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DMKNLD

I was on lift restrictions after surgery last summer, so I had our local small engine shop do the rebuild, which ended up being a bit of a Charlie Foxtrot. He re-bored the cylinder to +.010 with new piston, rings and valves, and he re-seated the new valves, but he used the old cam which he said 'looked fine'.

After he put it back together it wouldn't stay timed so he ended up pulling the engine again and found the pin that holds the cam to the case was worn, so he fabricated a fix for that. It still ran rough when I got it back so I checked the timing, which was off, so I static timed it and it ran OK snowblowing over the winter and mowing this summer, except for the wisps of breather smoke under load.

So not being as confidant in the rebuild as I'd like, maybe I'll pull the head and look at the valves to see if they're seating OK. How do I know if the exhaust valve stem has worn beyond specs?

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spyder400k

heres were id start. do a poor mans valve job take the motor out. ck the valve clearance both remove the head poor water in the intake and exh with both valves closed if its tight with water then use solvant its thinner than water if its a good seal your in. if the valve guide is in good shape on the exh side and not worn on the stem at the spring end id then ck the ring gap. the clearance is stock plus .010 up to 35 on the oil ring so that should give you a idea.

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powerking_one

Using 8 or so ounces of oil every 10 hours of operation is excessive for a properly rebuilt K-321 engine. With this condition along with the visible vapors pouring out the breather, it suggests you have serious blow-by issues with the rings. Perhaps a broken ring. Since the Kohler singles have auto compression release (ACR), you can't do a proper compression test while cranking it. It is possible the reed valve in the valve cover or the rubber sleeve is bad. Perhaps the rebuild "guy" installed the breather box upside down (the oil drain holes must be on the bottom). Checking out the breather assy is pretty easy compared to tearing the engine down.

Tom (PK)

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DMKNLD

Tom, you were spot on. I pulled the valve cover off to check the breather assembly and a bunch of oil seeped out, so I knew something was frigged up with it. The breather filter was all broken up and the rubber shaft seal was missing, so the breather plate ended up being all gooked up with dirt and oil that plugged up the oil drain hole. My local dealer had the replacement parts in stock so I cleaned it up, and after checking the valve clearances, which were good to go, put it all back together.

I'll have one more lawn mowing to do for the season to see if that fixed it, before I get it ready for snow blowing season, so hopefully that was the easy fix!! Thanks for the suggestions !

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OkieGT

I'd have a talk with the guy that rebuilt the engine, the fact that he didn't even pull the breather cover, or installed it back in that shape doesn't speak well from what kind he did on the rest of the rebuild. I'm just wondering why you didn't take it back to him to fix, since he did the work? hope your engine lasts.

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DMKNLD

I've actually had it back to him 3 times since the rebuild trying to get it running right. He put a different carb on it and a new coil and condenser when it just ended up being the timing off. At least he took those back and didn't charge me for them after I static timed it and got it running right and put the old parts back on it. I got tired of loading it up on my trailer to take it to his shop and then having to borrow a buddies tractor for another 2 weeks to mow my 3+ acre yard.

Granted, being a 'shade tree' tractor putterer also gives me enough knowledge to be dangerous some times. I know everyone is 'doing their best as they have it figured out', whether in life or small engine repair. Some have it figured out better.

And yes, it does make we wonder what other problems I might have with it going forward. That said, the $600 I bought it for off of CL 6 years ago , which included the mower and snow blower, has more than paid itself off, considering to pay someone to mow it for me would be $200 a pop for the 25 times I mowed this summer, and the $30 - 40 for every snow storm in the winter, beyond the fire wood hauling and other yard projects I use it on.

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OkieGT
quote:Originally posted by DMKNLD

I've actually had it back to him 3 times since the rebuild trying to get it running right. He put a different carb on it and a new coil and condenser when it just ended up being the timing off. At least he took those back and didn't charge me for them after I static timed it and got it running right and put the old parts back on it. I got tired of loading it up on my trailer to take it to his shop and then having to borrow a buddies tractor for another 2 weeks to mow my 3+ acre yard. Granted, being a 'shade tree' tractor putterer also gives me enough knowledge to be dangerous some times. I know everyone is 'doing their best as they have it figured out', whether in life or small engine repair. Some have it figured out better. And yes, it does make we wonder what other problems I might have with it going forward. That said, the $600 I bought it for off of CL 6 years ago , which included the mower and snow blower, has more than paid itself off, considering to pay someone to mow it for me would be $200 a pop for the 25 times I mowed this summer, and the $30 - 40 for every snow storm in the winter, beyond the fire wood hauling and other yard projects I use it on.


id="quote">
id="quote">Well said, sometimes you have really look at the big picture and not sweat the small stuff too much

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