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mattd860

Rebuilt Kohler K301 Issues

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My rebuilt K301 (+.010" piston/cylinder & -.010 rod) is running smooth but I am having a few problems that I can't iron out.

There seems to be an abundant amount of crank case pressure. I just took apart the breather vent and there are no blockages and it is assembled per the manual. I can also feel the crank case venting out of the breather. However, when I remove the dipstick, a very excessive amount of pressure is released. When Idling, if I put my hand over the dipstick tube, the engine will slowly stall.

Also - I think as a result of the high pressure, there is oil leaking into the carb and the exhaust sounds more like a POP POP POP instead of a smooth exit out of the muffler.

In addition - I can't seem to get rid of a backfire when I close the throttle. I've tried to fix this through tuning the carb but I just can't figure this one out.

Any help will be greatly appreciated!

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Are you sure you got your valve timing correct

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Are you referring to timing as set by the points or timing set by the cam and crank gears? I aligned the notches on the cam and crank gears and set the timing at the point to .018. I tried retarding the timing to .015 but this had absolutely no effect.

I also wanted to add that it's very very hard to start the motor when it's cold. Restarting the engine when it's warmed up is no problem. Don't know if that bit of info can help to solve my problem...

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I just want to quote from the Kohler "Guide to engine Rebuilding" manual.

"If positive pressure builds up in the crankcase from a clogged breather or from piston blowby, oil will be forced out of an engine from the seals, gaskets, or any other available spot. Positive pressures can also be caused by worn seals, loose dipstick, or clogged crankcase breather holes."

I have a similar cold starting issue with a Kawasaki engine caused by poor compression when the engine is cold. Your cold start issue could be a result of poor compression from improperly installed rings.

I would check to see if the rings were installed correctly. If you are getting blowby, that will cause the problem you are having.

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The crankcase itself should be at negative pressure when the engine is running. The K Series manual describes how to do a vacuum test on the engine.

I had a K181 that I picked up used and got running. It ran really well, and didnt smoke at all, but when you loaded it up it would pump oil out of the breather. A vacuum test confirmed that it was pressurising the crankcase, and a subsequent teardown found badly worn rings.

If you are absolutely sure that the breather assembly is correct, and there are no other sources of air leaks into the engine then the only other way the crankcase can get pressurised is blowby past the rings. I wouldnt worry about your other issues until the pressurisation issue has been taken care of.

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Ok thanks. I will tear it down again and inspect the rings. I don't know how they could be worn since they're brand new and I drenched them in oil. The rings came in a package of three - one chrome ring, one black ring, and the oil rings. I installed the chrome ring on top, black ring in the middle, and oil rings where they're supposed to go. The top two rings had the chamfer facing up.

I think the only reason I can think they would be worn is because they are aftermarket crap. How else can they badly wear if they are installed properly?

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The top two rings had the chamfer facing up.

I don't know if this will be of help to you, but here is a similar thread about rings. What is of note is that there is a chart of different ring types and how they are to be installed.

http://www.wheelhorseforum.com/index.php?...=22057&hl=rings

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Is it possible that when you installed the Piston Rings, that each Ring Gap was Not equally spaced opposite the others around the Bore?. If not, it will allow Oil and pressure past the Rings. The amount of Oil and Pressure depends on whether the Gaps are within tolerance.

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The top two rings had the chamfer facing up.

I don't know if this will be of help to you, but here is a similar thread about rings. What is of note is that there is a chart of different ring types and how they are to be installed.

http://www.wheelhorseforum.com/index.php?...=22057&hl=rings

I looked at the chart - It shows both the top and middle rings with chamfer to have the chamfer facing upward. This is what I did.

What about valve timing like was mentioned before? The crank has two marks etched into it. One mark is closer to the cam gear and the other mark is closer to the fly wheel. I aligned the cam gear with the mark on the crank shaft that was closest to the cam gear. My printed manual is a bit faded but I'm I'm pretty sure it was showing the mark that I'm currently using.

What is the second mark used for?

Is it possible to set valve timing 180

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What brand of piston and rings did you use? There are many different configurations of rings.

My last rings looked like this.

81db44a2.jpg

The chamfered ring at the top, the notched in the middle.

Here is the instruction sheet that came with them. I added the red circles:

d403fa95.jpg

One of my rings had chamfers on both edges and isn't shown on the chart. But since all top rings shown had the chamfer up, I assumed it to be the top ring. I had a ring with a notch on the outside, it couldn't be a top ring, therefore it had to be the middle ring.

Your pictures in the manual are correct, the crankshaft mark closest to the gear is the primary timing mark. It is for aligning with the camshaft mark. The other mark is the secondary timing mark and is for timing the balance gear (if you have them).

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I ordered a Piston and Ring set from ebay. The box had STENS written on it so I assume it was a STENS kit.

The rings came with directions that showed top and middle rings with the chamfer facing up. I know with absolute certainty that is how they are currently installed. There were no other notches or anything on the rings, just an inner chamfer.

If the rings are indeed worn, I will be buying genuine Kohler rings - lesson learned.

If the rings are worn - will it be obvious? What do I look for?

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How much operating time is actually on this engine? :banghead:

Before or after the rebuild?

The engine is a late 1960's model I believe from an Electro 12. Have no idea of the history. The K301 serial is 00300365 and the spec is 473400.

Since I rebuilt the motor, it's probably been run for 30 minutes.

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Just to clarify my previous post, I was talking about worn rings in a well worn engine. I believe these rings were failing to seal in the bore, and cause the combustion pressure to pressurise the crankcase.

I wouldnt expect your new rings to be 'worn", I am saying that maybe they arent "sealing" in the bore, and you are getting blowby.

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Just to clarify my previous post, I was talking about worn rings in a well worn engine. I believe these rings were failing to seal in the bore, and cause the combustion pressure to pressurise the crankcase.

I wouldnt expect your new rings to be 'worn", I am saying that maybe they arent "sealing" in the bore, and you are getting blowby.

The cylinder is freshly bored and the rod, piston, and rings are brand new (STENS). If the rings installed properly but aren't sealing, then what am I left to do?

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Since I rebuilt the motor, it's probably been run for 30 minutes.

OK - not exactly much time to break in yet.

Have you been able to get it "hot" or actually put a load on it yet?

Chrome rings can be a bastard to get seated in some cases. I try very hard to stay away from them when I can - for that particular reason.

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Since I rebuilt the motor, it's probably been run for 30 minutes.

OK - not exactly much time to break in yet.

Have you been able to get it "hot" or actually put a load on it yet?

Chrome rings can be a bastard to get seated in some cases. I try very hard to stay away from them when I can - for that particular reason.

I've let the engine warm up and I've taken around the yard a few times. I never applied any major load other than drive around in hi-range 3rd gear. Haven't mowed or plowed with it since the rebuild.

Are you suggesting I let it run and put some load on it to further seat the rings? that's really the only way to seat them correct?

Are the genuine Kohler rings chrome like the cheapy STENS kits?

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I need to think about this a bit more, Matt. There's a couple of things that puzzle me.

Idling, if I put my hand over the dipstick tube, the engine will slowly stall.

OK, so why is this different from having the dipstick sealing off the tube? The dipstick is suppossed to seal off the crankcase just like your hand is doing. So why doesnt it stall with the dipstick in?

I do wonder if the crankcase is breathing correctly, but you have said that you can feel the breather pulsing correctly, and have checked the breather assembly.

I gotta head back to work now, but I'll think about this some more and check in later.

I assume the machineshop honed the bore after boring it? Were the ring gaps within spec? Just throwing a few ideas out there :banghead:

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I need to think about this a bit more, Matt. There's a couple of things that puzzle me.

Idling, if I put my hand over the dipstick tube, the engine will slowly stall.

OK, so why is this different from having the dipstick sealing off the tube? The dipstick is suppossed to seal off the crankcase just like your hand is doing. So why doesnt it stall with the dipstick in?

I do wonder if the crankcase is breathing correctly, but you have said that you can feel the breather pulsing correctly, and have checked the breather assembly.

I gotta head back to work now, but I'll think about this some more and check in later.

I assume the machineshop honed the bore after boring it? Were the ring gaps within spec? Just throwing a few ideas out there :banghead:

The engine only stalls when idling if the oil fill tube is plugged (either with the dipstick or by hand). When the rpms or mid range or max, it won't stall but you can hear the engine run slightly differently if the dipstick or hand is plugging the hole.

The machine shop did hone the cylinder after the bored it .010 over.

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Not that I think you don't have it assembled correctly, but I recommend pulling the breather back apart.

Check the valve clearance again while you're in there.

Are the valves tight in the guides? :banghead:

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Not that I think you don't have it assembled correctly, but I recommend pulling the breather back apart.

Check the valve clearance again while you're in there.

Are the valves tight in the guides? :banghead:

Ok I will check this and report later today.

If all looks well do you suggest I let the engine run for a while with high rpms and try to load up the engine?

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Check the breather & valves and we can go from there.

It's impossible to accurately diagnose / troubleshoot problems of this nature over an internet connection, but we'll continue do our best to help. :banghead:

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LOL at this point i'm ready to fire up the grill and have a bunch of you guys over. We'll make it a mini Wheel Horse meet-n-greet while we're at it.

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I'll bring the Bratwurst and sauerkraut. Oh no, wait, it's a 7 hour drive, and I've got to work tomorrow. :banghead:

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I'll bring the Bratwurst and sauerkraut. Oh no, wait, it's a 7 hour drive, and I've got to work tomorrow. :banghead:

We'll have to make it next Saturday then!

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