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Sutty

C-140 8 Speed Kohler 321S

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Sutty

Hi Guys

 

I don't know if any of you remember me, but I have a C-140 8 speed, with a Kohler K321S engine, which is roughly 40 years old. Yes, a C-140 :D. I have an issue whereby the engine floods badly when the tank is full, or more accurately, when it's more than half full. It floods so badly that petrol almost literally pours out of the front of the carb, into the air filter, and runs out of the bottom of the air filter cover. I've been managing this for a good while by keeping the tank less than half full, but it's a bit too much of a pain, and I'd rather have it right. If I over fill the tank, by accident, as I did yesterday, I can also manage the issue by keep reaching down and turning off the fuel under the tank, and only turning it on for a few seconds when it starts to run out of fuel. A few seconds of on, every few minutes, will keep it running perfectly, but of course it's far from ideal.

 

I have changed the carb fairly recently, a few years ago, but the fault persisted across both carbs. I'm wondering if the fuel pump might need attention, and if it does, is it something that can be serviced by me, with only moderate skill. I suppose the pump will be as old as the horse, so it will also probably be 40 years old. I think I also read somewhere that you can get a spring to lift the float with a little more force, but I don't know if this is necessary, or the right course of action. I can almost guarantee that the float is clean and free, because it's new, and before I changed the carb, I also cleaned the old one up, good and proper, and it appeared to function as it should, very free, but the fault remained, which is why in the end I thought I would try a new carb. In the end, I was disappointed to find that the issue persisted through the carb change, though not overly disappointed, because the carb was cheap enough, and I guess I now have a working spare anyway. If I manually restrict the fuel, as described above, or keep the tank level below half, it runs very well, so I believe all the needle settings are correct. 

 

I have attached a few pictures that demonstrate the tank height in relation to the carb, and some that might help some of you identify the carb type and the fuel pump type. The pump may have been messed with, around 15 years ago by my late father, or the guy who used to help him with small engines, so maybe the strange looking red seal you can see sticking out is not the original? Even though that looks wavy and unseated, it doesn't leak there, but it doesn't mean it's right, or original, but I'm sure you'll know.

 

Anyone experienced similar, and have any suggestions? Is it easy to remove, disassemble, and service the pump, for example. I could just try, but I thought it sensible to seek expert advice first.

 

Thanks in advance, for any possible advice.

 

Best regards

 

Sutty

Carb.jpg

Engine.jpg

Pump.jpg

Tank.jpg

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Ed Kennell

Sounds like the float / shut off assembly in the carb bowl is not assembled or adjusted properly.

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RandyLittrell

The float in the carbs bowl is what lets fuel in and stops it from entering. I think you just had 2 carbs with the same issue. Check for leaks in the float and if you turn the carb upside down with the bowl off your float should be level. You can bend the tab on the float to adjust it. 

 

It can be junk in the main jet keeping the needle open as well. You might as well pull the carb and tank, clean them both well, then put a new line and filter. I know it seems like a lot of work, but trust me, its the only way to get rid of carb issues. 

 

 

 

 

Randy

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Marv

.:text-yeahthat:

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Sutty

Thanks guys. Yeah, over the last few years I have done those things, more than once, and the last time I checked and adjusted the float was only last summer, but nothing ever makes a difference. I went for the measurements in the manual, which if I remember correctly now, were simply to make sure it was horizontal when inverted, but I might be mixing that up in my memory with another carb. Definitely all worked freely, and as it should back then. I even blew through it, using a small piece of pipe, to make sure it shut off when the float was lifted, i.e. when inverted, which it did, and the floats were empty, with no fuel leaks filling them up.

 

I hear what you say about the line and tank, and several have mentioned it now, but I'm not entirely sure how it could be related to the tank and or line, when fuel is basically pissing out of the air filter cover, when running, if I overfill the tank. If I do it struggles to run, and eventually stops. Hardly surprising with fuel pouring out like that. If I don't overfill the tank, it runs absolutely perfectly, with no spill, and no tuning issues. I do see how it could be the float, but honestly, the number of times that this has been cleaned and checked, over the years, whilst this has persisted, must be in double figures. Each time, I listen for it closing when inverted, and blow to see if it shuts off when inverted, which it does. Also, how does it manage to function correctly, shutting off the carb fuel flow, as necessary, when the tank is half empty but not when full. It does, as I said before, run perfectly when the tank is half full or less. If the running varies with depth in the tank, from perfect, to suddenly atrocious, if I overfill it, surely this indicates that the fuel isn't being pumped at all, and is getting there by gravity. When the tank is full, maybe the height difference overwhelms the seal the float valve can provide in the bowl. 

 

Is it worth maybe setting the float slightly out of spec, such that I get more shut off float force? Lift the tab up a little? What might be the consequence of setting it to lift too high, if I went too far? Starved of fuel, and difficulty running at high revs or under heavy load? Any risks with trying that?

 

Over the years the only thing I haven't really looked at is the pump, so I think that's what I'll look at next, rather than setting the float out of spec. Are there any guides on how to perform maintenance on this type of pump. Right now I don't even know if that is the pump, or if it even has one. Looks like a pump, would make sense if it were, but still, I don't know for sure.

 

Okay, large delay between what I wrote above, and this paragraph. I looked at the manual, and pump removal and disassembly looked simple, which it was. I took it off, cleaned it all up with carb cleaner, and then disassembled it. The diaphragm looked fine, and when I sucked and blew on the input and output, the pump valves opened and closed, seemingly as they should, so I concluded all was well. I then went on to reassemble, and refit without difficulty. Before I fitted the output pipe to the carb, I opened the tank valve, and this is what I observed. Is this normal? It seems to me, when not running, that it should be closed off and no fuel should flow, but maybe not?

 

All seemed to be original on disassembly, so probably 40 years old.

 

 

 

Edited by Sutty
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Ed Kennell

This is certainly unusual and does not seem possible for the fuel pump to generate enough pressure to submerge  a properly working float and open the inlet valve.

The leaking of fuel through the fuel pump is not unusual.   Both the check valves in the pump are one direction...only closing and preventing flow back into the tank.  When you blow into the pump inlet, both valves open allowing flow.  When you blow in the outlet, both valves close preventing flow to the tank.

My suggestion is to simply bypass the pump and see if the fuel still leaks with the tank full.   The Kohler should run fine with out the fuel pump if the tank is full.

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RandyLittrell

You might also pull the bowl off and see if you can make the fuel stop leaking by lifting the float up by hand. Does sound unusual and I really don't see how the pump could cause it. 

 

Does it leak fuel when the tractor is not running?

 

 

 

 

Randy

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Sutty

Thanks for the clarification that the trickle through is normal. Now that you have explained it, I can see why it might, without meaning anything is failing. With regard to the fuel pump pressure, I was surprised at how high it squirts, when turning it over without being connected. Indeed, when I had it off in my hand, I was also surprised with how readily, and forcefully, what was inside squirted out as I simply caught the diaphragm actuator lever by mistake. Is it possible to misplace that lever, such that it gets moved too far, on each stroke, when remounting the pump?

 

As for trying it without pump, that seems like a great idea, and very simple to bypass with a short piece of pipe. If it works when full, and I can also run it until the tank is empty, the tank is quite high, as you can see from my picture, then this would be an acceptable solution. That having been said, my curiosity would probably still have the better of me as to why it might be going wrong with the pump in the circuit, so I'd still quite like to get to the bottom of it.

 

I'll report back on Tuesday as to how that goes, because I'm out from early doors tomorrow, fishing, and will not be back until late, so I won't have a chance to look at it at all tomorrow.  

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Ed Kennell

It is possible to install the pump incorrectly....with the lever below the cam, but the pump should not work in this condition.

 

The lever must be angled up during installation to get the lever above the cam.

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Sutty
2 minutes ago, RandyLittrell said:

You might also pull the bowl off and see if you can make the fuel stop leaking by lifting the float up by hand. Does sound unusual and I really don't see how the pump could cause it. 

 

Does it leak fuel when the tractor is not running?

 

 

 

 

Randy

Yes, if the tank is full, it leaks from the same place, but I neglected to mention that because I'd forgotten, as a result of being in the habit of shutting the fuel off. I got into this habit, because it would smell of fuel, if I returned to it after some days, but with no obvious puddle of fuel, as such. Enough to smell quite strongly though, and wiping my finger at the bottom of the air intake it would be enough to wet my finger. Sorry to have forgotten that, and well done for dragging it out of me.

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Sutty

Okay, so it's looking more and more like my float valve is not stopping the flow, for some reason, and across two carbs, one being quite new, and doing it from brand new. How strange. On Tuesday I will also make the check to see if I can stem the flow by lifting it manually, in the absence of the bowl.

 

Thanks for the tips and fault finding suggestions. 

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Ed Kennell

OK, if the fuel leaks out of the carb when the engine is not running, there are only two possibilities.

1. the fuel is leaking past the float shut off valve.

2. the diaphragm in the fuel pump has a hole allowing fuel to fill the crankcase and leak out thru the intake valve into the carb.

 

# 2  is not very likely, but  very dangerous. :happy-bouncyredfire:

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Sutty

Okay, thanks for the clarity. #2 would additionally seem unlikely, because only some hours ago, I had the pump in pieces, and inspected the diaphragm, and saw no obvious wear or holes. Also, if it were leaking past the intake valve, would that not mean there would have to be fuel in the head, potentially locking it, or giving me issues with turning it over, which I don't have?

 

Can hardly believe I could get a second carb with the same issue, unless of course it's a common problem with them. If it does turn out to be the float valve, how can it be corrected, if I already have the adjustment horizontal when inverted?

 

Anyway, not to worry about that for now. I need to get some sleep for my early start tomorrow, and will report back on Tuesday after having had a look at if I can shut it off manually by lifting the float.

 

Thanks all so far.

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RandyLittrell
37 minutes ago, Sutty said:

Okay, thanks for the clarity. #2 would additionally seem unlikely, because only some hours ago, I had the pump in pieces, and inspected the diaphragm, and saw no obvious wear or holes. Also, if it were leaking past the intake valve, would that not mean there would have to be fuel in the head, potentially locking it, or giving me issues with turning it over, which I don't have?

 

Can hardly believe I could get a second carb with the same issue, unless of course it's a common problem with them. If it does turn out to be the float valve, how can it be corrected, if I already have the adjustment horizontal when inverted?

 

Anyway, not to worry about that for now. I need to get some sleep for my early start tomorrow, and will report back on Tuesday after having had a look at if I can shut it off manually by lifting the float.

 

Thanks all so far.

 

 

The needle itself has rubber on it that seals the flow of fuel, these tractors are old and it may be in bad shape. You might pick up rebuild kit or at least get out the magnifying glass. At least I do, since getting old!!! 

 

 

 

 

Randy

Edited by RandyLittrell
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Rob R

I like all the above suggestions.... I'll make one also sometime SOON make sure that prior to getting this problem fixed you check your oil to make sure some of the excess gas is getting into the sump and thinning out your oil.... would hate to see you fix the problem and do a long run on the engine and burn a bearing or seize connecting rod or worse. 

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jay bee

Not saying this is the problem here but a friend of mine overhauled his carb three times trying to cure this same problem.  Brought the carb out to me to have fresh eyes look at it.  Took it apart, checked float adjustment and everything looked good and worked as it should as far as opening and closing the needle and seat.  Took the float out and shook it......you guessed it, a tiny amount of fuel inside of float.  Replaced with a new float and problem solved.

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Sarge

Exactly my thoughts - leaking floats will show the problems you describe and no change in float height settings will fix it. That float has to, well, float...

 

If you want to test it, either shake it or heat it up in hot water and hold it submerged for a while with a stick and watch for bubbles. Some leaking floats are very tough to diagnose, the issue only comes up at certain temperatures when immersed in gasoline. The solder joints can have micro cracks you cannot detect - if nothing else it's a common and easily replaced float. Not unusual to find a brand new carb with a bad float, either.

 

It would be really tough for that tiny fuel pump to push enough pressure to overrun the float on a Kohler, but it is possible. One way to test is to run the line to the carb into a container and spin the engine over for 15 seconds with the spark plug disconnected - should only be a few ounces of fuel. You could also use a fuel pressure gauge on that line, should be around 3psi max if everything is in order.

 

As mentioned above, get the oil out of that engine. Flooding to that level will destroy the lubrication properties of the oil and in turn destroy the internal moving parts quickly. Hopefully, it hasn't already done any major damage.

 

Sarge

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Sutty

Just got back from fishing, and thank you all for the extra replies and information. I'll be dropping the carb bowl tomorrow, and will look carefully at the float. The float is plastic, and slightly see through, so it is easy to see if there is fuel inside. I've looked before and never noticed it, but I will look extra carefully tomorrow, as I perform the proposed tests.

 

As for petrol in the oil, I had that exact same problem on a quad bike that I own, and it was due to the previous owner having swapped out the vacuum petcock for a standard one, and me then leaving it in the on position for a protracted period, with the tank full. Got away with that one, without any damage. but could easily tell it was contaminated, because I could even smell it when I removed the oil filler cover. When I drained it all it was very obvious, stunk to high heaven of petrol, and even seemed a little thinner to me as I drained it out. Did a further change, after a little running, and all is now well, having fitted an aftermarket vacuum petcock, so as to benefit from auto shut off, so it won't be likely to happen again.

 

I will change the oil soon whether it smells of petrol or not, since it must be due, but I'll change it immediately if it does smell of petrol.

 

Thanks all.

 

Updates tomorrow.

 

EDIT: I'm losing the plot. It's a metal circle, not plastic. I was mixing it up with the quad I was working on last year. Will be sure to check it as described, and will start by shaking it, just to listen.

Edited by Sutty
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953 nut

On Ebay in the USA you can find new carburetors that work very well for about $ 35.00 US. They are made in China and are probably offered on your auction site too. You may want to check them out to resolve your problem.

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Sutty

Thanks, but it was new, from ebay, at around that price, not that long ago, after my first failed attempts to fix this issue. I felt sure a complete new carb would fix it, but alas, no. Not ruling out getting another, as you say they are cheap, but just pointing out that it is already new(ish).

 

Anyway, because I'm impetuous, and even though I've had a long hard day fly fishing, and doing a few jobs on my cabin, after what seems to have been a long winter, I couldn't help myself but to go and check a few things out. Donning my head torch in the shed, this is what I have so far. First, if I invert it, at the moment the float is almost level, but if anything a tad high, when inverted, but barely perceptible. Sadly, if I'm clear on how it works, high should in theory be more likely to shut it off, because it would be a fraction lower in the bowl, and the lever should press on the needle a little sooner and harder as the bowl fills. Nothing in it though, it is nearly level, so basically in spec. Second, with it inverted, and only the needle in place I can easily blow through a pipe attached to the inlet, thereby lifting the weight of the needle itself. If I part assemble it, I cannot blow through it inverted, with the weight of the float pressing down on the needle. No matter how hard I try I cannot budge it, and not a breath of air passes, so it seems to be sealing. And I wasn't just lung blowing, I was using my cheeks to generate some more pressure, but still, not a squeak.

 

Next, if I shake the float I cannot hear or feel any fuel sloshing around inside it. If I put it in some boiled water, and submerge it, I get no bubbles, so based on the advice received earlier this would suggest the float is sound.

 

Last, definitely last for tonight, I smelled at the oil on the dipstick, by smearing it on my fingers, and fortunately I can smell no petrol. I know this is a small sample size, but if it had been anything like my quad bike last year, every last drop of oil absolutely stunk of petrol. I could even smell it outside, 10 yards away from my garage where the bowl of oil was, after draining it, if the door was open and it was a calm day.

 

On this basis, and thanks to your instructions, I conclude that the float and valve work as they should, when I can see them, and test them manually, but whether they stick when all closed up again, inside the bowl, I guess I can't say. A nice colourless bowl would be nice, lol.

 

Not tried any pressure or flow rate checks yet on the pump. Wil have to see if I have anything to measure the pressure. 3 psi would be about 90 inches of water, from what I've just pulled up off google, if I have to resort to some sort of home fashioned manometer. I suppose that would work, if I can find enough clear pipe?

 

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Sarge

Are you certain there is no interference in the needle's travel as the float moves up and down? Some of those needles and their wire clips that keep them against the float tab can be a problem. If the wire clip has been bent down too tightly, it can bind in the arc of the float as it moves with the tab where the needle rests against it. Not uncommon to see these get bent up as folks try to adjust the float height. Do not trust those imported carburetors to be perfect when they arrive - very common to see metal fragments in them as well as float settings being way off. Genuine Kohler carbs are a much higher quality casting and when fully rebuilt properly will perform like new. Hold the carb in it's installed position and cycle the float/needle through its movement - at no point should that needle bind and not close off the inlet in a very positive manner. Just fyi - common automotive vacuum/pressure testing gauges are cheap and can show up to 8-10psi of fuel pressure being they are a dual type gauge - might want to pick one up.

 

Keep in mind, the float height and resulting fuel level in the bowl can also affect the engine's fuel curve. If it's set far too low, it can create a flat spot coming off idle. If you don't have the Kohler book for carburetors, there is a free pdf copy here in our files section - it would be a good idea to read through the section associated with this carb so you can fully understand it's operation and settings. With the flooding, it's amazing that the oil hasn't become diluted with gasoline - you must have a very good set of rings in that engine. Personally, I'd still change it often until you can figure out the issue.

 

Sarge

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pfrederi

Double check your float adjustment (11/64" between housing and float when held upside down.)  Got one of the cheap chinese cabs for a techy recently.  The float setting wasn't even close it was well over 1/2"

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Sutty

Guys, such excellent advice. I really do appreciate all these tips and help. Now for the news of my activities today. I took a lot of pictures, as I put the carb back together, and I decided to cheat a little with the float, and make it lift the needle a little more than spec. Who knows, maybe this cheap carb isn't really made to spec. I was going to put all my pics in, so you could look out for any rookie mistakes, but instead I'll mainly just put in the float angle, so you can see how much I've cheated by. Since so many people mentioned it, and because I also figured there's no point chasing issues of a sticking float needle, if I might keep reintroducing dirt into it, I decided next I should clean out the tank, and replace the filter and lines. Someone said it might seem like a big job, but it didn't and it wasn't. These things are built so well, and designed so cleverly, that it was a piece of cake. Two line clamps, and a spring clip to release the tank, and swivel the output tap to the right angle to pass through the slot. That was it. Awesome.

 

To my surprise though, and now a massive smoking gun in terms of contamination, when I got the tank and the lines off, there was no filter to be found. I didn't know where it should have been, or should be, but was expecting to find it when I did the disassembly. No such luck. Anyway, in its absence, I had an inline filter available in my workshop, so I have now stuck that in, part way along, where I can see it nice and clearly. Since I don't know where they are meant to go, hopefully this is in a decent spot, and is adequate. You can see it in the short video.

 

The lines that came off were still very flexible, without cracks, or wear, but it seemed sensible to change them too, as advised, especially as the hose is only cheap, and only 1 metre is needed in total. I didn't know how to clean out the tank, so I made it up. I drained half of the fuel, then closed the tap and then shook it vigorously for several minutes, and then drained that fuel too. I then squirted in half a can of carb cleaner, and repeated the shaking, then drained that. I then took the tank in the house, and with the tap closed, and the cap in place, I washed it in hot soapy water in the sink, just to get the outside clean.

 

Attached are pictures of the float angle, sorry it's not such a good picture, I didn't realise it was so bad. A picture of the drained carb cleaner, with just a few bits, and what I was able to filter out of the drained petrol on a tissue. Not many bits in there, but maybe enough to keep jamming up a float needle, in the absence of a filter. Doh!

 

The video shows it running, as it has now, at those medium revs, for some 30 minutes, without any fuel leak from the front of the carb into the air filter. I didn't want to run any harder or longer due to remaining doubts with regard to the oil, as has been explained to me. That's a job for tomorrow now, when after I will fill the tank right up again, and give it a real good run.

 

The issue seems to be resolved, because, as I should already have mentioned, that thirty minutes of running began with a brim full tank! I could not have done that before, without fuel soon pouring out at the front, and there was not a drop to be seen. Thanks everyone for all the help, it's been invaluable. One last thing to ask I suppose. Is there a preferred or recommended oil type to put in it, when I change the oil tomorrow?

 

Here is the video of it running, which also shows where I put the fuel filter.

 

 

 

 

 

 

 

 

 

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pfrederi

Looking good.  That is where i put most of my filters....

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Sutty

I see I got moved to Engines. Sorry mods, I just saw wheel horse tractors, and thought that's where it should go. Thanks for sorting that out.

 

Thanks, it's good to know that this is an okay spot for the filter. Maybe my question for tomorrow got lost in my rather long post, I know I go on a bit, sorry, but I was hoping to change the oil tomorrow, at which point I'll also likely find out if it's contaminated with fuel or not.

 

I've tried to understand what oil people are using, or should be used in accordance with the manual too, but I get a little confused when it comes to oil. If I've got it right, for the temperate conditions here in the UK, I can use single grade SAE30, for my K321S. The table in the manual states for temperatures above 30F use SAE30 and states some multigrade options for lower temperatures. Since it's hardly ever less than 30F here, and even when it is I  likely won't be using the horse, I'm thinking I should get that, but, I don't think I've ever seen a single weight oil like that in the typical supermarket locations from which I normally get oil. I read, if I use multigrade, say 10W-30, recommended in the manual for temperatures down to 0F, I may use a little more oil, but does that really matter too much, if I check the oil level? Plus, how much more would we be talking, if indeed I understood what I read correctly? I mean I can easily pick up some synthetic 10W-30 tomorrow. That then begs the question, what about synthetic oil or not? I could guess that this 40 year old engine was built expecting to be run with normal oil, not synthetic, but surely if the spec is correct, modern synthetic oil should be fine too, and maybe even a little better, with all the modern additives in there?

 

Any bog standard 10W-30 from the supermarket, like castrol GTX okay? I could get this from Halfords tomorrow, which is just a mile away from me.

 

Maybe I didn't understand what I read at all though, so some guidance would be appreciated.

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