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edbeek
10-05-2011, 08:32 PM
Wondering if anyone might be able to give me a new clue regarding an old Kohler K141 side valve motor on a Howard 350 Rotavator.

It had been in storage for quite a while until I got it.
I've been working on it in spare time for quite a while now, and could never get it to rev up properly, and when it did it would be intermittent.
I've now got it to the stage where it will start first pull, and work perfectly for about 10-15 minutes. It will rev up and down with the throttle, and the governor works fine when I put it under load.

Thinking I've got it fixed, I idle it down and then it doesn't want to rev up again. Pull the throttle on and the governor opens right up and the motor wants to stall(gearbox & tiller disengaged). Close the throttle and it will idle perfectly. If I sneak on the throttle very slowly, I can sometimes get it to rev up fully, but the engine hunts on the governor. The more I try after this, the less the engine wants to do anything.

Come back tomorrow, and I'm sure it will run perfectly again for a short time.

So I'm thinking something is going wrong as the engine heats up.
It doesn't seem to be overheating. I've had the cowls off and cleaned out the fins, and there is a good breeze off the flywheel that doesn't feel too hot.
I've put new points, condenser and plug in.
Had the carby off and cleaned countless times.
Adjusted the float level.
Cleaned out the fuel tank and gauze strainer.
Doesn't blow smoke when it's running good.
Same symptoms with air cleaner on or off.
Plug stays nice and clean when it's running good, but sooty after it starts coughing.

My thoughts now are that maybe it has an intermittent leaky head gasket(when it warms up) or maybe a valve problem as the engine warms up.

I'm pretty sure I have all the normal problems covered due to it running nicely for 10-15 mins, so hoping for other ideas before I do more major surgery on it.

gcsmow
10-05-2011, 09:55 PM
I would recommend having another look at the fuel tank and cleaning it out again. Take it off pour a little bit of petrol in it, shake it up then tip the contents in to a clean pot then have a good look at what comes out. I always do this 3 times but if there is more crap in their do it a few more times, could have been something in there you missed.

Tighten head bolts, and carburettor bolts and screws to make sure there are no leaks.

Maybe you should take the head off to see what condition the valves are in, they may need cleaning or re-seating.

Is the muffler choked up with crud ?

Is there any hornets nests?

What is the compression like?

Glenn.

edbeek
10-05-2011, 10:28 PM
Hi Glenn, Yes I keep thinking about the fuel tank although it was pretty good and the strainer wasn't blocked.
Was just reading the book, and it has an auto decompressor on the exhaust valve cam. Works on centrifugal force to open the valve slightly at under 600rpm. I'm suspicious of this now. Looks to be a hassle to get a look at it though.
New muffler
Cleaned out all nests and debris
Can't test compression due to decompressor.

I'll set it up so revs can't get under about 800rpm tomorrow and see what happens.
It was a bit overfilled with oil, so maybe the fly-weights on the decomp mechanism are fouled by the oil, and not opening properly to let the exhaust valve close.

Thanks for your help.

SouthCoast Walker
11-05-2011, 01:14 AM
Have you adjusted the mixtures? Does it have a choke? If it has a choke try increasing the revs with the choke on and then backing the choke off, if that works it could be lean on the mixtures. My 16hp Kohler on my walker was doing a similar thing, couldn't accelerate without the choke on, I richened it up a bit and it now works fine.

edbeek
11-05-2011, 07:23 AM
Hi SCW,
I'm pretty sure I've got the carby tuned OK, because it will run sweet as for so long.

I'll give it another go this morning and probably pull the head off and have a look.

Funny thing is I'll probably get my vege garden and any garden beds I ever want ploughed up before I get the machine working properly. :)

gcsmow
11-05-2011, 11:16 PM
Did you know that Kohler also make toilets ? True story.

Blueline
12-05-2011, 05:30 PM
Check your fuel cap to make sure its venting,sounds like a fuel,inlet problem, cheers mick

edbeek
12-05-2011, 07:42 PM
I'm pretty sure it was the auto decompressor that was causing most of the probs.
I've now set the idle up pretty fast, to take it out of the equation and it seems to respond pretty good now. It still hunts a bit on full throttle with no load, but it knuckles down nicely when I load it up.
My theory now is that from sitting in storage for so long, the governor and decompressor that are internal, and work on centrifugal force, may have got sticky and weren't operating smoothly.
Speeding up from idle, the governor would snap over to fully open the carby instead of opening it gradually. Then the motor would falter and revs drop to the speed where the decompressor activated and opened the exhaust valve as if in starting mode.

Anyway, I'll give it a good workout over the weekend and hopefully it will be ok to do some vege garden preparation jobs over winter.