[AT] Kohler engine update - still having trouble

[Stephen Offiler]

Yes, what Larry said.

The line between the pump and the crankcase is what pulses the diaphragm.  It is alternately pressure (piston down) and suction (piston up).  These pulses flex the diaphragm back and forth and create the pumping effect, with the help of a couple tiny flap valves.  I’ve never seen a big obvious tear in a diaphragm.  I think they leak a tiny little bit only during the suction part of the stroke; you tend to get a lot of raw fuel accumulated in the crankcase simply because you get a tiny bit of fuel about 3600 times per minute or so.

SO


> On Jul 28, 2015, at 8:11 PM, <rlgoss at twc.com> <rlgoss at twc.com> wrote:
> 
> The diaphragm is in that round plastic area. It probably is nothing more than a pin hole where the spring rests against it, and may not be detectable.
> 
> 
> Larry
> ---- Mike <meulenms at gmx.com> wrote: 
>> Ok, so I started the engine, and pulled the line off the fuel pump that 
>> leads to the crankcase, no fuel leaking through at all, just suction. 
>> Shouldn't it be leaking fuel through that hose if the diaphragm is ruptured?
>> 
>> Thanks,
>> Mike
>> 
>> On 7/28/2015 7:31 PM, Steve Offiler wrote:
>>> Yup.  I've had two or three different Briggs with this problem.  It explains the raw fuel in the crankcase - fuel pump is a pulse-type and torn diaphragm opens fuel tank straight to crankcase.
>>> 
>>> SO
>>> 
>>> Sent from my iPhone
>>> 
>>>> On Jul 28, 2015, at 6:52 PM, <rlgoss at twc.com> wrote:
>>>> 
>>>> Blown diaphragm in the fuel pump.  It sets on top of one of the rocker arms.
>>>> 
>>>> 
>>>> Larry
>>>> --- Mike <meulenms at gmx.com> wrote:
>>>>> Several days ago, while mowing with my Simplicity Sovereign, Kohler
>>>>> CH18S) I completely blew out the front oil seal. Today, I replaced the
>>>>> seal, cleaned the carb, and put the crankcase vent tube back where it
>>>>> belongs. I figured since the tube had been exposed that I would change
>>>>> the oil and filter as well. When I drained the oil, I noticed it was
>>>>> very thin,  so I stuck a finger in the stream, and sure enough it was
>>>>> raw fuel. I put everything back together,and it started right up. I made
>>>>> two passes around the yard, and it was smoking so I check and it was
>>>>> already pushing oil past the seal. For some reason I am creating too
>>>>> much crankcase pressure. I pulled the crankcase vent tube and check for
>>>>> any obstructions, I found none. Any ideas what to check for? If I keep
>>>>> running it, it will just blow another seal. Thanks in advance.
>>>>> 
>>>>> Mike M
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