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Old 08-21-2020, 04:48 PM   #1
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Kohler Genset Pressure Switch Confusion??

Hello,

Odd issue here, maybe its just me...here goes.

Changing my 8E0ZD genset air filter yesterday and afterwards I was just looking around the genset area with a flashlight and I saw what looked like a pressure switch screwed into the heat exchanger manifold...upon closer look I saw only one wire was attached and I saw another wire that was not connected to anything. Hmmmmm...It was obvious that it was supposed to be connected to the other terminal of that switch but it clearly was not yet my generator still ran fine??

After some reading, it was found to be the LWP pressure switch (Low Water Pressure), it takes .5 PSI of impeller water pressure to close it, and it then provides a ground to P1-28 of the ADC module, however it shares that input with the ETS, (EAttachment 106852ngine Temp Sensor), which also provides an input.

Anyway..I ordered another LWP switch to be safe and today after noticing that the old one had a small leak I decided to replaced it and I connected "both" wires up this time ...but when I started the genset, it stopped after 30 seconds with a "LOC" code (Loss of Cooling) ??..I then checked with a meter and the switch closed after a slight pressure applied, so it is good..

Furthermore,.the schematic shows both sensors, LWP & ETS being tied together as they are, should provide a ground to P1-28 of the ADC module,.. under normal conditions, if either open, (no ground input) to pin 28, after 25-30 seconds, the ADC stops the genset...

My questions are--(If I am understanding this correctly so far)...

1. Why does my genset still run with the LWP wires completely disconnected?

2. Why does one section of the manual (Fault Shutdown Switches) say the ETS is "resistance" type, yet the wiring schematic shows an ETS that provides a ground to stop the genset from an when overtemp?

Comments and suggestions welcome..

Thanks...
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IMG_20200821_150628.jpg   sensors2.jpg   ets.jpg   sensors.jpg  
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Old 08-24-2020, 07:08 PM   #2
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Jeff
Not sure I can help as I haven't been into my gen at that depth... have changed anodes & air filter but that's about it.
I don't have my oper manual at home so can't look at mine. I don't recall the Ht X Chgr having a P Sw or any wired sensor in it but only my memory??

I'll attach the Service Manual PDF I have which lists other sensors & operation. (also available in the TF Library - Manuals)
I noticed a time delay used for a Low Oil Press Sw while starting and it has me wondering of the LWP Sw also has a time delay to let press build?- If so could it be the time delay is faulty?
Could it be an air bubble in the Ht X Chgr not opening the P Sw?
Hope the Service Manual helps and doesn't just add confusion if not applicable.

Please post your findings when you get it figured out.
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File Type: pdf Kohler Gen Set Service Manual.PDF (2.45 MB, 9 views)
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Old 08-25-2020, 12:09 AM   #3
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Im having a hard time with the info provided. Obviously more detail would be better. In your diagram under the picture that shows the three switches...it seems to me one of those is not drawn correctly. It seems to me the LWP is drawn in the normally open position when it may be that its supposed to be in the normally closed position. .5 PSI opening the switch. It seems to me that any of the three providing a ground would shut the engine down.

These switches can be ordered normally open or normally closed. Are you sure you have the right switch ordered? You stated yours closes with slight pressure. I am thinking it needs to go from closed to open with slight pressure. Otherwise it seems that P1-28 circuit cant work.

Without more details its hard to diagnose.
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Old 08-25-2020, 01:54 AM   #4
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jefndeb, once upon a time I found a disconnected wire on the exhaust line of my Onan while I had the sound shield off for something. "That needs connecting" I thought, so I did, thereafter it would not start and displayed its fault indicator. It was not even warm, let alone hot, someone must have discovered an overheat sensor fault and uncoupled it. Genset ran perfectly for the next 9 years. Sometimes there is a reason something is disconnected.
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Old 08-25-2020, 05:41 AM   #5
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Quote:
Originally Posted by Barking Sands View Post
Im having a hard time with the info provided. Obviously more detail would be better. In your diagram under the picture that shows the three switches...it seems to me one of those is not drawn correctly. It seems to me the LWP is drawn in the normally open position when it may be that its supposed to be in the normally closed position. .5 PSI opening the switch. It seems to me that any of the three providing a ground would shut the engine down.

These switches can be ordered normally open or normally closed. Are you sure you have the right switch ordered? You stated yours closes with slight pressure. I am thinking it needs to go from closed to open with slight pressure. Otherwise it seems that P1-28 circuit cant work.

Without more details its hard to diagnose.
Above consistent with my thoughts after scanning through the service manual.
When I looked up the part (not by # but by LWP function) it was listed as NC contacts which makes sense to me.
When Any one of the sensors close it should activate the fuel stop. Thats the reason they build in a delay for the LOP to allow time for oil P to build.
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Old 08-25-2020, 08:18 AM   #6
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Yes,..i agree that the switch seems to be wrong..maybe the part number from the service manual is wrong?....I compared both and they both closed with a little pressure....which explains why it was disconnected....

I wonder how to find and that same switch but in the opposite config?
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Old 08-25-2020, 08:37 AM   #7
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Try this -its the one I saw w/ NC contacts
https://marinepartssource.com/pressu...kohler-gm30263
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Old 08-25-2020, 08:46 AM   #8
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Ha, thats the one I ordered...i did find this info,,,has a different switch part number..maybe this is the answer?


https://www.colburnpower.com/mwdownl...d/link/id/226/
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Old 08-25-2020, 11:34 AM   #9
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OK, i talked to Nixon Power Services and there is a retro kit that provides the "correct Switch type" it seems....i have to do some more checking but it looks like the actual switch pn is GM77653. I will most likely just order the kit...



https://www.colburnpower.com/kohler-...e-service.html
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Old 08-25-2020, 12:13 PM   #10
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Let us know how it turns out. Just make sure you have continuity between the contacts when you get the switch and if you can test that the contacts open with pressure. Occasionally even the manual of an OEM is wrong. I wonder how many Kohler gens are running around with those wires disconnected...lol.

Even aircraft manuals are wrong at times. Rare..but it does happen.
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Old 08-25-2020, 12:23 PM   #11
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TT-1578 Seawater Pressure Switch Kit GM81332

Here is what I think i need.
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File Type: pdf TT-1578 Seawater Pressure Switch Kit GM81332.pdf (133.0 KB, 11 views)
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Old 08-25-2020, 12:31 PM   #12
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I wonder if Kohler has a recall or might provide the right switch for free.
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Old 08-25-2020, 12:33 PM   #13
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There's something to be said for "if it ain't broke, don't fix it". Sometimes my OCD gets too strong for my own good.
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Old 08-25-2020, 12:48 PM   #14
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Quote:
Originally Posted by Swfla View Post
There's something to be said for "if it ain't broke, don't fix it". Sometimes my OCD gets too strong for my own good.
My OCD--Everything broke must be fixed!

But I do get quite a bit of enjoyment of bringing things back to life as they were designed. It doesnt have to be pretty..it just has to work correctly.
I just spent the last few days getting my shower sump system working exactly as it was designed...lol. I dont think it has been worked on in 35 years. Had to change all hoses, float switch, clean out the brown goo...What great fun!
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Old 08-25-2020, 01:06 PM   #15
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LOL. I get it. It's unlikely you will cause any serious damage, so enjoy!
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Old 08-25-2020, 02:35 PM   #16
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I'm confused too. I have the same genset, 2003 model, and I don't have an LWP switch. The wiring diagram in the manual doesn't show one either. Maybe they added one in later years.
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