Next challenge .. genny shutting down?

dont have warmup/preheat i am aware of... getting what appears to be good flow out exhaust, suck more than can provide by hose when flushing..

think im going to try and test sensors then pull the exchanger... im a freak about flushing but i know the last 11 yrs previous owner, it was never...
 
I cannot speak for your generator, but my 6.5 MCCK Onan has normally closed sensors that are wired in series with each other. On start up, they are all bi-passed. After running for a while, that automatic by-pass is removed. If any sensor was faulty, it would open up and shut down the generator. If your generator has a similar control configuration, I would suggest that you temporarilly by-pass all of them. If the generator keeps running and does not shut down, remove the by-pass for each sensor one at a time to find the culpert.
 
When it quits pull a plug and see if you have spark. If you do it's not a sensor of any kind that is failed or correctly causing the shutdown; it's a fuel issue.

Fuel is mostly likely the shutdown (anti-diesel) solenoid or fuel pump, but could also be the filter or fuel valve solenoid.

I had these problems on my old boat. Drove me crazy. Replaced the anti-diesel solenoid and fuel pump and problems went away.
 
UPDATE

i pulled the heat exchanger and noticed some scale build up in hose and entry to exchanger..

soaked in CLR overnight, crud did come out upon flush

reinstalled and left out the thermostat...

SUCCESS! ran great and ran overnight running AC

so, its always warm water here and will be upper 80s soon.. do i really need the thermostat? my lazer thermo battery was dead so couldnt measure temps.. seems running as cool as possible in FL summer would be better..??
 
UPDATE..

well sh*t.. back to the same issue.. runs up to temp.. shuts down... let sit a bit.. same thing...

going to pull the temperature switch sensor and do the boiling water test... hopefully thats the issue...
 
If you're not careful you'll let that generator ruin your summer!!! I've done more cussing about generator issues.....it's enough to drive a man to drink.

Isn’t the point of putting engines in the hull to drive us to a drink?

On a more serious note, I’m in the create a jumper and find the bad sensor crowd. Had to do it for a bad temp sensor on mine. Small wire and two crimpable spade ends
 
UPDATE... back to the genny

I pulled the temp sensor and tried the water in pan test.. I never could get the sensor to close?

am i mistaken ... the sensor loop for Kohler is open? correct?
 
Did you ever get all of the air out of your cooling system with the bleed screw? Kohlers are funny about that, they dont appreciate air bubbles in the system. One more issue, when it quits, is it under load? Another Kohler quirk, some dont like to run without a load.
 
Did you ever get all of the air out of your cooling system with the bleed screw? Kohlers are funny about that, they dont appreciate air bubbles in the system. One more issue, when it quits, is it under load? Another Kohler quirk, some dont like to run without a load.

yes, tried my best to get all air out..
its been under load and not...

i did top off the oil... read that Kohler reads the oil from the stick not threaded down..

tested this weekend and it ran for 20 min no load and i shut it down...? hopeful..
 
Have u inspected the impeller? u can still have water flow with a damaged impeller. I’d remove the impeller cover and impeller,$(30 buck replacement) A fan blade could be in the hose leading to the exchanger or in the exchanger. Try placing garden hose on the generators water line and back flush towards the impeller. Then back flush the exchanger towards the water inlet. Could be a sensor issue but checking the impeller than the water flow through the system would be a first step.
 
Have u inspected the impeller? u can still have water flow with a damaged impeller. I’d remove the impeller cover and impeller,$(30 buck replacement) A fan blade could be in the hose leading to the exchanger or in the exchanger. Try placing garden hose on the generators water line and back flush towards the impeller. Then back flush the exchanger towards the water inlet. Could be a sensor issue but checking the impeller than the water flow through the system would be a first step.

i have removed the hose from pump...inspected and cleans .. clear
impeller was like new when i checked it, soft malleable, no bad bend memory..
thanks
 
Sorry I'm late to the fun! You didn't mention that you had cleared the raw water intake port which is the source of a lot of partial blockages (unless it was related to the hose/strainer comment).

If the intake is clear.....I believe you have chased the temperature related issues. The issue that remains is oil pressure which when the oil gets hot....the oil pressure can drop that triggers the sensor. Westerbeke had a slew of issues with low pressure oil switches which would shut down the generator as it got older. Kohler used a number of the same sensors. The sensor set point was too high for an older generator with less oil pressure. It was a pain to diagnose because it looked like a temperature issue but it wasn't. Sometimes the wrong oil would trip it.

The way that the sensors generally work is that the Exhaust water temperature, and engine temperature sensors are normally closed. The oil pressure switch is Normally open. The oil pressure switch closes when the generator starts (the startup sequence bypasses the switches). Once it starts, oil pressure keeps it closed and the circuit is complete unless one of the closed sensors opens up and the control board loses sensor connectivity and the shuts the generator down.

The sensor circuit is hard to diagnose because of the mix of sensors. I got to the point years ago that it was cheaper for me to put a set of helm gauges on the generator for oil pressure, temp, fuel pressure and alternator output (in tandem with the safety switches) than it was to keep guessing what is going on. The newer generators add safety switches for CO and coolant levels.

If you post the model number....I will see if I can find the schematic for your model.
 
PlayDate... thank you.

intake appears to be clear to pump..
i thought the 3 sensors were all N.O.

Do you suggest I replace the oil pressure sensor?

 
I would first bypass it to see if it helps. The trick to testing the sensors is to do the testing after the generator shuts itself down and won’t restart. A small set of alligator clips is ideal.

If you think about it the temperature sensitive sensors (exhaust and engine) are normally closed and open when they get too hot.

In the case of the oil pressure...it starts at zero and is normally open with a set point at 8 psi. The start sequence bypasses the oil pressure safety until oil pressure rises above the set point. It’s closed above 8 psi which is when the engine is running. If while the engine is running oil pressure drops below 8 psi you want the generator to shut down.

So it is almost the inverse of the temperature safety switches.

I’ll look up your model this evening.
 
If you're not careful you'll let that generator ruin your summer!!! I've done more cussing about generator issues.....it's enough to drive a man to drink.

I'm telling ya.....it's July 17th.....I've been down this path! :)

Joking aside I hope you get it figured out. You're getting a lot of good advice here (my comments notwithstanding).
 
The Kohler manual is excellent. It’s a bit hard to read on an iPhone but my first take is that the temperature sensors on your model are indeed normally open to ground meaning they have one wire on them. Other generators daisy chain the safetys together so that they make a single circuit. If your sensors reach a high temperature set point they close to ground and tell the control board to shut down the generator.

You have two oil pressure switches one closed and the other open which are probably used together by the control board.

The manual makes reference to a set of leds on the control board which should indicate if the K4 relay was tripped indicating a safety shutdown.

Do you recall seeing these leds and do you have a copy of operation manual?

To bypass a temperature sensor on a 5e is just a matter of unplugging a sensor.

The oil pressure is a little more complicated.
 
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