Generator Issue. 1998 Kohler 4kW

Discussion in 'Electrical Stuff' started by Little Ducky, Jul 13, 2019.

  1. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    In the 2 years I've owned this 1998 290 DA I've never really ran the generator for any length of time. Just enough time to do a Keurig coffee or use the microwave for a few minutes.

    So I went out for a brief swim and I decided to run the generator and keep the AC running.

    About 15 minutes later the generator stops. Can be restarted and then off again in 10-15 minutes. Coolant bottle full (not over heated) and water was flowing nicely out the exhaust. I'll check oil and feel around to make sure everything is snug when it cools off or tomorrow morning.

    I do have less than 1/2 tank of fuel on board if that makes any difference....so I was going to top off tomorrow as well and see if that changes anything.

    Wondering if the fuel pick up is higher in the tank than the engines?

    When the generator shuts down it just sounds like someone flipped the switch to off.

    I'll pull out the book and do some trouble shooting tomorrow.

    If anyone has any suggestions post them up.

    Thanks
     
    Last edited: Jul 14, 2019
  2. Wanderer 290

    Wanderer 290 Member

    101
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    Sounds like either an overheat condition or possible circuit board failure.

    You can pull the cover on the pub and see if and led’s flash a code.

    Yes the fuel p/u for the generator is shallower than the engine fuel p/u’s.

    Also it rpm steady up until it shuts down? If rpm varies the voltage regulator will shut down the generator.

    But I really suspect an overheat condition which is due to air in the heat exchanger.
     
  3. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    I thought I had an eureka moment today with regards to my generator issue.

    Gave the generator a good once over checking oil, coolant and strainer to make sure those are good to go. Then I found a spring ("governor linkage" according to the manual) disconnected. Once reconnected the generator started like it never did before and found it's idle immediately.

    Ran for a few minutes and then I loaded it up by turning on the AC. It took a very quick dip and then hummed away putting out 120v without any "wha, wha, wha" like before. I though it was it...... yes ....... running better then ever.

    I celebrated briefly ..... about 10-15 minutes went by then........ brrrrrrrrrrrrrrrrrrump. It shut down like before. :(

    So I'm going to order up a new pump impeller this week and change it out. I didn't want to take the plate off to inspect w/o having one on hand.

    I'll update as needed.
     
  4. Wanderer 290

    Wanderer 290 Member

    101
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    On top of the heat exchanger there is a small plug for for bleeding the air out of coolant side of the cooling system. Remove that plug and check the coolant level inside the heat exchanger. The coolant level should be almost overflowing. If not add coolant through the plug hole, make take several small doses over a period of up to 5 minutes, until full and re-install plug.
    Let me know what what you find with the impeller. If the impeller is in bad shape there may also be pieces in the exchanger that need to be removed too.
     
    susanandlance and Little Ducky like this.
  5. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    Just did one trouble shooting item last weekend and that was filled the boat with fuel.

    Generator still quit after 10-15 minutes of running.

    I read a bunch online this week with similar issues and some were fixed by replacing the spark plugs. They are cheap enough so I bought 2 to put in the next time I visit the boat.

    I also have:
    - Fuel/Water filter
    - New zinc
    - Impeller/O ring

    I'll also look further into the coolant system to see if there is any air in the system to rule that out.
     
  6. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    Just an update on my generator operating condition:

    Things I did so far:
    - Changed the impeller (old one was still in one piece)
    - Changed anode (old one broke off). Had to push the old one in to install the new. In doing so I had to remove the heat exchanger so I flushed out all sides, removed some old rubber bits from previous old impellers.
    - Replaced coolant and burped the system of air. Topped off until it won't take any more while observing coolant circulation.
    - Replaced both spark plugs. (Read where this might be an issue)
    - Replaced both exhaust temp sensors after finding a broken one.

    Generator still only runs for 15-20 minutes then turns off.
    Will start right up and continue to run with start button pushed.

    Things I'm going to do next:
    Add a little more oil (10w40) to see if it solves any pressure issues. (read about this while searching for a fix)
    Check / Replace the low pressure oil switch.
    Check / Replace the water high temperature switch.
     
  7. Wanderer 290

    Wanderer 290 Member

    101
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    Check your generator brushes. If the voltage regulator senses less than 120 volts it will cause a shutdown.
    Verify rpms are steady at 3600 - 3700. The rpms can be checked with a timing light that has the rpm function but because the plug wires are shielded you need to splice in a regular plug wire so that the inductive pick up senses the pulses.
    You can also disconnect each sensor, oil, water temp and exhaust temp one at a time and see if the run time exceeds previous?
    Monitor the operating temp with a infrared heat sensing gun to avoid and actual overheat condition with either temp sensor disconnected.
     
  8. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    I guess I needed to add it runs like a champ. RPM's are steady whether it's loaded or unloaded. The voltage indicator reads a steady 120v and when turning on the HVAC it only blips for a second when the compressor kicks in and then back to 120v. Loaded or unloaded it shuts off in the same amount of time.

    I'm going to look into the other 2 sensors and then probably turn it over to the local Kohler mechanic the marina uses.

    I'm not one to toss parts at something but the sensors are pretty resonable so I have them being sourced to have in hand.

    This was the one exhaust temp sensor when gave me some hope.

    2019-08-15 17.50.18.jpg
     
    Last edited: Aug 22, 2019
  9. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    Sometimes it is just easier to put a couple of mechanical gauges on it to see what is going on. The two other safeties are oil pressure and engine temperature. I would speculate that your unit is overheating based on your comments so far. The impeller creates a pressure of around 3 psi in the raw water cooling system.

    If the hull intake, strainer or connecting hoses have any blockages.....the pressure will drop and not pass enough water to cool the heat exchanger. After about 15 minutes....the unit will shut down.

    Frequently.....the pressure will drop to around 2 psi and still look like it is pushing "enough" water. A tell tale sign of a raw water cooling problem is the exhaust water is warm. The other possibility is that the heat exchanger is clogged which means even with enough water pressure....it can't remove the heat from the engine.

    A possible indication that the heat exchanger is clogged is the problem you had with the zinc replacement.
     
    Little Ducky likes this.
  10. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    When I had the heat exchanger off the generator I flushed both sides out throughly. For what I could see it looked pretty good on the inside. A good bit crap came out of the coolant side so I flushed with water until clear water exited.

    The exhaust water is surprisingly just a few degrees above the river water and the strainer is clean.

    Now one thing I just remembered when I cleaned the strainer at the end of the season the strainer had 2 gaskets one cork and one rubber...... I removed the rubber one. Even though it's not leaking river water maybe it's sucking some air into the system when the generator runs. I'll track down that gasket and put it back into position when I'm back on the boat.
     
    PlayDate likes this.

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