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Westerbeke 15kw diesel gen stalling

Discussion in 'Generators' started by CSkipR, Mar 30, 2013.

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  1. CSkipR

    CSkipR Member

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    My generator seems to run for 10-20 minutes and then start sputtering and die. If I hold the preheat switch down it will continue running. Any ideas? I've done the basics changing racor, line and bowl filter.
  2. NYCAP123

    NYCAP123 Senior Member

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    Have you checked the water flow and thermostat? I;m susoecting an overheat.
  3. Capt J

    Capt J Senior Member

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    If you hold down the preheat and it continues to run, then it is shutting off on a safety switch. Check all of your basic fluid levels. Check water flow, your sea-strainer and impellor. How many hours are on the unit? If these all check out ok, then when it does it, verify water temp and oil pressure, your boat has gauges for both on the panel. If they're ok, then disconnect 1 wire from each safety sensor and see which one it runs on. There should be a sensor for oil pressure, one for water temp, one for exhaust water/temp...... until you figure out which sensor is going bad......
  4. Capt Ralph

    Capt Ralph Senior Member

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    Skip
    What work did you do checking the bridge run light? Did you bump or loosen any wires? Make any changes?
    If so, work back-wards and undo anything you did and check (re-check) any terminal connects.
    Capt J is on the money on trouble shooting a bad sensor. Yep, they go bad.
  5. CSkipR

    CSkipR Member

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    Westerbeke 15kw

    NYCAP123 - water flow is great and no overheating. Gauges confirm as well as I shot with ir gun. Seastrainer clean.
    Capt J - all fluids are good (oil & water) new impeller. 1108 hrs. Regarding the preheat switch I only pushed it down when the engine started to stall and it seemed to correct the stalling although I didn't hold it down for a very long.
    So if I disconnect one wire from each sensor (1 at a time) and the engine quits what is that telling me its good. If it continues to run is that telling me the sensor is bad?
    Thanks
  6. CSkipR

    CSkipR Member

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    Rcrapps never got the light working and gave up on it. I stick a 120v plug with light in the outlet on the bridge so I can see if its running or not.
  7. Capt J

    Capt J Senior Member

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    Exactly, whichever one it stays running without is your culprit. You may also be able to ohm the shutoff switches, but if it's intermittent you may not find it that way. I've seen various sensors go bad on westerbekes with the amount of hours you have. Usually it's the water temp shut off sensor, next up would be the exhaust temp sensor, the oil pressure sensors usually last.
  8. Marmot

    Marmot Senior Member

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    Since the safety switches are normally closed except for the oil pressure switch, pulling a wire off will ensure it won't run.
  9. Capt J

    Capt J Senior Member

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    You might be right......He might have to jumper the two wires versus unhooking 1 wire. I couldn't remember if they were normally open or normally closed switches.
  10. CSkipR

    CSkipR Member

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    Westerbeke 15kw

    Capt J & Marmot
    Okay my first issue is locating the 3 sensors. Went through the parts diagram on the internet and not sure I located the sensors.
    Can you help me identify them? They are sensors and not solenoids correct?

    Once located and if they are normally closed what is my next step. You say jumper across the two wires. Are their two wires that are connected to the sensors? Are the two wires inside the connector?

    Thanks
  11. Pascal

    Pascal Senior Member

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    Look at the wiring diagram to ID the color of the wires.

    The Oil press switch should be on the block with a single wire attach to it. The coolant sensor will be in the cooling system, near the Tstat. Don't confuse them for the gauge senders. Exhaust temp switch will be in the exhaust where water is injected

    Indeed some switches are normally closed, others normally open. If normally open then did in disconnect one at a time till it stays running. If normally closed then ground its wire.

    I ve had oil press switch go bad, never a coolant though. So start with OP switch
  12. Capt J

    Capt J Senior Member

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    It should have 2 wires connected to each sensor. The sensors will look like a small spark plug almost but without the part the spark plug boot would go over and shorter, they'll have a nut looking flange on them like a spark plug that you would put a wrench on to take the sensor out. The sensor will have two terminal posts on the top of it, either two straight blades or 2 small studs that the wires either push on or have a small nut that holds their terminal end on. I cannot remember what Westerbeke uses as it's been a while since I've worked on one...... but you're also going to have similar looking ones for your oil pressure and water temperature gauges. If you have the schematics, follow the wiring for the shut off circuit to them. I can call a buddy of mine and he'd know where they are....or a good westerbeke dealer will tell you over the phone. The one is on the exhaust elbow, near where the rubber exhaust hose (that goes to your muffler) is located. Also at 1000 hours that exhaust riser elbow likes to go bad and you should consider changing it (thermostat housing also usually lasts 1000 hours on Westerbeke). The other one (water temp) if memory serves me right is on the front of the motor just above the fresh water pump and on the block near the thermostat housing....near the top of the engine on the front side......
  13. Marmot

    Marmot Senior Member

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    The oil pressure switch (2 wires NO) will be found very near the oil pressure sender (one wire) near the oil filter. The water temperature switch (2 wires NC) is on the outlet of the thermostat. The exhaust temperature switch (2 wires NC) is on the water injection elbow just downstream of the water injection point. That one is normally closed as well ... disconnnecting it will shut down the engine. The oil pressure switch is normally open.

    Please note the edits on the above paragraph. I made a mistake in the original and wrote that the exhaust switch was NO. It is NC.

    Go to Radio Shack and buy a little packet of alligator clip jumper wires. You can use them to connect the "sockets" on the sensor plugs to imitate a closed switch which is normal for the water temperature and exhaust temperature. The oil pressure switch is normally open (no circuit) until oil pressure builds up and closes the switch. That is why you hold the heater button on, it provides time for oil pressure to close the switch and when that happens the safety circuit is complete and the engine will run. The safety circuit is a loop with 3 switches in series, any one of them going "open" or off will shut down the engine. You are trying to fool the circuit into thinking all the switches are closed.

    If your clips won't quite fit into the socket, use a couple of little paper clips or tiny nails to reach the contacts so you can connect the clips. Use a helper because you really need three or four hands or you will go nuts.
  14. Capt J

    Capt J Senior Member

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    Your boat should have the Westerbeke 15btd
    OK, see diagrahm http://www.westerbeke.com/WiringDiagrams/12B-82B_108C_(39144_rev_j).pdf

    oil pressure switch will have 1 red/white wire piggybacked with a light blue to the same terminal, and 1 light blue on the 2nd terminal

    Water temp switch has 1 TAN colored wire

    http://www.westerbeke.com/OnlineManuals/37115_rev2_12C_20B_30B_Parts_List.pdf You have the 3 cylinder.

    See page 120, the water temp switch you're looking for is #18 and on the thermostat housing neck.

    See page 144 (page numbers are the number on the left side of the manual.) You're looking for #43 in the picture. I believe that is near the oil dipstick slightly above it and to the right.....

    Also, another thing that causes exactly what you describe and I've replaced many of them on Westerbekes is the fuel solenoid, it is round about the width of a C battery and about the length of 2 of them, then has a rubber boot on a shaft that pulls a lever......it is mounted right in the middle of the generator, on the side where the oil dipstick is and mounts sideways. When you hold the preheat button down, the solenoid pulls the lever to make the fuel pump run, then once the generator is running it keeps power to this solenoid, but the safety switches (or when you hold down the stop) allow the arm to go back and shutoff the fuel pump.)
  15. CSkipR

    CSkipR Member

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    Okay looked over the gen and I believe I have found two. The cooling system by the thermostat and the oil. Not positive but will experiment. Still looking for the one by the elbow?

    The Gen is a 4 cylinder. 15kw BTDC
  16. CSkipR

    CSkipR Member

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    Performed first test although not sure what its telling me. Disconnected the two wires going to the cooling (I believe) sensor and started generator. As long as I held preheat down it continued to run. When I released preheat it shutdown. Okay then I jumped the two wires together and the gen ran normally although I haven't run it very long. What does this tell me?
  17. CSkipR

    CSkipR Member

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    Okay performed test on what I believe to be the oil sensor. Question is there appear to be two of them right on top of each other. Top one has two black wires and bottom one has two red wires. I checked continuity on both sensors after removing the wires. The top one showed closed and the bottom one showed open? Why would this have two oil sensors? Here are pictures.
    First picture two oil sensors?
    Second picture cooling water sensor
    Third picture of gen

    Attached Files:

  18. Navatech

    Navatech New Member

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    Possibly one for oil pressure and one for oil temperature?
  19. NYCAP123

    NYCAP123 Senior Member

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    Still think I'd be checking that water flow first to eliminate that possibility. All you need do is suck in a plastic bag to reduce the water flow and you've got the situation you described. If you find it to be one of the sonsors then you still need to figure out if the sensor is bad or just doing its job and you have a bigger problem. I'd eliminate the simple possibilities first.
  20. K1W1

    K1W1 Senior Member

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    Hi,

    It looks like you actually have 3 sensors, that upside down pot type thing probably drives a gauge.

    The one that is NO when the engine is off will most likely be the shut down, it will close and stay closed when there is oil pressure, it will open when there is no pressure.