Westerbeke Question

We were running the 8KW generator today underway for a/c because it was blazing hot. We don’t generally do that.

Generator shut down after about an hour and a half. I opened up the engine room hatch and let the generator cool for a couple of hours. Then I started it to run the hydraulic bow thruster when we docked.

I just ran it for awhile and checked temps. Seems fine. Is it possible that it shut down just because engine room was very hot?

I have to admit I don’t take temps on the generator like I do the main engine. Does anyone take temps on a Westerbeke? Can you share where you shoot the temps and what they normally run?

Thanks, Mike

It didn’t shut down because the engine room was too hot. Generators usually shut down either from overtemp cooling, low oil pressure, or fuel starvation. Fuel starvation is usually caused by clogged filters or a failing electric fuel pump. Next time it shuts down check your temps and pressure.

might check the fuel shut off at the same time. They can get weak with age and are simply not strong enough to hold the shut off lever in place. For a time, they can fail periodically before completely going bad. Only reason I know it is it happened to me on the same generator. Easy to check.

How old, how many hours? When did you last service fuel filters? Has the fuel filter on the engine ever been changed, do you know where it's located? They're easy to overlook unless you're aware of them. Have you ever replaced the lift pump?
I agree, the heat of the engine room probably woudn't cause the generator to go over-temp, the engine isn't air cooled, and the air temp is probably lots lower than the coolant temps. so the ambient temps in the ER don't have much influence on the temps the genset is running at. It's probably more coincidental than not.

I'd be looking first at fuel supply.

The generator has about 4500 hours on it. Both engine and Racor fuel filters changed in February.

Of course, it was hot and noisy when this happened. I’m pretty sure the exhaust elbow switch tripped. However, when I ran it later that day, the exhaust elbow temps seemed fine. I was reading 170 upstream of where the water is injected and 116 downstream. Again, I’m not sure what the Westerbeke specific temps should be, but that seemed close to what I see on the engine.

Three things trip it electrically: Coolant temp on tstat housing, oil pressure, and exhaust mixer temp. The three switches are daisy-chained (in series) so any one opening contacts shuts it down. Normal coolant temp at tstat housing is about 170-185, trip about 195-200F. Exhaust should run about 100-120F with warm sea water. All of this is under load.

Fuel solenoid and electric fuel pump can also be affected by high ambient temp. If in doubt, but a new fuel pump in, they are cheap and fail more often than solenoids.

You could also have gotten a bag sucked up against water intake, and the unit was doing exactly as it should.

Run it under a load and monitor with IR gun. Best first step.

Thanks to all for the input. We are hauled out right now, but I’ll run it some more as soon as we are back in the water.

Ski in NC said:

Three things trip it electrically: Coolant temp on tstat housing, oil pressure, and exhaust mixer temp. The three switches are daisy-chained (in series) so any one opening contacts shuts it down. Normal coolant temp at tstat housing is about 170-185, trip about 195-200F. Exhaust should run about 100-120F with warm sea water. All of this is under load.

Fuel solenoid and electric fuel pump can also be affected by high ambient temp. If in doubt, but a new fuel pump in, they are cheap and fail more often than solenoids.

You could also have gotten a bag sucked up against water intake, and the unit was doing exactly as it should.

Run it under a load and monitor with IR gun. Best first step.

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Ski,

I just want to confirm that the three shutdowns you mention in the first sentence all trip the round breaker that is reset by pushing the button.

I assume that an issue with the fuel
solenoid or the fuel pump would not trip the breaker. It would just kill the engine, and I would be able to attempt to restart it without resetting the breaker.

Am I correct?

Thanks, Mike

No, if any of the three switches trip the unit, it just shuts it down. Should not trip the breaker.

The three “trips “ de-energize the RUN solenoid which shuts off the fuel to the injection pump. The round circuit breaker powers the control power circuit and if it trips due to an electric fault, the RUN solenoid also de-energizes and the engine stops.
Did the circuit breaker actually trip?
What model gen? 8 BTD?
One more thing. The WB cylinder shaped electric fuel pump has a internal filter behind the bottom cap that is not mentioned in their manual but is shown in the parts diagram. Mine looked like had never been touched in its life.

High Wire said:

The three “trips “ de-energize the RUN solenoid which shuts off the fuel to the injection pump. The round circuit breaker powers the control power circuit and if it trips due to an electric fault, the RUN solenoid also de-energizes and the engine stops.
Did the circuit breaker actually trip?
What model gen? 8 BTD?
One more thing. The WB cylinder shaped electric fuel pump has a internal filter behind the bottom cap that is not mentioned in their manual but is shown in the parts diagram. Mine looked like had never been touched in its life.

Click to expand...

Sorry...didn’t see this post. The circuit breaker did trip, and I think it was caused by the exhaust elbow temp sensor.

I have an 8KW BTD. As I understand it, there are two different fuel pumps that can be on a BTD. One has a filter and one doesn’t. I have the one that doesn’t.

Is it possible the reason it shut down was the generator was just overloaded? The air conditioner was on. Do you also have a electric stove? Someone run a hair drier at the same time? AC, stove, and refrigerator on at the same time?

Russell Clifton said:

Is it possible the reason it shut down was the generator was just overloaded? The air conditioner was on. Do you also have a electric stove? Someone run a hair drier at the same time? AC, stove, and refrigerator on at the same time?

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We were underway with 2 a/c’s running. It was very hot and the water temp was in the mid-80s. I really think it overheated due to those factors. I’ve run it under load since then without a shutdown.

MikeM said:

Sorry...didn’t see this post. The circuit breaker did trip, and I think it was caused by the exhaust elbow temp sensor.

I have an 8KW BTD. As I understand it, there are two different fuel pumps that can be on a BTD. One has a filter and one doesn’t. I have the one that doesn’t.

Click to expand...

The only thing that trips the circuit breaker is overcurrent through the breaker. If it tripped then there is an intermittent electrical fault/short or possible the breaker itself is tripping prematurely. It must be reset by pushing the button.

Low oil pressure, high coolant temp or high exhaust temp simply de-energize the solenoid to stop the engine.

Believe it or not, there is NO direct trip for overload condition except for the generator main output breaker. Doubt if that will ever trip except a dead short in the output wiring.

High coolant and high exhaust temp trips are indirect from overload.


8BTD = rated 66 amps at 120 volts

Guessing your loads...

2 air cond = ~30 amps
electric stove = ~ 10 amps per burner
Refer = 5 amps maybe
Hair dryer = 15 amps


Doubt very much that you overloaded it.


It is quite possible the control power circuit breaker tripped prematurely due to above normal engine room temp affecting the setpoint but there is not much current flowing while the engine is running except an amp or 2 for the run solenoid. I would order a replacement 20 amp breaker and change it out. If it is something else, it will trip again.

Just went through this same exercise with my 12.5WMD with 3900 hrs on it. The fuel solenoid was the culprit. The electromagnet in the solenoid was not pulling it in completely, most likely due to age. "Looked" like it was working normally, but did not bottom out. I had checked out the filters, injector pump (which I assumed was the problem as I got no fuel from it to the injectors while cranking). The lack of fuel to the injectors was due to the solenoid not pulling in completely. Just a thought for you.

chiropaul said:

Just went through this same exercise with my 12.5WMD with 3900 hrs on it. The fuel solenoid was the culprit. The electromagnet in the solenoid was not pulling it in completely, most likely due to age. "Looked" like it was working normally, but did not bottom out. I had checked out the filters, injector pump (which I assumed was the problem as I got no fuel from it to the injectors while cranking). The lack of fuel to the injectors was due to the solenoid not pulling in completely. Just a thought for you.

Click to expand...

Thanks.

If both ac's tried to start at the same time the surge could have been enough to trip a "old" breaker.

MM
As a flyer,

I've seen it where the genset raw water pickup doesn't work well with boat underway and unit kicks off due to high temperature. But, all is fine when at dock. When you can check under hull, sea strainer and plumbing to RW pump.