Gen set shutdown

My westerbeak keeps shutting down after an hour or so of running time. Is there a way to find out what is causing it? I'm thinking it is overheating. Just from a visual, the sea strainer looks clean. But the amount of water coming out of the exhaust doesn't look like it is enough. Other than that it seems to be running just fine right until shut down.

Pierce said:

My westerbeak keeps shutting down after an hour or so of running time. Is there a way to find out what is causing it? I'm thinking it is overheating. Just from a visual, the sea strainer looks clean. But the amount of water coming out of the exhaust doesn't look like it is enough. Other than that it seems to be running just fine right until shut down.

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Do you have a gauge or anything to tell you that it's over heating?Is there a water valve that could not be open all the way?Is the water pump impeller in good condition?Is there something blocking the sea strainer thru hull under the boat?It could be marine growth in the thru hull not allowing enough flow.

Since you mention that it doesn't seem to be exhausting enough water, when was the last time you changed the raw water pump impeller?

Three things that are sensed that will shut it down. Water temp, exhaust elbow temp and oil pressure. The unit has two water temp sensors. One is a temp sensor switch that will trip if water temp gets to high. your temp gauge comes from a different temp sensor so even if your water temp is showing good this sensor could be defective. In series with the temp switch is the oil pressure switch. Same as above, it is a different sensor than the one going to your gauge. Also in series with this is a temp switch mounted to the exhaust elbow. If any of these three are intermittent it will shut you down by removing power from your fuel pump.
Of course if your temp gauge is showing that it is getting hot the sensor is doing what it should by shutting you down. If this is the case then Ben's suggestions are spot on. If your exhaust water flow is down from before I would be thinking impeller and then check the heat exchanger also if impeller is missing parts. Easy to do by pulling the ends off. Just make sure you have O rings/gasket for the heat exchanger if you open it up.
Good luck.

The generator does not have any instrumentation on it. I just bought the boat in July so I really don't have any history on it. We hauled the boat out today for bottom paint and zincs and it looked like the thru hull/screen was a little plugged up. So I will clean it out and I will also go ahead and replace the impeller.
I do have a repair kit and I'll check to see if I have a spare impeller.

There are several more steps you need to take to determine what is going on and why. You might want to hirer a good mechanic to walk you through it this first time.

She starts right up. Runs for an hour or two. Yes I did put some load on it. She purrs like a kitten and the just shuts down. But yes I'll check with a mechanic at the yard tomorrow. Happy boating all!!

Pierce said:

She starts right up. Runs for an hour or two. Yes I did put some load on it. She purrs like a kitten and the just shuts down. But yes I'll check with a mechanic at the yard tomorrow. Happy boating all!!

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Go pick up a infrared temp gun ( h.dep or Lowes)and shoot the genset as it operates to monitor temps ( you should have one aboard as part of your boat tools anyway).. they are pretty cheap and a good to have aboard. Water temps at the expansion tank above 180 and the thing is getting too hot.
HOLLYWOOD

I have on and I checked it over. Most temps were in the 150+ temps. But I think I saw a 180ish temp. I'll check it over again once I get back in the water.

Do you have contact with the previous owner, he might know a "fix".

Fuel filter needs changing.

I had a a sailboat that had similar problem . It had two small Monel saddle tanks and it wound up being a cob web in the vent for one of the tanks . It was wound tight like a Q tip . I found it after reading Nigle Calder diesel repair book .

I'm gas. Runs off the main tanks. But it does have it's own fuel filter.
Thanks for the help guys!!

Assuming your shutdown is temperature related'....If your impeller looks good, you may want to check your raw water heat exchanger as it may be fouled and not cooling properly.

Thanks Bligh!! I will do just that!

Pierce said:

I'm gas. Runs off the main tanks. But it does have it's own fuel filter.
Thanks for the help guys!!

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We had controller issues on the Sea Ray we sold last year.. it would run great then for no reason crap out and die. One day I was standing by the panel and I noticed the voltage climbed to about 125v then the unit shut down. I figured out that unless it was loaded fairly heavy when the voltage hit a high set point it would shut down. Most of the time this coincided with the big charger switching from bulk to float charging.

I had never had a gas genset in a boat before and I sure do miss how quiet and smooth the little 4 banger ran.. not at all like the clattering beast that is my current Onan 7.5

HOLLYWOOD

If you are going to live with a Westerbeke generator (likely any generator) but mine is Westerbeke, you need to know how to determine whether you are overheating. The instrument panel is a must as it shows the water temperature level. As a Westerbeke approaches 200 degrees F it shuts down (assuming all is working correctly). Then check the exhaust elbow where there is another temperature gauge. If either of these are overheating there is a problem in the cooling system, from the impeller to the heat exchanger or the thermstat.

Next you need to check if you have a slow air leak. The way you do that is when the unit shuts down open the bleed value and start the genset up. Fuel should pour out. If bubbles you have a small air leak in the fuel delivery which after an hour or so shuts down the genset. Usually you can tell this if it take a couple of cranks to start the genset after a shut down. This is a sign the self bleeding function is getting rid of the air.

If after the genset shuts down and cools for an hour or so it starts up immediately it is more likely the cooling system or one of the sensors on the cooling system. The sensors are cheap.

Another test you can do is when the genset shuts down try and start it immediately, if t runs as long as you hold down the start button then it is one of the sensors sensing something is wrong. The start button overrides the sensors.

Checked the seastrainer today while I'm on the hard for bottom paint. yep, it was plugged!! Now we'll see how she runs once I'm back in the water.
Thanks for all your help folks!!!!!

Here is what I found

Oh drat! There were supposed to be pictures in that post.

Nope. That wasn't it either. Looks like I'm going to change the impeller next.

Yep, that was it! Much more water coming out of the exhaust.

This is one of two active generator raw water coolant threads on TF right now. I've had several near-misses with my Onan nearly overheating, with different causes each time. So I'm following these threads with interest.

There's good advice about impellers, heat exchangers, intake hoses, strainers and thru-hulls.

But I'm looking for an easy way to find out BEFORE it overheats. My current system is to climb down to the swim platform every 10 minutes and check the coolant flow coming out with the exhaust. Not convenient.

I plan to install one of those alarms that uses a sensor on the outside of the exhaust hose. A remote coolant temperature gauge would be good too.

Ideally, I'd like a flow sensor that I can glance at once in a while for peace of mind. Also, I could spot a longer-term trend of diminishing flow before it became a problem.

I haven't really found one that fits the bill. Most seem for larger systems or industrial process control, not monitoring my little Onan diesel.

Capt. Tom
Does not your remote control panel have a coolant gauge?

Bay Pelican said:

Does not your remote control panel have a coolant gauge?

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Nope:


I do have room below this panel for some remote gauges. I'm thinking that a flow gauge would be more helpful than a coolant temp gauge. I could watch for any slow changes over time, and fix things before it got to the point where the jacket water was overheating. I've never seen this done, so maybe there's a reason for that.

Pierce

By remote panel I was referring to a Westerbeke remote display and control:

This is called the Admiral's Panel and is one of the more useful items you can have in terms of knowing what is going on with the generator.

CaptTom said:

Nope:

I do have room below this panel for some remote gauges. I'm thinking that a flow gauge would be more helpful than a coolant temp gauge. I could watch for any slow changes over time, and fix things before it got to the point where the jacket water was overheating. I've never seen this done, so maybe there's a reason for that.

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Does it have a coolant temp gauge on the genny? If so, temporarily relocate the gauge somewhere convienient above deck until you find the problem.
A high exhaust temp alarm is what you want long term. Here is a link to one:
http://www.trawlerforum.com/forums/s6/exhaust-mixing-elbow-temperature-14381.html

Pierce said:

Yep, that was it! Much more water coming out of the exhaust.

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So what did the old impeller look like? Did you get all the pieces of the old one out?

High Wire said:

Does it have a coolant temp gauge on the genny?

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No

High Wire said:

A high exhaust temp alarm is what you want long term.

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Yes. I have two of those already that I plan to install on the mains to let me know when it's overheating. I'll probably get one for the genset, too.

But I was also hoping to be more proactive and see if there was any way to monitor the coolant flow rate over time, rather than wait until it's too low to cool the exhaust.

As far as I can tell, the genset has been working fine the last few times I've run it. Hopefully all the gremlins that kept affecting coolant flow have been fixed. I just want to know if and when they come back.

Gen should have switches on both the exhaust mixer and in the coolant circuit. Should shut itself down if it overheats. These switches can be tested, but takes a little work.

Gauges are pretty to look at, but who is going to watch them to catch an overheat?

If you want to make sure cooling system is working ok, get an IR temp gun, load it up to the max and monitor engine temps with the gun.