Westerbeke GAS generator troubleshooting

[370Dancer]

I know there's a lot of overlap in systems on the genset, regardless of what's pushing the piston. I think Gas owners will gravitate to something specific, as will diesel owners.

So, here's mine. 1998 Westerbeke 7.0BCG, commonly found in 370 Sundancers, and others.

Starts, runs, backfires occasionally during warmup, but especially with load. shuts down after a while (10 minutes to 1 hour). restarts immediately, runs for a while, then repeat. Some days, third restart lasts for hours, sometimes just minutes. Digital gauge on dash is 115-125v at 59 to 61 hz depending on load. Don't think it's any of the 3 safety shutdowns. Overspeed? Doesn't sound like it's running up before shutdown. Governor gives up? Maybe. Gov Oil is full, don't see any leaks. It's all 22 years old.
I am monitoring temp. It is good. Don't think I'm running out of fuel. Facet pump is fairly new as well.

 

[LG111]

Ugh! Gremlin's!
Well start with the easy stuff first. Since the governor controls speed and load, try lubricating the spring, pin and all moving parts in that area. Just touching those parts makes the genny jump, so maybe something is sticking. Backfiring is generally to much fuel or timing issues so maybe the carberator floats are getting heavy with fuel or timing has slipped over the years. How's the belt? Is it slipping?

Mark

 

[hughespat57]

This is an old points and condenser distributor, last time you put new points and cond in?
The over head cam is belt driven, have you ever changed it? or the tensioner?
How many hours on engine?

 

[Mark.60]

I have seen the overspeed shutdown cause of kinds of problems. You can disconnect it and give it a test run.The overspeed sends a ground to the coil when it detects a problem. A quick , intermittent ground to coil could cause the backfire. Hope this is helpful.

 

[bahamabreisus]

I know you said you replaced the fuel pump, but that sounds like the common fuel pump overheating and shutting down, then restart. You might change the coil, they can overheat. Lastly, when was last time heat exchanger was cleaned. Our diesel was doing similar and final thing was heat exchanger, that fixed it.

 

[370Dancer]

Great comments all. Finishing another project, and then I'll jump back on this.

 

[370Dancer]

This is an old points and condenser distributor, last time you put new points and cond in?
The over head cam is belt driven, have you ever changed it? or the tensioner?
How many hours on engine?

OK, this one is back in focus. 1400+ hours. Might just yank it for a rebuild. Not sure I can get it out without removing the Stbd engine though. Any late 90's 370 Sundancer owners out who have pulled the genset without pulling the block? I'll have the manifolds off doing a change out for that. 98's hatch system is very different from 95-??

 

[370Dancer]

Been thinking about disconnecting the governor from throttle control, and just let it be an engine to see if it shuts down eventually. If it did, then I'd be inclined to start looking at the safety circuits. If it doesn't, then I'd start looking hard at speed control. When it's working, it's working great. Then, it just changes its mind........

 

[Mark.60]

I don’t have a wire diagram for your generator but you can jump the safety circuit on the board and try to run it. I would try to troubleshoot it before removing the whole thing. Could be a lot of unnecessary work

 

[370Dancer]

I have all of the wiring diagrams, service manuals, troubleshooting guides, parts manuals, and owner's manuals for this beast. Pulling the gen, even if it were the only engine in the bilge is still an expensive proposition because I don't own a yard, and I don't own a cherry picker to pluck it out, so no rush to judgement. We will do this in logical, baby steps.
Having said that, I did have it on the bench in 2017 during the Hurricane Irma engine repower. Never fired it up though. Just superficial cleanup, repaint, change the oil, look for stuff on the side I can never see due to where it's located.

 

[hughespat57]

I have all of the wiring diagrams, service manuals, troubleshooting guides, parts manuals, and owner's manuals for this beast. Pulling the gen, even if it were the only engine in the bilge is still an expensive proposition because I don't own a yard, and I don't own a cherry picker to pluck it out, so no rush to judgement. We will do this in logical, baby steps.
Having said that, I did have it on the bench in 2017 during the Hurricane Irma engine repower. Never fired it up though. Just superficial cleanup, repaint, change the oil, look for stuff on the side I can never see due to where it's located.

Correct approach, 1400 hours is not necessarily a problem if it has had regular oil changes. treat it just like you would a propulsion engine.
Start with a full battery, pull plugs, do a compression check. Low compression ok, may have burned valves or a blown head gasket do a leak down test, but if good no worries. "213 psi (14.0 kg/cm2) at 400 rpm" "28 psi diff max"
Pull an oil sample and send it out, while trends are better even a one time oil analysis is useful. High copper, yeah the bearings are worn out but if it comes back decent no worries.
I have a Lincoln Ranger 200 Amp welder generator with 2500+ hours and still going strong.
Stalling and shutdowns are not likely to be a mechanical problem.
The back firing is a possible sign of valve bent/burnt or the timing belt having jumped a tooth. But that should show up in compression test.

If the above is good, focus on the control system and ignition system.

 

[mrsrobinson]

Agreed, everything I have heard from genny mechanic's is these things can go for 5000+ hours. My last issue turned out to be the fuel pump, replaced and all was good.

 

[370Dancer]

Gettin there. Just got called out of town for 48 hours. Just like the old days.......
Meanwhile, we did get a bit of a family reunion. Missing a few of the kids, but here's the Angler, Nautilus, Yamaha AR, and Beach House, in the water at the same time. The Wellcraft is in Ft Myers, and the SeaDoo Explorer is in Huntsville.
I forget where the rest are.....

 

[370Dancer]

Because I like threads that wrap up with solutions rather than getting forgotten about.
Sunday morning, I sat down serious with my volt/frequency monitor to see where I was. Started the gen and after a bit it will start shutting down and then more frequently. Monitoring the voltage (no load) I was up around 143 with 65 hz. Hmmmm, that's high, even for no load. So, I started adjusting the speed control until I got it down to about 125 @ 61. It still shut down, even with me holding the bypass, and I didn't have to push Stop to reset the overspeed, like I would expect to have to. Nonetheless, it was still this seemingly random reason for stopping. So, I performed the overspeed bypass test by lifting the coil wire from TB-1. It started running rock solid. I couldn't get it to quit. So, started adding load to the genset, and at my normal operating load, it was starting to get close to 105v, albeit still at 59-60hz. Then it dawned on me. I have always run both A/Cs on leg 2 and everything but the stove and water heater on leg one since I got the boat. BUT, a few years ago, I swapped out the tired 7Kw and 9Kw A/Cs with a 16K and a 12K. Over time, I've been adjusting the genset speed at load based on all this stuff drawing. That's why it was so high at startup. My random shutdowns were probably more from both a/c's going offline at the same time than anything else. With the genset dialed down to a reasonable voltage, we ran for 6 hours using just the salon A/C (16K), and it never even coughed. That's a first time in a long time. So, I'm surmising that I did it to myself, and probably wore out the overspeed circuit to where it didn't care anymore. I left it off for that day because I can constantly monitor voltage and frequency at the helm. The motor is purring just like it should, moving water just like it should, and playing power company for us just like it should. Hope I didn't just jinx that......
Lesson learned. Be cognizant of the changes you make to the vessel over time. It can change the specs, which my changes did.

 

[Phasma]

I had an issue a few years ago with my gennie. The impeller grenaded and pieces of it made its way inside the heat exchanger. Not realizing the issue.....duh.......I started getting an intermittent overheat problem. Scratched my head for half a summer before feeling inside the exchanger and finding bits and pieces. All is well now. I did run into one other issue with sea weed plugging the hose from the through hull to the sea strainer. Strainer was clear. It took my dumb ass a couple of peaks to figure it out.