Westerbeke 7.0 BCG low voltage output

[J Levine]

My gennie is only putting out about 105 volts per the meter on the AC panel. When the compressor in the 7 ton AC unit in the master stateroom tries to start the generator cant take the load. The motor is also running rough and vibrating more than normal

Here are some guesses:

1) The plugs are fowled. I have run the generator for an hour or two recenty with not much load against it which I know is not a good idea. I have new plugs and plan on installing them next weekend.

2) The small fuel filter in the carburator is clogged. I have a new element that I bought last fall and never installed. The generator is original to the boat and has about 700 hours on it and I dont think this filter has ever been changed as the paint on the fitting looks undistrubed.

3) The governor needs to be adjusted. I removed the governor last fall the change the oil in it which is recomended at 500 hours. I tried not to disturb the adjustments but maybe I need to adjust the speed.

Other thoughts or ideas for me? I guess I should check the points too. When I bought the boat 5 years ago I had the generator surveyed and it showed no compression in one cylinder. Turned out to be a broken exhaust valve spring which was replaced by a Westerbeke dealer by the seller. It has run like a champ ever since. When I change the plugs I think I will do a compression check just to rule this out too.

 

[fc3]

You need to check the speed of the generator. Do you have a digital voltmeter that can read frequency? If not, I'll be around this weekend in Brick and will have my HP 974A with me. Just put the meter probes into an AC outlet, crank up the generator, flip the transfer switches, check the meter for 60Hz power.

BTW, seven tons?! That's 84,000 BTUs. Enough for a good sized house. Well, not Gary's but maybe his shed.

Best regards,
Frank C

 

[RollerCoastr]

I would've said fouled plug even before reading that you ran it w/o a load, but that almost guarantees it.

It's easy to run them w/o load, and then it punishes you, so I learned to take a shortcut:

Fire it up, let it run for just a few minutes and shutdown. Feel around the valve cover near each plug - the fouled cylinder will be cooler.

Replace that plug, fire it back up and load it up with everything you can, and you'll should be ok.

Another note: if you do have a fouled plug, the exhaust discharge water will have a aerated/milky look to it and smell lightly of fuel.

 

[J Levine]

Thanks for the suggestions guys, much appreciated.

Sorry Frank... getting my terms screwed up. It is a 7,000 BTU unit not 7 tons. I have 7,000 up front and a 5,000 in the salon. Thanks for the correction. I will have to check my digital VOM at home tonight to see if it can measure Hz. I know you rebuilt your 4.5 a few years ago so I appreciate your guidance as I know you have been there and done that when it comes to this unit and I believe there is only a minor difference between yours and mine.

I am going to check the compression, do the plugs and the filter and see if it improves. If I cant measure Hz with the VOM I know I can at least check the voltage to compare it against the meter in the AC pannel

Rollercoaster, you make a good point, the exhaust flow was different and may have been a little milky. Between the shake and the sound I think it has a miss.

Hopefully this is a easy fix.

 

[fc3]

Same engine, different alternator. I had a heck of a time getting the plugs out. It's a large plug socket. 13/16 I think? Use a 6" extension on a 3/8" ratchet wrench; 1/2" extensions don't fit right.

Good luck getting a compression gauge into the plug holes. I don't see where you'd have room to do it. But maybe your 370 has a lot more room on the flip side of the genny.

Which reminds me, I gotta set the valve lash this year. It's enough hours after the semi-rebuild. What fun.

Best regards,
Frank

 

[J Levine]

I hear ya on the plug removal, what a PITA. I ended up buying a 13/16" 3/8" drive flex spark plug socket to change the plugs 2 years ago. One of those jobs where you say "how hard can it be to change the plugs in this little 3 banger" until you try to do it. On the 95 370 the top of the unit is about 1/3 exposed when you remove the starboard aft cockpit hatch cover and there is about 6" from the underside of the cockpit sole to the top of the valve cover so it is not impossible, but still real ugly to work on.

 

[osd9]

Getting the new plugs IN is no picnic either!!! On my '98 330DA I used the old piece-of-rubber-vacuum-hose-over-the-plug-end trick to 'gently' get the new plugs started in the hole. A mirror is also handy to see what you are up against.

 

[fc3]

I cheated when I put the plugs back in. Installed them before I installed the genset.

 

[J Levine]

I have actually done some other work on the unit including replacing the raw water pump, replacing the exhaust riser and pulling the heat exchanger to have it serviced/overhauled. None of it is a lot of fun, but I have had worse, like the doing anything in the engine room of the 95 290 DA with twin 4.3's

 

[J Levine]

Update,

New plugs and a new fuel filter and it works great. Thanks for the help.

 

[fc3]

Glad to hear it. Was a nice day for being down over the engine.

Best regards,
Frank

 

[J Levine]

I actually changed the plugs at about 10:00 PM on Saturday night to beat the heat, wasn't that bad...

 

[fc3]

I started changing the engine coolant at around 4 and finished at about 7. Fun!