Westerbeke generator question

[DavidM]

He suggested shorting the cap before doing the test for two reasons: It can give you quite a shock if it really works if you have just shut the genset down; it can also blow your meter if you don't first discharge it.

I have never tried this test with a digital meter. These use a very low voltage to measure ohms, so it may take a while to build up a charge on the capacitor to show the resstance dropping. I also like to see things change in analogue form rather than chase digits bouncng around and maybe even autoranging confusing things.

But give it a try.

David

[Ski in NC]

No worries about discharging cap. Winding loop it is attached to is a dead short with machine off.

Some mid range up DVM's have a microfarad setting for testing caps.

With clever use of ohm or volt setting with a chargeup, you can establish whether it has some capacitor function, but it will not be easy to test conclusively.

And it could just need a flash.

[what_barnacles]

Could just need a flash???

[BruceK]

Originally Posted by what_barnacles

Could just need a flash???

Should be easy, some marinas have a resident flasher, ours does, late at night.

[Egregious]

Originally Posted by seattleboatguy

Your link to the service manual is fantastic! That should prove very useful to either me or (if necessary) the repair guy. Thanks very much.

Call Westerbeke ((800) 548-6252 ). They are very helpful and you'll get a human being after a few rings. They're used to dealing with the old models. They also have any parts, except for injector pipes, but you can have one of those fabricated at any injector shop.

[seattleboatguy]

Originally Posted by Egregious

Call Westerbeke ((800) 548-6252 ). They are very helpful and you'll get a human being after a few rings. They're used to dealing with the old models. They also have any parts, except for injector pipes, but you can have one of those fabricated at any injector shop.

Good idea. Couldn't hurt. Thanks!

[seattleboatguy]

Originally Posted by djmarchand

seattleboatguy:

Before you even think about removing and shipping to Broward, check or replace your capacitor. Most are 40 mfd and Amazon has them for less than $10.

To check, disconnect the wires and hook up an analogue ohmmeter set to low range to the terminals. The resistance should start out low and then slowly rise as the capacitor charges to the meter's resistance sensing voltage. If it is immediately high, it is bad.

These fail routinely on marine generators due to heat. So if you have that kind of capacitor excitation, and it looks like you do, then 99% of the time a bad capacitor is what causes no ouput voltage.

David

Hi David. I did the test you suggested, made a video while the test was running, then loaded the first 30 seconds of test results into a spreadsheet. Each second, I was able to record 2 or 3 readings from the multimeter. The multimeter was set on "2K" of the "OHM" scale. Before I hit the generator start button, the multimeter read .001 . After I hit the start button, the multimeter readings bounced around quite a bit between -.364 and +1. The test result data is shown below. I could see no clear trend in the data. Does this mean the capacitor is shot?

http://www.seattleboatguy.com/tmp/2017-02-22_a.jpg

http://www.seattleboatguy.com/tmp/2017-02-22_b.jpg

[High Wire]

Picture don't work for me. Go to YouTube and search "testing capacitors " watch at least five different videos and you will get the point.

[twistedtree]

Originally Posted by seattleboatguy

Hi David. I did the test you suggested, made a video while the test was running, then loaded the first 30 seconds of test results into a spreadsheet. Each second, I was able to record 2 or 3 readings from the multimeter. The multimeter was set on "2K" of the "OHM" scale. Before I hit the generator start button, the multimeter read .001 . After I hit the start button, the multimeter readings bounced around quite a bit between -.364 and +1. The test result data is shown below. I could see no clear trend in the data. Does this mean the capacitor is shot?

http://www.seattleboatguy.com/tmp/2017-02-22_a.jpg

http://www.seattleboatguy.com/tmp/2017-02-22_b.jpg

I don't think you did the test correctly. It's done with the generator off, and the capacitor disconnected. Only the meter probes should be on the capacitor.

[DavidM]

Twistedtree is correct. Read my original post. You remove the wires from the capacitor, hook up an ohmeter to the BARE terminals and read the resistance. It should start low and build up as it charges the capacitor. If it starts high and stays high, then it is shot.

I will admit, it is a subjective test and a lot depends on the characteristics of the ohmeter, but if the resistance starts low and rises, it is probably good.

But it is cheap. Just replace it for $10 if you are not sure.

David

[Daddyo]

Originally Posted by seattleboatguy

Did you somehow unbolt the "electrical end" of the generator and ship it via UPS, or did you have to give the whole generator to some shipping company?

I removed the back end. Not easy or light!!

[seattleboatguy]

Originally Posted by djmarchand

Twistedtree is correct. Read my original post. You remove the wires from the capacitor, hook up an ohmeter to the BARE terminals and read the resistance. It should start low and build up as it charges the capacitor. If it starts high and stays high, then it is shot.

Hi David. I guess I did not understand your original instructions, but I'm with you now. Messing with the inside of a generator is new territory for me. I'll regroup and try the test again. Thanks.

[twistedtree]

Originally Posted by seattleboatguy

Hi David. I guess I did not understand your original instructions, but I'm with you now. Messing with the inside of a generator is new territory for me. I'll regroup and try the test again. Thanks.

Also, set you meter to the lowest range. It looks like that's 200 ohms on your meter. You were on the 2k scale before.

[seattleboatguy]

Originally Posted by High Wire

Picture don't work for me. Go to YouTube and search "testing capacitors " watch at least five different videos and you will get the point.

Good idea. Thanks.

[seattleboatguy]

Originally Posted by djmarchand

Twistedtree is correct. Read my original post. You remove the wires from the capacitor, hook up an ohmeter to the BARE terminals and read the resistance. It should start low and build up as it charges the capacitor. If it starts high and stays high, then it is shot.
David

Hi David. I watched a couple YouTube videos, then tried it again. My meter reads "1." both before and after touching the capacitor's terminals. I changed the dial on the multimeter to various resistance values, but got the same result. I guess that means at least one of my problems is a dead capacitor.

[High Wire]

Looks like WB part number 041199 Capacitor 35 MFD.

[Ski in NC]

With meter in ohms and clips attached, short between clips and meter should go to near zero. Remove the short and it should slowly rise to infinity, or on that meter "1 ."

If you are near a decent sized town, any electrical supply house or HVAC supply house or motor repair shop will stock caps. Make sure to get same diameter so clip works. And get one with at least as high a volt rating, most are 450v, which is fine.

[DavidM]

I guess Ski is right and the "1" means the meter is reading infinity ohms as soon as it is connected. That is why I don't like digital meters ;-).

Amazon has capacitors. Try one of these for $10.00: https://www.amazon.com/Capacitor-Rou...5%3A2470955011

Bend the clips if necessary to get it to fit, but make sure that the length works.

David

[seattleboatguy]

Originally Posted by Ski in NC

With meter in ohms and clips attached, short between clips and meter should go to near zero. Remove the short and it should slowly rise to infinity, or on that meter "1 ."

When I do your test, applying the short does not make my meter go to zero. It dances all over the place with all sorts of numbers flashing on the display. As soon as I take away the short, the meter goes back to "1." .

[Ski in NC]

If numbers dance, you are not making a good connection. Or a crappy meter.

What does it do when you clip the two probes together?