Westerbeke 4.5 Fuse Blowing

[gcluett]

1999 340DA. 155hrs on the genset, in otherwise great shape. All of a sudden, dead start circuit. Traced to 8 amp fuse on the control panel. replaced fuse, clicked remote start, no lights nothing, fuse is blown again. Read about issues with the water temp sensor (normally closed) so pulled the two wires on that, hit the switch, nothing blown fuse again. So there has to be a ground fault prior to the water temp switch or it would not have blown the fuse with the wires off as the start circuit was not complete.

Any thoughts on next steps for fault diagnosis

George

 

[dtfeld]

I'm not familiar with this particular model, but other westerbekes (diesel model) have a diode in the start circuit that have been failing and causing this exact symptom. I'll take a look at the schematic and see if there are not some similarities.

What is the exact model #?

 

[PlayDate]

That fuse blows due to a fault in the control board circuit.

Assuming you have tried to start the unit at the generator as well to eliminate a problem with the remote harness......the control relays are the first thing I would look at. There are two K1 and K2 page 33 of your Operators Manual. K1 controls the starting circuit.

 

[PlayDate]

I'm not familiar with this particular model, but other westerbekes (diesel model) have a diode in the start circuit that have been failing and causing this exact symptom. I'll take a look at the schematic and see if there are not some similarities.

What is the exact model #?

I took a guess that he has a 4.5 Westerbeke......gas...... based on his engine profile.

 

[dtfeld]

I took a guess that he has a 4.5 Westerbeke......gas...... based on his engine profile.

@PlayDate correct...4.5kw but I think there are several models.

Looking at the BCGT series manual from 1999, there are several diodes in the start circuit as well as internal diodes on the K1 and K2 start relays as you mentioned, and looks to have a couple more somewhere in the overspeed circuit board.

 

[gcluett]

I'm not familiar with this particular model, but other westerbekes (diesel model) have a diode in the start circuit that have been failing and causing this exact symptom. I'll take a look at the schematic and see if there are not some similarities.

What is the exact model #?

Thanks. Exact model is BCGTC. Wiring Diagram attached.

 

[gcluett]

@PlayDate correct...4.5kw but I think there are several models.

Looking at the BCGT series manual from 1999, there are several diodes in the start circuit as well as internal diodes on the K1 and K2 start relays as you mentioned, and looks to have a couple more somewhere in the overspeed circuit board.

Yes - those diodes are part of the overspeed circuit board.

 

[PlayDate]

I'm still leaning towards the K1 relay. I know they are tough to get to on your boat but as you can see in the wiring diagram......it gets energized by the 8 amp fuse which in turn activates the starter via the starter switch.

If that relay fails.....it draws too much current to close the relay when you hit the start switch and poof there goes another fuse.

 

[dtfeld]

Didnt have time to anamyze schematic, but relays are cheap and probably available on Amazon. Based on Playdates rec, would be first thing I'd try.

 

[gcluett]

I'm still leaning towards the K1 relay. I know they are tough to get to on your boat but as you can see in the wiring diagram......it gets energized by the 8 amp fuse which in turn activates the starter via the starter switch.

If that relay fails.....it draws too much current to close the relay when you hit the start switch and poof there goes another fuse.

Thanks. I am going to play around with it some more to try and isolate some areas of the circuit to narrow down the likely suspects.

 

[PlayDate]

Thanks. I am going to play around with it some more to try and isolate some areas of the circuit to narrow down the likely suspects.

I would start by ohm testing the K1 relay coil.


Relay. The relays used in the control system have coils which are polarized by the fact that they have internal freewheeling suppression diodes across them. Relay coil terminal86 must be maintained(+), terminal 85(-). The relay coil is rated 12V DC, and the coil resistance is typically 85 ohms. With B+ on terminal 86, direct grounding of terminal 85 is permissible for testing purposes

 

[ttmott]

Most of the small amp fuse issues revolve around a diode shorting. The BCD's are renown for the issue. The diode for the run circuit was/is grossly under sized for the current.

 

[gcluett]

Update - I tried to start using the panel on the generator - I got the initial engagement on the starter (so the starter solenoid actuated) and then the fuse blew. So its definitely in the starter circuit or when the "run" override toggle switch is engaged. I sent Westerbeke a note asking if they have a fault isolation procedure for the 8 amp fuse blowing - no response yet. Would like to get to the bottom of it sometime soon although I am really glad its winter and not losing any time on the boat where I need it!

 

[dtfeld]

Replace the K1 and K2 relays. They are typically Bosch relays and available at most auto parts stores.

 

[gcluett]

To all - Westerbeke is not helpful at all. I wrote to them to see if they had a diagnostic procedure for the fuse blowing. Here is their response:

"Thank you for your inquiry. The trouble could be as simple as a safety shutdown circuit switch that is shorted to ground. The best recommendation we can provide is to suggest you consider seeking advice or hiring the services of a qualified marine technician or electrician.

Our distributor for your area is Trans Pacific Distributors in Fairfield, CA. They are your best source for product information and sales, technical advice, or Genuine Westerbeke spare parts, and they will provide you with the fastest service. They can also direct you to a dealer closest to your location. Trans Pacific can be reached by phone at (707) 426-6670 or via e-mail at sales@marinegate.com.

Thanks again for your inquiry. We appreciate your business!"

Nice to know I have their permission to write a blank check for a mechanic to figure it out....
I ordered K1 and K2 relays and will check the resistance on the ones on the unit. If thats not it, I am planning to get a new circuit board (for $400...) and try that. I'd still prefer to replace parts than pay $500 for a service call. This should be simple....

George

 

[PlayDate]

To all - Westerbeke is not helpful at all. I wrote to them to see if they had a diagnostic procedure for the fuse blowing. Here is their response:

"Thank you for your inquiry. The trouble could be as simple as a safety shutdown circuit switch that is shorted to ground. The best recommendation we can provide is to suggest you consider seeking advice or hiring the services of a qualified marine technician or electrician.

Our distributor for your area is Trans Pacific Distributors in Fairfield, CA. They are your best source for product information and sales, technical advice, or Genuine Westerbeke spare parts, and they will provide you with the fastest service. They can also direct you to a dealer closest to your location. Trans Pacific can be reached by phone at (707) 426-6670 or via e-mail at sales@marinegate.com.

Thanks again for your inquiry. We appreciate your business!"

Nice to know I have their permission to write a blank check for a mechanic to figure it out....
I ordered K1 and K2 relays and will check the resistance on the ones on the unit. If thats not it, I am planning to get a new circuit board (for $400...) and try that. I'd still prefer to replace parts than pay $500 for a service call. This should be simple....

George

George,

The last thing they want is someone touching a live generator that isn't qualified. Pretty sure you would get the same response from GM, Ford, Tesla or any other car manufacturer about a fuse blowing. The liability is just way too great today.

Let's see what happens with the relays. Did you check the ohms on the existing ones or just order new ones?

 

[dtfeld]

Side benefit of doing your own work makes you a better boat owner. The more you know, the more confident you’ll be and less likely to be stuck somewhere.

Good on you!

 

[AllTideUp]

I had a 2001 Sea Ray 340 with the 4.5 BCGB Westerbeke in it. That 8 amp fuse would always blow for the various sensors that are in line. If any sensor was tripped or faulty, the fuse would blow. There should be 1-2 oil pressure sensors, exhaust temp sensor and water temp sensor. Locate each of these, by pass one at a time and find the bad sensor. I'd do this before replacing anything. I always kept one of each of these sensors as spares on the boat just incase they went bad along with a bunch of the 8 amp fuses as I couldn't find them locally.