Universal/Westerbeke Engine harness - B series engines

[KWKloeber]

I've been working on a customer's engine harness from a 1990 M-25XPB and found something interesting...

Westerbeke's engine harness is manufactured with -

SAE wire, which is bare copper, heavy-stranded, Type 2 (e.g., 10 gauge is 16 stands of conductors), with polyethylene insulation.

Instead of from -

UL 1426 tinned, fine stranded, Type 3, marine wire (e.g., 10 gauge is 105 strands), with PVC insulation.

And e.g., 10-gauge SAE has about 15% greater voltage loss compared to 10 AWG marine wire.   

Does the SAE wire work?  Yeah, but.........  with all that Westerbeke buys, couldn't they get a good enough price on UL Marine wire, instead of Truck wire, and "do it right" with tinned, flexible, wire ?   

Simply one more reason why I hold Westerbeke and its products in high esteem compared to other marine engines.   


kk

[lazybone]

Makes you wonder why the Sailboat manufacturer didn't insist on the proper wire?

[Noah]

Ken: At least the the oft-maligned replacement harness from Catalina Direct uses the "correct" wire.😎

[Ron Hill]

Ken : Your findings make me feel good, because I removed the entire wiring harness from my new M25XPB engine. 

It made more sense to me to wire the new engine to match the boat wiring than rewire the boat to match the engine.
It also solved all of the future problems involved with the goofy oil pressure/glow plugs/fuel pump wiring setup!!

A few thoughts

[KWKloeber]

Ron,

How did you handle the oil alarm?  Use a single terminal switch?
The fuel pump shut off was an OK concept, out could have been executed better I think.  What I found was really STUPID, was Wb running the power feed to the alarm in a separate wire, from the cockpit/key switch, to the oil switch, to the alternator, and back to the alarm.  That didn't make any sense me.  Why not jumper from the key to the alarm?   It's not like someone is going to put the alarm in a remote location other than at the engine panel!

k

[2ndwish]

Hmm. This thread just became very interesting to me. We now have a 42B Four on our new-to-us C380. When you mentioned the funky wiring of the fuel pump, glow plug, alternator, alarm, I realized the wiring diagram of the M25XPB and the WB 42B Four are the same. Just checked the WB site and indeed they are.

I was having some interesting problems with the engine electrical - buzzer wasn't working. Replaced the buzzer with the Radio Shack equivalent (one of Ron's earlier suggestions)and it still didn't work. Measured voltages throughout the system and found that with the key on, engine off, the voltage on the -P terminal of the buzzer was ~8V which was not enough to provide the 4V minimum needed to trigger the buzzer. Checked the pressure switch - seemed opened when the engine was off and low resistance (on) when the engine is running. Checked power and ground harness resistances and they were ok. Disconnected the indicator lights from the buzzer and got a reading closer to 0V and the buzzer worked great. It struck me that the design is funky because it looks like the buzzer should be triggered by the current path to ground through the fuel pump when the oil pressure sender switch is off and not providing +12 V to the pump. It looks like they added a 1000 ohm resistor to ground when they switched to the solid state pump which has internal circuitry to run the pump. The problem is that the Seaward panel has the bulb right across the buzzer terminals and with its relatively low resistance (bulb resistance is between 20 and 1000 ohms), drags that -P to a higher voltage.

That made me think that others must be having the same problem. I figured that there was inadequate margin in the design and the original buzzers had enough margin to work, but the replacement didn't. Funny thing is that no one on the 380 site reported problems. I concluded that the Radio Shack buzzer, which has identical specs to the Intervox original, must somehow be different. This was further indicated by the fact that the OP buzzer wouldn't work when I hooked up the OT light (which will hold the -C terminal high unless the engine overheats). I've been happily using the engine with the lights disconnected and all seems  to work. I stand by my conclusion that the design margin is poor and the original buzzer is just different enough to work. I will  test it by buying an Intervox buzzer and trying it(just too cheep to spend the 12 bucks right now).

This whole thing pointed to another wiring mystery that someone may be able to shed light on. The fuel pump in the key-on, engine-on position gets power through the oil pressure switch, the idea being that the oil pressure drops and the engine will auto stop when the voltage cuts out- seems like a good idea. So I tried it- disconnected the fuel pump power wire while running assuming the engine would cut out. After 15 minutes of running under load I got tired of waiting for it to stop and ended the experiment. I thought the Facet Cube pump WB uses has a positive shut off. Apparently it does not. The fuel tank on the 380 is high enough that once running, it will keep going, even without a pump and only half a tank of fuel- which begs the question. Why is it wired that way in the first place?

Given the similarity in wiring, I'd be curious to know if C34 owners with M25XPBs have seen anything like this. Sorry for the long post. Even the local WB rep was mystified.     

[KWKloeber]

2nd,

One thing that often gets lost in the conversations, is to remember that the engines, be they M-25s, XP, B series, Atomic 4, - they aren't unique to CTY.  So what may 'work' regarding a fuel shut off and tank feed on one boat, may not on a CTY.  Also the wiring is basically a Wb decision, not the boat mfgrs.  Even though the schematic says "Catalina" the only difference is in the start sequence (Westerbeke panels use the key S-position start, not a push-button start.)  So the wiring at the engine is identical, but what that wire connects to at the panel is the difference (S terminal of the key switch, vs the push button.)   For the life of me, I can't understand all the hullabaloo of the start system and layout of the panels over the years.  Supposedly owners complained about needing to use two hands to start (hold preheat switch, turn key (as on my '84 C-30 panel,) so over the years things evolved thru different systems.  The push-button (or key turn) preheat and push button start still takes two hands (or one if you preheat and then let go, so I just don't see the benefit of this.  I think it's just like Windows version whatever - being different for different's sake, not because it's better or easier. What's the benefit of turning a key to preheat, versus pushing a button?  And pushing a button to crank, versus turning a key?  I don't GET IT.

If CTY or Seward wanted to deploy a really top-notch system, they would have used a PTC (push to choke) key switch.  Then it's all one-hand operation. Off - Ignition - Start and preheat all on one switch (which is what I will use when I redo my panel.)

On the resistor, what I figured out from the customer's harness and schematic -- and I may be mistaken -- is that the normal flow path (engine running) for the oil alarm is to the preheat I terminal post (via the hot side of the oil switch,) then to ground thru the resistor.  That sounds the alarm if pressure goes low.  During preheat, the I terminal is hot and so feeds the pump.  Thus the need for the resistor, otherwise the oil alarm ground would be a dead short.  When preheat is off (running) the I terminal goes hot in the "other direction" (thru the oil switch,) so there is no alarm.

BUT at the same time, there is always a current path to ground thru the resistor while the key switch is in the I position.  Doesn't seem to me to be the 'best' solution??!??   A different oil switch -- one that had three terminals - two being a normally open switch (for fuel pump), and the third being a normally closed ground post would be better.  Maybe they don't make such an animal, but I would think with Wb's pull, someone could fill the need.

BTW, that 10 amp circuit breaker should be pulled and deep-sixed.  It is terrible.  Besides that ABYC doesn't allow auto-reset beakers, it's a very poor "automobile engine" component.  The harness I just finished - the breaker was so corroded I couldn't get the mounting bar off w/o literally destroying the entire breaker.  I found the guts were so corroded that I doubt it would ever have functioned if wire to the fuel pump shorted out.  It should be replaced with an moisture-proof ATC or ATM in-line fuse holder.  Or a marine breaker.

Cheers,
Ken

[Ron Hill]

Ken : Yes, I bought a single pole oil pressure switch just like the M25XP engine has.  The rewiring simply was a "no brainer"!!

A thought

[Stu Jackson]

This whole thing pointed to another wiring mystery that someone may be able to shed light on. The fuel pump in the key-on, engine-on position gets power through the oil pressure switch, the idea being that the oil pressure drops and the engine will auto stop when the voltage cuts out- seems like a good idea. So I tried it- disconnected the fuel pump power wire while running assuming the engine would cut out. After 15 minutes of running under load I got tired of waiting for it to stop and ended the experiment. I thought the Facet Cube pump WB uses has a positive shut off. Apparently it does not. The fuel tank on the 380 is high enough that once running, it will keep going, even without a pump and only half a tank of fuel- which begs the question. Why is it wired that way in the first place?

Given the similarity in wiring, I'd be curious to know if C34 owners with M25XPBs have seen anything like this. Sorry for the long post. Even the local WB rep was mystified.     

2nd, it's not only the XPBs, it's the M35s, too.  We discussed the unforeseen consequences of this idea in the Critical Upgrades sticky topic, which has links to earlier discussions which get into A GREAT LEVEL of detail.  Rather than trying to summarize those, why not try looking into it.

Short answer?  My recommendation was to "fix it" by eliminating the pump stoppage, just like the M25s, which worked just fine and still do work.  I put in a shutoff toggle switch to turn the pump OFF when I'm bleeding the secondary filter on the engine.

KISS 

[2ndwish]

Stu- Your memory continues to amaze (I have no clue what I had for lunch yesterday). Those posts were spot on and might have even solved a further mystery we had - a sudden and unrepeatable power loss when our tank was half full. I'm going to take a close look at the spade connector on the oil switch.  Two questions remain: Facet makes a positive shut-off version of the same Cube fuel pump- why didn't WB use that one? Given the flakey design of the fuel pump/solenoid/OP buzzer circuit, why don't more owners see buzzer/light issues when starting?

[Ron Hill]

Two questions remain: Facet makes a positive shut-off version of the same Cube fuel pump- why didn't WB use that one? Given the flakey design of the fuel pump/solenoid/OP buzzer circuit, why don't more owners see buzzer/light issues when starting?

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2nd : Don't ask us because we've already figured it out!!  Ask Westerbeke !!

A thought