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Old 06-24-2018, 03:27 PM   #1
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Northern Lights relays vibrating loose

It's been a year and a half, but I think I've finally figured out why my Northern Lights 16kw genset suffers from intermittent shut-down / won't-start issues. As I've suspected for a long time, it's related to the four Bosch relays in the control box that allow the engine to start, and to keep running, as long as none of the three safety shut-downs activate (low oil pressure, high coolant temp, high exhaust temp).

Today, when the genset was running, but the gauge needles were vibrating (usually a precursor to a shut-down), I pushed down firmly on the relays while my wife watched the gauges, and she said the needles were rock solid as long as I was pushing them. As soon as I let go of them, and jiggled one a tiny bit, it shut down. Based on this, and on the fact that every other time I've had a problem with this genset, and have gotten it working again, the fix involed one or more relays - I have decided the problem is simply that the relays are not being held solidly in place in their sockets.

Has anyone dealt with this particular issue? Can I do something to the sockets to make them "grip" the relay pins better? Can I replace the sockets with new ones? I'm thinking of using some zip ties and a short length of 1/2" x 1/2" wood to snug them into place, basically doing what I did with my fingers to steady the needles.
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Old 06-24-2018, 04:04 PM   #2
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Most of the "cube" relays are fairly inexpensive, since they targeted the automotive market. I would replace them all with new. Fretting corrosion at either the socket or relay end of things could cause loss of electrical continuity. If new relays don't fix this, then you may be looking at a much harder job of replacing the sockets.
It's a long shot too, but do the engine mounts appear healthy?
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Old 06-24-2018, 05:04 PM   #3
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A common problem is the ground wire that attaches to the generator end housing below the electric box. Be sure that is good and tight. If loose, it can create all sorts of off problems. Your pressing on the relays may just be moving wires enough to remedy a bad ground. Also, the push-button DC breaker that is labeled "fuse" is a problem child. They don't hold up well over time. You could try shorting across the fuse terminal as a test to see if teh problem resolves.
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Old 06-24-2018, 05:07 PM   #4
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I would get a pair of needle-nose pliers and "tweak" the pins of the relay so you have to use a bit more force to install them (or gnurl the faces of the pins with vise-grips) as well as a scotsche of dielectric grease to ensure no corrosion. I would also buy a few spares. They used to be VW headlight relays but now they are everywhere.
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Old 06-24-2018, 05:33 PM   #5
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All of the above suggestions are good ideas to deal with what's been happening but I would wonder - WHY is the control box/engine vibrating so much?? It should be pretty much dead smooth. Is something loose?

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Old 06-25-2018, 06:54 AM   #6
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All of the above suggestions are good ideas to deal with what's been happening but I would wonder - WHY is the control box/engine vibrating so much?? It should be pretty much dead smooth. Is something loose?

Ken

Good point, and well worth checking. Relay failures are not super common.
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Old 06-25-2018, 07:19 AM   #7
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Can you post a good clean closeup photo of the empty socket?
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Old 06-25-2018, 11:21 AM   #8
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All - thanks for all the great input so far! As an update, after my post yesterday, I fashioned a "hold down" from some Starboard and zip ties to very, very firmly hold the relays in place in their sockets. And it didn't help. So now I'm thinking it's either the pins of the relays not maintaining perfect contact with their sockets (for which a couple suggestions were made, and which I will try), or the wiring on one of the sockets isn't perfect, which I will check (again).

Corrosion is not an issue - there has never been a drop of water anywhere near the control box, and everything in it is squeaky clean. However, I know there can still be less-than-perfect electrical contacts, so I'll tackle that with some of the suggestions.

Question: is there any compound that can be used on an electrical connection that improves the connection? I know dielectric grease helps prevent corrosion, but by being dielectric (non-conducting), it doesn't actually improve the connection. I'm thinking something that's the opposite of a dielectric that would help a less than physically perfect connection still conduct electricity perfectly.

As for the ground to the case, it's rock solid and corrosion-free. Already checked that.

As for the vibration - it's not excessive, but it's not silky smooth, either. The end of the zip tie (which I didn't clip off, and which sticks up in the air a few inches) definitely shows some vibration happening. But it certainly doesn't seem like enough to cause any real harm. Besides, at this point, short of replacing motor mounts with soft new ones, I don't know how I could lessen the vibration, so I've got to focus my efforts elsewhere initially.

Oh, as for replacing the relays - I had two spares, but one of them is currently in the position of the relay that seems to be causing the problem (the Run Relay). And I've bench tested all of the relays, and they seem fine - of course, that doesn't take vibration into account. I'll keep looking for another obvious problem, but may go ahead and order four new ones. (I'm in the Bahamas, so it's not as easy as an Amazon Prime delivery!)
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Old 06-25-2018, 11:40 AM   #9
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Per post #4 I’ve gotten balky spade fuses and relays to work. I believe the tweak XS is referring to is a twist of the male part so it seats tighter in the female part. (For electrical connections now guys)

A dry ER is no guarantee for subtle corrosion coating the relay surfaces. Spray the connections too. Both tricks are quick and painless.
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Old 06-25-2018, 11:58 AM   #10
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NL gennies can be afflicted by flaky DC power breaker. The kind with red button that pops out on overload. The vibes wear out the internals. Try jumpering that and see if it helps.

You know that by wiggling things, the fault can come and go, but probably can not conclude the fault is in the relay connections. That would be a PITA to replace, basically the whole harness.

Replaced many of the DC breakers. Never had a problem with the relay connections.
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Old 06-25-2018, 12:06 PM   #11
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I had exactly the same problem with the same generator. I had to go down and push in the cube relays each time it would stall out and would run for a while. Eventually solved the problem with new cubes which worked great thereafter. Parts were easy to get and not expensive. Easy to install. Good luck.
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Old 06-28-2018, 07:29 PM   #12
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Well, so far, so good. I ordered 8 new Bosch brand relays, but won't have them for awhile, so I did everything else everyone suggested: removed each relay and put a little twist in each pin, made sure all pins were perfectly free of corrosion, put a little dielectric grease in the female part of every connection, put the relays in and out of the sockets several times, used my bracket to make sure they can't come loose, inspected every connection, and bypassed the fuse that was recommended in post #10. I also didn't reattach the block of relays and sockets to the metal control box. Instead, I used some zip ties to suspend the whole assembly in mid-air in the control box, to totally eliminate any vibration.

As soon as I pushed the pre-heat / oil pressure bypass switch, the gauges came on and the needles were rock solid. Started right up, and now, 30 minutes in, they're still rock solid. But I've seen this before - a couple hours go by before it shuts down. And I can't run it that long right now. But like I said - so far, so good.

Thanks everyone for your input! TF really is my go-to source for advice - you guys rock!
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Old 06-28-2018, 08:05 PM   #13
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Are the genset isolation mounts working? If you have a collapsed or worn out mount, it will pass a lot of vibration to the box.
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Old 06-28-2018, 09:38 PM   #14
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Have the identical problem. A less than secure socket on the “run” relay looks like it may be a prime candidate. Shutdown was measured in many hours, then a few hours, now inside 30 minutes. I may rebuild the whole box if need be, but I still need to check the position of the sensors. Pain in the butt on these hot days at anchor when you need the A/C.
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Old 06-29-2018, 07:03 AM   #15
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Quote:
Originally Posted by Ski in NC View Post
NL gennies can be afflicted by flaky DC power breaker. The kind with red button that pops out on overload. The vibes wear out the internals. Try jumpering that and see if it helps.

You know that by wiggling things, the fault can come and go, but probably can not conclude the fault is in the relay connections. That would be a PITA to replace, basically the whole harness.

Replaced many of the DC breakers. Never had a problem with the relay connections.

I mentioned this earlier too, and think it is very possibly your problem. These breakers are notoriously fragile and will cause your exact symptoms because it controls the power to the relays.


It's super easy to bypass and test this. Just pull off the space connectors from the breaker and put them on an automotive blade fuse. Then tape around it if necessary to insulate. I'll bet your generator will be rock solid after this workaround, and you can then order a new breaker.
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Old 06-29-2018, 08:35 AM   #16
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Are the genset isolation mounts working? If you have a collapsed or worn out mount, it will pass a lot of vibration to the box.
Well, they're still in place, but maybe they've hardened over the years. I've noticed that when I push down on one particular corner of the control box, the vibration of the whole box seems to lessen somewhat.

I guess I should find the part number and see if I can get some new ones, or just get any rubber dampers of the right size.
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Old 06-29-2018, 08:41 AM   #17
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Have the identical problem. A less than secure socket on the “run” relay looks like it may be a prime candidate. Shutdown was measured in many hours, then a few hours, now inside 30 minutes. I may rebuild the whole box if need be, but I still need to check the position of the sensors. Pain in the butt on these hot days at anchor when you need the A/C.
Larry, I'd try what was suggested here - pull the relays out, use pliers to put a very minor twist in each pin, then put them back in with dielectric grease on each connection. Put them in and out several times to make sure they're making good contact.

Then, to eliminate vibration as the culprit, disconnect the whole relay/socket bank from the side of the control box (just two nuts and bolts - don't drop them!), and use some long zip ties to suspend that whole bank in the air in the middle of the box, thereby eliminating 99% of the vibration on the relay/socket bank. (This is just temporary - at some point, I'll reattach it to the control box.

The only other thing I did was put a jumper around the fuse as described in post #10, above. I won't know for sure if it's fixed until I run it for a solid 2 - 3 hours, but it behaved perfectly for an hour yesterday!
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Old 06-29-2018, 08:44 AM   #18
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I mentioned this earlier too, and think it is very possibly your problem. These breakers are notoriously fragile and will cause your exact symptoms because it controls the power to the relays.


It's super easy to bypass and test this. Just pull off the space connectors from the breaker and put them on an automotive blade fuse. Then tape around it if necessary to insulate. I'll bet your generator will be rock solid after this workaround, and you can then order a new breaker.
I did bypass this fuse (although not as ingeniously as you suggested - I should probably do it that way, to keep some fusing action in place). So far - after an hour of running - everything looks great.

I'll order another of those fuses, though, and put it in place. Can't hurt.
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Old 06-29-2018, 11:33 AM   #19
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Balky fuses and relays making poor contact on two different boats have caused my main engines to not start or go into limp mode. Recently one of my fly bridge sounder readouts went dead. Removed plug connection sprayed with corrosion block and bingo.

Many professional Marine mechanics and electricians prefer changing parts to trouble shooting. Problem solved for awhile maybe but often the real issue rises again such as bad mountings, normal metal contact corrosion, electrical connections getting loose or wire chafe.

Brian, the final resolution will help us all. Thanks for keeping us informed.
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Old 07-02-2018, 08:04 AM   #20
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UPDATE: One short run (30 minutes) and one long run (well over an hour), and still, everything is rock solid. I still have the jumper around the fuse, and still have the relay block suspended in mid-air with zip ties to eliminate vibration as much as possible (they barely move hanging out there by the zip ties).

I've got a new NL fuse coming, but I also have a Blue Sea Systems 15 amp "reset only" fuse coming. I will probably put the new NL fuse in first, because it'll just clip right in, whereas the Blue Sea will take a little reconfiguring. Once the fuse is in place, I'll run it like that for awhile. If it keeps working, I may not re-mount the relay block to the control box - I can't see any harm from leaving it suspended by the zip ties, especially after I put the lid back on the control box.
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