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Wmiii 01-10-2016 07:43 AM

Update on stopped Cummins
I thought I would send an update on what the mechanic found and the repair for my QSB 5.9 230 hp Cummins diesel.
We were cruising down to Ft Myers Beach from Bradenton, as we were going through the mooring field to our mooring, the engine stopped. We were towed to a mooring and after troubleshooting, discovered I needed professional help.
The mechanic came last Wednesday and found coolant moisture in the wireing harness and the related corrosion. That shorted my ECM out.
Apparently, coolant from the reservoir seeped into the wireing harness though a low coolant sensor. This has probably been going on for a while and now just caused the problem.
Apparently this is not a common problem, but one the service people had experienced before.
Now we are good to go on down to the Keyes as soon as the weather cooperates.

Wm Mayberry
Mariner 40

Ft Myers Beach

Ski in NC 01-10-2016 09:16 AM

Interesting. I drive a VW diesel car and they had the same problem. Coolant level sensor would leak and coolant would wick into wiring harness, causing all sorts of havoc, often very far physically from the sensor. The fix is to drill a little vent hole in the sensor receptacle so if there was any leakage, it vents out harmlessly.

Glad you got it sorted.

sunchaser 01-10-2016 10:04 AM

Ski andWmiii

Is this an area where a drip loop or elevation could be utilized?

Wmiii 01-11-2016 07:28 AM

I don't really know at this time what I could or should have done to prevent this. When we had the boat surveyed about 18 months ago, the surveyor didn't check the connections.
This would have happened somewhere, sometime, we are just fortunate that it stopped when we were in the Ft Myers Beach mooring field and to our destination for a couple of weeks.

Wm Mayberry
Mariner 40

sunchaser 01-11-2016 08:00 AM


Originally Posted by Wmiii (Post 403412)
I don't really know at this time what I could or should have done to prevent this
Wm Mayberry
Mariner 40

Going forward surely you will do something to prevent a re-occurrence? A drip loop on the coolant sensor or reposition the connection plugs or ??

Ski in NC 01-11-2016 01:03 PM

The problem with the VW coolant sensor was that the electrical plug had some pretty good seals, and if the probes into the tank leaked, it was coolant under pressure that went into the plug. The plug seals were designed well to keep water from the outside from getting in. It also prevented the water from the INSIDE, under pressure, from getting out. Drill a tiny hole in the receptacle and it provides a vent path.

I can't remember how the QSB coolant level sensor plug is arranged, but if I owned one I'd look at drilling a vent like on VW's.

jleonard 01-11-2016 01:17 PM

When I worked at a company that made solenoid valves, failed coils due to moisture wicking thru wire leads was often a problem in field failures.
Even epoxy potting/sealing could be subjected to wicking depending on conditions. A hot engine compartment contributed at times.
So did corrosive liquids like pesticides, and I would put salt water in that group.

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