Volvo D2-55 hot when not in use.

[DavidMLee]

On our catamaran, our starboard engine remains almost too hot to put your hand on even after it hasn’t been operated for 24 hrs. At the same time we seem to have a large electrical draw in that with no generation (but operating only the self steering) the voltage on a 180AmpHr battery bank will drop from 12.6V to 11.3V in 3 hours.

All we can think of is that the engine pre heat / flow plus are permanently on.

As we’re 2 degrees below the equator, ambient temperatures are 25+. We have another 20 days sail to the Marquesas.

Has anyone had any experience with this and/or can offer diagnosis and/or work around fixes.

Regards
David Lee

[barnab]

Turn off the water heater. It is lower than the engine, so the hot water rises to the engine and keeps it hot. As the water cools down it flows back to the heater, the heater heats it up again and happily drains your battery.

[DougR]

I would be very surprised if your house hot water is heated by 12 volts, but if it is, turn it off and see what happens. It’s also possible that the heat in the hot water heater is thermo siphoning back to the engine. Try shutting the engine coolant water valves to the heater ( if you have them) and see what happens.

As for the glow plugs heating up the entire engine, it could be though I’ve never come across that.

If you have a D2-55 A, B or C version, the glow plugs are controlled by a relay found in the electrical harness connection box mounted on the heat exchanger side of the engine. There are two relays in that box, one for glow plug control, and the other for starter motor control. You can figure out which is which by simple trial and error. Remove the glow plug control relay and see what happens. If the engine cools off normally, the relay is bad. If you don’t have a spare, the engine should still start with a few more seconds of cranking given the ambient temp at your location. These relays are common Bosch type relays and can be found in auto stores. If you have a volt meter you can also check for continuous voltage on the glow plug feed strip, a metal strip that connects to all four glow plugs. It should have voltage only when the key is turned to glow or the glow button is energized. (Depending on the panel you have)

If you have a later model engine with the MDI system, all of the above still applies except that the relay is embedded in the MDI box and you can’t access it.
In that case check the voltage on the glow plug feed strip or simply disconnect the current feed wire from the strip. By sure to insulate the end of the wire if it’s energized.

I suppose there is a chance that there is some sort of short or backfeed in the alternator or regulator, but I would think the heat would be confined to that part and not heating up the entire engine.

There is always the chance that the glow plugs are eating up some juice, or that a thermo siphon is going on, and the autopilot is taking the rest......

[skipperpete]

Hi David and welcome to the forum. Follow DougR’s advice regarding the mysteriously hot engine, I’m curious about the glow plugs, my old Pajero diesel ( god rest its soul) did exactly this but fairly quickly melted the Glow plugs… definitely less than half an hour, probably 10 minutes.
Is there any possibility that there’s a solar hotwater link to the domestic supply (a loop of black poly pipe would do er) and have you got hot water at the outlets?

[DavidMLee]

Hi DougR
Thank you for your very detailed reply.

Our first thought was also the water heating being used to heat the engine and indeed the electric water heating switch was in the on position. However, like yourself we didn’t expect that water heating via 12 W would have been designed into the boat, regardless we turned that switch off and that had no effect.

We have also noted that the leads from the hot water cylinder to the engine themselves, not hot so in our view that discounts any thermos siphoning option.

What we have done before getting your reply Was too switch. The electrical supply breaker switch to the engine to the off position. This had the effect that these men started to pull down and now some 6 to 8 hours later it is back to the ambient temperature.

So unless there is some other electrical heating element in the engine, it does seem that the glow plugs being permanently on Is the issue. I note that a second respondent said that he would expect the glow plugs on his Pajero to have burnt out after the number of hours, but perhaps Volvo ones are made of stronger materials.

We haven’t yet tried your suggestions re the relay box, etc, but will have a go at that in a day or two after we have investigated a different issue with our water maker.

Thanks again and all the crew were very impressed with the speed of your reply and the detail contained. Thank you again for that.

Regards,
David Lee.

[DavidMLee]

Hi Skipper Pete
Thanks for your reply. I think we have now water heating as being the problem if you see my reply to DougR.
We are also quite surprised that glow plugs could be on for days on end and not burn out.

Regards
David Lee

[DavidMLee]

Hi DougR

… we have now eliminated water…