Advice needed on hydronic heating problem

Mr Rehab

Traveller
We're in southern Argentina at a small place called Tres Lagos, heading to the nearest large town with mechanics, El Calafate.

The camper hot water system is plugged into the engine heating/cooling line to provide engine heat when running. ATW schematic attached.

Yesterday we noticed there wasn't any heat coming through the rear into the camper system ie no circulation of engine coolant. I initially thought the tap at the hot air radiator was blocked but it checked OK - ran the diesel furnace and the system in the camper seemed to heat OK with hot water and coolant apparently circulating in the camper system.

Later I found the radiator reservoir was filling with ‘excess' coolant - engine temperature has stayed normal throughout. Tried the heating system in the driving cab but no heat coming through. Drained about 2 litres of extra coolant out of the reservoir over the next 100km then it settled at normal fluid levels. The engine temp indications seem normal ie indicates cool after a stop then rises to normal range when driving.

So it seems:
- the camper heating system and taps are heating and circulating OK when the diesel furnace is operating.
- engine cooling seems OK with normal temp indication over 150km of stop start driving.
- no circulation of coolant from the engine system back through the camper system.
- no circulation of engine coolant/heat through the cab heating system.

I'm thinking one of the valves (or associated relays? )indicated in the schematic for the camper has failed; probably the ‘inlet' valve to bring coolant back to the camper system is not opening. This would explain why there was an initial build up of excess coolant in the reservoir as it could exit the camper system but not return?

I can't see why the cab heating system would also stop, unless its reliant on the coolant coming back from the camper?

Thought maybe the thermostat had failed but the engine has 2 thermostats and temp indications are normal. Concerned that the engine temp is reading off the coolant temp and this may be reading incorrectly but it all seems OK so far. About to lift the cab and check the radiator levels and a general inspection. I've been under the truck and located the camper valves which appears undamaged. Attached a schematic of the engine cooling system as well.

Any advice appreciated.

24C6283E-41C6-4279-947B-DED9EE0AD7FE.jpgCheers
 

javajoe79

Fabricator
Let the camper system cool off. Run the engine and feel the hoses until you find where the hoses aren't hot anymore. That should be your blockage or closed valve.....
 

Mr Rehab

Traveller
Thanks Joe. A good tip for next time but sometimes it's the simple things.

Went to put some air in the tyres this afternoon and found the compressor wasn't running either. Lightbulb moment ��

Found the 24V cab supply had been switched off - I checked fuses yesterday but overlooked the circuit breakers. On that circuit are the driving lights, air compressor and heater valves.

We had about 8 local Argentines through the truck yesterday, including 4yr old Bruno, who spent a few hrs visiting and playing. Somebody's fingers or boot has flicked the switch off.

Arrived in El Chalten late afternoon. The mountains are on the edge of town and look spectacular. All good.
 

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