• A Plus Truck Repair

Thermoking Tripac APU Road Repair

Updated: Jul 3

Recently I was working on one of this Thermoking APU ( Auxiliary Power Unit), which had a problem of raptured coolant line and caused the Freightliner Truck to shut down as a safety future (due to low coolant level) to prevent engine overheating. The reason for this wwas that teh APU makes single coolant loop with truck's engine and truck cab's heater core. When dispatcher of this trucking company called me up for a road service I have tried to clarify which hose was cracked and was told that the 3/4" hose that runs from tractor to APU. When I finally got to driver (the truck was sitting on the road shoulder) and opened up the cover of APU the driver pointed out at the factory prefabricated hose that connects thermostat housing with lower radiator pipe and has two different diameter openings - one end is about 3/4" the other end's diameter is about 1 1/2". My hose I have bought on my way to this road call was bulk length of cooling hose 3/4" diameter. I have realized that I will have to come up with some original idea on how to fix this truck. I decided to disconnect the supply and return coolant lines that run into and from APU and joined them with 3/4" splicer, attached two clamps and torqued those down. After topping off the coolant into the tractor, which took about 7 gallons I let the engine idle for about 10 minutes to make sure all the air pockets were filled up with expanding coolant. The reason I decided to splice the in and out coolant lines to APU and not just shutting the valves off was that coolant needs to circulate and was designed to "form a loop" running from tractor's cooling system into APU's and function as one combined coolant system. Simply shutting off the coolant line valves will not sort out the issue since coolant will not circulate and prevent engine from operating properly, ultimately leading to engine safety shut down again. Below are some pictures to demonstrate the hose that cracked, splicer, and hoses that were disconnected and spliced together as a temporary repair solution. All of them are sitting right on the top of Tripac APU radiator and provide an easy access to work on them.

Coolant circled lines at the top were spliced together to complete a coolant circulation loop

Splicer used for joining two coolant hoses together as a temporary fix to get truck back in service

I-80 passed exit 170 eastbound during mobile emergency road repair service

Cracked coolant hose that caused a tractor to loose 7 Gal of coolant and eventually shut down to prevent engine overheating

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