A coolant leak with three faults hiding behind it — how we worked it back
“I’m losing coolant and I don’t know where it’s going”
This is a pretty standard request — “I’m losing coolant, no idea where it’s going.” A customer rolled in with exactly that. He also mentioned the truck felt down on power. Two complaints, one truck. We started looking.
Why this matters
Coolant loss left alone cooks engines. A truck down on power left alone wears parts and burns extra fuel. Three faults stacked on top of each other left alone is a roadside breakdown waiting to happen. None of these symptoms point neatly at one fix — and that’s exactly the problem.
Round one — two leaks, a cracked intercooler, and a missing O-ring
We pressurised the cooling system. Two leaks turned up: one around the air compressor, one out of the bottom of the radiator. The radiator was the bigger of the two and that’s what we pointed the customer at.
While we were under the bonnet, the lack of power had its own list. The intercooler was completely cracked. And the turbo had been replaced elsewhere before we got involved — when we looked at the turbo intake pipe, the O-ring was missing. Without that O-ring, the turbo can’t build the pressure it needs. Combined with the cracked intercooler, the engine wasn’t getting the air pressure it needs to make power.
We quoted the lot. The customer decided not to proceed at that time. That’s their call.
Related reading: Inside the Workshop · Services · Why Do We Punch a Hole in the Oil Filter?
Round two — the truck came back, now “overheating”
Couple of days later, the same truck back in. New complaint this time: it’s overheating. On the first visit we took it for a test drive and couldn’t get it to overheat, and the customer hadn’t mentioned overheating then.
Started fresh. Tested for exhaust gases in the cooling system first — that’s the head gasket check. No exhaust gases. But the cooling system pressurised almost instantly the moment the air compressor kicked in. Disconnected the air compressor. Started the truck again. Cooling system stayed put.
There’s the third fault. The air compressor was forcing air into the cooling system, pushing the coolant out, mimicking an overheating engine. Same truck. Three independent faults, each making a different symptom.
Takeaway
When the symptoms don’t add up, the answer is usually more than one fault. Real diagnostic work pays for itself — every time. If your truck has a symptom that won’t quit or seems to change every week, get it looked at. Book in and we’ll work it back to the actual cause.
