The call comes through.
Coolant’s being pushed out.
And there’s something else…
An oily sludge coating the front of the truck.
Straight away, you know — that’s not normal.
We get it into the workshop.
Pop the header tank cap…
And there it is.
Oil sitting on top of the coolant.
Thick. Sludgy. Wrong.
Now the question isn’t if something’s failed.
It’s where.
On these Volvo engines, the oil cooler runs oil and coolant side by side.
It’s designed to control temperature.
Keep everything stable.
But when it fails…
the pressure difference takes over.
Oil runs at a higher pressure than coolant.
So when there’s a breach — oil doesn’t stay where it should.
It gets pushed straight into the cooling system.
And that’s what you’re seeing.
Not just a leak.
Contamination.
Leave it too long, and it doesn’t stay contained.
That oil starts working its way through the system.
Breaking down hoses.
Softening seals.
Coating everything it touches.
Cooling efficiency drops.
Temperatures climb.
And suddenly what started as a cooler failure…
turns into something much bigger.
Overheating.
Liner damage.
Cracked components.
The kind of repairs no one plans for.
But this one came in early.
Before it had the chance to escalate.
So we get to work.
Replace the oil cooler.
Flush the entire cooling system properly — not just a quick rinse.
Clean it out until it’s right.
Because when it comes to contamination, halfway doesn’t cut it.
You either remove it properly…
or it comes back to bite you.
By the time it leaves, the system is clean.
Coolant where it should be.
Oil where it belongs.
And a truck that’s back to doing what it’s meant to do.
Because sometimes the biggest problems don’t start with a bang.
They start quietly.
And if you catch them early…
they stay small.
📍 Webbie’s Mechanical | Welshpool
📞 (08) 9353 1289
Fix it early. Keep it simple. Keep it moving.
