A tradie rang us from a street at Parafield Gardens. Two litres of AdBlue had gone into the diesel tank of their Ford Transit, on a tank that was already full. The engine had never been started. The key had been turned to ignition.
That last sentence is the one that decided how we treated the job, and it is the part most people would never think to mention on the phone.
Why turning the key matters nearly as much as starting it
On a modern diesel, switching the ignition on runs the fuel pump for a few seconds to prime the system. The engine does not need to turn over for that to happen. AdBlue is a urea and water solution and it is heavier than diesel, so it sinks straight to the bottom of the tank, which is exactly where the pickup sits. Prime the system with AdBlue sitting on the pickup and you can move it out of the tank and into the lines before the engine has done a thing.
So we treated the van as though it had been run. Not just a tank drain, but a full flush of the supply side as well. That is a bit more time on the kerb, and it is the difference between a clean job and a phone call in a fortnight.
What we did on the kerb
- Kept the ignition off from the moment we arrived, so nothing primed a second time.
- Drained the tank out completely, 65 litres of diesel and AdBlue.
- Flushed the supply lines.
- Cleaned the fuel filter and the water separator.
- Took it out for test drives, to be sure it was running the way it should before we left.
Why AdBlue gets treated differently to petrol in a diesel
Petrol in a diesel is a lubrication problem. Petrol thins the diesel and strips the film the high pressure pump relies on. AdBlue is a different animal. It is water based, it corrodes the metals in a fuel system, and heat inside that system dries the urea into crystals that block the fine passages in the injectors. That is why an AdBlue drain gets a heavier flush than a petrol job, and why the clock counts for more.
If you have just done this
- Leave the key alone. Not to ignition, not to move the car, not to put a window up.
- If the engine is running, switch it off.
- Call us on (08) 7083 9699 and say two things: what went in, and whether the key has been turned. Both change how we plan the job.
We come to you, wherever it happened, and Parafield Gardens sits well inside our northern suburbs patch. The full detail on this fault is on our AdBlue misfill page, and if you are standing at the pump reading this right now, the first 60 seconds post is the short version.
