Put Petrol in a Diesel Mercedes G-Class by Mistake?
When you have got petrol in a diesel Mercedes G-Class and the motor hasn't been started, keep it turned off, including to move it clear of the petrol pump. With the motor kept off, the petrol stays where it is in your tank, and in most cases a fuel drain is all the G-Class needs.
We come to misfuelled cars instead of the other way round, so with Petrol in Diesel the Mercedes G-Class stays at the forecourt or wherever it ended up. Hold off attempting anything yourself till you've rung us, and we'll tell you what to do.
Your first steps with petrol in a diesel G-Class
- With petrol in your tank, a diesel G-Class will generally still fire up and run, and seem perfectly ordinary for some miles. That is why people frequently drive off without noticing a fault, and the reason the engine needs to be left off.
- Leave your ignition off too. On a lot of diesels switching it on will set the fuel pump priming, which draws fuel from the tank to the injectors.
- Don't fill the remainder of the tank with diesel to dilute it. Your G-Class takes up to 96 litres, and filling it up simply leaves more contaminated fuel to empty out. Super unleaded is petrol here too.
- Ask the forecourt attendants when your car is in the way of a pump. They usually help roll the vehicle out of the way once it's in neutral.
- Once you phone 0333 366 0103, we need to know which G-Class you have, where it is, how much petrol you reckon was put in and whether the engine has been started. The exact version is useful too when it's on the badging, for instance the G 350 CDI lang.
Wrong fuel in your Mercedes G-Class once your engine has been run
Whilst it sits inside your tank, wrong fuel in your Mercedes G-Class does not reach the motor. That only starts when it is drawn out, which is what happens when the engine is started. The high-pressure fuel pump and the fuel injectors on a diesel engine are oiled by the fuel running through them. With petrol thinning the diesel, that protection is lost, and driving any distance on it is then what can do damage.
Stop somewhere safe and switch off when the G-Class has already been on the road. It can still be dealt with, with your tank drained and the lines and fuel filter cleaned till the last of the tainted fuel has been removed. Provided it is flushed out properly after being caught soon, it very seldom leaves permanent damage.
The G 400 CDI kurz is no different here from any other variant of the G-Class.
Your Mercedes G-Class fuel tank capacity, by version
The size of the tank counts because the danger rests on how much of the fuel in it is petrol, so the same couple of litres are more of a worry if the tank was close to empty when you fuelled up.
Tank capacities across the Mercedes G-Class range from 95 to 96 litres according to the version.
Our data place the largest tank in the G 350 CDI kurz and the smallest in the G 300 Diesel lang.
The G 400 CDI lang has a tank holding 96 litres.
| Version | Fuel tank |
|---|---|
| Mercedes G 300 Diesel Cabrio | 95 litres |
| Mercedes G 300 Diesel kurz | 95 litres |
| Mercedes G 300 Diesel lang | 95 litres |
| Mercedes G 300 Turbodiesel Cabrio | 96 litres |
| Mercedes G 300 Turbodiesel kurz | 96 litres |
| Mercedes G 300 Turbodiesel lang | 96 litres |
| Mercedes G 320 CDI Cabrio | 96 litres |
| Mercedes G 320 CDI kurz | 96 litres |
| Mercedes G 320 CDI lang | 96 litres |
| Mercedes G 350 Bluetec kurz | 96 litres |
| Mercedes G 350 Bluetec lang | 96 litres |
| Mercedes G 350 CDI Cabrio | 96 litres |
| Mercedes G 350 CDI kurz | 96 litres |
| Mercedes G 350 CDI lang | 96 litres |
| Mercedes G 350 Turbodiesel Cabrio | 96 litres |
| Mercedes G 350 Turbodiesel kurz | 96 litres |
| Mercedes G 350 Turbodiesel lang | 96 litres |
| Mercedes G 400 CDI Cabrio | 96 litres |
| Mercedes G 400 CDI kurz | 96 litres |
| Mercedes G 400 CDI lang | 96 litres |
What diesel G-Class do you have?
Check the badging on your boot lid, which usually shows the variant, then tell us what it says when you call.
On a diesel G-Class you will see CDI and BlueTEC on the badging.
The CDI badge is the commonest in our records, though the G 350 Bluetec lang is badged BlueTEC.
AdBlue in a diesel Mercedes G-Class
Certain diesel vehicles carry a mix of water and urea, called AdBlue, in a tank of its own with a dedicated filler, and rely on it to treat their exhaust. Even to move the car, do not turn your key when you've got AdBlue in a diesel Mercedes G-Class after it went in the wrong filler.
Even a tank of up to 96 litres won't dilute AdBlue as it would dilute petrol. AdBlue does not mix with diesel, so it settles to the base, right where the pump takes its fuel, and being mainly water it neither ignites nor gives the fuel pump any protection.
Even a little of it is plenty to end up in the fuel line. Once the water has dried off, what is left is urea, which forms crystals in your fuel system, filter and injectors among them, and eats into any metal it touches.
Check under your fuel flap if the G-Class has an AdBlue filler, since on many vehicles it is right alongside the diesel filler. AdBlue caps are typically blue and fit a much narrower nozzle than diesel.
What we do in a fuel drain on your Mercedes G-Class
A fuel drain on your Mercedes G-Class is carried out at the vehicle, and it doesn't need to be taken to a garage. On the G-Class the tank takes up to 96 litres, and we drain all of it after we have found out what was put in and whether your motor has run. Your fuel pipes and your filter are flushed after that, then we refill with clean diesel and prime your system before starting your engine.
The fuel tank in the G 300 Turbodiesel Cabrio carries 96 litres.
By the end, your G-Class is running on clean diesel once more and all set for you to take away.
AdBlue removal from a diesel Mercedes G-Class, explained
We take the same steps for AdBlue removal from a diesel Mercedes G-Class as we do for clearing petrol. AdBlue gathers at the base of the tank rather than blending in, and if the G-Class has been started it can leave deposits in the lines, so we rinse those through as well and replace your fuel filter if it needs it.
Here, AdBlue removal means getting AdBlue back out of a diesel tank it was put into through the incorrect filler. Disabling or taking out the AdBlue system on a car is not what it means.
What decides the price of a fuel drain on the Mercedes G-Class
A fixed quote isn't something we publish, because no two jobs need the same work. It mainly comes down to the following:
- whether the G-Class has been started or driven, which makes the greatest difference
- the volume put in, measured against the capacity of your tank
- whether it was petrol or AdBlue
- where you are with the G-Class, and whether it is safe to bring our van there
The G 350 CDI Cabrio takes 96 litres when full, for comparison.
We can let you know what this work will probably involve once you call and give us those details.
Questions about petrol in a diesel Mercedes G-Class
How many litres is the Mercedes G-Class fuel tank capacity?
It depends on the variant, from 95 to 96 litres, and each one is listed in the table above.
Can I fill up with diesel if I only put a little petrol in my G-Class?
It is not something we'd advise, as adding diesel does nothing to take out that petrol. It only lowers its proportion, and the petrol is still in the fuel system after you drive off. All of it is removed with a fuel drain, which for a modest quantity is normally everything the G-Class needs.
Should my G-Class go to the Mercedes dealer?
No. We are independent with no link with Mercedes or its dealers, plus we empty and clean your G-Class wherever it has stopped, so there's no need to move it anywhere.
Does it matter which G-Class I own?
It is useful for us to know which one you have when you ring, because we have data for 20 diesel variants of the G-Class.
Will my policy pay for wrong fuel in my Mercedes G-Class?
Some policies carry misfuelling cover and some do not, so it is worth checking yours. Whichever it is, we come out to drain the car for you.
What if I pour diesel in the AdBlue tank of my G-Class?
In this case, too, the right thing is to leave the ignition alone. Limp mode and a warning are what most vehicles show you when they are driven in that state, and their AdBlue system will need draining. Tell us which tank your fuel went into when you call.
Already driven my G-Class: what do I do?
Until we arrive, the motor needs to remain off, so pull over where it's safe then switch it off. Wherever you have stopped, the system is drained and cleaned there, and caught early like this, it very rarely leaves long-term harm.