Not my finest moment, I forgot to put the fuel cap on after filling up a couple of days back (fuel cap is in North Wales, I'm now in Essex... Not much chance of seeing that again). I went through one of those machine car washes at BP and noticed the fuel filler door was ajar... Thought nothing of it at the time. Have since driven a few miles home and all seem to be fine (so far?), no particularly rough idling, no lack of acceleration, no clouds of smoke behind me when accelerating.

 

Does the Octavia have any 'second line of defence' after the fuel cap? Have I put myself in for a very expensive Christmas present to myself 🙃 due to a ton of water going straight into the fuel tank? And is there any obvious way of telling if water got in (i.e. fuel gauge reading higher, etc.)? Any easy remedial actions, or is this a "just get the tank drained" situation?

 

Just to top it off, this is a diesel as well...

I don't think there is a second line of defence. Maybe some antisiphoning flaps etc. But the design of the fuel flap and fuel cap collar may have minimised or even eliminated water entry.

 

You need a new fuel cap. You can get aftermarket.

 

Given the risk. a drain off of some of the fuel tank may not be a bad idea after leaving for a while to settle.  Then again, it may be unnecessary, but how will you know and what are the consequences: Hint; Bad.

 

 

Edited 20 December, 20214 yr by TheClient

You could try some additives that ‘dry’ your fuel, i.e. makes the water miscible with the fuel

 

https://www.eurocarparts.com/p/wynns-dry-fuel-325-ml-555770570?type=shopping&gclid=Cj0KCQiA8ICOBhDmARIsAEGI6o0Unyp4zmXHx7KW48HlZHHNSk442qOrypsnV7-o6SNjoyFoIfUhMS4aArRYEALw_wcB

 

Get yourself a replacement fuel cap ASAP. I believe it is an offence to drive with a missing or leaking cap. It’s an mot failure if it is. 

Forget the snake oil, like most of them its a non solution to a problem that does not exist for you.

 

You will be fine, open the drain tap on the diesel filter housing and you will see any water come out first, the inverted filter bowl is designed to collect water.

 

Replace the filter of course, if the bowl does not have a drain then siphon out the contents.

 

Cycle the ignition to prime the injection system before starting.

Edited 20 December, 20214 yr by J.R.

By pure coincidence It's going for a service tomorrow, so I'll ask the guys there what they think, and may get them to take a sample of the fuel then.

 

Definitely will be getting a new fuel cap tomorrow as well, literally only just noticed it was missing this afternoon.

Cheers for the link as well, I wasn't having much luck finding ones compatible with diesel.

 

Again, I'm getting it serviced tomorrow so filter should be getting replaced then anyway

 

Am I right in saying that diesel floats on water? And if so, does that mean that either:

1. Any water will get siphoned before diesel (i.e. don't have to drain the whole tank)?
2. If no water comes out immediately, I can assume a negligible amount is in the tank anyway?

Diesel floats on water.

 

If the flap was open in the car wash was it not going to be pushed closed by the roller brushes or ripped off.

I do not expect water to have got in. 

 

But then again i could be wrong.  There is a 50/50 chance. 

To clarify: the fuel door was closed when I went in but was found ajar when I came out (as if you'd clicked it in to unlatch it).

 

Also, yes, it was a roller brush carwash, not one of the touchless ones... If they even exist in the UK, I don't think I've seen one.

14 minutes ago, TheHungriestBadger said:

the fuel door was closed when I went in but was found ajar when I came out

You absolutely need that new filler cap. It's an MOT failure to not have one when/if you get that length, and meantime "using an unroadworthy vehicle" if the wrong cop stops you for any reason.

I'd say drain the fuel filter out into a jar and have a look what's in there for signs of the diesel floating on water or any weird colours from the car wash detergent (they'll probably sit in or on the diesel rather than mixing with it).

 

From there on in, it depends how cautious you want to be. Full blown worried, would be drain and refill the tank with fresh diesel. Not mildly concerned would be just carry on and see what happens. I'd probably just keep the tank topped up as much as possible for a few thousand miles. 

 

If you did North Wales to Essex since you filled up, I'd be inclined to say that anything really, really bad that was going to happen would probably have already happened, but then I'm a bit of a fatalist. 

Edited 23 December, 20214 yr by StevesTruck

Only went through the car wash when I was back down to Essex, but I have done some driving since (home from car wash, to and from garage). I've fitted a new fuel cap, brimmed the tank and chucked in a bottle of Wynn's Dry Fuel (linked in a previous post), car still runs indentically to how it did previously, so I will probably just keep the tank topped up for the foreseeable future. I'll get a good 300 mile run when I head back up to uni in North Wales after New Year's.

 

Cheers for all the input guys.

Keeping the tank topped up has no affect on things, the fuel pickup is at the bottom of the tank where the water would be and any contaminants will be held captive in the fuel filter/assembly.

Very concise and well put!

So just a change of the fuel filter and remove whatever's in the actual filter housing itself?

 

In which case:

 

1) is the fuel filter as easy to access and replace on the 2.0PD as in the 1.9PD (which has several YouTube videos on how to replace)? I assume so.

 

2) If I was to drain the fuel filter housing as is being implied, is it just a case of cycling the ignition a few times to run the fuel pump and fill the housing back up?

1. If it looks the same then most likely.

 

2. If the filter unit is the same as on the 1.9PD with UFI type there is no drain plug, you will have to open the unit.

 

You will see if there is any water/debris upon removing the top of the unit, fuel can be siphoned, syringed or blotted out.

 

If contamination is minor just clean it out to prevent rust and reassemble keeping the filter until your next service schedule, no point fitting a new filter prematurely if it's running fine.

 

If it has significant contamination, again clean the cannister but refrain from replacing the filter if it's running fine and run it for half a tankful before rechecking.  It's only necessary to replace the filter if you experience running issues e.g. lack of power at high power demand.

 

To prime an empty fuel filter, assemble the unit and cycle the ignition off/on to the 1st position ~10 times waiting 3 seconds each time to allow the tank pump to fill the unit then start as normal.

Appreciate the advice there MicMac, as you've probably gathered, I'm not great with cars, but I'm always keen to learn and things like filters seem like a good place to start from what I've seen online so far. It's not much, but it's something at least.

Advice...

 

Wipe the unit clean before opening to avoid dirt ingress and surround it with plenty of kitchen towels to catch inevitable diesel spills especially on the auxiliary belt and pulleys.

 

Lever the top off gently and evenly using a large flat screwdriver in the pry slots to avoid deformation.

 

Clean the sealing o-ring and apply diesel to it and the matching sealing surface to ease refitting, don't overtighten the screws.

Edited 24 December, 20214 yr by MicMac

If you can see significant corrosion in the recessed "well" on the filter top cover then set aside some time to remove and treat the rust and repaint it, if left it will eventually perforate spraying diesel all over the place and starving the engine.

 

Very good instructions and advice from MicMac 👍

13 hours ago, MicMac said:

Keeping the tank topped up has no affect on things, the fuel pickup is at the bottom of the tank where the water would be and any contaminants will be held captive in the fuel filter/assembly.

 

True enough  but I'd keep it topped up to hedge my bets as the contents of the tank move about as the car does. 

 

As I say, the only way to know you're totally safe would be drain and refill, but I wouldn't part with 50l of diesel that easily at todays prices  Although if he did, I'd be happy to give it a home!