Do not fill up to the brim

[Alex Roux]

Some Fuel jockeys (and car owners) like the idea of filling up the fuel to the brim, i.e. up to the point where you can actually see the fuel in the pipe before closing the lid.
This was done on my car just before a trip in which we drove quite hard in 35+ degrees celcius heat.
At the next stop the petrol pipe got loose from the clamp! Possibly due to to pressure building up that needed to be equalised (due to the heat?).
So the car was spitting petrol at the back! It was standing at a slight incline.
I moved that car to stand in the opposite direction (on a slight decline). The spitting petrol stopped and reconnectd the hose at the back with the clamp.

Although there is a breather, this breather apparently only really works if the pipe running into the tank is not filled with petrol as well.
So the conclusion is to only filll up until the petrol pump stops the first time.

Maybe I got this wrong, but please comment if you have had similar problems or if I got this wrong.

Thanks

[Grootseun]

Alex the braether pipe is moslty to release the air form the tank as you fill it up , if you are reffering to 2nd pipe you see in the filler neck , the possible cause here if you had a pressure build up is either the pressure release valve in you cap that should allow pressure to release or and i must say im unsure that 2004 TDI will have this system - the canister purge valve system that electronically releases the pressure into the intake manifold , but for pressure build up to push of a clamped pipe the clamp muyst have been badly fitted to start with in my opinion

[Alex Roux]

Hi Grootseun

Interesting. So the pressure could/should never have been that much unless the clamp was not properly fitted.
What does that fit usually look like. I have not looked at this on another Patrol. Is it just a clamp around the pipe?
Thanks.

[Grootseun]

Jip if you look at the metal ipe around which the rubber house goes youll see a small bead on the end , the rubber pipe must be pushed over that and the clamp must be tightened on the rubber pipe behind that bead so that it in essence locks the pipe in place as well as seals it and yes if the pressure release setup is in good working order that pipe should have never come off , so im geussing here - not the pressure release just a bad fitting pipe , ive seen petrol tanks blow up like balloons before they push pipes off

Easy way to check if its working is to simply listen next time you open your cap on n hot day if it releases vacuum or pressure youll here it when you take the cap of then you know youve got a problem

[dieselfan]

My manual on both the VW and the Pathfinder say fill up until the "double click". When the guy fills up say to first click, wait a few seconds then fill till second click. When they fill up to visual I do an extra 80-120km on a tank but NOT without the fuel marks on outside the cap ruining my paint work.

On ALL my vehicles I "double click", the NP200, Golf, Pathy, Disco heck even the 330Bm all show fuel leaks / residue when driven AFTER filling up to visual check.

[Herrie]

I always fill it up completely full and never had any problems or leaks - the Patrol, Safari, Skyline, Sentra, Audi, Indica, and even the wife's Pajero.

[Alex Roux]

This should not have happenend. This made me click this morning.
I pretty sure I know what happened now.
I added custom fitted rubber inner fender liners. This was also tied arond the petrol hose with a cable tie. Stupid and unnecessary. Driving faster than usual, the pressure from drag must have pulled the hose off.

Moral of the story: we have the potential to really mess things up when we fiddle with things.

[David]

Moral of the story: we have the potential to really mess things up when we fiddle with things.

Ha ha - Isn't it most times the culprit

[dieselfan]

I always fill it up completely full and never had any problems or leaks - the Patrol, Safari, Skyline, Sentra, Audi, Indica, and even the wife's Pajero.

Perhaps I take my corners too quick

[Peter Connan]

When fuel heats up, it expands. The filling and breather arrangement are designed so that when the tank is filled to specifications (usually double-click), there is still enough room in the tank to take care of usual temperature fluctuations. In other words, you should be able to fill in the cool of early morning and not have a leak at midday.

However, as a secondary safety measure, fuel caps are designed not to be able to seal completely. This is bad news if you do really deep water crossings, but good news the rest of the time. the other very important reason for this, is that if the fuel cap sealed, then using fuel from the tank would result in the tank developing a vacuum, which would either cause the tank to collapse or fuel to stop flowing. Sometimes caps can get blocked by dust, and if you ever open your tank and the tank either blows or sucks air audibly, you need to have a look at your cap.

With a properly functioning fuel cap there should never be any risk of pipes popping off due to pressure build-up, but there may well be a slight leak especcially if you fill up when it is cool.

Off course, long-range tanks are seldom designed with the same carefull attention to filling rates and levels as OEM equipment, and on my setup if I were to stop on the click, I would be around 100l from full.

I generally do not fill to the brim except when I know I will drive at least 200-300km directly thereafter. Of course there is also the temptation to fill on the first tuesday of the month most months, but when I am just driving to work and back my car will leak fuel for a week or more thereafter.