Thread: Diesel fuel

No diesel wont evaporate to that extent at all. It will evaporate but only at a very minor rate, especially as was in a tank with only a narrow opening and a flap. All liquids do evaporate to some point, but oil based liquids take quite some time to do so (years even). The rate shown in some journals shows that it is possible for up to 50% of diesel to evaporate in open topped containers, that are exposed over 100days. But and its a big but that is wide open top containers in the most extreme upper limit. Your fuel tank is a closed system and even with the cap missing is effectively closed if you have a fuel flap. Petrol on the other hand can evaporate much quicker and if left stagnant for a period of time will do so and leave sticky deposits. I know with my motor bike it did this as there was still some fuel in the fuel bowl when it was stored even after I drained it. Result was a complete carby kit required.Are you sure you left the cap off or someone has been into your fuel? It is also possible that if you filled right up you may have lost a small amount cornering etc.
I know what you are saying I left 3 caps behind in 12 months. What was even more troubling was that I rang the servos between 1hr and 3hrs to see if they were still on the bowser, to be told no they were not. Now they are pretty much useless to anyone else as were keyed.
A friend informed me that a lot of servos keep them and sell them cheap to others, keep them and give to others or cant be bothered and throw them out. Some hold them and return them if contacted. Now we all know some brand caps can be rather expensive to replace genuine.
On the return trip after losing one in the wheatbelt of WA, I thought I would put it to the test. I asked at this particular servo if they had a new cap that would fit as I was running a generic plastic cap. They said no and only had the plastic generic new. However they pulled a box out from under the counter and said if I could find one I could have it for $5. Mine was not there as had been 2 weeks so someone else must have grabbed it. Only hoped it would lock on them. Did the same a couple of weeks later at a servo I had left one at and they also had a box, but if I could find it or one that fitted I could just have it.
I know in the past I have handed in quite a few, there are some dishonest people out there.

Dunno about your car, but on some vehicles the cap plays a role in emission control. Perhaps your high usage is a result of that. Just speculation, really.

Thanks. I think I will stay with the orange plastic cap. only $1.50

I'd replace the cap ASAP simply because of the higher risk of water and dust entering the tank due to a poorly fitting cap. The door doesn't really stop water from dripping down onto the cap area. Most of the modern screw type caps are interchangeable so any auto store should have a suitable one.

I'm surprised that there is no way to keep the cap with the car to prevent leaving it on the bowser.

Our Subaru has the cap tied to the car, the Range Rover has a place in the flap to sit the cap so one cannot close the flap with the cap located there.

I would get a proper cap. You should be able to get one from Supercheap or similar. There are really only a couple of different threads. I know the one on my defender is just the diesel one from there. Yellow in colour so hard to miss and only about $14. Previously before they released the yellow diesel on I had a Commodore one that is the same thread. They are slightly harder to lock but do lock.
Cheers
Craig

Interestingly, except for the VW I owned while at Uni, and the D2 I sort of own now, every vehicle I have ever owned (over more than fifty years) has had a captive fuel cap, including my County and 2a and Citroen. I am at a loss to know why they do not all have them.

John

Originally Posted by JDNSW

Interestingly, except for the VW I owned while at Uni, and the D2 I sort of own now, every vehicle I have ever owned (over more than fifty years) has had a captive fuel cap, including my County and 2a and Citroen. I am at a loss to know why they do not all have them.

John

It is a cost thing. I knew an engineer that worked for Ford and his job was to design fuel caps and doors. He said that Subaru's design was one of the most expensive to manufacture.
My D2 has a factory "string" attached, so unless this gets broken, it should not get lost.