Puma Diesel Leak from Fuel Tank

[The Cone of Silence]

Righto chaps, a fuel pickle for your Monday minds.

Monty has a 45l Front Runner aux fuel tank fitted to the driver's side rear wheel arch from which the fuel drip feeds into the standard tank. The 'inlet' into the standard tank from the FR AUX tank seems to be at a fairly low point in the standard tank, on the driver's side.

I filled up last weekend and, as always, filled right up to the top. many clicks. Much goodness.

Got home and noticed some dripping diesel on the driveway (which is flat) from the driver's side of the standard tank bracket. I put a bucket under it and was counting about 2-3 drips every few seconds. I couldn't see exactly where it was coming from but the Front Runner tank looked fine and dry and the hoses looked good too.

Eventually, after a couple of hours, the dripping slowed and then stopped. I wondered if this could be pressure/ temperature related as it was getting later in the day and cooling down.

Next day, I drove about 10kms and then noticed at home the dripping had started again...at the same rate as before. Again, it slowed and then stopped.

Total diesel in the bucket from these two episodes of drippage - about half a litre over 5 hours of dripping.

The next day I drove it a lot (mostly in paddocks and dirt tracks, avoiding roads where possible) to try and get the fuel level down to only the standard tank and and it seems to be a correlation i.e. once I'd used all of the AUX 45l and the needle on the dashboard gauge started moving down from the FULL mark, the drippage was no more. TA DAAAAAHH!

This suggests to me that it's a loose seal on the main tank somewhere.

Sender unit perhaps? Is there anything else up on top of the tank that it could be?
Cracks in the tank perhaps?
Where is the breather hose located? I've heard that might be a place to have a butchers at too.
I suppose the real questions is whether I need to drop the tank out to check it and how much of an embuggerance that job will end up being.


So many questions....
Appreciate as ever your advice, be it brilliant or terrible ;-)

[martnH]

Check fuel tank breather pipe

[martnH]

The tdci defender has its fuel tank breather dangling above the chassis near the rear wheel arch.
I know it sounds okay but It means the breather will be lower than the filler neck where you filled the tank up to the maximum

I am not expert but basic physics tells me it's a stupid idea. The liquid in the tank will maintain equal level in all connect vessels. So the breather must be and has to be above the maximum fuel tank level in order not to leak. Again this is basic phsycis

I am not sure what land rover have done. Maybe they fit a filter/valve at the breather so that air can escape but not diesel and I think that filter probably failed on your truck

[The Cone of Silence]

Thanks Martin, I'll have a gander at the breather. it's never been a problem before so it must be a failure somewhere along the line.

I know there's a valve in the pipe to allow air in but not diesel out so with any luck, this is an easy bit to replace.

[martnH]

No worries. It's very likely the breather as the leakage in your case is fuel level related.

I am about to install a long range fuel tank and my plan for the fuel tank breather is to use the factory breather But to extend it all the way to the engine bay.

I have seen nugget's defender fuel tank breather kit that goes along the chassis up engine bay This might be a good idea but my questions to the expert here is that in this case where the breather extension line simply starts from factory breather (lower than filler neck) to the engine bay along chassis, in the case of a breather valve failure, won't the fuel fill the entire extension line all the way to the engine bay?

And my solution is to extend the tank breather line all the way up above the filler neck then come back down and follow the chassis to the engine bay (in a "n" shape loop). Will this solve the issue? Only then I can remove the factory valve?

Cheers

[cuppabillytea]

My breather is now zip tied to the filler pipe, so it's right up near the filler. I filled it up one cool night, just one click, and the next day was hot. The pressure in the tank caused a drip from even that hight. The problem is, there's a non return valve in the breather line which is there to prevent the tank from going below atmospheric pressure. It's a poor design and doesn't last long. My guess is: Yours has past it's use by date and needs to be replaced.

[martnH]

So I installed the ARB long range fuel tank.
I have relocate the fuel tank breather by simply flipped it around, so that the pig tail is on the filler neck side, not the chassis side.

I have done 3k kms since and nothing leaks

[roverrescue]

The small breather serves no good purpose
Just get rid of it
Tank will breathe just fine with the single 5/8 breather that flows into the filler neck
It’s how tdi we’re plumbed and has been how my tdci 130 has been plumbed since I got rid of the pointless thing

S

[Samblers]

No extra tank here but I did have the problem of fuel spewing onto the fuel station forecourt (search my posts). I extended the fuel breather pipe to high up inside the rear corner, looped it once and capped it with a cheap inline fuel filter. I used clear fuel tube too so that i could occasionally check what was happening in there.

No problems since

Sam

[Grappler]

From previous threads it seems this is a common problem. Mine was bad if I used hiflo nozzle Like Sambler i extended the breather tube. I have a 130 so extended it up between the cabin and tub No problems since