Leaking sub-tank

Engines and Engine Systems
EttiennedK
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Leaking sub-tank

Post by EttiennedK »

Apologies in advance if this has already been discussed previously - I couldn't find it, but as I'm still quite new to this Forum I'm still learning how to "drive" it.

My Patrol has now been with me for nearly 5 months and I'm loving it - especially the fact that it returns better fuel consumption if I drove it like I stole it as opposed to driving like an old geezer with a goatee and a pipe in his mouth (which is what I am :biggrin: ). I usually drive till the fuel gauge hits a quarter and then fill up both main and sub tanks. Once the main goes under half, I pump the sub over to the main.

To get anywhere, I have to do 25km's of badly corrugated and potholed dirt road before I get to the black stuff. About 3 weeks ago I filled up and drove about 200km's before I got home. A couple of days later I had to move it and noticed that the sub tank gauge was sitting below full, but thought it might be a false reading due to the car having been parked on an incline. I then wasn't able to drive the car for more than 2 weeks due to contracting the damn 'Rona virus.

Having been granted bail for good behavior, I took it to town yesterday - the sub tank was sitting just above half and I had a patch of dead grass below the rear right-hand corner.

Question to those in the know: Are these sub tanks prone/known to leak/rupture/chafe? Is it likely to be the tank itself, or pipes? Is fixing it a job one can tackle yourself? If so, where can I find the info of how to go about it? If not, where/who can I take it to in the WC (I'm outside Caledon)? :helpsign:

It appears to be the factory fitted (40L) tank, the grass where it was parked for the 2 weeks is not on an incline and the tank wasn't filled to the brim.

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Peter Connan
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Re: Leaking sub-tank

Post by Peter Connan »

Is rhe patch of dead grass at the corner of the vehicle or at the corner of the tank?
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Re: Leaking sub-tank

Post by hugejp »

Can you smell any fuel? Have you looked under the vehicle? What about brake fluid?
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EttiennedK
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Re: Leaking sub-tank

Post by EttiennedK »

Peter, ek het die kar klaar geskuif toe ek agterkom hoe vêr die meter se naald gesak het. Die ding het egter lank genoeg daar gestaan dat sy wielmerke ook behoort te wys, ek sal gaan sekermaak as dit lig is.

JP, I'm aware that the pump apparently activates when you start the vehicle and therefore pumps a small amount of fuel to the main tank each time. However, the vehicle had only been started twice after filling it up and according to the needle I'd lost just under 10 liters of fuel during the 2 weeks it was stationary . There's no really noticeable smell of petrol, but on the other hand the inside of the wheel/tire is dry and there's no loss of fluid from the reservoir.

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Peter Connan
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Re: Leaking sub-tank

Post by Peter Connan »

I have never actually heard of a leaking sub-tank, but to lose 10l in two weeks there would have to be a pretty noticeable leak. I am guessing it's most likely to be piping, but if the dead spot is at the corner of the vehicle, behind the rear wheel then the only explanation I can think of is that the pump somehow turned on. If the main tank is full and the sub-tank pump keeps running, it would pump fuel out of the breather which is located just under the filler necks?
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Tinus lotz
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Re: Leaking sub-tank

Post by Tinus lotz »

You have the pump over problem there . Mine does the same when you start it pumps over a bit ...if you dont have leaks you are burning it .

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Re: Leaking sub-tank

Post by EttiennedK »

Peter, as the Patrollie stood there for 2 weeks, I've got 4 dead spots for the wheels and one for the leak. Leak was just behind the right rear tire. Has the pump been known to activate like you suggest and if it does, won't it just pump into the main tank? (There was enough capacity in the main tank - I'd been dragging 1 ton worth of trailer with a 3,5 ton digger on it, so the Patrol had been rather thirsty).

Tinus, I lost the fuel while the car stood for 2 weeks.

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Peter Connan
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Re: Leaking sub-tank

Post by Peter Connan »

No, if there was room in the main tank it should go in there.

But all the fuel connections in that area are considerably higher than the top of the sub-tank, unless the car is parked against an uphill.

So in short, I don't know what's going on and I suspect you are going to have to fill it up and then search for the wet spot...

Edit: maybe check if the sub-tank builds pressure on a hot day? But even that should not be able to account for almost a litre a day. That is quite a significant leak and you should be able to find evidence of it.
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EttiennedK
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Re: Leaking sub-tank

Post by EttiennedK »

Thanks Peter - I'll fill up the sub as soon as there's enough room in the main (won't take long :biggrin: ) and report back/ask for more help.

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Re: Leaking sub-tank

Post by Dungbeetle »

Swop the 2 fuel caps.
Last edited by Dungbeetle on 18 Jan 2021 07:11, edited 1 time in total.
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