Hilux 4x4 Forum

Hi

I plan to, in the near future hopefully, to install both an extra fuel tank and a free flow exhaust.

These have both been discussed before, but I have specific questions.

I do not want to fit an Extra tank at the back above the spare, I would prefer the extra weight stay between the wheels, and so I prefer the idea of adding the extra tank opposite the original tank.

But if I do this, will it be possible to fit a free flow? Where would it go? I doubt it would be particularly straight as well. Will this nullify the point of the free flow?

Finally, is there a standard OEM tank that fits opposite the original tank in the IFS DC Petrol, or will I have to have one built up?

Cheers


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Hi Drew, fitting an extra tank on the other side of the drive-shaft poses a few problems. You have to have a link pipe both top and bottom for it to fill / drain properly and dispel air. The top pipe is no problem but the bottom one is, because you would have to route it under the drive-shaft, allowing space for downward movement of the shaft when the suspension extends. That pipe is then completely exposed and vulnerable, so it's a no-no. The other option is to use a thick filler pipe that's spliced into the OEM filler pipe and have a manually switched pump that pumps fuel over to the OEM tank when it gets low. A schlep, to say the least and you never know just how much fuel is in the extra tank without a separate fuel gauge (I had a system like that). Then you still have to have space to run the exhaust through, so that diminishes the extra tank capacity quite a bit.

The way I see it, the extra fuel capacity and the number of times that you need the extra fuel doesn't always warrant that kind of aggravation. Carrying a few extra jerry cans might well be the better option.

Taking the above factors into account, I wanted some extra capacity and opted for extending the existing tank over the drive-shaft without a 'trough' on the extension - that way I have no filling / draining issues, no need for pipes and no modification to my fuel gauge (it just drops very slowly until a little above the ½ way mark). I gained an extra 36 litres capacity.

There are some pics and you can see what I did to the tank here (page 2) - viewtopic.php?f=8&t=15977&p=487393&hili ... ux#p487393

I don't know if your tank shape will allow for exactly the same modification, but I'm sure you can achieve something similar.

Mud Dog wrote:Hi Drew, fitting an extra tank on the other side of the drive-shaft poses a few problems. You have to have a link pipe both top and bottom for it to fill / drain properly and dispel air. The top pipe is no problem but the bottom one is, because you would have to route it under the drive-shaft, allowing space for downward movement of the shaft when the suspension extends. That pipe is then completely exposed and vulnerable, so it's a no-no. The other option is to use a thick filler pipe that's spliced into the OEM filler pipe and have a manually switched pump that pumps fuel over to the OEM tank when it gets low. A schlep, to say the least and you never know just how much fuel is in the extra tank without a separate fuel gauge (I had a system like that). Then you still have to have space to run the exhaust through, so that diminishes the extra tank capacity quite a bit.

The way I see it, the extra fuel capacity and the number of times that you need the extra fuel doesn't always warrant that kind of aggravation. Carrying a few extra jerry cans might well be the better option.

Taking the above factors into account, I wanted some extra capacity and opted for extending the existing tank over the drive-shaft without a 'trough' on the extension - that way I have no filling / draining issues, no need for pipes and no modification to my fuel gauge (it just drops very slowly until a little above the ½ way mark). I gained an extra 36 litres capacity.

There are some pics and you can see what I did to the tank here (page 2) - viewtopic.php?f=8&t=15977&p=487393&hili ... ux#p487393

I don't know if your tank shape will allow for exactly the same modification, but I'm sure you can achieve something similar.

Thanks for the advice. Always appreciate your input.

I have read about the piping issue before but would that not also be experienced if the extra tank was above the spare in the back?

I have actually already read that thread of yours thanks. It feels like a big mission for just a little over Jerry cans worth of fuel extra (no offence). But I think it is something I am going to have to consider.

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Ask Hilux 1
He has an exstra 1 side by side fitted to his ifs

No offence taken. But yes, it only gives me about one and three quarter jerry cans extra and if I anticipate needing a longer range I can always carry an extra jerry can or two packed in somewhere. As it is, it gives me a further range of 300 km plus and it's not such a big mission if you consider that with any of these other mods you would have to remove the OEM tank anyway to route and connect pipes, perhaps even to weld in some nipples for the extra piping - then you still have to make up or modify another tank which also has to be mounted. My way is just modify existing tank and add mounting points - done. And my spare stays tucked away nice and high up.

you wrote:I have read about the piping issue before but would that not also be experienced if the extra tank was above the spare in the back?

No, because the extra tank above the spare sits higher than the OEM tank and can gravity feed. All that's required is a reasonable size pipe from the bottom of the extra tank to the top of the OEM tank (the bigger it is the less time you stand at the pumps) and a breather from the top of the extra tank to the filler neck breather.

I guess an easier idea would be to buy thise 55/60L plastic tanks from Makro that fits in the loadbin. Drill one small hole in bin to connect into filling line.

And you only carry it around when using it.

Hi Drew. I have a setup just like you are looking at. Problem is, I bought my bakkie like that and the didn't put much effort into routing the exhaust, something I'll fix when the finances allows it. You shoyld be able to route your exhaust next tobthe extra tank, providwd you also fit a heat shield next to the tank. At least, that is what I have in mind. I'll try and post some pics tonight of the tanks. But, like Andy said, you never know how much fuel you really have, unless you fit an extra gauge on the second tank.

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A heat shield is always a good idea, but not really necessary unless the exhaust is very close to the tank. On my previous Lux I had a complete replacement LR tank that was made from polypropylene and the exhaust ran through under the narrow section with about 1½ inches clearance without any problems over a period of more than 10yrs.

However, heat transfer into the fuel can lead to a little fuel loss through excessive vapour relief and in some instances like on a particularly hot day and where there is an EFI system, the pump might cavitate since the warmer fuel aerates a lot more easily. When that happens there is no fuel pressure and the motor dies - had that problem once before with a BMW but must add that the newer type pumps have improved to the point where cavitation is very rare.

Drew

My second tank sits maybe a 1 cm higher than the original just to ensure all fuel runs out to original, the same fuel gauge works for both as the tanks fill up simultaneous. it is not as accurate, i still need to make an adjustments as we bent the level the wrong way, so it already on empty and i can still go about 100-150km. but I've not been bothered about that yet as i know my vehicle range already and it being a schlep to remove both tanks again is just to much effort for now...... the WIFE on the other hand does not agree with my feelings............

I've sent you a PM.

Hilux 1 wrote:Drew

My second tank sits maybe a 1 cm higher than the original just to ensure all fuel runs out to original, the same fuel gauge works for both as the tanks fill up simultaneous. it is not as accurate, i still need to make an adjustments as we bent the level the wrong way, so it already on empty and i can still go about 100-150km. but I've not been bothered about that yet as i know my vehicle range already and it being a schlep to remove both tanks again is just to much effort for now...... the WIFE on the other hand does not agree with my feelings............

I've sent you a PM.

Thanks Tertius, will respond ASAP.

Hi Drew,

I finally managed to take the pics as promised. I hope this will give you an idea of how to fit yours. I have added the tape measurement in order for you to see what gaps you have to work with for the free flow. The bottom of the tank is lower than the chassis, so you might be able to guide the exhaust closer to the chassis. The only problem I foresee then is between the shock, over the rear axle.













Let me know if you need more pics.

Clearly that didn't work. I'll try again.

Got it figured out

These are too small. Will load bigger pics

Carrying a bit of a load and one decent bump or dip in the road is going to push the drive-shaft right up into that lower connection pipe and snap it off. When that happens, both tanks will drain out in under a minute.

True that. I realised when I took the pics that there are a bit of work to be done there. I don't know by whom or when the extra tank was fitted, but clearly they did not put a lot of thought into it. I also noticed that the brackets holding the rear end of the tank are made up of bits and pieces of steel welded together.

I'm thinking of moving the forward a bit, maybe an inch or two, that would give me more clearance at the shock to run my exhaust to the back. Also, I'm playing with the idea of a one way valve between the two tanks, so that the extra tank will 'gravity feed' the std tank. That will also prevent petrol running back into the extra tank. Maybe have an overflow at the top of the std tank into the extra tank for filling purposes.
The other alternative is the electric pump with a switch in the cab to transfer when the std tank is nearly empty.

Would like some opinions. Maybe it will help Drew as well

Getting the exhaust past that shock may pose some interesting challenges - it will be right up against the tank. A heat shield and some insulative exhaust wrapping tape might do the trick. Moving the tank forward a bit might help but what bothers me a bit without actually seeing it is if there's enough space to remove that shock if it needs to be replaced. I don't know how much space you have to play with in moving the aux tank forward, but it might just do the trick.

With the set-up that you have takes me back to my earlier post - that lower connection is a potentially serious problem and should be removed. (As it is, it looks like it's not even at the very bottom of the tank, so you're not getting use of the full tank capacity.) Then there will no longer be a gravity feed and the only way is to pump it across.Also, you won't know how much fuel is in the aux tank without an aux fuel gauge. Becomes a bit of a mission, but it works. The similar set-up I had before had a pump operated from the cab and a separate gauge.

Then the size of the upper interconnecting pipe is what becomes an issue when filling up and the aux tank needs a breather as well to allow the passage of head-space air.

Thanks Andy,

Maybe I must reconsider keeping the Aux tank. If I'm not going to really use it, maybe take it out and blank of that bottom pipe on the Std tank.

The other alternative is the electric pump with a switch in the cab to transfer when the std tank is nearly empty.

Maybe this is your best option, Drew. No hassle.

Thanks for all the input gentlemen, at this stage in leaning towards either replacing /enlarging the original tank or installing the aux tank above the spare.

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Again, it comes down to your personal intended future use of the vehicle. Fitting LR tanks is synonymous with over-landing / long distance travel where fuel availability is sometimes scarce or erratic, particularly as in neighbouring countries.

If you don't intend going that route, then you might do well to consider scrapping it. Otherwise you will have to come up with a workable solution.

Working with what you already have, the fuel transfer pump would be the logical answer if you can get past the filling issue. Perhaps a filler hose teed off from the original (if there's space for it) or a separate filler cap on the other side.

This filling problem was one of the reasons why I opted for the extension but besides that, although I still enjoy doing some of the rougher stuff, those days are becoming fewer and I'm looking towards doing a bit more travelling. So my personal needs are pegged somewhere in the middle between the two, and the way I see it, I don't want the spare hanging too low with a tank above it and an extra spare is more important than a whole lot of extra fuel. A dual swing-arm at the back (still to be built and fitted) gives me an extra spare and a jerry can holder that don't affect the COG too badly. (As a rule I don't pack heavy stuff high up.)

Anyway, I digress a bit ... that tank extension plus a jerry can gives me about 150 lit of fuel with an open road range of roughly 1200km plus (and if really needed, I can pack an extra jerry or two in the back). That's good enough for me. I can always leave the extra spare and jerry can off when not needed so that I'm not permanently carrying the additional weight, there's no extra gadgetry like transfer pumps, filler / breather hoses and the OEM fuel gauge works just fine.

Hope this helps you decide.