cracked fuel tank neck?

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cracked fuel tank neck?

Postby Rich10000 » Sat 10.10.2015, 20:02

After reading around I have all the symptoms of a cracked fuel tank. is there a detailed procedure described anywhere for removing the tank? all I can find so far is jack up high, release from the top, remove RNS suspension, remove tank straps and drop out the tank.

anymore details.

any details would be most gratefully received.

thanks

Rich
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Re: cracked fuel tank neck?

Postby lotusflasherman » Sat 10.10.2015, 23:25

Rich,
It's all in Section LG in the manual but it's a very difficult / dangerous DIY job because the tank is a cube which is quite a tight fit up inside a cubic void and it needs to be done with the car up on a hoist. The tank has to be able to drop straight down out of the void and is quite tall. Therefore the underside of the car has to be at least the height of the tank off the ground. The rear N/S suspension also has to come off to allow it to come out.

I had a leaky seam and bought a secondhand 'good un' that I thought I'd fit myself. I ended up with my car sitting with the front wheels on ramps and another set of ramps with blocks of wood on and jacks on the wood lifting under the rear jacking points so the car was as high as I could get it in a domestic garage. Having done all the prep' work to disconnect pipes etc before it went up in the air, I removed the N/S rear suspension and dropped the tank but could not get it out as the car just wasn't quite high enough! Car was dangerously wobbly so wasn't prepared to try to get it any higher so put tank back into position, reconnected everything and took it to my local friendly garage who put the replacement tank in for £180 with it up on a hoist - at least all the nuts & bolts came out easily for them so I wasn't paying them for mucking around with seized tank strap bolts.
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Re: cracked fuel tank neck?

Postby Rich10000 » Sun 11.10.2015, 14:17

thanks Phil

very helpful... much appreciated

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Re: cracked fuel tank neck?

Postby epipete » Mon 12.10.2015, 11:39

Apart from the inherent complications of petrol, once removed is it possible to repair it rather than buy new? And for those who have replaced a tank and presumably have an old broken only sitting around collecting dust could then recycle the old ones, just a thought!
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Re: cracked fuel tank neck?

Postby dapinky » Mon 12.10.2015, 13:25

epipete wrote:Apart from the inherent complications of petrol, once removed is it possible to repair it rather than buy new? And for those who have replaced a tank and presumably have an old broken only sitting around collecting dust could then recycle the old ones, just a thought!


Short answer - yes!

Longer answer, it will depend on how bad the damage is, how good you are with tools, or where to take it to.

Basically, there is no 'glue' which will work on the tank and remain fuel-proof (although some people claim to have found suitable things, I wouldn't trust them as a 'sole' method of repair.)

The basic principle is to heat up the plastic to the correct temperature where the individual molecules 'flow' and melt together properly - not just so it goes sticky and sort-of joins.....

Safety first - petrol vapour is explosive - take appropriate precautions!

The tank needs to be 'bare' - ie, remove pump/sender unit and any attached pipework from the plastic box. drain it thouroughly, and leave it outside for as long as possible for all petrol to evaporate away.

Fill with water, drain, repeat..... as many times as it takes to get rid of the smell of petrol (then keep doing it anyway!).

Fill with water so you can see exactly how far the crack extends, then drill a 4mm hole at the ends of the crack to stop it spreading.

If you look on utube there are plenty of split plastic 'repairs' shown - some are better than others, but there is only one 'proper' way to do it.....

You will need:- Soldering iron, hot-air gun, filler material (or some other way to get the plastic to the right temperature and fill the gaps).

Using a 'standard' electrical soldering iron, place the hot tip across the crack at intervals along its length - don't push all the way through (although if you do, you can fill the holes in the next stage) - this just gives a temporary 'stitch' to the damage to hold it in place - some videos leave it at that and call it a 'repair', which is okay on cosmetic items, but not for a fuel tank.

to fill the holes, you need a proper material - not just any old plastic which you have lying around.... unless the 'any old plastic' just happens to be a 4-pint milk container :wink: (if the colour match is impotant to you, then you need to shave a bit off your neighbours wheely bin whilst they're not home).

The lid of the milk bottles (orange in my case, but green, red or blue also work!) is the right stuff, but don't throw away the opaque white bottle yet.

Take the white plastic and cut a piece big enough to cover the crack and extended by about a cm all round (so if the crack is 4", you need a piece 5" x 1") - this goes inside the tank at the right place (if you can get it there). hold the bit of plastic using 2 aluminium pop rivets through the 4mm holes you drilled earlier (obviously, you need to drill some holes in it first :roll: ) - you can manage without this piece, but it will give the repair some extra body and help prevent the whole tank folding in when it gets hot in a minute.

Stand the tank so that the repair is upermost, and fill with as much water as you can (so there is the smallest possible air/vapour oportunity) - the repair area needs to be open to air both sides or you will never get the plastic hot enough to melt!

Use the hot air gun to heat the area and the specific crack - i used 2 guns - a basic electric hot-air gun to warm the area, and a butane soldering iron (with tip removed) as the actual welding gun. It is at this point that you realise that you only have 2 hands, and you need an assistant who doesn't mind being sworn at, or some method of holding the hot-air gun pointing in the general area.

The plastic needs to be at the point where it is becoming 'floppy', then discard the big hot-air gun and grab the lid of the milk bottle. (you may decide that you should have cut it into thin strips previously, but i couldn't be bothered, so did it the harder way) Heat the edge of the lid until it melts into a 'string' and pull it into something which looks like strimmer line - apply the heat from the soldering iron to the crack and you will see when it gets to the melting point as it turns from dull to shiny - add the filler plastic and work your way along the crack. Each section should flow into the last one.

Remove the pop rivets (keeping as much of the swarf out of the tank as possible - I actually just heated them up and pulled them out, leaving a slightly bigger hole. Fill the holes in the same way as the crack.

Job (nearly) done!

Once it's dropped its temperature (plastic is dull again, and retains its shape), stand the tank up so that the repaired section os under the water level - this will cool it down to ambient temperature, and you will (hopefully) see no leakage. Go and have a well-deserved brew, and see if it seeps over time (it shouldn't).

The repair should be smooth, but if it looks like the satelite view of the Himalayas, don't worry - as long as it's water tight. It may well feel a bit 'thin' in places (because it is!), and if you want to, you can add material to those areas.

Drain the water out, leave it outside to fully evaporate, refit the pump/sender.

Just to add some extra reinforcement, I covered the area with sikaflex to prevent a recurrence.

(as i was doing it to a tank I had removed, I also added Sikaflex to the tank I fitted in its place - hopefully it will stop that one from splitting, but who knows).

Basically, it's a straightforward plastic repair using standard techniques and tools. If you don't fancy it yourself, then anyone who does plastic welding will be capable of a good job - and they're everywhere these days - just ask any motorcycle repair shop who to use - with the cost of bike fairings these days, it's become very common in that industry - it's all about using the correct filler for the plastic you're repairing.
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Re: cracked fuel tank neck?

Postby John Syracuse » Mon 14.03.2016, 01:06

I'm in the process of removing the tank to fix the same thing right now, is there any unsaid secret about getting the fuel tank to drop from it's position? I've unhooked the fuel lines, filler lines, and breather, and taken apart the whole underside as needed along with the straps and I can't seem to get the large filler opening to clear it's opening through the body to allow the tank to drop. I've followed the shop manual to the letter and I keep trying to get a look up in around the sides to see if there are any other obstructions that might not be listed.

I'm afraid to muscle it out cause I have it up pretty high on jack stands, has anyone else had trouble with this step or is it supposed to just drop out without any trouble?

Thanks in advance.

Chris
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Re: cracked fuel tank neck?

Postby Brit-Car-Nut » Mon 14.03.2016, 03:01

Chris: have you removed the fuel pump / Tank unit already or is it hanging up on the large nut that holds those pieces in the tank?

To remove the nut, you can try a BIG pair of channel-lock pliers or use a flat piece of 1x2 like a drift and strike the nut trying to turn in counter-clockwise.
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Re: cracked fuel tank neck?

Postby John Syracuse » Tue 15.03.2016, 01:18

It's not getting hung up on the fuel pump penetration panel, it's getting hung up on the large port on the driver's side for the fuel filler hose. I can't move the fuel tank enough towards the right side to get the nozzle to fit through it's opening to let it drop. I've tried angling the left side down first and just pushing the as hard as I can towards the left side, nothing seems to work to get it out. I'm afraid to do too much to coerce it out, unless that's what everyone else has had to do...

Anyone?

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Re: cracked fuel tank neck?

Postby lotusrepair » Tue 15.03.2016, 04:12

I read that you followed the shop manual. Did you follow the replacement guide in the tech update?


I picked up a new tank to replace the leaking one in the car we bought. When all was said and done the problem was the filler hose was leaking. There is a metal insert that is pushed in from inside the tank up into the plastic neck. It keeps the neck from being deformed from the clamp. That insert was still inside the tank rolling around but had dropped out of the neck causing the leak. There was no crack in the tank. Since you have the pump out you should be able to feel inside and see if the metal piece is in place.
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Re: cracked fuel tank neck?

Postby Brit-Car-Nut » Tue 15.03.2016, 04:47

I am probably insulting you (not intentionally), but here are the replacement instructions that came as part of the warranty process.

I didn't look at the service manual since I assumed ou did that already.

Fuel Tank Warranty Replacement Write-Up.pdf
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Re: cracked fuel tank neck?

Postby Specky » Tue 15.03.2016, 06:16

John Syracuse wrote:I'm in the process of removing the tank to fix the same thing right now, is there any unsaid secret about getting the fuel tank to drop from it's position? I've unhooked the fuel lines, filler lines, and breather, and taken apart the whole underside as needed along with the straps and I can't seem to get the large filler opening to clear it's opening through the body to allow the tank to drop. I've followed the shop manual to the letter and I keep trying to get a look up in around the sides to see if there are any other obstructions that might not be listed.

I'm afraid to muscle it out cause I have it up pretty high on jack stands, has anyone else had trouble with this step or is it supposed to just drop out without any trouble?

Thanks in advance.

Chris


The top tips

... Get the car as high as possible... And then some.

Don't assume you get away with short cuts, such as just lowering the wishbone or just disconnecting the damper...

It's a fiddly tight job, and that tank is quite heavy if you have any reasonable amount of fuel in... Early disconnection of the upper connections is a must, because there's not much give in any of the associated pipework and connections.

When I did mine the neck also caught on the Aperture of the tub, it all came down to manipulation and teasing it out. The first impression was one of "That'll never come out of there", but it does.

Have you removed the bottom tray of the hood compartment so you can access where it's catching?

Sadly it's one of those tasks which is easier with hindsight.
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Re: cracked fuel tank neck?

Postby John Syracuse » Tue 15.03.2016, 06:21

I actually haven't bothered taking the fuel pump out yet cause it should come out with the tank as it is right now, but I can maybe give that a try to find the metal piece. I'd rather inspect the tank myself though and I can't do that unless the tank is out.

As for the tech directions, they are almost verbatim to the shop manual, so no clues as to a secret to dropping the tank. I appreciate you providing anyways though.

If I get a chance I'll post some pictures up, maybe that'll help illustrate where the tank is getting hung up on its way out. Either way, I haven't short cut through any step yet, so if the tank is just a tight fit, sounds like coercing the tank out is just what I'm going to need to do.

Chris
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Re: cracked fuel tank neck?

Postby Specky » Tue 15.03.2016, 06:27

IIRC the tank neck catches the tub by about two centimetres...

With re angling of the tank you can reduce it to 3-4 mm overhang...

Then it's manipulation...

The neck will then slide down the wall scrapping crud into the filler neck aperture.

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Re: cracked fuel tank neck?

Postby John Syracuse » Tue 15.03.2016, 23:55

Well, that's bad news that it scrapes and hits, but at least now I know I'm not just having an abnormal experience and that it's going to take some umpf to get the job done.

Appreciate the help from everyone, hopefully I can report that I have the problem solved this weekend.

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Re: cracked fuel tank neck?

Postby John Syracuse » Sun 20.03.2016, 02:13

The fuel tank is now out! I figure I'll post pictures and tell some tales in case anyone else wants to do this in the future.

The picture below shows what I had to remove to get the tank out. I didn't have to raise the car so high to clear the pump out as others have experience, but what I did have to do was move the entire lower wishbone out of the way and fully remove the spring/coil. I used a jack stand and jack to keep the brake line from stretching.

Removed stuff.jpg


The following picture gives you an idea of how high the car was raised to do this. I had it on three jack stands total, two in the front, one in the rear. I didn't use the "recommended" locations for jacking in the rear, you can actually tell from the previous picture where I put the jack to keep some room. It's just next to the rear wishbone to chassis connection, worked just fine.

Void Space.jpg


The following pic shows the opening that the pump nozzle was getting hung up on. It helped to remove the grommet first, before I was trying to remove the pump with the grommet still in there and it was getting hung up. After reading that it was going to get hung up by 3-4 mm, it just made sense to remove it to get it out of the way. Right after I took the grommet out, the tank was immediately able to drop slowly out.

Opening.jpg


The following pic shows the tank out of the car. I'd removed the fuel pump by this point. There was the metal pipe piece in the bottom of the tank as mentioned previously in this thread, and I also threw the grommet I removed into the picture.

Fuel Tank.jpg


The following pic shows the nozzle (same one that was giving me problems on it's way out). There are a couple cracking locations that I'm going to try to plastic weld or something, but even if I do that, it's not certain to keep from cracking again later.

Nozzle.jpg



That said, does anyone have pictures of what the replacement tanks look like? I just want to get an idea what Lotus did to fix these tanks.

Either way, hope this helps. If no one else has said this already, the rules to post pictures on this forum are kinda frustrating.

Chris
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