gas tank repair

[Giniw]

There has been a recall in the USA in the 90s(?), so it's more probably a design flaw.

[Brit-Car-Nut]

I don't think it was a direct tank design flaw, rather a fitment issue that puts the tank in a different stress situation.

Remember to put the 2"x2" pads back in the correct locations. They are in either the Service Manual or the Service Bulletins.

[tedtaylor]

yes, I think it was stress on the bottom seam. The actual tank is pretty thick to begin with, but the seam along the bottom was heat sealed from the factory. It appears the tank was in two halves, formed and heat pressed together to form the one tank. What I did notice was the very bottom, beneath the fuel pump bowl section, that the bottom appears to bow upward/inward to the tank. My thinking is that when the tank is empty, the plastic rises to its original shape (with slight bow inward/upward at that point), and then when there is 10 gallons of fuel inside, the bottom of the tank "flexes" somewhat downward/outward from the shear weight of the fuel. So over 26 years of full tank, empty tank, full tank, empty tank, it flexed enough to stress that bottom seam thereby cracking the plastic enough to start the seepage of fuel.
I think when I remount the tank, I may put a shim or wedge at that exact point to support the seam and hope eliminate the flexing.

IMG_3404.JPG

I'm considering using PVC pipe cement (two part epoxy that plumbers use on domestic water systems) on the exterior of the final patch job to hopefully seal any miniscule pinpoints and lapping edges just for some peace of mind.

[tedtaylor]

couple notes/questions:

1) does anyone know how much pressure (psi) builds up inside the fuel tank? just curious...

2) forgot to note, regardless of my yellow highlight notes on my copy of the service manual on the tank removal instructions highlighting "marking" the toe-in alignment on the eccentric for the rear wishbone, dummy me forgot. Now i'll need a wheel alignment when it's back on the road. I originally thought to look at the hub end of the wishbone thinking that is the location of the toe in alignment eccentric, but since I did not just "lower" the wishbone, I actually didn't have to dismantle the outer hub end after all, so I put it out of my mind. It was only then, when I was disconnecting the wishbone at the central backbone chassis, did I see the eccentric bolts, but oh, too late, already spun around while loosening. dag nab it! !@#$%^&

3) i spray painted the bottom of the tank repair flat black, so you really can't tell it's been repaired. Looks great.

4) I filled the tank halfway on the work bench with gasoline (like 5 or so gallons) and let it sit for several hours. I checked the bottom and so far, so good, with no evidence of any more leaking or seepage at the seam.

5) I ordered the two tank grommits from Dave Bean. I found out the large fill tube grommit is the same one used for the air intake duct into the front fender. Since mine was also perished, i ordered two of them. $70 bucks each!!! WOW!

6)I think while i'm starting reassembly and waiting for those parts, i might as well change out the fuel filter since it is right there in front of me. I don't think i've ever changed it and i now have 60K miles, so the smart thing to do.

I'll follow up later in the week with more results and pictures.

[lotusrepair]

I had a noisy fuel pump when mine tank went back in. The noise was gone in a week. There is a check valve in the pump line. Trapped air was what I came up with for the noise. While you have the tank out... are you having any trouble with the drain at the filler neck? The tank covers the drain line if it needs cleaned out.

Chris

[Brit-Car-Nut]

couple notes/questions:

1) does anyone know how much pressure (psi) builds up inside the fuel tank? just curious...

There should not be any pressure, possibly a slight vacuum when the pump is running but the tank is vented into the charcoal canister. You should consider testing it to make sure it isn't clogged.

6)I think while I'm starting reassembly and waiting for those parts, I might as well change out the fuel filter since it is right there in front of me. I don't think I've ever changed it and i now have 60K miles, so the smart thing to do.

Be careful to prevent the plastic line going from the tank to the filter from turning with the fitting. It will break the plastic line and they don't exist any more. After saturating the fittings with penetrant, carefully break the nut loose and see if it is frozen. If it is, try the nut for the line going to the engine as I have found them more forgiving and mine were able to "slip" correctly. Once the front line is removed, hold the rear line nut securely and rotate the filter to remove it.

Check valves, (pulsators) are readily available from Rock Auto: part # FP27. I found the fuel pump filter to be more similar to the Volvo than most GM products. It needs to be offset to fit into the fuel well in the tank. I think an STR08 will work too. P240KC or E3902 from e-Herko (eBay) are low cost replacement fuel pumps as well.

[tedtaylor]

Thanks "lotus repair" and "brit-car-nut" for the help and suggestions.

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As mentioned before, this metal collar just slips/slides easily right back into the tank, so I peened the edge to create a very small lip on the edge (similar to the breather tube flared collar). Now the metal anti-crush collar fits and STAYS right where it is supposed to be. No more falling into the tank!

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I pulled the old fuel filter out (AC delco GF481) and i'm glad I did. Dirty black fuel spilled/emptied out of it. It was clearly doing its job well over 60K miles. Maybe this dirty filter was partially attributing to my previous stumbling / hesitation issues. I will replace those little O-rings too. Getting at the filter is awkward, but easy to do while everything is apart - especially the convertible top floor tray. Actually, my filter end fittings came undone very easily, they weren't frozen or super tight. I couldn't get a "line wrench" in the space, so used a regular open end wrench.

IMG_3407.JPG

I have a question about the rubber pads to be affixed to the tank. The Lotus service notes seem to make a big deal out of the one "lower right" side giving very specific and precise measurements of 33mm from center indent and 85mm from bottom. They state all the others are clearly marked on the tank itself with little embossed right angles. Instead of silicone adhesive, I used 3M double sided tape. The three top pads are already in place and stuck to the car shelf so I left them there. The four side ones I have to affix, but my tank HAS the location marking on the lower right side already. So my question is does this couple inches make a difference? The picture shows the raised emboss left and I have a sticky note where the measurements would place it. Which location is correct? or does it not really matter?

IMG_3408.JPG

[Brit-Car-Nut]

I have a question about the rubber pads to be affixed to the tank. The Lotus service notes seem to make a big deal out of the one "lower right" side giving very specific and precise measurements of 33mm from center indent and 85mm from bottom. They state all the others are clearly marked on the tank itself with little embossed right angles. Instead of silicone adhesive, I used 3M double sided tape. The three top pads are already in place and stuck to the car shelf so I left them there. The four side ones I have to affix, but my tank HAS the location marking on the lower right side already. So my question is does this couple inches make a difference? The picture shows the raised emboss left and I have a sticky note where the measurements would place it. Which location is correct? or does it not really matter?

IMG_3408.JPG

You are quoting the Service Manual. Read the Service Bulletin for the newest info.

[tedtaylor]

i have that documentation, but it really doesn't answer my question. I'll have to check that "M" to see if it is written on my tank, but I can only assume I have the older original tank with the embossed right angles on all four corners (and top 3 areas too)? The updated bulletin you provide states that bottom right side embossed corner is NOT there, thus the given measurements of 33mm and 85mm. What i'm saying with the picture is that the original embossed corner right angle marking is there on my lower right side tank (going against what the service bulletin states) and that the 33mm 85mm location they indicate is actually two inches inward toward the middle of the tank. Oh what to do...

[Brit-Car-Nut]

The Service Bulletin clearly states the Chassis / Vin number range of the old tanks (and what the problems were). If your chassis number is after 6161 (mine is 8019), then you should use the location stated in the bulletin. They didn't re-issue the service manual every time they made a change, they put the changes in the bulletins.

That is the best I can suggest. There is a lot of vagueness in all of the literature as they kept tweaking the cars and the parts as they found issues. I found the FED recall requirements once but don't remember where that was, but I believe the servicing dealer was supposed to write the VIN somewhere like the fuel door so it could be verified as to being done.

I would ignore the service manual and follow the service bulletin for the final location of the pads. I would also use a decent adhesive like urethane sealant and not double sided tape. Windscreen install adhesive would be my choice since it won't dry out and the pads on my "spare" tanks don't want to come off, so weren't held on with double sided tape. Both spares I have came from UK cars. The tank area from Steve M's body has the pads glued to the body and not the tank, so that is also a weird thing. Maybe the FED recall required a change?

I will see if I can remember where I found the recall instructions. It was close to 10 years ago, right after I got my first M100. I will be at the doctor most of the day but I will climb up the racking to see if I can get a few pictures of the tanks I have that are out of the cars and I will take a few pictures of that body section of Steve's original tub.

I would also follow the instructions for resealing the filler neck too. My car didn't have any sealer where the bulletin suggests (and I know my car was never inspected for the recall).

[tedtaylor]

OK, more success! The car is running on its own power without any leaks so far. I have yet to put the rest of the car back together, suspension, boot tray, button up everything, so i'll do that in the coming days.

A couple notes:

1) I found both quick disconnect fuel fittings on the pump top lid (red & white), for supply and return, had the O-rings in wrong. I popped the cap off and pulled them out. They had the black nitro one at the outer most and the green one deeper, closest to the fuel. The service bulletin was quite clear to insert the black nitro one in first, followed by the green one last. They were both in perfect shape, no distortions, pliable, so i reused them, but inserted them in as per the service manual. I found that interesting.

2) Indeed i confirm that the rubber pad placement on the forward lower right side must be affixed by the specified 35mm/85mm since this brings that one closer to the center of the tank. I found that the body/bulkhead behind seat is indented there, so in order to catch and press the tank against the body, the pad must be moved over toward the center, so there was a very good reason for that. I guess either body design changed a little, or they just found the void and corrected the placement of the pad.

3) It was a one man job EXCEPT for getting the inner strap up to the bolt. You really need someone up top wrenching the bolt, while someone below tries to bring the strap anchor up to it. I did it myself and was lucky. it IS a two person job.

4) I don't know what all the fuss over getting the tank out was all about. I did not have to use a lift and it drops right down with a little leverage. It's a "wedge" fit, plain and simple. I used a car jack with a piece of board under the tank and jacked it right up into the void. again, wedged between the body and wishbone center mounts and top shock frame mount. Snug is the word, but not stuck. Easy getting out and easy going back in. Car was quite secure on ramps and jack stands. No need for a lift or jacking up too high or unsafely.

5) I used a $5.00 NAPA fuel filter (direct replacement for the AC Delco unit) and replaced the two O-rings. I filled the tank with 5 gallons, hooked up the electric connections and battery (reset the inertia switch) and turned it over and it fired right off. The electric fuel pump was quiet (not noisy as 'lotus-repair' warned me about). The car ran smooth and NO LEAKS !!!!

6) I'm waiting on the new grommits in the mail and will fit them and tidy up all the loose ends.

that's all for now. I'm a happy camper.

[Saltire]

Great job and really comprehensive write-up for those who may need it in the future

[steve matthews]

Well done Ted.

[tedtaylor]

I'm under a time crunch here since I have a Lotus gathering event coming up Saturday I was hoping to drive the Elan to, however i'm still waiting for the grommits from DB. So I assembled everything else, but leaving the boot tray out to gain access to the grommits when they arrive. I'll be able to drive the car and complete those little items later on.

While reassembling the suspension, I found everything nice, clean, lubricated and not corroded in the least. This made for easy extraction and movement of the top hub bolt and bushing, making it easier to swing up and connect. I did find the little "ball joint" rubber boot on the end of the sway bar had the securing snap ring come off and thereby leaving the rubber boot open to the elements (I did this accidentally while disassembly). I was able to easily squeeze the rubber boot top and reinstall the snap ring. Now it is once again weather tight.

I made the mistake of leaving the sway bar "over" the wishbone crossbar while reassembling the suspension. All bolts in place except the last connection being the ball joint of the sway bar. While connecting the top hub bolt, found I could not get it high/close enough because the sway bar was on top of the wishbone cross bar. It is supposed to be fed "through" and "under" that crossbar in the middle center area of the wishbone, so off everything came again, and this time put the sway bar in correct position.

Luckily, i took photos of the suspension prior to disassembly, so since i did NOT mark the eccentric bolt on the forward wishbone alignment, i will refer to the pictures to approximate the last known position. That will just have to do until i actually get a full 4 wheel alignment.

[lotusrepair]

Sounds like Kyle is having an event this weekend.
Chris

[tedtaylor]

yes Chris, it's the annual 1st of the season Lotus get together to shake off those Winter blues... details on the PALS ning site

[tedtaylor]

The final chapter.

I finally got the 2 grommets from DB (quite expensive) and installed them this evening. What a bear!!! There is so little room to get your hands and fingers down there, especially with that body mount frame brace that crosses back to front right across the access opening. Additionally, the fuel tank filler pipe from the tank is not quite centered exactly in the body opening. The grommets are a tight fit. I used silicone spray to make them slippery to aide slipping them on and getting them to seat in the body fiberglass opening. Very delicate and challenging. I didn't want to poke a hole using sharp screw drivers, so my fingers and other blunt rounded probes were used. I actually had to fully remove the rubber filler hose and breather hose out of the area to allow extra wiggle and access room.

Once grommets installed and filler and breather hoses secured, the final step was to reassemble the roof storage floor panel, side panels and carpeting. Tedious, but taking it step by step, finally came together. Those little "scrivets" (plastic screws) are a drag and the Phillips head easily strips out. I could not find any similar replacements from a hardware store. I actually had to use a hacksaw to make a cross cut over the Phillips head to make a "slotted" head, and then used the flat thin putty knife like as my flat headed screw driver and was better able to finish securing everything.

I bought a 2nd large grommet which are exactly the same, for the front air duct to fender well grommet replacement. That was very easy to replace in comparison.
So the car is now completely reassembled and the job is done.
NOW PLEASE, MY PLASTIC WELDING JOB, NEVER LEAK AGAIN !!!!!!


Now my next project is bleeding the brakes (replacing/flushing the hydraulic fluid with new) and possibly a new set of tires?