Fuel tank leak

General information about the first-generation Nissan Maxima in the US. What was the Datsun 810 became the luxury leader Maxima in the US in 1981.

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rlaggren
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Location: San Francisco

Fuel tank leak

#1

Post by rlaggren » 12 years ago

Before crawling around under the car last week to adjust the e-brake I sprayed some of the low hanging cruddy spots w/brake cleaner and wiped them off so I might come out looking less like a streak of grease. After I finished the job I was deeply chagrined to find a big dark spot on the newly cleaned fuel tank . I rubbed it and it proceeded to drip. I went to find a small bucket and came bag to small stream. Well, no confusion about what the problem is anyway...!

A wad of electricians tape, a small block and bungee cord to clamp it against the spot made a temporary fix; it looks like it'll do the job until I get the (newly filled!) tank run down some and line up my ducks for the next step.

I've msg'd OEM-surplus who appear to have a tank available. Depending on their price, I may go that route.

However... I have read several accounts where tanks have been repaired with epoxy GRP (fiberglass). Some repairs were made from inside the tank and some were made from the outside; reportedly both types of fix have lasted 5 years and more. I happen to have all the necessary to do that kind of repair and I'm inclined apply an exterior patch on the theory that it will take 1/20 the time and trouble and $$ and won't hurt anything - and it might completely solve the problem.

Empty the tank and tilt the car so my hole runneth dry. Clean the area again w/brake cleaner and acetone, sand w/80 grit, and lay on the patch. Let set overnight and install a charm on the dash.

The pin-hole _may_ be the result of a rock or it may be rust; the outside of the tank shows no rust on the bottom around the hole. Rust would not surprise me, but I'm not sure I want to try to get the drain plug out because torquing the fitting might stress some pretty thin metal if the problem is indeed internal rust. For the same reason, I'm not inclined to try to plug it w/a sheet metal screw - not sure what I have to grab onto there. I may just clean up the whole bottom of the tank and cover the whole thing w/a layer of glass. Kind a a hit/miss wing & prayer approach but I don't know if I want to put a lot of shiny new parts into this car; it has 5 or 6 real healthy rust holes in the rails and then theres the rust at the sheet metal joints. It looks good from a distance, but cleaning it up fully may not be feasible.

Still thinking about this. I have about a week before I run the tank down. Ah - I need the car reliable on the 9th to 25th; that looks like too soon to count on receiving a new tank. Definitely going to patch this.

After that I may consider how lucky I feel and try to get the plug out... Or how ambitious I feel and pull the tank and clean it from the top. Any thoughts?

Rufus
82 Maxima wagon

Carimbo
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Re: Fuel tank leak

#2

Post by Carimbo » 12 years ago

rlaggren wrote:Empty the tank and tilt the car so my hole runneth dry. Clean the area again w/brake cleaner and acetone, sand w/80 grit, and lay on the patch. Let set overnight and install a charm on the dash.
This method worked for me successfully for several years, using JB Weld. Siphoned out all the fuel, jacked up the side of the car so the leaking area stayed clear and dried completely, rough-sanded the area to be patched well (the outside) to give bite, cleaned w/ lacquer thinner, applied the JB Weld and clamped a 60W lamp close to supply heat. Let it set up for at least 24 hours.

It was leaking from a few small bb-sized indentations within a 2 sq. in. area on the bottom of the tank-- probably something that got thrown up under the car.

The key is making sure the area is dry, sanded, clean.

Most rust I have seen in fuel tanks have been near the top, or on the perimeter seam.

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kassim503
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Location: Stony Brook, NY

#3

Post by kassim503 » 12 years ago

I repaired a gas tank with JB weld with successfully results as well. All I did was clean it, roughened it up a little, and took the gas cap off to alleviate pressure, slabbered JB weld, and came back in the morning to see satisfactory results.

JB weld is gasoline resistant once it cures, so its just about perfect for this job.

I removed the plug on my gas tank with no surprises- surprisingly. It came off with a average amount of pressure. But if you break, or strip something doing this, a really easy job just got really hairy.

I would just recommend siphoning the gas out, just be careful and use a siphon pump so you don't asphyxiate yourself
'83 maxima sedan, l24e, a/t, black

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rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#4

Post by rlaggren » 12 years ago

Glad to hear further reports of the outside patch working.

I was thinking of pulling the plug because if there's internal rust, it's because of water in the bottom of the tank. But now I remember the sequence of how it happened, all the hole produced was diesel (about a quart before I stopped it); so I think I'll forget the plug and just lay a large patch on.

Thanks.


Rufus
82 Maxima wagon

rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#5

Post by rlaggren » 12 years ago

Put the patch on over the weekend. Two layers of light weight glass cloth about 4x8" with West System epoxy. Looks plausible but I haven't driven the car since because of my schedule and the need to line up a ride to/from the borrowed garage.

The bottom front of the tank by the RR wheel was definitely dinged up some; no large bash marks, lots of dings so it's likely from stones. The actual leak was not there but on the bottom of the tank, about in the center; it was tiny (but quite sufficient) and had no ding mark around it. The metal at the hole and all around it _seemed_ sound maybe there's rust; one reason I used a moderately large patch - smother its brothers before they get born. <g> I did open the drain plug with out any problems and all the fuel I drained looked totally clean; and the fuel that leaked from the hole last week before I stopped it was diesel, not water. Hard to say. Unfortunately the tank drain is not placed to ensure complete draining. Doubtless for manufacturing purposes possibly combined with a need to NOT have the plug protruding down to be the the lowest point on the tank (the part the gets knocked off by the big rock...) there is about 1/4" of fluid left in the tank. Jacking the car around still leaves 1/8-3/16" puddle behind the drain hole; to drain completely the tank would need to be at a 20-30D angle. Since there was more room behind the hole, I opted to jack the front of the car up to move the puddle to the rear. I reused the washer for the plug; the logistics of getting a new one in time for the weekend didn't work. Time will tell.

I pumped a bunch (100) at the primer button, but got only a teaspoon max out the return hose; guess that probably means the primer is kaput. Especially since the engine started right up so there was clearly fuel available at the IP.

Looked a few new places for the camera, but no luck - sorry. Might have to just buy one soon..

Cheers, Rufus
82 Maxima wagon

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asavage
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#6

Post by asavage » 12 years ago

If the leak was at the low point, any water that may have contributed to a rust-through has leaked out, so you wouldn't see any foreign liquid at the drain plug.

rlaggren
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#7

Post by rlaggren » 12 years ago

If the leak was at the low point, any water that may have contributed to a rust-through has leaked out, so you wouldn't see any foreign liquid at the drain plug.
True. But I think it had to be a very small amount because I caught the leak when it was just a dark patch on the bottom, before any drops had hit the ground. It did start dripping after I wiped it with a cloth, but what I got on my hands immediately was diesel - so there wasn't much water in there.,,

Now you've got me thinking, though. The car was on jack stands to adjust the e-brake when I found the leak and may have been tilted forward a little; meaning the low point was no longer over the hole. Can't remember the exact setup. Darned if I can think right off of any fool-proof way to eliminate a tiny puddle of water in a spot that won't drain; without dropping the tank and swabbing it out (assuming the access hole is large enough) that is. Maybe cobble up an attachment for a shop vac with a 12" piece of 3/8 tube; flatten and chamfer the business end a little, angle the last 1/2 down a little. Stick it through the drain hole and move it around to suck the bottom dry; might have to use a 1/4 or 5/16" tube. Run it back toward the vac with some similar diameter hose; put a small liquid trap in the line before adapting to the the vac connection.

Listening to myself, sounds like a lot of work. <g> I think I'll look at the emulsifiers sold for marine applications. Supposed to "dissolve" the water into the diesel and send it out through the engine. Actually, I'll look the specs for the Stanadyne (sp?) additive first - maybe that's part of their concoction.

Thanks. Rufus
82 Maxima wagon

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asavage
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#8

Post by asavage » 12 years ago

There seem to be two kinds of diesel treatments, those that emulsify the water (probably using an alcohol of some sort), and those that claim to encourage separation of water, so your water trap or filter will catch it.

Next time you're going on a trip (and can run out most of the fuel in the tank), run the tank down, add the treatment that absorbs the water, fill the tank 1/4 to 1/2, run it down again, then fill as normal. That should take care of it, I would imagine.

I wish tank pickups were really on the bottom of the tank. Myself, I prefer to have any crap or water immediately pulled up to the filter.

rlaggren
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Location: San Francisco

#9

Post by rlaggren » 12 years ago

Update.

The patch appears intact after 1500 miles, about 30 over gravel fire roads. On thinking about it, if I did it again, I'd lay on another 2 or 3 layers of glass, but it looks good so far. This appears to be an appropriate fix.

Rufus
82 Maxima wagon

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