Gas leak question

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Some Guy with a BMW
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Location: British Columbia

Gas leak question

Post by Some Guy with a BMW » Sat Oct 14, 2017 8:29 pm

I have a quick question regarding a gas leak in my e12.

Are there any common leak locations on or near the gas tank?

I've definitely found that the 3 hoses going to the expansion tank are leaking when the car's been running for a bit. They look original, and a PITA to swap out.

I've also found some weepage on the tank seam lip at the front of the tank, so I'm going to be checking the main hose line from the pump out.

Do these leak at the seam at all or any other potential spots I'm not thinking of? The tank isn't at all rusty, at least on the outside. The smell is stronger than I'd like, but I don't get anything at all from the front of the car.

Thanks,
Chris
1961 Volvo PV544
1981 BMW 528i
1991 Volvo 240 5-speed
2018 Ford Flex (wife's car)
2014 Chalet XL1930

T.Hanson
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Post by T.Hanson » Sat Oct 14, 2017 10:39 pm

I just did that, thought to change the gas filter and went on the fantastic journey.

35 years has every leak location possible, depending upon the geographic location of the car. Generally, the fuel lines and those to the expansion tank are pretty crunchy by now if neglected.

See a recent post asking about fuel pump longevity. I chose the simple solution, junked the oldsters I had in favor of a new pump from Autohauz.

The car will be going up on a hoist or jack stands to safely remove the passenger side rear wheel. The trick in replacing the parts and lines is in taking photos or the time to draw detailed sketches of how the lines connect, hose clamp orientation, everything. The factory parts exploded views are good for back up reference.

This photo, sketch approach applies to the expansion tank lines. 3 from the tank tubes near the filler neck, and the larger diameter connecting to the charcoal canister. See that recent post also.

The small pinch clamps on the old clear lines will clip off if you find the right end nippers, sharp, with very long handles to get the leverage.

I used black rubber fuel line, proper I.D. for replacement. The gray plastic collector box unbolts to access the male fitting ends more easily.

If your tank filler tube is still surrounded by the factory rubber safety spill plastic rectangle thing, you'll have to fool with pulling that out to access the three male expansion tube fittings without dropping the tank.

The rubber fuel lines fit so tightly on the fittings for the expansion tank I skipped fooling around with looking for little teeny hose clamps,... thinking the lines are moving vapor, not liquid fuel.

A hair dryer for warming the ends and water for slip is handy for getting the lines on the fittings.

Rather than continuing with this lecture, you may be happy to know my removing the gas tank found no monster rust on the top or under the trunk floor. This after 20 years of salt slush.

Weepage, from the old tank lines, connections, or a crack in the tank,... ask for further instructions.

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Mike W.
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Post by Mike W. » Sun Oct 15, 2017 12:35 pm

Not that the tanks can't get rusty and leak with age, but the 4 evap lines are a definite problem. I don't know how many 70s-80s BMWs I've owned I've had to replace them on, all of them it seems. More of a PITA than difficult, pressure wash everything to minimize all the crap that will be falling down in your face, you won't prevent it, but less is better. I usually use 1/4 and 5/16 rubber fuel line as it's cheaper and so much easier to find, but it usually won't go thru the grommets, you have to remove them. The 6MM line in particular is very difficult to find. 6' of each is enough to have a little left over.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

Some Guy with a BMW
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Joined: Wed May 31, 2017 12:57 am
Location: British Columbia

Post by Some Guy with a BMW » Sun Oct 15, 2017 2:34 pm

Thanks very much.

Quick question - how you do get those factory BMW ear style clamps off the evap hoses?
1961 Volvo PV544
1981 BMW 528i
1991 Volvo 240 5-speed
2018 Ford Flex (wife's car)
2014 Chalet XL1930

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Mike W.
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Post by Mike W. » Sun Oct 15, 2017 2:49 pm

Some Guy with a BMW wrote:Thanks very much.

Quick question - how you do get those factory BMW ear style clamps off the evap hoses?
With a good quality wire cutter and a lot of pressure. With caution, a lot of caution, you can work a small screwdriver in there and spread them. But usually I just cut them off.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

PatinaBeforePolish
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Location: Baltimore, Md.

Post by PatinaBeforePolish » Sun Oct 15, 2017 5:44 pm

I agree it seemed more intimidating than it is. Cleaning the area really helps and loosening the tank bolts lowers it just enough to more easily feed the lines into the rear of the wheel well. Belmetrics carries the correct metric cloth braided fuel line as well as reasonably priced stainless clamps that have the rolled shoulders.
78 F150
79 528i
01 540i
86 944
08 X3 don’t judge me it’s there to preserve the others

T.Hanson
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Joined: Wed Jul 26, 2006 7:39 am

Post by T.Hanson » Sun Oct 15, 2017 6:52 pm

Good to have the experts for sourcing the correct lines and pieces.

Mike W.'s advice helped me remove the line clamps, the final solution being a sharp end cutter with handles over a foot long. Big leverage does the simple clipping.

Some Guy with a BMW
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Location: British Columbia

Post by Some Guy with a BMW » Sun Oct 15, 2017 10:11 pm

Thanks for all the tips.

1. I took a good look underneath. I could NOT find any evidence of any fuel leak up to the solid fuel lines that run to the motor. I ran it for a while to see what might happen. None of these rubber lines here are original/factory.

2. Since I was there, I replaced the fuel filter. It was high on the to-do list. It turns out the old one really needed to go. It was clogged city. Could this have caused any back-pressure on the system? Smell seems much less.

3. There is a VERY small amount of weepage from the bolts that bolt-down the in-tank pre-pump. I mean small weepage. I tried gently tightening this, and they felt loose, but didn't want to tighten too much. Maybe some sort of gas-resistant sealer to shore this up?

4. I couldn't do the exp. tank hoses (yet) given lack of tools that would do the job. I removed the rubber filler neck seal.

Do I need to move the wheel or part-drop the tank to get at these? It doesn't look like I need to? I probably would have to drop/part drop the tank to get at the main fuel line, but it's newer/not original and looks ok.

Thanks
Chris
1961 Volvo PV544
1981 BMW 528i
1991 Volvo 240 5-speed
2018 Ford Flex (wife's car)
2014 Chalet XL1930

T.Hanson
Posts: 1696
Joined: Wed Jul 26, 2006 7:39 am

Post by T.Hanson » Mon Oct 16, 2017 8:40 am

My 2¢, my priority list + time $$ factors,...

If it ain't broke,... or leaking. Making ominous noises, do what you want as you decide. I am now too aware there is too much input of things inviting stress.

The in tank pump uses a rubber seal ring wanting to be clean, not cracked or rock hard. If you are not seeing a gas puddle and the bolts, clamps are tight, your call for applying topical ointment goop.

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Mike W.
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Post by Mike W. » Mon Oct 16, 2017 11:44 am

Some Guy with a BMW wrote:Thanks for all the tips.

1. I took a good look underneath. I could NOT find any evidence of any fuel leak up to the solid fuel lines that run to the motor. I ran it for a while to see what might happen. None of these rubber lines here are original/factory.

2. Since I was there, I replaced the fuel filter. It was high on the to-do list. It turns out the old one really needed to go. It was clogged city. Could this have caused any back-pressure on the system? Smell seems much less.
No, the only added back pressure would be between the fuel pump and the filter, one short hose.
3. There is a VERY small amount of weepage from the bolts that bolt-down the in-tank pre-pump. I mean small weepage. I tried gently tightening this, and they felt loose, but didn't want to tighten too much. Maybe some sort of gas-resistant sealer to shore this up?
If tightening doesn't work replace the gasket, don't putz around with any sealant, it won't work anyway.
4. I couldn't do the exp. tank hoses (yet) given lack of tools that would do the job. I removed the rubber filler neck seal.

Do I need to move the wheel or part-drop the tank to get at these? It doesn't look like I need to? I probably would have to drop/part drop the tank to get at the main fuel line, but it's newer/not original and looks ok.

Thanks
Chris
You will need to lower it some but not drop it. Try to do it with the minimum amount of gas and at the very least not a full tank.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

T.Hanson
Posts: 1696
Joined: Wed Jul 26, 2006 7:39 am

Post by T.Hanson » Mon Oct 16, 2017 4:06 pm

Under the tank looking up there are two large bolts going through flat triangular brackets. The lips on the brackets curl down, the longest side parallels the tank.

To lower the tank sufficiently to take advantage of the potential space between the top of the tank and the trunk floor, I used a floor jack to hold the tank close in case either bolt fell clear of the threads.

You will find pushing the new lines through the proper side tank top channel to the in tank pump fittings is easy that way. Adding the tie wraps to hold them on their way to the fuel pump.

Some Guy with a BMW
Posts: 38
Joined: Wed May 31, 2017 12:57 am
Location: British Columbia

Post by Some Guy with a BMW » Wed Oct 18, 2017 2:05 am

Thanks very much for the replies.

I got the ear clamps off in the interior, and the weeping from the fuel pump seems to have stopped with a bit of tightening. I see the gasket is still available if need be.

The car was already prepped for winter storage with full gas tank, so hopefully the fumes are in check and I can tackle this properly in the spring. If not then I'll have to do it shortly...
1961 Volvo PV544
1981 BMW 528i
1991 Volvo 240 5-speed
2018 Ford Flex (wife's car)
2014 Chalet XL1930

cory58
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Joined: Thu Aug 25, 2016 8:49 pm
Location: Charlotte, NC

Post by cory58 » Thu Nov 02, 2017 4:51 am

Trying to finish up the gas tank replacement on my '77 530i and ran into a snag. When reinstalling the tank, the hose clamp on the supply line is sticking up high enough so that I can't install the cover plate. I've rotated it as far as possible both ways and nothing helps. These are the same hose clamps that I took off during disassembly.

My first thought was that it should have been an oetiker clamp instead of worm drive clamp, but per realOEM, the worm drive clamp is correct.

What am I doing wrong? Any help or advice would be greatly appreciated.

Thanks, Cory
1977 530i
1988 320i Touring (euro)
1992 325i Cabrio
2015 328i (wife's car)
2001 325i (R.I.P., still missed)

PatinaBeforePolish
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Post by PatinaBeforePolish » Thu Nov 02, 2017 7:28 am

I know this is a simple suggestion, but have you rotated the engagement side of the clamp to the low side? Are you installing the cover upside down?
78 F150
79 528i
01 540i
86 944
08 X3 don’t judge me it’s there to preserve the others

cory58
Posts: 109
Joined: Thu Aug 25, 2016 8:49 pm
Location: Charlotte, NC

Post by cory58 » Thu Nov 02, 2017 8:38 am

PatinaBeforePolish wrote:I know this is a simple suggestion, but have you rotated the engagement side of the clamp to the low side? Are you installing the cover upside down?
Thank you. No offense taken! When you're knee-deep in a problem, sometimes it's hard to see the big picture and simple things get missed. I'm definitely not putting the cover on upside down, because the seal is facing down.

I'm not sure what you mean about the hose clamp. When the worm gear body is parallel with the trunk floor, the screw head is facing away from the return line. I've rotated it to the right as far as it will go, which puts the screw head facing up at about 12:30, and rotated it to the left as far as possible that still allows me to get a wrench on it, which puts the head at about 8:00. One thing I did not do is remove the clamp and turn it around so that the screw head is facing the return line, because I did not think that would make a difference.

I'm doing something wrong, but have not figured it out yet. Frustrating, after getting the new tank in relatively easily.

Thanks, Cory
1977 530i
1988 320i Touring (euro)
1992 325i Cabrio
2015 328i (wife's car)
2001 325i (R.I.P., still missed)

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