Magnet on Fuel Tank - Makes Sense?

[Pawel66]

I just thought of small pieces of rust in the tank...

What if I placed a small but strong neodyme magnet on the outside of the fuel tank, underneath, right under or close to the point where we have the fuel sender in the upper part of tank?

I checked that the stuff I took out of the filter is magnetic - it sticks to magnet strongly.

If I place a magnet under the bottom of the tank, it should catch at least part of the floating rust pieces and keep them away from the fower pot bottom passage. Then it would be easy to take it out through the sender opening with another magnet.

Does this make sense?

It is not a remedy for rust in the tank. It is not a remedy for non-metalic gunk there. But as long as it does not interfere with how the sender is working, maybe it will help a bit keep the flower pot passage clean. Also: we know that magnet is not a bad way to clean this passage, so this is just adding a preventitive element to it, just like we put magnet in the oil drain plug.

[cfm65@me.com]

Hi Pawel,
Magnets are quite commonly used by the vintage car fraternity.
I have one in my 1928 Model A Ford Pickup as well as one in my 29 Chevy.
The best position is possibly under the filler neck where the debri could easily be removed with another magnet,  through the filler neck, that is if you are concerned that the magnetic field could interfere with the gauge.
Regards
Chris

[Pawel66]

Thank you!

I thought I was clever...

[scoot]

I would put the magnet inside the tank, not outside the tank, on the bottom somewhere.

[Pawel66]

Yeah, could be better. If you lose it if placed outside, all the rust will flow nicely to tho hole...

[AndrisV]

Hook a chain between magnet and filler cap. Win-win.

[Pawel66]

Good to post an idea - it will always get enhanced!
Thanks!

[Mike K]

The magnet's a good idea Pawel!
It depends of course how much rust there is in the tank....see pic below of what came out my fuel tank before I replaced it.

Best is to flush and drain from the filter port at the bottom of the tank.

Mike

[Pawel66]

Just done it. Thinking as preventive measure.
The tank and filter were surprisingly clean in my case.
I see you have some mess to attend to there...

I spent 2 hours undoing the filter in the bottom of the tank.

[Mike K]

I had some serious mess in the tank! I ended up replacing the fuel tank, fuel lines and fuel pump....

Best
Mike

[Pawel66]

I was afraid of having a mess in the tank. I was thinking about getting there for a year or two. Until I drove somewhere three weeks ago and I could not come back home.

Then I diagnose fuel starvation and looked into tank, pump, filtrs etc.

[mdsalemi]

Hate to be the bearer of bad news...but "rust" (red iron oxide, Fe2O3)as we know it, isn't all that magnetic. While some of it will stick directly to a magnet, the attraction is weak at best, and in the presence of the "sloshing around" of gasoline in a tank I'd imagine that whatever might stick could easily be dislodged. While the idea is great--in fact, some factory delivered cars have a magnet built into the oil drain plug--what might come out of a transmission or engine (bits of iron and steel) is different than what comes out of an aging fuel tank.

Probably can't hurt, but what you really want to do is spend your time earning money for a new fuel tank!  If the one you have is rusting, it's nearing the end of its service life, and you are simply living on borrowed time.  Been there and done that.

[Pawel66]

Michael, yes - all good points. The trick with oil drain plug I have. It is clear where the attention needs to go - fuel system in good shape. However... there is always "however"... I have seen photographs of the stuff that people are taking out of the fuel filters and then I saw some of the same stuff coming out of my filter. Not a lot, but some. it is small grains of metal/rust. They are remains of bigger particles, I suppose, milled by gas and tank like rocks in the river. When I look into the tank with a camera, it looks nice and clean, but must have some spots on the top if I get some amount of this grains, looking like thick dark sand. I think there is stil some life in front of my tank, but as there may be just some contamination -  maybe it is good to try to catch it for the price of a magnet, wich is $0.2 up to $0.5.
This rust "sand" is very  magnetic - I checked it. It is quite difficult to clean it off the magnet, actually...

[mdsalemi]

Pawel, you might consider removing the tank entirely and totally cleaning and degreasing the inside. There are a number of ways to do this--search online--and a number of degreasing and cleaning solvents you can use.

[Pawel66]

Michael, thank you!
I looked inside with the camera. It does look quite decent, actually. There are small spots on the top, but not a lot. I think I had some residue from the restoration time. I changed the filters. I will give it some time and then if need be - I will do what you kindly advised.

[Mike K]

Hi Pawel,
I agree with Michael's advice, I went through the same process. I bought my car in the Netherlands and drove back to the South of France, the car kept dying on me.
https://www.sl113.org/forums/index.php?topic=19421.0
 
When I got home and checked the tank with an endoscope camera, it looked OK, that was until I drained it and opened up the engine fuel filter.

The amount of fine sand-like rust that came out was staggering! This fine rust ended up trashing my fuel pump to the point where that also needed replacing.

The fine particles of gunk that came out of my tank and the fuel filter would or could never have been picked up by a magnet. As a working example to illustrate this, I fly helicopters, there are several magnetic warning chip detectors in the turbine and in the main and tail rotor gearboxes as well. Their function is to detect metal particles in the event that things start coming apart internally. Even these high tech magnetic chip detectors often do not pick up very fine metal particles which can be found in the turbine or gearboxes.
 
FWIW my advice is to get a new fuel tank and have peace of mind.

Best,
Mike

[Pawel66]

Mike,

Thank you!

I know your post from before by heart .

I will do what is necessary, thank you!

[rgafitanu@gmail.com]

For the last three years, every 4-5 tank fills I have to take out the fuel pump screen and clean it. The rust dust in the picture is not magnetic unfortunately.

[Pawel66]

This definitely would mean work on tank or a new tank...

[rgafitanu@gmail.com]

I was hoping that continuous tank fill ups the rust flake off would be gone in time. I guess the ethanol in the gasoline with its hygroscopic property keeps moisture in the tank. A new W111 tank is more than $800 with all possible discounts.

[mdsalemi]

I understand that everyone in this situation tries to hold off on purchasing a new tank, because of the cost. Once it starts rusting, it's gone--and you may as well face reality that it's time for a new tank. Nothing else, I'm afraid will do...

I did the same thing, but I lived with the continuous troubles of a bad tank for several years. It was a constant battle; I could never rely on the car behaving properly. Once I changed it all was well.

There was nobody to tell me this, or even suggest it...otherwise I would have done it. I had taken the car to many places and finally one mechanic said it's your tank. We changed the tank and all the troubles disappeared.

[paults1]

I use Sta-Bil 360 when I fill up with E 10 gasoline. Sta-Bill 360 claims it prevents corrosion in the fuel tank with its vapor technology, prevents ethanol damage, stabilizes fuel up tp 12 months. I plan on taking the top fuel gage sending unit out to inspect the inside of the tank when the fuel level is low, remove the tank filter and drain the remainder. I have never had any problems with rust in the tank, probably because the PO had installed a new tank sometime prior to 1993.
Regards, Paul Sorgen, '63 230SL
 

[Pawel66]

If I have to worry every 2-3k kilometers about filters and rust, I will go for a new tank. They are expensive, but they will not be cheaper in a year or two. I would prefer not to spend half of the money on labour and chemicals just to buy a new tank in the end.

[Mike K]

My new fuel tank came from here, no issues whatsoever:
https://www.mbclassics.de/fuel-tank-W113-250SL-280SL

Best
Mike

[mbzse]

My new fuel tank came from here.../...

Looks like the "dansk" repro fuel tank, Klokkerholm. Discussed in the Forum recently.
https://www.sl113.org/forums/index.php?topic=26118.msg189475#msg189475
https://www.sl113.org/forums/index.php?topic=27729.msg199390#msg199390