Fuel Tank Flower Pot Question

[Tomnistuff]

I've spent several hours studying the Technical Manual and searching the forum to resolve the fuel supply system issues with my '67 230 SL.  I still have two questions that I can't find consistent answers for.  1)  Is the flower pot metal or plastic?  2) If it's plastic, how is it attached to the floor of the tank? 

Here's why it's important to me  My tank sat for four years with 30 liters of fuel which turned very very sour.  The fuel is gone to the toxic waste recycling center but the tank still has lots of mud, crud, varnish, and maybe rust in the bottom and a pin-hole leak on the bottom surface.  The leak doesn't even drip.  It's so slow that it evaporates faster than it leaks, leaving a stain around the pin hole.

I took the tank to a radiator shop this afternoon to have the tank cleaned, acid flushed, and the pin-hole soldered or brazed next monday, but realized on the way home that the pin-hole leak is at about where the rear edge of the flower pot is on the inside, and if the flower pot is plastic or has plastic parts, it will be damaged by the heat of brazing or soldering.  Since the tank is locked up at the shop for the weekend, I can't pull the level sensor cover that I made and examine the flower pot.  I have until Monday morning to find the answer and develop a strategy.  There are lots of options:
1) have the shop clean out the crud, flush out the rust with acid, braze the pin-hole and melt the flower pot, then throw it all away and buy a new tank.
2) have the shop clean out the crud, flush out the rust with acid, bring it home, tape the pin-hole on the outside and coat the inside with POR15 or KBS coat (very carefully to seal the pin-hole but not the fuel outlet, return line, or vent line) , then blow out the tubes, wait nine days for it to cure while praying that at the end of the nine days I won't have to throw it all away and buy a new tank.
3) call the radiator shop and tell them to throw it all away so I can go buy a new tank.

I suspect that my best option is number two above, unless of course the flower pot is steel.

JA17?  Benz Dr?

Thanks,

Tom Kizer

[ja17]

Hello Tom,

All the flower pots I have seen are plastic. They are held in place by fold over metal tabs. Damage during weld repairs is possible, but most likely will l not cause significant damage if any. Alert the shop making the repairs of a plastic component inside the tank  Make sure that the shop understands how these tanks work and what is inside so important things are not plugged up with sealer.

[Benz Dr.]

It's plastic for sure. You might try a cold weld with some sort of epoxy. Since there's no pressure it won't take much to stop the leak.



  Note: The term '' Flower Pot '' is used by permission of me, The Benz Dr.

[mdsalemi]

Tom,

Having lived through a variety of fuel issues after a restoration, my own humble opinion (not entirely shared here by everyone, but some have indeed become believers) is that, frankly, screwing around with a 40+ year old fuel tank--particularly one that has sat for any length of time--is just buying time at best, or wasting time and money on the inevitable at worst.  Only you can decide the value of your time and your tolerance for getting stuck on the road somewhere.

If you can get inside with a scope to see the level of crud in the flower pot (TM, used by permission) and there isn't any--well, maybe you can salvage it.  If there is crud, the clock is ticking.

Short of that, save the pennies to get a new fuel tank.  They are not cheap, but what is?  I put this project off for 2 years and regretted it, getting stuck on the road repeatedly with one issue after another.  I took it to one guy here (who apprenticed in Sindelfingen) and he said what I'm saying.  A few days and a new fuel tank and the problems disappeared.  That was about 4-5 years ago now.

K&K sells repro tanks.  I think it is the larger 280 tank, but give them a call if you don't want to get a new OEM tank.

[Tomnistuff]

Thank you, gentlemen.  I appreciate the attention given to a new member with only four posts, by three Pagoda veteran experts with a total of 7,950 posts.

Mr. Salemi, I think friendly and open minded disagreement is healthy and beneficial to the learning process.  You are probably right about the cost/benefit of working on a 40+ year old tank, but having spent several years restoring a 40+ year old Ferrari by hand, for which almost no parts exist, and total production was700 cars, it has become apparent that I have a masochistic streak.  AND, I apparently work for about $0.05 per hour or less.  I’ve resurrected a lot of parts for which no replacement existed, so it has become my first instinct; some would say, “fault”.  P.S. I miss the Novi Shopping Center.  I spent 21 years living in Farmington Hills.

Mr. Caron, I think the epoxy “cold weld” idea is a really good one.  In conjuction with a coating inside, it’s likely to last forever as a leak preventer.  I used your “Flower Pot” name in the posting because it was familiar to everyone here and kept me from having to research the name for the device that we used in the auto industry.  I’ve been retired 10 years and can no longer remember the “familiar” name that we used for similar devices during those years when I was responsible for Jeep “off-road” fuel system design.  The name was most certainly not, “Labyrinth Inlet, High Angularity, Temporary Fuel Retention Reservoir”.  Thank you for coining the term, “Flower Pot”.  It saves a lot of words.  If I have your permission, I will continue to use it here only.

Mr. Alexander, now that I know the attachment method, I think I can see one of the fold-over tabs in the bottom of the “Flower Pot” in one of your photos.  I have shown your photos to the radiator repair shop owner and explained how it works and what is important, but knowing that and being able to seal the inside of the tank without plugging something up are two different things.  You are also probably right about the heat damage to the “Flower Pot”.  It will probably just distort and move away from the hot spot.  If it doesn’t develop a major hole, it will probably have little detrimental effect.  At any rate, I think I will tell the shop to ignore the pin-hole leak and do everything else.  After the inside is coated, I can epoxy it from the outside as insurance before ever putting fuel in the tank.  At least replacement tanks exist for Pagodas.

Another possibility that just came to me for the pin-hole leak is a steel closed-end blind rivet with a sealant.  The aircraft industry does that.

Thank you again, gentlemen.  I will post results, good or bad.

Tom Kizer

[Benz Dr.]

The only thing I won't use is tank coating or sealant. If it's cleaned properly it should be OK. I've seen that coating stuff come off and make a real mess.

Leave the fuel tank with the rad shop for the whole weekend so it can soak for two or three days. If that doesn't get it clean then it's junk.

[Tomnistuff]

Benz Dr, after a little reflection on your last post, I realize just how good it is.  Why coat it in the first place?  If it's rusty enough to need coating, it's probably too thin in places to be safe in an accident.  If it's not already too rusty after 43 years, then when it's clean and kept full of fuel, it won't rust significantly.  If it does leak some day in the future, I'll just replace it.  I know it has lots of varnish, mud, and crud from the old fuel.  I don't really know yet if it's rusty inside or not.  The outside has only a little surface rust in the areas where the paint has been stone chipped.  The tank still stinks too badly for me to get down close and look inside.  I'll know more when it's cleaned next week.

I'll just have the shop clean it, de-rust it, and fix the pin-hole leak; if it's still good, then I'll install it and keep it relatively full of fuel. 

That's my plan.  I'll let you know the results.

Thanks all.

Tom Kizer

[ja17]

Yes, it's all a matter of good judgement.  You look at the situation, what you have, the alternatives, the consequences and the costs then you make a judgement call. If we were not interested in fixing, restoring and re-conditioning then we could all take our cars to the MB dealers where the trained parts replacers could swap out expensive parts all day long until the car runs again.

If your judgement is good you will not be back doing it over in the near future. Every situation is different.

[mdsalemi]

Another thing to consider Tom, is that the fuel tanks were not designed to last forever.  They will eventually rust, and a 40 year life should be acceptable.  There are many tanks out there fully original, but more than likely these are not from cars that sat for extended periods of time, but more likely cars that have been kept running all these years.

Years ago as you know, gas was gas.  Today, and for the past few years--gas is gas plus ethanol.  Ethanol attracts and dissolves moisture from the air, and this then stays in the tank, which contributes to the tank starting to rust...  We didn't have this problem years ago, but we have it now.

Joe's advice is sage: use your best judgement.  Doc's is sage as well: don't coat the tank.

Oh, btw, if you work for $.05 an hour, come work for me.  I'll pay you TEN TIMES that amount...

[Benz Dr.]

Sage advice:  tastes good on chicken too.

[Tomnistuff]

Well, I got the tank back from the radiator shop.  To review, I decided to have it cleaned, de-rusted (if that's a word), and a pin-hole leak repaired.  After the acid wash, there were a couple of other pin-hole leaks discovered.  All three leaks were repaired with minimum heat to avoid damage to the nearby "Flower Pot", and about a liter (that's a guess) of transmission oil poured in the tank to inhibit rust until I can get the car back together and fill the tank with fuel.  The only damage was probably caused by mishandling.  The plastic frame of the strainer was mechanically bent, not heat distorted, and the mesh was torn away from the frame.  Another 30 odd dollars down the toilet.

I plan to put the tank back in the car last, so just before installing it, I'll pour out as much oil as I can, rinse the tank with a couple of quarts of gasoline to dilute the remaining oil as much as possible, pour that out, install the tank, and fill it up.  Does that sound right or am I forgetting something?

One last comment.  This is more like an observation that, for me at least, has become a truism.  Apparently all radiator shops look like old west blacksmith shops, with dirt floors (probably 1/2 " deep on top of cement, however).  It is impossible to walk through without dirtying your clothes, and every one I've ever seen appears like a scene out of Danté's Inferno.  The parts you take to them, although usually leak free when they come back, are actually dirtier than when you delivered them to the shop.  I visited all the shops in town and took the tank to the cleanest (excuse me, the least dirty) shop in town.  Has anyone else noticed this as being typical, or is it just me?

Tom Kizer

P.S. I just installed the shift lever bushing kit and the shifter now works like new.  The transmission end bushings were all gone.  The others were like new, but I replaced them anyway.  Many thanks to all the shifter rebuild threads and the Tech Manual.

[Benz Dr.]

If you enter a place that rebuilds gages the place will not be dirty, or at least it shouldn't be. This type of work requires a very clean work place.

Most rad shops have been around a long time so they tend to look old. The place I go to looks like the places you describe - this means nothing for the most part. Most places really don't even work with brass tanks anymore and a lot of them can't be bothered with it either. The place I use does a lot of work for RM Restorations - this is high end work. If you want it pretty, it will be.
This kind of work is dirty, grubby stuff. Lots of big truck rads, tractors and cars - things like that. Lots of dirt and years of grime all over everything. It's not for everyone.
 Some customers never enter the '' back room '' for good reason. The end result is all you really need to be concerned about for rad shops.