re-installing the fuel tank - 2 questions

[1000nutsnbolts]

Hello All -

My 1970 280SL which I purchased last fall - it hadn't been run in a few years. I removed the tank and had it "boiled out", cleaned, at a local radiator business. I did a POR15 sealant and 3 coats of Rustoleum rubber truck bed paint on exterior. Changed strainer and gas filter. Blew out lines. Cleaned and replaced everything needed in the area of fuel storage and feed up to the injection unit.

1) Those two little breather tubes to the fuel evaporation tank were a **** to reconnect. Did I need to do that? I am a bit of a perfectionist and I was considering just pinching them off.  There's not a whole lot of vapor/gas flow that goes thru them anyway.

2) Wrestling the tank back in with tubes connected, I dislodged the rubber tank filler neck boot/escutcheon that surrounds the filler neck and trims out to the transom body panel. Any words of wisdom as to how to get that rubber body seal seated back in place WITHOUT pulling the tank back out??

How would a paint shop do it?

It's really a job that can use a pair of helping hands. But everyone I know shudders at the thought of working on a car. I can't understand - it's so much fun!

And I won't ask my wife. It's just too costly.

Thanks

[Rolf-Dieter ✝︎]

Hi Tom,

Go to the Technical Manual and search for Pagoda Notes. Then scroll down to PN 1 - 4 in that issue Joe Alexander prepared a nice article with photographs on the fuel tank. Or click on the Restricted link (that only Full Members can open) perhaps you find some help there.

Good Luck,

Dieter
——> https://www.sl113.org/wiki/Restricted/PagodaNotes?action=download&upname=PNv1i4.pdf

[Charles 230SL]

...I dislodged the rubber tank filler neck boot/escutcheon that surrounds the filler neck and trims out to the transom body panel. Any words of wisdom as to how to get that rubber body seal seated back in place WITHOUT pulling the tank back out??

Tom, you should be able to seat that gas neck grommet with the fuel tank installed. If it's not pliable, let it sit in boiling water for a few mins to soften it up.

[Nicolas Aristodemou]

And the fuel evap lines to the evap tank should be installed else you will never get the car running properly...

[Shvegel]

to expand quickly on the above posts the two lines are the vents for the fuel tank.  As your cap cap is not vented you will need them connected or your fuel tank will be under vacuum and the car will not run properly. 

Forward of the plastic than there should be a black hockey puck looking thing with some lines running through the trunk floor.  One of those lines should run forward all the way to the front of the engine.  That lines sounds the fuel vapors to the engine to be burned. 

You mentioned sealing your tank.  There is a fairly complex setup in the tank that keeps the fuel supply even when the tank is very low (Search "Flower Pot").  If you clogged this while you were sealing the tank the car will die with 1/4 tank of fuel remaining.  Don't get too far from a phone the first  time you reach 1/4 tank.

[Pawel66]

These drawings are sometimes helpful in the kind of jobs you are doing: https://www.sls-hh-shop.de/main/en/mercedes-230-280sl-w113-/47-fuel-tank

You have two systems of evaporation shown there - earlier and later one, with a bigger tank. They are very important.

Do not forget the pads on top of tank.

Did you clean the screen in the inlet of the fuel pump (if you have one)? It is a good practice also to install in-line filter between tank and the fuel tank, especially after work done on the tank.

You have a lot, as indicated by previous replies, about the fuel tank and lines in Technical Manual.

[1000nutsnbolts]

Thank You Dieter - I had read up on the the "flower pot", printed some photos and brought them to the guy who cleaned the tank.

If it's of help - being new, I sometimes confused as to the best way to search for technical questions. The inclination is to go to search in the upper right on this main screen. But eventually after reading some gentle admonitions, I realized that it's better to search along a lower line. I have attached an image for others who struggle.

Thanks Again.

[1000nutsnbolts]

Thanks Charles - now it comes back to me. This is what we used to do to get our baskets back onto our cross country ski poles. Regards.

[1000nutsnbolts]

Thanks Nick. I did get them reconnected, but it took some contortions and extra long needle nose pliers.

[1000nutsnbolts]

Thanks Shvegel - this is very helpful and reinforces many of my suspicions. I was careful on the sealing. The POR15 - 2 coats are pretty thin.  But I will be watchful and keep my AAA membership card close at hand.

https://por15.com/collections/fuel-tank-restoration/products/fuel-tank-sealer?variant=39607017177255

After thoroughly dry, I blew thru all openings. The two (fuel supply to the pump) were clear and breathing well. I had plugged the outlets and cleaned after. I had read up on the flower pot.

The two breathers up by the fill neck -  I had inserted wire, one is straight (I think on the right) but the other takes a bend in the tank. After, the straight one was clear and with flow. The one with the bend, well, it is open but not flowing as well as its twin.

I appreciate that the cap is not vented - what concerns me is that the diameters of fuel outlets are far larger than those two small vents (approx 2.5 mm dia each). I don't know how it is that there isn't a vacuum created in the tank when running at higher RPMs and fuel demand

[1000nutsnbolts]

Thank You Pawel - I have noticed that you are a regular contributor with very helpful advice and information. You are one of several Gems in this Pagoda Group.

My 280SL has the larger evap tank hugging the left rear fender. YES - I did the pads. Looks like they could dampen any diagramming with trunk floor?

And YES - I changed the fuel filter in the engine compartment AND the Benzin (22mm) strainer (new) in the center of the flower pot. Blew out all feed lines. At that point I figured why stop and I pulled the pump and I'm having it flushed out. NOTE - neither me, or my MB mechanic, saw any evidence of an inlet screen.? Not much could happen to fuel between that tank strainer and pump inlet.  Pump is larger type.

MB mechanic said he didn't want to disassemble the pump to access and clean the impeller as he thought he might not be able to get it back together.

Didn't you also suggest changing that paper element filter that vents the injection unit? Sincerely - thanks Again.

[Pawel66]

Thanks

The screen should be there in the inlet fitting to the fuel pump. If you search the forum - you will find it. You do not dismantle the pump - just undo the inlet fitting. If the screen is not there - I would find it on the market and fit it. I also fitted the in-line filter between the tank and the fuel pump. What can happen there between the tank and fuel pump? about a 100g of dirt within 2-3 months after work on fuel system. That is what I had.

Yes, the air filter for the injection pump is available at Mercedes, there were also indications of other places.

[bracurrie]

For what its worth I showed my old tank to a tank rebuilder and he said because of the flower pot the only way to insure his service would be complete was to split the tank in two, service and reassemble. New tank was cheaper.  Mine was a rust issue and it was rust in the flower pot that probably caused me the most problems.
I too changed all filters in the fuel system and I am also contemplating putting a filter in between the tank and fuel pump.

[Pawel66]

Put the filter there. If you have the correct fuel lines, they are 9mm diameter inside while most of the filters are 8mm. Kent Bergsma shows the way how to deal with it, I have another way: find a filter that has 9mm fittings.

The screen in the fuel pump is also important.