Cheap Fuel Tanks
 

O.K., back to the O.P. :

There's one right near you, why not go buy it ? .

If there's any holes punched in it, take it directly to the local indie muffler shop in your Barrio and have the Mexican guy there weld it up ~ he'll have the knowledge and practice to do it plus it shouldn't be over $35 ~ $50 .

Any W123 fuel tank will suit, the 300D's are slightly larger than the 240D's are but bolt right in .

If there's any rust left on the inside vent tubes it's because you didn't use the correct chemical or you rushed the job .

Don't make this molehill into a mountain .

Keeping an eye on the clear plastic intake sc reen is nice but fine rust silt particles will go right through it and grind your injection pump up plus clog up the injector nozzles .

Fine rust particles have a nasty habit of passing through filters and pumps then joining hands when they get to some part of the fuel delivery system when they'll cause the most mischief .

Your call here .

Lastly, Harbor Freight sells rare earth magnets that are disc shaped and easy to place inside the filler cap and on the nose of the drain plugs for the engine, final drive and so on, they're easy to clean the collected SWARF off of and will scare you the first time you see the accumulated SWARF .

I put on a new spin filter. Hard to imagine large bits getting through that. But your point is well taken, I'll look at that tank on the CDT. Can take out the sender and have a good looksee.

I've got the original tank back in, I'll use it for a while, I have some other pressing repairs going on.

Rusty Tank
 

Just to - day I was salvaging parts off a tired 1979 240D and noticed the fuel tank had NO HOLES PUNCHED .

I grabbed the fuel gauge sender, there's some fungus build up in it, but I know how to clean them .

It turns out that soaking them in purple de greaser saturates the composite float dammit .

LKQ raised the sender price, it used to be $16, now it's $22 .

Still a bargain .

Keep us posted .

I have cleaned a W123 tank before and have cut one open to look inside. W123 tanks are quality tanks made from good metals with some kind of Terne coating inside and out that's resistant to rust. https://en.wikipedia.org/wiki/Terne

Here are some recommendations if you are going to clean one:

1. Make sure the vents are not blocked first. Unblock it if it is blocked . Do not use any kind of tank sealers unless you are able to keep the serpentine tank vent tubes from being closed off by the tank sealer.

2. Take the tank out. Mount it to a long pole as if you are doing a pig roast. Support it on 2 forked tree branches driven into the ground. Attach a crank so you can turn it.

3. Put in a few hand full of round beach pebbles or ball bearings that's slightly larger than the vent opening, together with a gallon of good degreaser + hot water (follow recommended product mix ratio), close off tank openings and crank away. It helps to have a borescope so you can look inside for a before and after. Repeat as necessary.

If after the de-greasing, and you still see rust, repeat step 3 with phosphoric acid solution.

Rinse well with water then final rinse with hot water. Dry it off quickly with compressed air, or a leaf blower.

Talk & Fuel Gauge Sender Cleaning
 

LOL ~ I like the idea of putting the tank on a spit and rotaing it .

As it turns out I didn't saturate the composite float in the sender I cleaned ~ it had massive amounts of fungus crud every where and when I cleaned the sliding contacts in the float I moved the delicate hair thin wire out side of them .

I fiddled with it late last night and it's in and working fine .

Time to clean the gooey crud out of the sender I removed again .

I'd be reluctant to use the stones in any mb tank of mine. I believe the factory coating is a good thing and the crud is probably minimal.

I have pulled cars out of old garages that had been sitting for decades, drained the tank and used it without doing anything. If it has a lid on it what is going to get inside?

I like the biocide though and it will liquefy most of the bacteria so they flow through the filter and are burned.

Phosphoric acid leaves somewhat of a rust resistant coating on the metal.

In the majority of cases some sensible cleaning should take place. To establish the real condition of the inside metal surfaces. Just having a general look inside these old diesel tanks will probably not reveal much. Of the overall general condition unless they are already very clean.

A lot we see in these old tanks may be from the long ago era. Where there where a multitude of issues with diesel fuels that where common. Especially from small vendors. Too high a percentage of diesel fuel was delivered to vendors by bulk carriers of all liquids.

Simply because the volume was low. It is totally impossible to establish what was mixed in with the diesel fuel all too often .

At least this far north seldom did we find the steel manufacturers. Applied coating on the steel destroyed on automotive gas tanks. On the inside of tanks but very common on the outside of them.

I saw this in NYC on my way into work. I tried to convince the driver I knew someone who really, really needed it. He was not convinced

The greater beater Benz community thanks you for your service. This time fell short but eventually the great bull riding shaking tank cleaning service will be a reality.

What? Is there a gas tank in there?

Silly me, that pristine CDT arrived on the yard November 5th. It must’ve been stripped in a hurry cuzzin it was gone completely when I got there cousin. The tank probably going to the shredder (sad trombone).

I think you’re right, I rushed the procedure a bit. On the other hand I got it roadworthy the day before yesterday by putting in the new oil cooler lines, drove yesterday 550 miles to Eugene, stayed at an Airbnb, having breakfast now. The primary filter as clean as can be, well, a couple of tiny bits.

Performed pretty well all in all but something in the turbo needs help. After that, the front end is not ideal. Took me about five or six or seven cranking attempts to get it started in this 25° weather.

Progress !
 

Yay ! .

Glad to hear this, I filled up and had to change the clear plastic primary screen yet again but it's a lot less crud than used to be and is only fungus debris, no rust / etc.


As far as cold starting, under 40* F there's a specific starting drill that works, every time, even with bad injectors and a worn out engine :

Depress and release the throttle twice then cycle the glow plugs TWICE then hold the throttle to the floor and operate the starter, not letting up until all five cylinders are firing ~ the engine will begin to rev. up farther that I like but follow this and the car will start easily, every time in below freezing weather, BT, DT in my older beat to crap 1978 Mandarin Red NA 300CD after I discovered the factory cold weather starting tips card under the seat .

Try it, you'll like it .

I also use and recommend thinner winter oils when the temperature is going to be below 40 as they allow faster cranking speeds .

Sounds like you might be sucking air in one of your fuel lines...or at a fitting. The lack of power may also be because of a crack in a small vac line which loops behind the back of the valve cover. If cracked you will not get the correct fuel enrichment when you put your throttle down. If you kick down the transmission at 50 to third it will not accelerate, just get louder. It can be fixed with a piece of shrink wrap.

Pick-A-Part Turnover
 

That's a real pisser ~ the yard apes seem to have specific rows they like to turn over every week or less, others will leave a gutted carcass languishing for three months....

When you'd hot for an item you need to check daily for a few weeks until you find what you need .