W123 Fuel Hose Question
 

Does anyone know the size of the clear fuel hose that goes from the
spin-on filter assembly to the injection pump? Also is there a particular brand/type recommended due to the heat these lines are exposed to?

You can replace it with 1/4" ID Regular Fuel Hose from the Auto Part Chain Stores; that Hose is also rated for Diesel. And, you will need Hose Clamps.

To get the Old Plastic off you need to heat it just enough to soften it and pull it off. That can be done with a Butane Lighter or a Candle.

it's a pressure hose, so replacement is best done at a dealership, as it's a special clear hose.
there have been members that have changed the hose with other hose, using clamps etc, but you lose the clear functionality of seeing if air is in the line.

i have removed that line in place i have put a large filter... i would say you do not need to go to the dealer to replace... just go to your local parts place and ask for some 1/4 fuel hose and get some fuel injection hose clamps not the normal hose clamps...

The hose appears to be polyurethane clear hose.

did you put back clear hose? or is your filter now the bubble checker?

I changed mine to Rubber Hose for the same reason.

You can buy all of the Plastic Fuel Lines; but at some expense. The real advantage of the Plastic Lines is longivity.
I donot see a huge advantage in being able to observe Air Leak Bubbles because the Plastic Tubing is gong to discolor and make it hard to observe bubbles and the symptoms of an Air Leak are obvious.
Not to mention there is really only 3 common sources of Air leaks. The FueL inlet Hoses, the Plastic Primary Filter or the Hand Primer.

A long time ago one of our members replaced his Plastic Tubing with I think it was Tygon; the US equivilant of what the Germans used. But, that suff is extremely stiff to get back on the Hose Barbs of the Fittings. He said He heated up the Plastic and shoved it on.
I did not think I would have success at that so I went with the Rubber Hose.

Could be some answers here:
240D Transparent Fuel Line Replacement Tips?
http://www.peachparts.com/shopforum/diesel-discussion/312374-240d-transparent-fuel-line-replacement-tips.html#post2878680

The tubing on my spare IP has: DIN-78878-PA-TECALAN-79 a arrow and a bunch of widley spaced 2 digit numbers?
When I looked several years ago TECALAN does not seem to be sold here in the US.

Another related thread.
http://www.peachparts.com/shopforum/diesel-discussion/251800-clear-fuel-tubing.html

Saint Gobain is the Manufacturer
 

of Tygothane clear fuel line usable tubing.Bio-Diesel and WVO proof.
It is Pressure rated far above our uses,and comes in a "Strengthened" version
also.

U.S. Plastics is the vendor.