1978 300D - Injector Return Lines
 

I have a 1978 300D non turbo. I noticed the other day that my fuel injector return lines are wet (the braided lines) are wet and one of my injectors has some fuel pooling around it.

I want to replace the lines before I dive into the injectors or whatever, so would I be correct in the following assumptions?

(1) I don't have a Mercedes dealer in the area, but there is a VW dealer. The braided fuel lines they carry for their older diesel rabbits is the same as what I need?

(2) The lines just carefully pull off (they may fall apart) without clamps or washers or whatnot

(3) Replacement lines can just be carefully pushed back on.

(4) The last line needs to have some sort of plug in it. I can re use the metal plug in the existing line.

Thanks in advance, and any advice/feedback would be appreciated.

all correct.

keep in mind, if you are planning on injector service, that now is a better time to service than after you replace the lines, because they only go on once. after they've been run, you must replace them.

also, Peachparts does stock the line, so you can order it from this site, and it'll show up at your door.
lastly, the end plug sometimes is a metal plug in a little line, sometimes it's a closed rubber plug... find out before you get the replacement line!

Thanks, I will definetly confirm the plug details before I hack anything apart. I'm not planning on doing anything to the injectors for a bit, the car runs superbly but has the usual list of small things to attend to.

New battery is done, next is this fuel leak, after that will probably be the rust horror on the driver's side door. I was about to buy a new door and then the battery died.

You can reused the Metal Piece that is the Plug.

In one of the Treads below should have the VW Part Number. Also NAPA used to sell it and some have used the NAPA 1.8" ID Fuel Hose.

Where to buy fuel return hose VW RAbbit
Diesel Injector return lines, where to buy? - PeachParts Mercedes ShopForum
The Thread with the part numbers
fuel return line replacement part - PeachParts Mercedes ShopForum

Some where in the below threads are alternative Hoses for the return lines.
DIY Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum

PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles

if they've been on there a while (and they probably have if they're leaking) they can break when you pull them off, leaving hose on the injector barb. if that happens, just be careful in that area when prying the remaining bits off, you dont want to nick or scratch the tip of the barb.

Just wanted to update the thread with my progress. I picked up some line from the local VW dealership as I didn't want to wait for parts to arrive in the mail

Job wasn't too hard but by God it was annoying. The return lines had the consistancy of straw, they all snapped as soon as I touched them. They I had the joy of slowly picking off all the little stuck on bits of hose from the nipples.

The third injector from the firewall defeated me for a while, it's right under all the throttle jazz and I just could not fit my hand in their to push the line on the nipple, had to wait till one of the girls got home, then I introduced them to a three generation family tradition of "you have little hands, reach in there and do this".

This is absolutely a job that I am not going to postpone like the PO did, think I'll do this every couple of years while the lines are still supple and stuff.

That's what I'm doing now with a car I just picked up from a friend who moved away. During the years that he owned it I warned him not to let "Albert" work on the car. But he was cheap and close so.........
I am now re doing everything that "Albert" had anything to do with and doing everything that he didn't do!
Which in this case is a blessing since it limits the amount of things that he could have damaged. Good thing these cars are so stout.

What kind of results are folks getting using 1/8" rubber fuel line as opposed to the braided OEM hose? What's the consensus here? Thanks.

I used regular fuel line on both my previous car and my current one. Seems to work fine. The hose is a little thicker than the braided line so you need to work it onto the nipples to get it to seat properly. No problems for the last 30,000km and counting

Brining it back to life. I have an 85 300d turbo.

Got the 1 meter of line from my dealer.

Install goes like this?

Remove old line by slipping off on both side -

Cut new line to size

Slip on


That all?

That is pretty much what I did. My existing return lines were so old they immediately snapped when I touched them, so I had a lot of fun picking old bits of hose off the metal nipples on the injectors. The very last bit of hose closest to the firewall had a metal plug in it that I very carefully cut out of the old hose it was in and put in the replacement hose.

For the cost of the return line hose and the amount of annoyance the old ones cost me when they disintegrated I should make this an every couple of years or perhaps even an annual maintenance thing.

I use a long handle pair of needle nose pliers with angled end, and I grab the side if the hose where it touches the injector, and pinch it off. this cleanly removes the old hose from the nipples, and is easier than pulling it off, then digging for the little bits that remain.
I then use the needle nose to push the new hose on.
I like to use a section of 1/8" weed eater fuel hose so I can see bubbles from the injectors to see if there is a leaker generating air...

I believe the OE line is 3mm and the 1/8" is 3.2mm, but I've used it for years without any problems on VW, MB and Chevrolet 6.5. The sidewall of the 1/8" fuel line is thicker so there's a little less give when you go to install it but it holds up well.

I was just going to write the exact same thing. Great minds think alike. It's just about the only time I use my long angled needle nose pliers.

You can get clear small engine fuel line that works at many auto parts stores.