Replacing injector return lines
 

I have a 76 300D 115, I noticed the injector return lines are leaking, do you just cut them to length of the old ones if they are longer? Is there any tricks to doing this job or is it pretty straight forward pull the onld ones off and pop the new ones on? Thanks much

I have the same car and just replaced mine this week. I would buy/order new lines and end plug. I pulled my old ones off gently with pliers and cut the new lines to size and slipped them on. So far no more leaks.

Thanks alot!

yes and no, pull off the old ones, cut new to fit. Don't try to find "lines that will work" Go with original MB lines, you will be gad you did, also check out the last "plug" and replace as well

Be careful not to grip them to hard with the pliers when pulling the old ones off. You can crimp the nipples on the injectors. Making a cut with a razor blade , helps to get them off without a struggle. Hose grip pliers are nice to have:cool:

What's the deal with that end plug, anyway? I ordered some new line but the plug didn't come with it. That part doesn't appear to be leaking, so I think I'm OK for now, but for future reference, where could I get one of those plugs for cheap?

Thanks.

You don't need to change the plug, it is just a chunk of steel. All it does is block the end of the return lines to prevent fuel from coming out that end.

Just cut the old line away from the plug and stick it in some new line.

You can re use the old plug, if its a metal plug. Be warned there were some rubber cap type plugs made for this purpose, but they tend to blow off so don't ever use (or re-use) them. Only use the metal piece with barbs that dig into the hose like the barbs on the injectors. You can cut the old hose very carefully using a sharp knife. I've used a some sharp dikes (diagonal cutters) successfully too.

The plug on #5 on my 300TD blew in the middle of the desert once. It is amazing how much fuels squirts out of that little spigot!
I was leaking fuel so bad that I was misting cars behind me (one fellow who tailgated me a short while switched on his w/s wipers and hit the wash button and he suddenly dropped back about ten car lengths, I think it messed up his view pretty bad (good way to get rid of tailgaters huh?) anyhow I finally found a gas station and stopped to try and fix it becaue I didn't want to find the car ablaze with fuel dripping down on the exhaust line!

Since the plug (and line) was long gone I found that I could cut off a short hunk of the excess line that runs from the filter housing to the #1 injector and found a machine screw and used it as a plug and that worked well until I made it back some 150-200 miles.

I am now testing Viton hose as return lines on a 603 engine. So far it is holding up very well. I will post results about a year from now as to their longevity. I believe Viton will significantly outlast the OE hose material. The reason the material deteriorates so fast (18 months is about all it is good for) is because the fuel is really hot coming off the injectors and hot fuel aggressively attacks the OE rubber and it gets soft and fuel weeps thru.

You can crimp the nipples on the injectors.

When pulling the old ones off, grab the pliers at the line itself and rip it off in pieces, it will break pretty easily. Don't even squeeze the nipples.

Don't touch the end plug if its not leaking. It's easyest to cut a slit up the lines and they pull right off. It's a tough rubber so be careful not to slit your finger as well. Diesel burns. Trust me.

only thing i would add is have the new line ready to go before you pull the old ones..

also sticking a rag underneath where the injector is helps to sop up spilled fuel.

Viton!
 

I've been using Viton on all my diesels for the past 2 years.

I was changing the OE injector lines on my TDI regularly because they kept weeping and eventually melting. B100 everywhere!

Switched to Viton and no more problems at all. I've never had to replace them in over 2 years and the lines are still flexible. The OE lines were stiff within a week of installation.

I was so happy I changed the 300D and 300TD over to Viton too.

JWJ

Tip
 

Cut your new lines a half inch longer than the old lines then when the start to weep in 2 years you can cut off a little of the old lkine and the part you reinstall is as good as new from a cheap scape. Ps also some times the lines push right on others there a real pain a pair of the bent needle hose pliers can come in real handy with some injectors.
Dave S

18 months? Come on. Closer to ten years on pump diesel.