300SDL Leaking fuel. Injector line?

['87300SDL]

Hi all,

This is my first post, so please let me know if I have done anything incorrectly.

First off, I drive a 1987 300SDL with 250k miles.

Based on reading through the posts on this forum, I think that I have the problem diagnosed, but I wanted to confirm before I started tearing into things.

What happened...

I was driving home and everything seemed to be fine while I was on the highway, but when I got to town and stopped at the first light I noticed that the car was idling roughly, almost like a cylinder wasn't firing. I made it home and I popped the hood to take a look (with the car running). Sure enough injector #5 was leaking fuel all over the engine.

(I need to replace the cloth lines, but that is a separate issue)

I wiped everything down and started it up again to confirm where the leak was. The fuel appears to be coming out between the fuel line and the nut that holds it down. (See pic below)

Taking this apart I found what appears to be a hairline fracture (My eyes aren't good enough to confirm given the lighting, but I can't think of any other reason why this would have started leaking, it wasn't loose or anything. (See pic)

I also noticed that many of the plastic clips that hold the hard lines were broken which may have been what allowed this to happen to begin with.

My plan of action is to replace the #5 line and see if that fixes the issue, but I wanted to check here first to see if there is anything else that I should try \ look into.

(Side note: I took the #5 injector apart to check it over and everything seemed fine, the question that I have is in relation to the rubber washer type item shown in the picture below. On all of the assembly guides that I have found, they do not show this piece, rather the inject just screws together with nothing there. I can't tell if there is fuel leaking there or if it was just running down the injector from the fuel line, but I wanted to check how this is supposed to be put together regardless.)

Assuming that you all think that I am correct and it is a fracture in fuel line #5, I will post a reply with what tools \ materials I think that I need to make the fix.

Please let me know if there is anything else that I can provide which would be helpful and thank you all for your time.

-Nick

[Diesel911]

Sounds like you have diagnosed it correctly.
Vibration is one of the things that can crack a Fuel Injection Hard Line. All of the Broken clamps will also need to be replaced to help prevent it from happening again.

The Rubber Band that goes around the Injector is there so that when they rebuild the Injectors they can use any upper Injector Body and not have to worry about how many Bar of pressure is stamped on the Body; the Band covers that up.
The Rubber Band also has the Rebuilt Injector Part Number on it.
That Rubber Band does not seal any thing.

I would have left the Injector alone until I had the new Fuel Injection Hard Line to see if that stopped the leak.
Sometime when you take an Injector apart and put it back together without lapping the Flat surfaces that leak between the Injector Nut and the Upper Body.

[86-300sdl]

No doubt you need a new steel hard line & get a set of new clips. Both dealer items, or maybe Phil at Fastlane on this site can help. About $60 for the fuel line and around $25 total for the clips. Replace the braided line sections between the injectors too. Also get that from the dealer (grey cloth covering). I went with aftermarket last time and it only lasted a year / 35,000 miles.

I just went through this on my sdl #5 too. Thought it was misaligned or a crack in the line, only to find it was a worn "tip". When you get the new line you will be surprised how the new tip on the injector side of the line looks more like a mushroom shape verses the cone shape the old tip now is. Problem is without the clips the tip vibrates on the harder injector material and wears down.

I messed with mine for a while i.e. getting the perfect alignment, varying nut torque etc...No Joy

Hey also take comparative photos of the old tip and new before installation. Our site tech guru "Whunter" had asked me for some & I can't find them for him.

P.S. and follw what ever "Diesel911" says....he's gooooooood.

['87300SDL]

I ordered everything from Phil yesterday, I will make sure and post some pictures once we get it all fixed up.

Thanks again for all the help.

['87300SDL]

Well the old boy is back up and running.

@86-300sdl - You were right, worn tips, no cracks to speak of.

Attached are the requested pictures, plus one showing the old and new cloth lines (dry vs soaked in fuel) and the new plastic clip that should have been replaced a while back and would have kept all of this from happening to begin with.

[tisdale36]

I can't find the part. Mine is also the number 5. Where do I find it?

[86-300sdl]

Originally Posted by tisdale36

I can't find the part. Mine is also the number 5. Where do I find it?

Pelican / MB Part #: 602-070-04-33-MBZ

[SpaceCowboy!]

[QUOTE='87300SDL;2960128]I ordered everything from Phil yesterday, I will make sure and post some pictures once we get it all fixed up.

Where do i find this Phil guy? i have the exact same problem but #3
Is he with Pelican parts? Thanks

[Mike D]

Phil passed away a few years ago sad to say but the folks at Pelican Parts should be able to guide you in the direction you need to go.

[SpaceCowboy!]

Originally Posted by Mike D

Phil passed away a few years ago sad to say but the folks at Pelican Parts should be able to guide you in the direction you need to go.

Well damn hate to hear that. :/

I went ahead and ordered all new high press fuel line & brackets from Mercedes Parts Center.