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Three of my injector feed hoses are leaking quite badly so I have to tackle this first before anything else.

Is there a step-by-step guide to removing the entire fuel rail? It looks pretty scary to me. What is holding it in and where?

OK, I can see there are two hoses coming in from the left rear engine bay - fuel in and return, so I know those have to be disconnected at least.

Thanks! Andy
 

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I like to pull the injectors off with the fuel rail then remove the injectors from the fuel rail. Each injector is held in position by a collar fastened by a 10mm bolt. This also provides an opportunity to replace the seals on the injectors and the rubber hold down rings underneath the collars. Snap ring pliers are used to remove the snap ring and rubber hold down rings. Be careful not to let loose items fall into the intake; use rags to plug the injector holes as you remove them.

With the fuel rail and injectors off, it is easier to replace the rubber hoses from the rail to the injectors. Strongly recommend replacement with the proper metric fuel line:

https://www.autohausaz.com/pn/916030000527

Here are the injector seals - evaluate which ones you need after you disassemble everything:

https://www.autohausaz.com/catalog/c/mercedes/1973/1194892-450sl/22-fuel_air_system/11223-fuel_injector_seal?s=d&page=1

As for the clamps, recommend proper fuel injection hose clamps - not the toothed kind that tend to bunch up and stretch the hose (causing leaks). AutohausAZ sells the ABA clamps but I like the original Gemi 13mm clamps better - I get them from salvage cars.

If you replace all the perishable rubber bits, you have a better chance of solving fuel and air leaks. See the attached service manual articles for more information. These articles discuss a clamping ring of various types for the lower injector hose connection - just use another clamp (one at the injector, one at the fuel rail).

When you get into this, you will notice the fragile state of your engine harness. Do not panic if connectors crumble in your hands; I can help you fix that too.
 

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Andya,

Cush covered just about everything.

Once you get the injectors out, you may find that some of the pintle caps are missing. These are not as easy to find on-line.

I bought the caps as well as the top hat seals & bungs from our dealer Prices were reasonable at the time. As cush said, use 7.5mm ID injector hose and proper clamps. If you still have the original clamps, they should be OK. Another option is to send injector for cleaning. They will put on new hoses, caps and seals. Not sure of cost, but likely $20-$30 each?

Here is a thread from way back when I was first learning about these things :)
Injectors on D-Jets - Question about seals - PeachParts Mercedes-Benz Forum
 

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Discussion Starter #5
Brad and Graham, firstly let me say many thanks for all the detailed D-Jet information you share with everyone else! It's greatly appreciated!

Yes, I have version three.

All of my injectors except one only have a clamp at the top of the hose, so perhaps it is all original? However feast your eyes on the mess that is #7.
 

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Not pretty! Good that you are addressing leakage problem. It can be dangerous. If you install new hoses yourself, you will end up with clamps top and bottom. Injector shops may still swage one end. Witchhunter's site says they will clean injectors and install new filter baskets, o-rings, seals, and pintle caps (where applicable) for $22 each. Plus $5 for new hoses. Might be worthwhile if those are original. You can do all that yourself, but it is quite a lot of work.

Check Cush's thread on harnesses too. Those injector plug boots don't look too good :)
 

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That thread needs a house cleaning. The methods prescribed early in the discussion evolved into a much improved process toward the end. The two most important elements are use of JPT terminals (in lieu of rolled clips), and the use of much improved wire jacket to protect the integrity of the leads near the hot section of the engine.

Every D-Jet system I've ever seen in a salvage yard looks the same - poorly maintained fuel delivery system and a ratty looking engine harness. On these cars, I find new sensors placed there in an attempt to make the car run well again. I harvest these sensors (new and old). When I examine them, it is clear that the sensors are not the problem. Spark, Fuel, Air in that order is the path to getting a D-Jet system to run well again.

Replacement of the ignition contact points in the distributor with a Pertronix system is a vital improvement in terms of reliability. Your efforts to tighten up the fuel system are vital in terms of safety.
 

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Those are the pintle caps, but whether they are correct fit, I can't say. They may. They seem to be aftermarket make. Check the exact injectors that you have and provide that to vendor. Likely 0280150036.

These seem similar to those in your link. https://www.theslshop.com/parts-shop/mercedes-benz-sl-slc-450-107-locking-cap-for-d-jet-injector-0009871048.html

These are the original parts, but price is crazy:
https://www.ecstuning.com/b-genuine-mercedes-benz-parts/cap/0009875345/

I bought from dealer back in 2008, they were about 1 C$ each! 0009875345. Now US$3.92 from this discount dealer https://parts.mbofwilmington.com/oem-parts/mercedes-benz-cap-0009875345

In the US, these look like the ones you linked to, except far less expensive:
https://injector-rehab.com/shop/Bosch-Denso-Pintle-Cap.html

If they replace the pintle caps, filters and seals, the Witchhunter cleaning at $22 looks quite good!

Good Luck.
 

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Discussion Starter #10
Thanks Graham for your detailed reply! Witchhunter does look good but they are not currently taking new orders.

If I do the work myself I get the impression that there is something I need to cut off the injectors to replace the hoses? Barbs of some kind?

This page: https://oldtimer.tips/en/d-jetronic/injector mentions "First you have to cut off the old bushing with a side-cutting plier or a tool like a Dremel" but it's not clear to me looking at the pictures what this is referring to.

Andy
 

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I edited your picture; a yellow arrow points to the fuel hose crimped fitting that seals the rubber fuel hose to the injector. I use a rotary cutting tool (Dremmel type) to cut through this and remove the old fuel hose from the injector. Replace this with a 13mm Gemi clamp like the one above it. As Graham said earlier, you will have 2 clamps per injector when you reassemble everything. Use the type that is above the yellow arrow, not the tooth type on injector 7.

Authentic classics sell the Norma version of this clamp:

https://www.authenticclassics.com/NOS-Original-Screw-type-Hose-Clamp-13mm-size-p/auth-004314.htm

Here is another option; 4 of these kits would do the injectors - you would still need some bulk length fuel hose to renew the pieces on and around the fuel rail:

https://www.pelicanparts.com/More_Info/0005869907.htm?pn=000-586-99-07-M20
 

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If I do the work myself I get the impression that there is something I need to cut off the injectors to replace the hoses? Barbs of some kind?
Andy - this is covered in the shop manual. Maybe one of the links cush provided (https://www.benzworld.org/forums/attachments/r-c107-sl-slc-class/2534740d1565968677-removing-d-jet-fuel-rail-074-220.pdf) Basically, you have to remove the metal outer part of the swaged fitting - Not the barbs! You do need to make sure you do not damage the barbed part of the injector while doing the removal. You end up with a barbed fitting that you can slip the new hose onto.

Sorry, I was a bit late with posting this reply!
 
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