PeachParts Mercedes-Benz Forum - View Single Post

jay_bob · #7 10-01-2012, 12:32 AM

I just started doing this on mine yesterday. It's a pretty big job.

You will need a LONG 6 mm hex wrench. Some of the 12 manifold to head bolts are child's play, others are nearly impossible.

I would recommend a 6 mm with a solid (not a ball) end to break torque on the bolts, then you can switch to a ball end to ease the bolts out. The worst is the lower bolt on #6, it is up tight against the firewall. It was necessary to remove some of the secondary covers in this area below the wiper to allow enough access to get to the bolt.

---deleted, you don't need to break the hard lines to get the manifold off. ----

While you are in there, change all the injection hard line clips. It will cost around $70 for the parts. These are not there for cosmetic reasons, unsecured hard lines are bad and the vibrations will cause the lines to fail.

Take lots of pictures (or have a friend take pictures, it's a dirty job) so you can see how all the bolts and brackets go back together. It's a huge Chinese puzzle.

Once you get the manifold off, you can start on the glow plugs.
Note that you have 6 open holes staring at you. There are obvious negative consequences if something goes into those holes so take precautions to prevent that from happening.

While the manifold is off you also have the decision to make about cleaning the grunge from the inside. You can thank the wonderful EGR for dumping all that nasty sticky black crud in there. Many threads about what to do about it. I recommend cleaning it if at all possible. Search also for EGR delete so you can avoid this in the future.

Now take loose the 6 harness nuts from the back of the glow plugs, then using a 12 mm deep socket work those babies out carefully. Slow and gentle are the key words here. Give the end of the ratchet handle a gentle hand blow or 2 to break torque.

To ream or not to ream. That is the question. Your choice. Many threads on this subject.

Coat the threads with anti-seize before reinstalling. Do not overtorque these, the plug body is stainless, and you are going into aluminum! Use a 1/4" drive socket wrench with a short handle, to help yourself avoid over torquing.

Hook up the electrical connections, baby torque here, it just has to stay securely hooked up...very easy to overtorque and strip out the insides. Pay close attention to the angle of the connector, if it is clocked wrong it will short against the manifold.

Once you have all the plugs in place go over to your GP relay and unplug the 6-pin plug and grab your meter and check resistance between the 6 pins and ground. Each pin should give you approximately 1 ohm to ground (this is the heater in each plug). Between any 2 pins you should have 2 ohms (2 heaters in series - out 1st wire, thru 1st plug, thru the head, back thru 2nd plug, back up 2nd wire).

(I'm at the hold point waiting for hard line clips and the little gasket between the crossover pipe and the manifold, this is as far as I got in one day.)

Now put your manifold back together.

After getting everything back together, do a final check on your harness, make sure the terminals are not touching something they are not supposed to and another ohm check isn't a bad idea. Don't forget to plug it back in!

---deleted, referred to purging hard lines, not necessary----

Not trying to scare you off but just a reality check so you can be prepared. Before taking the manifold off you want to make sure you have the new hard line clips, the intake and cross over pipe gasket, and the o-ring for the supply end of the cross over pipe. And of course the glow plugs.

On my 240D/OM616 it took me 30 minutes start to finish and it was super easy. Not so much on the 603.