M119 Camshaft Oil Tube Replacement on M119 / W124

[y2kimmel]

A buddy and I finally replaced the camshaft oiler tubes on our cars this weekend - on my 1995 E420 and his 1993 500E.

Some observations to help anyone else considering doing this on their W124 cars:

1) Make sure that you, in fact, have plastic oil tubes that need replacing! We got the valve covers on the 500E open and discovered that the oiler tubes were the metal ones. The build date on this car is 12/92, so maybe it was close to the cut-over date when plastic was used. The E420 did have plastic tubes, but there were NO plug-ends blown out, which is the reason for replacing these. Regardless, a good preventative measure.

2) Have all new rubber breather tubes ready - they'll need replacing. On both the 500E and the E420, these rubber crankcase ventilation tubes were hardened like fossils, and needed replacement. You'll need the small gauge tubes for the driver's side valve cover, and the wide gauge tubes for the passenger side.

Note that the passenger side wide-gauge tube connects to the throttle body, and requires removal of the throttle body to replace the 3rd of three tubes (held together with connectors). The tube connected to the throttle body is held on with a clamp. I chose to NOT replace this tube, because I didn't feel like removing the entire throttle body to replace a tube that was probably clamped on tight anyway.

3) Have a 1/4 inch 5mm socket drive WITH ELBOWs ready. We did not have this tool available, and we really needed it to remove the back valve cover bolts down by the firewall. They were REALLY hard to remove - requiring cutting down an allen wrench, pushing the engine to one side, and holding the allen wrench in place with needle nose pliers to "break' the bolt loose. My mechanic said that a 1/4" drive 5mm allen socket will do this job well, but all we had were 3/8" sockets, which DO NOT work.

4) make sure to remove the spark plug connectors and blow out the wells BEFORE removing the valve covers, or else grit will fly out all over your camshafts.

5) Torque all of the valve-cover bolts on to 1/2 of required spec first, then tighten again to full torque spec. The covers have quite a bit of crush to them - and will sit better if they all come down evenly.

6) the engine bay in the 500E is slightly larger than the E420. This was most evident when trying to get the passenger side valve cover bolt removed closest to the firewall. On the 500E it was hard, on the E420 it was damn near impossible (without the proper tools).

7) The wiring harnesses on both cars were noticeably deteriorated. You can get the best idea for your harness's condition by looking at the brown ground wire that connects to the intake manifold on the passenger side of the engine, right underneath the air cleaner assembly. This is visible with only the air cleaner removed - so anyone can check their harness in about 1 minute. The insulation on both cars was cracked in several places.

8) The idiot award for past maintenance goes to me. i didn't realize that the air cleaner assembly removes by pulling up on the front and sliding it out. I actually used to unlatch all of the air cleaner clips (even those real tough ones back by the firewall) to replace my air filters. I felt real dumb when my buddy took the whole box off in about 4 seconds.

We took pictures of this job and will try to work a companion piece to the excellent DIY article by Greg Baxter, specific to the W124.

Troy
1995 E420