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

Awesome! I have been thinking about doing this for a while now as one of my 420's doesn’t seem to have as much punch as the other. Did you notice any difference on how the car ran after changing the tubes, even if they didnt appear to need changing?

A few questions:

1) Where did you buy the tubes and how much were they? Oh and how many of them are there?

2) If you happen to remember, how many rubber breather tubes are there in total (both small and wide gauge) and where did you get those?

3) did you get new gaskets for the valve covers as well?

4) It sounds like you're a handy guy, how long did it take you to complete the job?

5) Do you know what the torque number is for the valve cover bolts?

6) Now I havent seen what the oiler tubes look like, but how exactly do you change one out? just grab it with needle-nose pliers and pull?

sorry for the million questions

Also, don’t feel bad. While I did know that the air clear just lifts and slides out.....it NEVER occurred to me (until you mentioned it) that I can take it out to change the filters. My busted fingers thank you.

1) Where did you buy the tubes and how much were they? Oh and how many of them are there? - Get them from fastlane - I think they're $13 each. Perhaps a Mercedes Club membership could get you a discount. i got them from the dealer with the club discount for around $11. You'll need 16.

2) If you happen to remember, how many rubber breather tubes are there in total (both small and wide gauge) and where did you get those? There are 3 wide gauge rubber hoses, with 2 plastic connectors. I believe there are 3 or 4 narrow-gauge pieces, with 2 or 3 standard connectors and one special connector that lets a vacuum tube run off it. The dealer or Phil can pull up the part sheet and make sure that you get all the correct parts.

3) did you get new gaskets for the valve covers as well? Yes. I always replace gaskets after they've been removed.

4) It sounds like you're a handy guy, how long did it take you to complete the job? Including the 2+ hours we spent working to get a single bolt loose, about 8 hours. BUT - we were working with 2 cars. Expect to spend around 4-5 hours unless you're real familiar with the engine.

5) Do you know what the torque number is for the valve cover bolts? I believe that it's 9 newton Meters. You'll also need to torque the camshaft fittings (which you remove to access the oiler tubes) to the same torque, I believe. Consult the repair CD for exact measures.

6) Now I havent seen what the oiler tubes look like, but how exactly do you change one out? just grab it with needle-nose pliers and pull? You'll remove the camshaft bearing holders, with 4 allen bolts each, to access each "bank" of tubes. There are 5 "banks" - 3 in the middle have 2 tubes each, and on the end there are 2 banks that hold 1 tube each. Once you have the holders removed, just pull the tubes straight out. Easy.

This repair isn't cheap, oiler tubes should run around $200, plus rubber tubes (maybe $80) and valve cover gaskets (around $40-80). make sure to change the spark plugs while you're in there, takes about 5 minutes extra. it's worth the cost for the piece of mind.

OH - and I forgot - replace the timing chain guide while you're in there. These are plastic, 2-piece guides that wrap around the top of the chain. Cheap parts (I think $10 each), one set for each side). BE CAREFUL when you remove the old parts, as they WILL come apart. Stuff a bunch of plastic wrap underneath the part when you remove it to catch the little plastic piece s that will snap off. Replacement is easy - just bolt the main part onto the engine, and snap the 2nd part into place around the chain.

Thanks for taking the time to answer my questions, I appreciate it. I noticed you said that none of the tubes had blown plug-ends....which is the reason one would go though the trouble of fixing them. After you finished, did you notice any improvement in anything, maybe rough idle gone, or creepy noises stopped, or maybe some kind of performance change?

Slight improvement change - for the better. Could be new plugs, could be new tubes. Or could be psychosomatic, not sure.

I do feel much better at least knowing that I'm good with the new tubes for a long time. Now all i have to worry about is when my engine wiring harness will fail.
troy
1995 E420 94k