Hey folks,

I just purchased a used 1997 S420. It's great. I'd like to know if anyone has changed their own plugs and what advice they might have. I'm doing a Volkswagen and I've found that I need a few special tools.

I don't have the shop manual yet, but I've also discovered that the shop manuals don't always have all the information.

Cheers

 

Hi,

Stick with OE (ie Merecedes) plugs (most probably platinum tipped).

Change at circa 50k miles.

No special tools required but time consuming.

Stuart

 

What about Bosch Platinum 2's....I'd think they would be nearly identical to MB OEM plugs. Any comments?

Also, time consuming, I would think it would be 5 minutes per plug, or 40 minutes to and hour. Am I missing something?

 

Hi,
Not sure whether OE are Bosch. Could be Beru.
I recommend OE (MB) rather than aftermarket.
However Bosch are a reputable make and should be OK.

Only problem when doing the job is getting:
The air filter box (plastic moulding) off. Just pulls off.
2. the lead covers off the plug. Use open ended spanner.

Problem is access. Fiddly.

Oh. Ensure you have a plug spannerthat fits. Thin wall 3/8" drive.

DO NOT OVER TIGHTEN plugs when replacing. Coat threads with copper slip or similar otherwise you will neverget them out again!!

Stuart

 

OE MB, Beru , Bosch Platinum tipped,sparkplugs after market would be good because these are what i used on most Mercede benz that i use in brunei

Rockerfella174
Brunei

 

Thanks guys. I'll tackle this on my own as opposed to independent mechanic.

 

Guys,

I'm deep into this project now. There's what appears to be a "hardline" electrical harness over the top off all 8 cyclinders. I've unbolted the 10mm bolts, and there seem to be several "tubes" that come into the "hardline" harness.

Also, I noted that a "hardline" plastic tube is cracked in the area, part number 119 094 77 82, there is a network of these tubes running over the top of the engine, they all have part numbers starting with 119 094. On the Mecedes-Benz STAR CD, I can't find any part numbers starting with this number.

I don't think I cracked it, its a clean crack, all the way around now so that the tube actually can be pulled away from the other "half" of the tube. It's right near the connection point on the drivers side of the engine. I'm wondering if it is some kind of "breather" tube for the oil system. If so, I could leak oil when running the engine. Not sure.

Should I continue to work on the plugs? I'm getting a bit nervous as I see this cracked plug, and also, I can't seem to get the "hardline" harness off the engine.

Please help!!

 

Ok, before you guys rip on me too bad....I found out what's happening...I'm looking at the Fuel Injectors!!

I'm now onto the plugs. But I still have that cracked tube, 119 094 77 82....I'm going to pay $18 bucks at the dealer, unless electrical tape will hold me over. Let me know.

 

Update on this project.

I live in Arizona, and the car is an Arizona car. After picking up the $18 dealer hose, which was about 4 inches long, I notice how pliable and flexible the new hose was.

It turns out the entire breather set of hoses had become brittle over the last 10 years. So I went on line and ordered the remaining 4 hoses.

I received them and found that I needed soem bugger connectors that were hiding in the old hoses. I got a few out, but went to the dealer to buy a few more connectors and one tee connector.

I reassembled the system, put the air filter system back in place and started it up. Ran great. Took it for a 20 minute spin without problems.

Next morning, drove to work about 16 miles. Car sat in the parking lot all day. On return trip home, it started running rough. Check Engine light came on and I was thinking of bailing out 10 miles from home. Decided that I was probably only running on 7 of 8 cylinders and drove home.

I found the "breather hose" line off the tee to the drivers side wall was not connected.

I talked to a local friend from work and he thought using the Bosch Platinum 2's might have been the problem. I went to the dealer and bought their plugs for less than the Bosch Platinum 2's, I'm getting pretty good at changing these plugs now, took 90 minutes.

Dealer didn't have a line for me to replace, nor could find a diagram. It looked like the previous owner just used some standard tubing to fix it.

I did the same.

Friend told me to disconnect the negative cable to the battery to reset the "Check Engine" light. That was to determine if it was a hard code or soft.

Did that, Started up the engine with "fixing" all that I thought could require fixing. Still ran rough, Check Engine light was off for 5 minutes, so I felt good about the "soft" code versus "hard" code thing.

I like my independent mechanic and will they will be looking at it Tuesday, July 31st.

I must have done something, hopefully nothing major, as the car was running fine until I started trying to make things better.

thought you would like to know how it went. If you can ease my mind, I would appreciate it.

 

Hi,
Since the CEL Check Engine is ON codes will be set and the car is likely in LHM Limp Home Mode.

The dealer should RECORD and RESET the code.

The code should give a lead on what is the cause of the problem.

Sounds like a hose run issue of sorts. Open evap line or similar.

As I stated previously i prefer to use genuine replacement spark plugs rather than aftermarket "HYPED" plugs...better gas mileage etc...since they are what was used when the engine was developed. However an after market recommended plug shouldn't have caused your problem...unless of course they weren't the correct sort.

Stuart