DIY Spark Plug, Wire, and Distributor Cap Replacement? - 1980 450SL

[supercanuck]

I just picked up a new set of plug wires, spark plugs, distributor cap and rotor for my 1980 450SL, and I plan on trying to replace it all in the next week or so...

Only problem is that I don't know how to.

Does anyone know of a good DIY page, or can someone post instructions on how to do this (and what tools, etc I need).

Thanks!!
zack

[BenzToy]

Originally Posted by supercanuck

I just picked up a new set of plug wires, spark plugs, distributor cap and rotor for my 1980 450SL, and I plan on trying to replace it all in the next week or so...

Only problem is that I don't know how to.

Does anyone know of a good DIY page, or can someone post instructions on how to do this (and what tools, etc I need).

Thanks!!
zack

Just be sure and do the plugs and wires one at a time. With the dist. cap do the same, pull one wire and match it on the new cap. Doing them one at a time helps prevent mixing up the wires. The rotor is pretty much idiot proof. A 13/16th spark plug socket, ratchet and extensions with maybe a screwdriver or two should be all you need.
Good luck.

[MBGraham]

Originally Posted by supercanuck

I just picked up a new set of plug wires, spark plugs, distributor cap and rotor for my 1980 450SL, and I plan on trying to replace it all in the next week or so...

Only problem is that I don't know how to.

Does anyone know of a good DIY page, or can someone post instructions on how to do this (and what tools, etc I need).

Thanks!!
zack

Firstly, you will need to remove the air cleaner.

I would then try to understand how the cylinders are marked - Starting passenger side, #1 is 1st cylinder at front. 2 is next one back, 3 3rd and 4 4th. Then you start again at front cylinder on driver side - it is 5 and 8 is the back one.

Once you know this, follow the wires and mark and make a diagram of where the wires attach to the distributor. Mark the top of new distributor with a marker pen to show which wire goes where. Also mark the existing wires at both ends if they don't have markers on the wires (originals on my car did).

It is a good idea to try and change one at a time, but it is a bit difficult because you should match up the lengths to the new wires and you have two caps to contend with. If you have marked the existing carefully, then mark the new to match and you should not have a problem.

Plugs come out easily enough, but you may need some extensions or universal drives to get at a couple of them. But easier than many cars. Not sure what torque is supposed to be, but I make mine just as tight as I can get them with the short ratchet that I use.

By the way, the wire ends will have metal shrouds - Thats were I marked mine - those shrouds just pull off - pull on the shroud, not the wire.

The rotor cap just clips on, but make sure you get the new one seated properly - it should be firmly in place with no slack. The rotor just pulls off and new one is pushed on.

There are clips on the rocker covers that separate the wires - These are often broken - new ones are cheap and just push on.

When running the new wires, make sure they are well clear of any of the rubber fuel injection lines. I had one wire arcing across to the gas filled rubber fuel hose which had as a result been charred and cracked - almost ready to let go! The original car had the wires grouped and bundled together through insulating sheaths. Only wire sets from MB are likely to still have those sheaths. I am using some split loom to cover the wires to avoid any shorting out. I would recommend covering them - special covers are available on-line somewhere.

What type of wires and plugs did you buy?

[Shawnkey]

What should the wires say for the resistance on the boot. Mine is a 73 450sl, that says 1k ohm. Is this OEM or added aftermarket. They also have what seems to be a MB part # 0 356 301 022

[ussun]

I was told to make surre that you put the rotor in the same way you take it off and don't turn it at all. But it is just pull up and replace with new.

[BenzToy]

^^^
I said, pretty much.
BT edit:

[MBGraham]

Originally Posted by ussun

I was told to make surre that you put the rotor in the same way you take it off and don't turn it at all. But it is just pull up and replace with new.

Rotor can only go in one place. Maybe you were told to put the distributor itself back in the same place - VERY important

Ask me how I know - I got mine one tooth out and pulled my hair out before finding out what was wrong.

[MBGraham]

Originally Posted by Shawnkey

What should the wires say for the resistance on the boot. Mine is a 73 450sl, that says 1k ohm. Is this OEM or added aftermarket. They also have what seems to be a MB part # 0 356 301 022

There are resistors at both ends, at least on the ones that came off my '72 car and they looked original (having the plastic sheaths to protect the wires)

I can't recall all the numbers, but I think the overall end to end resistance of the original wires was about 8 ohms (vs 1.6 ohms for the new Bosch wires). I also seem to recall measuring one of the resistors at 1.6 ohms - I still have one lying around somewhere. OK, I found it - it must be the other end - it measures 5.34 kohms which makes sense, because if other end was 1.6 total is about 7 kohms and overall wire measured 8 kohms.

Plugs recommended to be used with OE or Beru wires (with resistors) are apparently W7DC or NGK BP6ES. But, my feeling is that if you use the newer lower resistance Bosch wires, then you might want resistance plugs like W7RDC. I ended up with the new Bosch wires and resistance plugs. You have to be careful with the Bosch numbers - they use the same part number for the resistance as the old non-resistance plugs - something like 9070 (from memory)

All of this seems like black art anyway