I have just ordered my 3rd cap and rotor for my 1988 300E in the last 15,000 miles. 5000 miles doesn't seem to be a long time for a cap and rotor to last. The cap has a lot of black material on each of the contacts and the car is running rough. The large round brown plate with the o-ring that sits behind the rotor is destroyed, I have a new one but cannot get the piece the rotor attaches to off. Does it require a special puller? Is the fact that the brown disc is "missing" causing my cap longevity challenge? Do I need a new distributor? How could I test that?

Whew, got all the questions out. Any and all advice greatly appreciated.

Is the brown disc part number 103-158-00-88 ?
The area of the engine you're in is best covered on the 126 CD-Rom in engine 103 service task 01-212 - Removing, installing top front cover.

You mention the disc being destroyed, then further down - missing. Which is it? I've been here once and can't say for sure, but it seems like you might be taking in oil if the part number I mentioned above matches the one you just bought and it's either cracked or missing.

The photo's in the service task show the disc(guard cover) affixed with a bolt going thru a triangulated piece called a driver. When reinstalling, the groove in the driver must engage the pin in the camshaft. Bolt is torqued at around 15 ft. lbs. approx.

You may be leaking oil from the timing cover cam seal into the distributor cap,causing fouling on the cap contacts. If you purchase a Bosch cap and rotor it should be good for 50K.

Also the piece that holds the rotor is held on by a T-30 Torx Bit fastener. It can be purchased at Sears or most auto parts stores For about $5. Once the fastener is removed the piece will pull right off.

Thanks for the help. The brown disc on there now has the center torn out and the o-ring is certainly not sealing anything, so oil could be getting in. I have a new cap and rotor on the way from those super-efficient guys at PartsShop.com, so I'll replace cap, rotor and brown disc and see what happpens. I remember removing the screw that holds on the rotor mount, but I couldn't pull it off easily. Guess I'll use a mini puller and see if that works.

Thanks again!

Lucky Me Again
 

Brothers of The Benz, All
My 1987 300E, 14 years of age and with 177,000 miles still is on the original cap and rotor.
They have been inspected and show no carbon tracks or oil leaking into the cavity.
As so many times, frequent oil changes have prolonged the life of the seal.
Happy Trails Beep Beep from The Spiderman in Houston!!!

Just replaced the cap and rotor. Here are a few notes. The piece the rotor fastens to (I think it's called the driver) could not be pulled off after removing the bolt. (8mm dia, uses 6mm allen on my car). I would not recommend trying to pry it off, the aluminum flexes and it wouldn't be tough to really damage something. I ended up using a puller and it came off without too much trouble. Sanded it slightly and put a little grease on it when reassembling. The original brown disc had the pieces of the center chipped out. Looking at it, I think the last person to replace the disc didn't want to take the trouble to pull the driver and just chopped out the center of the disc so the disc would fit over the driver. Or possibly, the non-Bosch rotor had screws that were too long. The camshaft seal is not leaking (phew)and everything went together fine and it seems to run smoother. We'll see how long it lasts, car has 214,000 miles on it and going strong. The last cap and rotor I bought from my local import shop and they were not Bosch parts. The cap was german made (Bermi?) and the rotor was made it Italy. The Bosch parts appear to be of significantly higher quality, and btw, cost less than the inferior parts because I purchased them through PartsShop.

If I have have the same luck as The Spiderman in Houston, I won't have to replace the cap and rotor until at least 391,000 miles. That would be nice.

My experience is the same as Donald's, original cap and rotor and they still look perfect.

Mine has had religious hot oil changes at 3,300 mile intervals.

If there is ANY oil leaking past the cam shaft seal, I would remove the cover and replace the seal. You will need; the shaft seal, the bottom u-seal and the translucent blue, acrylic smelling sealer from MB. With this sealer the cover can be slid rearward over the u-seal without moving the u-seal. Don't forget to gob some sealer at the lower rear corners of the cover area, lubricate the shaft seal, and carefully start the seal on the shaft with your fingernail.

Good luck,

Not to brag, but I have 189,766 on my original pieces. Have cleaned them a couple of times, but still running strong. I probably should replace them based on guilt alone. :):):)

The Guilt Syndro something
 

Brother of The Benz, jeffsr
That guilt feeling you're having over your cap and rotor, must be contagious.
In reviewing 14 years of repairs, and planning to go to my home state of New Mexico next month; I noted that the original water pump was replaced at 90,000 miles.
Now with 177,000 miles I feel it should be replaced before it leaves me high and dry, beside the road in either West Texas or Eastern New Mexico without a Benz shop within 1000 miles.
Best laid plans of, oh you know who!
Happy Trails Beep Beep from The Spiderman in Houston!!!