My '88 300TE started running rough after warming up. It quickly got worse and now does not even start.

I've been reading though the many threads with similar problems. It appears to be an electrical issue (plugs are black and dry). Checked the coil and crank angle sensor resistances and some basic voltages I can measure with a multimeter. Since I had a new cap and rotor, decided to replace those.

After struggling to get the cap off (following someone's suggestion I cut off an allen wrench and used it in a socket to get off the bottom bolt) I found things didn't look too bad but contacts were black and green and looked pretty fried.

To (finally) get to the point, I found there was a black "gasket" behind the cap that was split as shown in the picture. I put gasket in quotes because it is very hard. The question is, what should this gasket look like? Should it be hard and split or do I need a new one? The cap gaskets I've found online are orange. Is that the right one?

Thanks,
BoB

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1988 300TE
1991 Miata

You can find the ''O''ring here

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1ZX0L3NOG1ZY15MPW6&year=1990&make=MB&model=300-E-002&category=F&part=Distributor+Cap+Gasket

Bob, the 0-rings I got when ordering new have been orange. Just get the cap, rotor and o-ring and replace the black brittle one with the new orange one. It looks like your backing plate is ok. You don't mention how long the existing cap and rotor have been in place. I'm a relative newbie here but it seems like these 103 engines consume caps and rotors at a high rate.
Chuck.

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1983 M-B 240D-Gone too.
1976 M-B 300D-Departed.

"Good" is the worst enemy of "Great".

Thanks guys. For all I know, the cap and rotor are original. I'll order a new o-ring to go with the new cap and rotor. Hope that gets me going again.

BoB

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1988 300TE
1991 Miata

Sort of surprised you got no response to your description of plugs as being black. My experiences with M103 and M104 engines is that proper electrode color is more brown/grey. The pro mechanics may have some input.

Steve

Bob, be sure to replace the spark plugs too. Dry black deposits on the spark plugs would indicate that the fuel mixtue is too rich ... if black and wet it's likely time for new valve stem seals.

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Fred Hoelzle