'89 300E Distributor Cap/Rotor Lifespan?

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Thom - 05 Jul 2006 21:35 GMT

All,

I have been troubleshooting my cars inablility to start after sitting
for a week. I cleaned and check all sensors. I found that my
Distibutor Cap had some condensation in it and all connections were
very green/corroded. Also, the pin that extrudes from the coil
connection no longer protrudes to connect to the rotor, thus no spark.

I just replaced this 2 1/2 years ago, and norw it is completely worn
out. I know I have placed about 40K or so miles on it, is that pretty
much the life of it? I also noticed the plastic around the coil
connection (on the inside of the cap) is partiall worn/burned away. I
feel the seal failed, thus allowing the condensation to set in during a
very warm/humid/rainy week of sitting.

So, I am replacing the Cap, Rotor and Seal. Should I expect that it is
only good for 40K miles, or is the wear due to the condensation?

Thanks,

Thom
'89 300E

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T.G. Lambach - 06 Jul 2006 05:56 GMT

There's lots of rain in Germany so it's doubtful that the ignition
suffered only from moisture. The clue to that is your comment about the
coil's connector. There's no reason for it to be eroded, regardless of
moisture, except if its connection to the coil wire were poor and
sparked on that account.

I suggest you check the wiring schematic to ensure all is correctly
installed AND that the ignition wires & coil wire are the correct ones
for the motor.

Final thought: the distributor cap's wetness and the corrosion of its
contacts suggests the motor may be running below 80 degrees C. - not hot
enough to expel moisture.

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Thom - 06 Jul 2006 14:36 GMT

> There's lots of rain in Germany so it's doubtful that the ignition
> suffered only from moisture. The clue to that is your comment about the
[quoted text clipped - 9 lines]
> contacts suggests the motor may be running below 80 degrees C. - not hot
> enough to expel moisture.

I verified all connections and parts as part of my troubleshooting,
they all match up. The car is alwaysrun at over 80c, it is my daily
driver and It is driven 14 miles one way each time.

This car has had this problem for a while, only in very humid warm
months. Maybe the quality parts I have ordered will be better than
what I got locally.

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RobP - 06 Jul 2006 11:56 GMT

It is very important to use only original Bosch parts for the ignition.
Other brands like Beru won’t last nearly as long. 40K very good for a
Beru set, 100K or more is normal for a Bosch. Some parts dealers try to
sell other brands as original Bosch because the are listed in their
pricelist as “system Bosch”. You should not worry to much about the
seal, only ignitions designed to be submerged are completely sealed. And
those ignitions often trap moisture inside.
The damage to the cap is caused by the worn carbon pin..

Rob

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Thom - 06 Jul 2006 14:31 GMT

> It is very important to use only original Bosch parts for the ignition.
> Other brands like Beru won't last nearly as long. 40K very good for a
[quoted text clipped - 6 lines]
>
> Rob

I thought the last one I put on there was a Bosch, but I see it wasn't.
It came as a set, and not seperate like the parts I just ordered. I
am still replacing the seal, the old one looks real crispy. I would
figure it has a mojority of the 260K miles on it.

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Guenter Scholz - 06 Jul 2006 14:48 GMT

>All,
>
>So, I am replacing the Cap, Rotor and Seal. Should I expect that it is
>only good for 40K miles, or is the wear due to the condensation?

My '89 300E's cap and rotor have over 250k km on them (that's well
over 150k miles for you) and are working as expected still

cheers

ps buy a dehumidifier.... hate to think what else might be corroding

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Thom - 06 Jul 2006 15:18 GMT

> >All,
> >
[quoted text clipped - 7 lines]
>
> ps buy a dehumidifier.... hate to think what else might be corroding

Wouldn't do any good, no garage for the car. Actually, this has been
my only issue with any type of corrosion in the engine compartment. I
had this problem once before when my son drove it through high water a
couple years ago (it then snowed 8 inches, so I couldn't get the car
towed for a couple days, which toasted the dist cap)

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