[NC_Mike]

I'd scored 3 sets of OEM Bosch W9DC0 spark plugs for my 87 560SEL from my dealer. I was so excited about installing them... getting rid of the platinums that were supposedly in the car when I purchased it.

To my dismay, I started pulling out Bosch W9DCs. 1 had heavy deposits, 1 had light deposits, 2 were wet with gas and 4 were clean and dry.

The rough idle when cold went away... but OUCH!!!

Also on the service records was a new rotor (but not a cap!). So I checked both. Here's what I found. I'm not an expert, but it seems both need replaced. And what are those black marks in between?

Thanks,
Mike

 

[jhodg5ck]

That's arcing....big time.

Were I in your shoes I would do all the plugs, cap/rotor and wires.

the deposits are letting you know your heads are tired...on the plugs that are showing deposits I would bring your gap down to 30.

Jonathan

 

[dave420]

Jonathan, great suggestions. One question... could the deposits between the contacts be a timing issue? I'm wondering what the mileage and timing chain service history is on Mike's car. I have seen this before on a (believe it or not) Opel Manta - circa 1972 - and the timing belt was loose - they had strict replacement advisories that were rarely followed in those days.

Anyway, just a thought… I really value your advice and appreciate your attention to our questions. I have learned a lot.

Dave

 

[DarkOneSK]

OMG! Bigtime arc. Looks like a bit of scoring on the cap too.
Question. have you looked at your cams lately? and what does the deposits in the tailpipe look like?

 

[NC_Mike]

OMG... the engine only has 86,000 miles! The thing is, it readily runs to redline with the sound of a super-cool jet engine.

Jono, do you mean the cylinder heads?

I've already ordered a new cap and rotor from Arizona AH. I was told the wires were new with the rotor (18,000 miles ago). But if I need to replace them anyway I will.

I was also told the timing chain was not replaced due to the fact that the rails were not cracked.

So I should replace the wires and chain as well? I asked about the chain in another thread and was told to leave it alone for a while due to age and guide rail condition.(d%^&%!).

Anything else I should know? I will obviously do anything that is required. I can't imagine installing my Tri-ys and downpipes until the engine is in perfect running order.

Thanks again, Mike

 

[NC_Mike]

I can't wait to see how she runs when this is fixed!!!

 

[jhodg5ck]

I would change the rails because of their age straight away. While you are there it would (to me @ least) make sense to do the chain and tensioner just to be Safe.

BTW, my warehouse should be 1 day UPS ground to you...while AH's closest WH is prob. down here in Atlanta.

We'll hope the deposits are from horrible ignition components.

I'm curious who changed a rotor and not a cap..sheesh.

Jonathan

 

[Batou]

i changed my rotor w/o changing my cap... but that's cause i had just put the new cap in a few weeks earlier, and didn't notice the rotor starting to crack.

 

[benzwag]

Mike--That doesnt look like a new rotor. Looks like a 40,000 mile rotor. The cap looks worse, like a 65000 mile cap. The plugs dont look too bad. if it were me I would definitely change the cap and rotor, and if the wires are more than 8 years old, them too. You have major arcing going on in the cap, so I would bet that some wires are bad (have high resistance). Check them with an ohmmeter. They should be around 1000 ohms between the connections. Also, I would check the timing of the distributor (although from the distributor wear, it looks nearly right). The manual tells you how. And if it were my car, I would bite the bullet and do the 100K maintenance now: chain rails, chain, thermostat, new voltage regulator, new radiator hoses. And if I had access to the right tools, I would also put in new valve stem seals. Have fun, Charlie

 

[NC_Mike]

Mike--That doesnt look like a new rotor. Looks like a 40,000 mile rotor. The cap looks worse, like a 65000 mile cap. The plugs dont look too bad. if it were me I would definitely change the cap and rotor, and if the wires are more than 8 years old, them too. You have major arcing going on in the cap, so I would bet that some wires are bad (have high resistance). Check them with an ohmmeter. They should be around 1000 ohms between the connections. Also, I would check the timing of the distributor (although from the distributor wear, it looks nearly right). The manual tells you how. And if it were my car, I would bite the bullet and do the 100K maintenance now: chain rails, chain, thermostat, new voltage regulator, new radiator hoses. And if I had access to the right tools, I would also put in new valve stem seals. Have fun, Charlie

When you pull the cap, it's obvious the rotor is fairly new (except for the arcing). Something ate it up in a hurry. The cap is definitely much older. Again, why anyone would replace a rotor without the cap is beyond me. The plug wires are supposedly rather new as well... I will test them per your suggestion. Thanks.

 

[NC_Mike]

Finally replaced cap and rotor today

I finally replaced my cap and rotor today. I was very excited, almost like I had time to get my Tri-Ys installed (but trivial things keep getting in the way, like ignition problems... and brakes :crybaby2: ha ha.

Still have the rough cold idle (runs rich... see my new thread) but I put it into reverse to take it for a drive and almost gave myself whiplash! Wow! The power!

I never thought I'd say this but (until I get used to it), my throttle is actually kind of TOUCHY !

Thanks,
Mike