Distributor cap and rotor cleaning with razorblade

[PandaBear]

Not trying to save money here but just trying do see how a cap / rotor age, learning and fun.

Kept my old cap and rotor and found out that the 4 terminals on the cap have some build up that doesn't go away with sanding, and one even fell out like a scale. So I use a box cutter to scrape on the terminal and sure enough all of the build up eventually fell off.

Then I sand off the rotor and put them back on the car. Ran a lot smoother and the idle rpm is about 200 higher as well.

Is it possible to keep using the cap if I clean it this way? The rotor I use have 2 fiber glass sandwich a metal plate, and the metal plate seems "burnt", so I probably have to replace it.

 

[jstutz]

I have scraped mine with a small screwdriver before just as a fix, unitl i get a new one. Not sure about long temp use. I dont think there is any kind of special coating on the posts so i dont see why it wouldnt work.

 

[daman]

I would replace it but in the mean time i see no problems with cleaning it up then using it.

 

[UncleS2]

I have a good amount of experience with this- when you own an ancient 1966 Volvo in the boonies(finally sold in 9/97), & your distributor/points/cap/rotor is different than what the parts books claim it is, you learn these things!

If you don't remove too much metal, it'll probably go on for a long time & many thousands more miles. BUT: if you're smart, you'll keep a spare cap & rotor- brand new is great- for the day when one of 'em gets mad & quits!

Don't ask me how I learned this one.

 

[Audi Junkie]

I just get a mini dremel style grinding wheel and use that.

Keep a spare in the car because they are a weak point. Look for the better quality caps, Bake-O-Lite teracotta colour with brass electrodes, not grey plastic with aluminum.

That rotor sounds like a Honda. Yes, just file it a little bit and resue.

 

[Kestas]

I also clean caps and rotors. But I worry about the gap getting too wide. This would reduce the available energy needed to jump the spark plug gap.

The cap on my 85 Omni used ignition cable blade-type terminals poking through as the contact points. Once there was enough wear on the terminals, I flipped them around for another round of service.

 

[punisher]

Originally Posted By: Kestas
This would reduce the available energy needed to jump the spark plug gap.


Kinda the opposite.

Nothing wrong with cleaning a cap/rotor but be aware that many caps have coatings on the electrodes to retard deposit/oxidation formation. You might not get the same service life out of the cleaned cap as you would a new one. Still, if you don't mind checking it out once in awhile, it works out fine.

 

[Mr_Incredible]

I used to have a '72 Satellite that would get a buildup on the contacts like crazy. IIRC, it's some kind of calcium buildup caused by the sparks and water vapor. I used to use a pocket knife to scrape it off when it started acting stupid. I suppose I could have gotten a new base gasket and been done with it, but I was not yet as smart as I am now.

 

[eljefino]

The gap is engineered in and insignificant, as it's at atmospheric pressure and not that hard to jump. In fact when one gets those sharp burrs I wonder if they're metallic/ conductive in nature and something of a feedback loop, growing as needed until mowed down by the passing rotor.

I can agree on avoiding the plastic/aluminum junk. Wells is notorious for this. My only cap/rotor problems showed on a 1982 cadillac cimarron. I love my coil packs on everything else!

 

[mechtech2]

I've cleaned umpteen jillion carps and rotors.
Scraping and sanding work well.
but eventually, the center contact gets worn, and there is no contact made. also, the rotor leaf spring contacts can get worn through.
The gap increases and increases every time you clean it like this, in addition to normal driving.
So there are limits.

BTW, the cleaned old cap and rotor gave you 200 RPM more idle than the 'new' ones that were on there?
With a computer controlled idle?
Remarkable!

 

[onion]

It can get you by for a quick fix. But replacement is a better option for all the reasons stated so far- unless you're flat broke and/or in the middle of nowhere on a Sunday night.

 

[PandaBear]

Originally Posted By: mechtech2
BTW, the cleaned old cap and rotor gave you 200 RPM more idle than the 'new' ones that were on there?
With a computer controlled idle?
Remarkable!


Originally 600rpm on an old worn out cap, cleaned out and put it back gives me 800rpm. About 1 week now it gives me 750rpm or so. The computer controlled idle must be a bit worn out, or some sensor is dirty, or something, it is a 230K car that's 12 years old after all.

 

[Steve S]

High quality new cap and rotor!!! Sparkplug wires as well.

 

[Steve S]

Originally Posted By: mechtech2
the cleaned old cap and rotor gave you 200 RPM more idle than the 'new' ones that were on there?
With a computer controlled idle?
Remarkable!

 

[mechtech2]

PandaBear - You did something right. It just does not make immediate sense to me.

 

[oilboy123]

I would only scrape them one time.

 

[Drew99GT]

I just did this on my Corolla and the difference in performance is incredible. The cap and rotor contacts on this car get the buildup fairly quickly, and buying a new cap and rotor every 30K seems like a waste, so I sanded the contacts and polished them with a dremel, and also cleaned the spark plugs and regapped them. Keep in mind the plugs, wires, cap, and rotor only have about 50,000 miles on them. I like to do a full tuneup when doing he timing belt.

Idle is as smooth as a baby's you know what, and there is much more get up and go.

 

[hsd]

I also clean caps and rotors on my cars that still have them. I noticed on my 97 Jeep it built up deposits faster when I switched to the hotter MSD coil, presumably due to the higher voltage it provides.