Of Distributor Caps & Dielectric Grease
erco
Posts: 20,256
Phipi's "watch conundrum" thread reminded me of an old personal mystery. tonyp12 mentioned dielectric grease around the battery terminals as a potential problem...
I was a grease monkey (Ford dealership mechanic) in the summer of 1980, when I bought my trusty(?) Corvair. Then-modern cars had electronic ignitions with distributor caps & rotors. Any time we did tune-ups or ignition system repair, we followed dealership SOP and sprayed a bunch of ordinary aerosol lithium grease inside the distributor cap. Indiscriminately, everywhere. I asked everyone there why (izzit supposed to conduct or insulate or seal?) and never got the same answer twice. I never did this on my own car with old-school points & condenser, quite the opposite, I kept it real clean.
My best guess is that on the electronic ignition cars, the HV spark mostly burns/vaporizes the grease away, and whatever bit is left runs down to make a pseudo-seal around the distributor cap to keep dirt & water out.
The debate rages on at https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=552408
Anybody have more insight?
I was a grease monkey (Ford dealership mechanic) in the summer of 1980, when I bought my trusty(?) Corvair. Then-modern cars had electronic ignitions with distributor caps & rotors. Any time we did tune-ups or ignition system repair, we followed dealership SOP and sprayed a bunch of ordinary aerosol lithium grease inside the distributor cap. Indiscriminately, everywhere. I asked everyone there why (izzit supposed to conduct or insulate or seal?) and never got the same answer twice. I never did this on my own car with old-school points & condenser, quite the opposite, I kept it real clean.
My best guess is that on the electronic ignition cars, the HV spark mostly burns/vaporizes the grease away, and whatever bit is left runs down to make a pseudo-seal around the distributor cap to keep dirt & water out.
The debate rages on at https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=552408
Anybody have more insight?
Comments
I was a Kawasaki motorcycle & jet ski, Seadoo and other brands of watercraft mechanic, so no distributor
caps.
Perhaps they thought it would make it water proof? VW's seem to quit, right after they drive through a
mud puddle.
Bill M.
-Phil
If I recollect, it had a proper funeral.
Can't find the picture right now.
Proper execution. Didn't deserve a funeral.
-Phil
http://forums.parallax.com/attachment.php?attachmentid=64920
-Phil
Ah, the unforgettable Pinto. I drove one for about a year after returning my company car when five of us started our own service business. Always wondered if today was the day my seat would drop through the floor going over the dipsy-doodle on the way to downtown Toronto. Must have been 8-10 inches of flex up and down.
Never heard of anyone using grease on the distributor cap innards, but I think it would be wiped off as the rotor passed over the contacts.
My next three cars, including the current one, were fuel-injected diesels. I do not miss dwell and timing adjustments, cracked disty caps, or spark plug cleaning/gapping/replacements one little bit.
-Phil
Was spraying a distributor cap with silicon spray a procedure or did someone tell you to do that?
For my late 80's Escort I remember the Ford manual said to apply dielectric grease to parts of the rotor and I believe also the plastic just outside the points of the cap. It also said to apply dielectric grease to the inside of the spark plug boots.
Dielectric grease is support to prevent arcing and I think I saw it on the light bulb terminals of a Toyota.
One thing that drove me batty was that I had to keep replacing the spark plug wires of my Escort because after the 2nd or 3rd time one of the wires would no longer lock on the spark plug. Even Motorcraft wires did that.
I've only had to replace my Toyota plug wires once.
http://mmb.maverick.to/threads/dizzy-dielectric-grease.79919/
Never saw a TSB, but my boss did it and told us all to do it. He had the fastest Mustang in the Lowcountry and I was a punk kid who could barely afford a $650 Corvair, so who was I to argue?
Drove my '78 Z-28 through about a foot of water, engine died, still no go after about 12 hours. My father shows up with a can of WD-40, thoroughly sprays inside of the HEI cap, starts right up.
C.W.
Perhaps some dielectric grease in there might have prevented that.
We just put it down to the usual crappy Lucas electrics.
Old Minis did not like the wet. What with having their spark plus in a line facing the front grill. Drive through a big puddle and you are stuck. They could have used a gob of dielectric grease as well.
I use it on the outside only. Plug and Coil wires.
Outside on plugs, coil, and wires makes sense. Keeps water, oil, and crud from damaging the plastic and rubber components. Used silicone grease on my cars for that.
Standards were a lot laxer back then but I will ask my fast Mustang friend about that.
Kwinn,
I still have a tube of tune-up (dielectric) grease that I bought back in the mid 90's. I use that and anti-"sleeze" when I change plugs.
Triumph Dolomites? That takes me back (though the Toledo was the real classic)!
As any fule no, the risk of wet distributors can be mitigated with a rubber glove with one spark plug lead out of each 'finger' and the HT lead through the thumb.
I talked to my Mustang friend and he doesn't like to use anything on the distributor cap.