dr bob

After they are all cleaned and shiny again, add a film of dielectric grease to connections to keep corrosive stuff out and the spark energy in.

Let us know how this works out.

Kevin in Atlanta

Cleaned them up and they all ohm around 4k. Rechecked in the dark and now #6 wire is shorting to ground near the oil dipstick. Didn't see that last night.

Am I correct to believe that the short to ground is a wire problem? These are about 2 years old, wires alone sourced from Roger - the wires look great.

I am real close to simply buying a brand new set $$$.

dr bob

A new set will obviously help with the leakage you are seeing. At the same time, carefully visit the cable routing. I'm pretty sure that there are additional sleeves on the originals where the wires get close to things. I also know that there are no additional protective sleeves on the "just-the-wire" aftermarket wire sets, where you get to dress the wires and use your own ends. I still have a set of those in the spares drawer, donated by a clinic victim. Meanwhile, the fully-assembled 32V Beru wire sets come with all those sleeves, the hold-down blocks and the plug-end boots already installed, ready to drop in. The wires are individually numbered just like the originals.

One might be tempted to try and add just a piece of black shrink tubing or similar where they have an arc-through fault. Remember that black shrink tube uses somewhat-conductive carbon black for the coloring. So OK to install on new wires with no faults, not so reliable as a fix to already-faulted insulation.

dr bob

Adding some to this recommendation --

A 'lister reminded me by PM about the mounting list of reasons not to use dielectric grease. I am generally against dielectric grease on wiring. I propose that it's appropriate to use to seal high-voltage connections. So for this application, you don't coat the metal connections but do add a film that will help seal the joint between the wire and the boots. "Dielectric grease" is a non-metallic non-hardening silicone grease. Unfortunately it's not totally waterproof, although it does prevent casual splash moisture and corrosive vapors out so long as the film integrity is maintained. Biggest thing to remember is that it's an insulator, so as it moves around and gets into connections, there's always a risk that it will be drawn into spring-tension blade connections. Bottom line is that it has its place as a vapor barrier, but it's not a good thing to just smear onto actual connection points.

Back to our regularly scheduled discussions....

Kevin in Atlanta

The original short went through the sheath to the radiator hose. The sheaths were not the OEM ones, but coolant overflow hoses sourced from an auto parts store.

At this point I am going to run the engine and pull spark plug connectors to see which cylinders are not firing - then 'll follow up by pulling the plugs to see if they are wet.

I know I have to replace the spark plug wires, but I want to do the tests while I wait for them to arrive.

SeanR

I had a very similar issue when I used generic leads and put them on the factory ends. The new wires didn't last long at all and caused running issues such as you are encountering. Replaced with stock Beru plug wires and never had the issue again. This is why those are the only ones I'll install on any car.

hacker-pschorr

This needs to be repeated again & again, and has nothing to do with "only going with OEM" mentality.

Few years ago a friend of mine and I went through 5-6 sets of Bosch spark plug wires. The plug end was some generic piece (the old ones were stamped BURU on Bosch wires). They would not properly "clip" onto the spark plug.

Long story short, the only way you know you'll be getting the good buru ends is buying the buru wire-sets. Cannot even trust Bosch anymore...

Kevin in Atlanta

I agree, but the wires sans connectors were Beru sourced from Roger. I reused the ends. I did this on my 87 and have had no issues.

But, I will go new complete set this time.

dr bob

Arcing through a sheath/sleeve to a coolant hose is a new one for me. There are several close-to-metal spots in the normal routing path that would seem better candidates for an insulation breakdown. Perhaps during installation the failing section was bent too tight, or there's some chemical contamination damage (brake cleaner?) that's broken down the dielectric strength of the insulation?

Porsche was careful to make sure that the ignition voltage is more than adequate. There's a warning on the radiator label that's more than just for show. The performance six-cylinder air-cooled cars suffered when ignition was under-performing. Folks who owned them quickly upgraded from points-and-condenser to at least a CDI, or planned to replace spark plugs much more frequently. Fast-forward to what we have now -- much higher voltage and a need for better plug wires to carry it.

Other manufacturers discovered the same thing, and many went to 8mm (or greater) wires to prevent casual energy leakage. Fitting larger wire is a chore on the 32V 928, since they don't fit in the stock holders and don't fit the plug connectors.

I haven't bothered to compare the Beru wires-only kit with a new custom Beru assembly to see if there are any noticeable differences. I have both in a spares bin somewhere. SeanR or Kevin or Stan or GregB can probably comment to the differences they've seen; they see a LOT more cars than I do.

Kevin in Atlanta

I would like to close this thread with the resolution.

One, I cleaned all the distributor end connectors and ohm'd everything.

Still a misfire.

The solution was pretty embarrassing. I pulled the plugs and found one of the tips was bent nearly touching the electrode. The reason it is embarrassing is I remember dropping a spark plug and noting it bent the tip.

But, apparently I forgot to address it when I put the plugs in. D'oh!

Idles and runs great now.

Getting old is a bitch.