Death by Distributor cap

[Ronzo_volvo_guy]

Forum;

The center contact in the Dist Cap is a carbon brush, little different than the brushes in the Starter, Alternator, Blower, or any other DC motor...its job is to make a good elec connection between a moving and a stationary component...and that is precisely what it is also doing in the Distributor...it contacts the Rotor...or at least is supposed to...and that contact is supposed to be under a little spring preload, provided by a spring behind the brush, so that no arcing occurs!

From the picture above, it looks like the brush is not protruding and wanting to push down onto the Rotor...brush or spring are somehow jammed, so with no contact, this presents yet a third place where the high voltage must arc across (in addition to at spark-plug and rotor-to-individual plug wire station)...and the carbonizing damage this arcing has left is unmistakable...I expect the condition was quite possibly accompanied by difficult starting, misfires and rough running...or any combination of those...

You could try to repair the carbonized area (lightly grind away the carbonized cap material) and try to repair brush and its spring, because the 4 individual Plug wire stations look to be in almost-new condition!... (then again, I'm an I-can-fix-that-kinda-guy)...otherwise, I suggest you replace the Cap, and before installation, have a look inside, and check that brush is obviously present, protruding from its hole a little (about 1/4"), with some spring preload if you lightly push on it.

...and here's a Tip: Put the tiniest dab of synthgrease on that brush before installation. Yes, I realize this might be an unusual suggestions (and you may have heard it here first!), but this will lightly lube the Brush to rotating Copper of Rotor interface surface and significantly decrease wear of the brush (the resulting carbon dust inside the Distr Cap is not such a good thing as it can cause HV tracking and discharge, especially when combined with condensation droplets on a cold morning startup). Remember, just the tiniest dab of lube on that brush will do it...I will not be held responsible for giving bad advice if lube is applied from ten feet away, with a shovel!

Cheers from the vintage Volvo world! (We love Bosch too!)

Edit: I have added some detailed Pix of the Brush to these comments and posted them on the SW-EM site, as the info applies to the vintage Volvo community also. If interested, see: https://www.sw-em.com/Check_Your_Distributor_Cap_Brush.htm

[mbwesty]

Since this thread had resurfaced, something happened recently with the van very rough idling and it turned out to be the rotor this time. The burnt rotor I got cheaper from an online outlet. Comparing the burnt and the new I got from a local VW import parts store. I suspect the plastic/ploymer/materials just aren't the same even though they both had the Bosch label. One's more brittle? Buy cheap u get cheap would be my guess. Part of the rotor basically had disintegrated as I pull the cap off. I was surprised I made two round trips from LA to SD in that condition. Only a VW can do that...add to the title "also death by rotor"...LOL

[Ronzo_volvo_guy]

DAMN SON!

...I guess the dieletric properties of those chinashit counterfeit ignition parts, made of reconstituted, 14 day old wonton filling is not quite what it needs to be!

Caveat emptor!

[AtlasShrugged]

Thankfully the cap and rotor are available new OEM from VW. Not cheap. Cap 027905207 is about $23 and rotor 055905225B about $19

Those parts were used for years on various 4 cylinder VWs. about 66 different models.

When parts quality is a problem you just need to go OEM VW like coolant bottle pressure caps, fuel injection sensors or ignition bits, if available.

And..that cap center carbon burnt distributor electrode can indicate a worn distributor. Check the up and down movement of the distributor shaft, it should be about .5mm play. There are shims and a fiber washer down towards the bottom. If the shaft has any noticeable lateral play, time to rebuild or replace.

You can check VW parts price and availability here:

https://www.jimellisvwparts.com/cars/Volkswagen-VW/1990/Vanagon-21L/car-parts.html
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'Let's Go Brandon'