Vortec Distributor Cap Corrosion

At first glance i thought the dark area on the cap was grease.

Vortec distributor cap corrosion.

Look and see there should be one or two vent holes that have a metal screen on them. 998 chevy vortec 4 3 has developed an appetite for distributor caps. Presently has 235 000 miles runs great until the cap develops corrosion on the inner terminals. The a c hose above the cap deposits water on the cap as well on models with the hose routed over the cap.

But looking more closely i ve seen a dark brown material coating like this before appearing like a very fine powder. It recommends taking out the wire screens located somewhere on the base of the distributor. I only get 1 2 years before the distributor cap gets so gunked up it misfires and has to be replaced. The engine starts and runs nicely with the.

I have considered using a higher dwell module and high performance coil but i m not completely sure this. 1 the air gap between the rotor and cap electrodes is greater on the 5 7 vortec engine causing the rotor to prematurely burn. Vents are plugged easily and cause white brown cap dust and green black rotor issues moisture gases corrosion all directly related to poor running and the p0300 because the distributor cant vent correctly. I replaced the coil a year ago when it went.

One other thing to look at is the bottom plate of the distributor. I clean with contacts with a dremel brush and the green corrosion comes right off. Gm parts cost a little more but they last 3 or 4 times longer. Gm has a technical bulletin included in the new cap that speaks of a lack of ventilation which can cause pre mature corrosion of the cap.

I have tried brass and aluminum contact caps i ve replaced the wires with low resistance models and use bosch double platinum plugs. 2 could their be a defect in the distributor itself that wont allow the moisture to leave causing the corrosion. I warm up my engines every couple of weeks and i find a layer of green corrosion on the contacts after a couple of months. Most often i see this on the inside of hei distributors but it can be common on any distributor this material is iron oxide and is the result of misfires inside the cap from errant sparks inside.