Oxidation Build Up In Distributor Cap

[mjk1040]

So not knowing the last time the plugs, cap and rotor were looked at or changed I thought I'd put it on the winter 2 do list. Went to double check on the style of distributor and rotor before ordering them and low and behold the contacts in the distributors were built up with quite a bit of oxidation, almost 1/4" thick. A winter project for sure now. Does anyone have any tricks when installing the new caps and rotors that could or should be done to minimize this type of build up in the future. There seemed to be no gasket, should I silicone seal the cap? Apply a spray? Or is this just the nature of the marine beast?

[bud37]

Mike, for shame ...I'm kidding......clean up good, vac it out, if there is a vent screen make sure it is not plugged , inside there needs to breath , make sure you have the gasket in place and marine cap, the gasket will set the correct height for the cap and rotor relationship.... do not seal the cap. You can spray but really if it is clean and checked every now and again you will be just fine.

Are you going to change the ignition modules as well ?

[mjk1040]

Bud, no vent, vent screen or gasket noted presently or in the Crusader Parts Diagram for an GM EST ignition system. Hadn't planned on changing the ignition modules, Pricey from $75>$160 per unit! Being the 4th owner of this boat with 670 hours on the Crusaders and 20 years old, these may be the original caps, rotors and plugs for all I know! That being said what was noted inside the present caps is not that bad! As always thanks for your insight.

[Viper]

Not really much out of the ordinary to do with the EST. I find the rotors can be a pain to remove if the shaft is corroded. They'll advise against lubricating but what I usually do is use very fine emery cloth to remove as much rust as I can without digging into the shaft. I also clean out the slot in the shaft. Then I'll apply some grease on the shaft and in the slot then wipe it all off. I find this leaves just enough lubrication without ending up all over the rest of the components during operation and helps prevent the shaft from rusting again. It makes it way easier to remove the rotor next time.

Remove the wiring plugs from the module and check the contacts for corrosion. With compressed air either from a compressor of aerosol can, give the components a blow. Also, always check the gap on the spark plugs and set to spec before installing them.

[mjk1040]

Geez Viper the rotors on an EST can't be as bad as those ones Mercrusier uses on the tapered shafts and takes 2 pry bars to get them off.

[Viper]

Source of the post Geez Viper the rotors on an EST can't be as bad as those ones Mercrusier uses on the tapered shafts and takes 2 pry bars to get them off.

Ya those are bad.