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    Merc distributor cap corrosion-gctid406738

    I was wondering, would putting some dielectric grease on the contacts of the spider cap (or any dist cap) be a good idea to help prevent corrosion of the contacts?

    I had a problem with my cap, at about 2 years old, with the contacts being corroded (these were the aluminum contacts, the newer caps seem to be made with brass contacts). Heard this was an inherent problem with Merc distributor caps.

    Or is this just a bad idea and would affect engine performance?

    Just wondering...thoughts?

    Joey
    2007 Discovery 246
    5.0L MPI BRAVO III
    The "BAY-BEA"

    #2
    joeydiver wrote:
    I was wondering, would putting some dielectric grease on the contacts of the spider cap (or any dist cap) be a good idea to help prevent corrosion of the contacts?

    I had a problem with my cap, at about 2 years old, with the contacts being corroded (these were the aluminum contacts, the newer caps seem to be made with brass contacts). Heard this was an inherent problem with Merc distributor caps.

    Or is this just a bad idea and would affect engine performance?

    Just wondering...thoughts?

    Joey
    It's good to just replace the cap and rotor every ~2 years if you're boating in the salt anyway.

    Comment


      #3
      dielectric grease does not conduct electric. Having that inside your cap is not a good idea. As leedub stated, change it out every two, maybe three years.

      Dielectric grease is a non-conductive, http://"http://www.wisegeek.com/what...br /> silicone grease designed to seal out moisture and, therefore, prevent http://"http://www.wisegeek.com/what...r /> corrosion on electrical connectors. Being non-conductive, it does not enhance the flow of electrical current. This property makes it an ideal lubricant and sealant for the rubber portions of electrical connectors.
      Doug ;}
      MMSI: 338068776
      "Go Aweigh to" Photos < click on red letters... 2001 Bayliner 2452 w/6.2 HO (paid for)


      sigpic

      Comment


        #4
        Go Aweigh2452 wrote:
        dielectric grease does not conduct electric. Having that inside your cap is not a good idea. As leedub stated, change it out every two, maybe three years.
        OK...makes sense. I'll order a cap and rotor and keep it as a standby....

        Joey
        2007 Discovery 246
        5.0L MPI BRAVO III
        The "BAY-BEA"

        Comment


          #5
          Best advice I ever got from Flowers Marine was to do an annual distributor cap change. These marine motors are operating at higher than average RPM and much heavier current requirements than most vehicles and the high current arc erosion takes it's toll on the contacts quickly. The boat ran like new again and was money well spent.
          Custom CNC Design And Dash Panels

          iBoatNW

          1980 CHB Europa 42 Trawler- "Honey Badger"

          Comment


            #6
            Plus I would worry that the "arcing" would burn the grease and maybe make a worse problem than the corrosion.

            Even brass contacts on dist caps corrode - heck on mine I am lucky to get 1-1/2 years use.

            Comment


              #7
              Thanks all. The boat seemed like its gotten slightly sluggish in the past month, no significant growth on the bottom or props. Filters are Spring fresh...plugs, wires, cap and rotor were replaced in July 2010, after I experienced the same problem, so looks like I'm due. I thought I could get another year or two out of it since I only use the boat May - October, but....I'll replace it this weekend and give an update.

              Joey
              2007 Discovery 246
              5.0L MPI BRAVO III
              The "BAY-BEA"

              Comment


                #8
                Joey, you can pull the corroded cap and clean it with on/off or other corrosion cleaners and keep as an emergency spare if it is not too worn. I have to tear half the electronics off the top of the engine just to get near mine... a PITA... and lets not forget the special tool for the 6.2... oh and Merc just happens to have two different size distributor cap hold down screws. My last cap I had a dickens of a time to get the new screws in the hole only to find out the screws were the wrong ones packed in with the cap. I had to use the old screws... Just a heads up...
                Doug ;}
                MMSI: 338068776
                "Go Aweigh to" Photos < click on red letters... 2001 Bayliner 2452 w/6.2 HO (paid for)


                sigpic

                Comment


                  #9
                  Good idea Doug. I remember changing the last one wasn't TOO bad. Compared to changing out the water pump, piece of cake! LoL

                  Joey
                  2007 Discovery 246
                  5.0L MPI BRAVO III
                  The "BAY-BEA"

                  Comment


                    #10
                    I just changed my caps, rotors, plugs and wires.

                    This was due to the port engine sputtering, dying and refusing to start about 20 miles from our marina. On return to the marina I found the inside of the port cap wet and corroded. Of note also the cap gaskets were installed on the underside of the cap rather than the top of the distributor. The gasket on the port cap was torn and I think that allowed moisture into the cap. Wiping out the port cap the engine fired up. But I subsequently did the full tune up.
                    Jim McNeely
                    New Hope a 2004 Bayliner 305 Sunbridge Express Cruiser
                    Twin 5.7s with Bravo2 drives
                    Brighton, Michigan USA
                    MMSI # 367393410

                    Comment


                      #11
                      Replaced the cap and rotor .Heres a pic of the OEM Merc cap I just pulled off, replaced July10, 2010...thats about 2 years old; my summer season lasts from May to October, so thats about 12 months of use total. Corrosion present on the stubs (and I have a bone dry bilge):



                      Performance did get much better, btw...

                      Joey
                      2007 Discovery 246
                      5.0L MPI BRAVO III
                      The "BAY-BEA"

                      Comment


                        #12
                        That actually happens more during the months of non use.

                        Comment


                          #13
                          The contacts can be cleaned, be sure that you install the ring gasket supplied with marine dist. caps.
                          Pat says: DO-IT-RIGHT THE FIRST TIME!

                          Bayliner 3870 "ALASKA33)
                          Twin 350 GM power
                          Located in Seward, AK
                          Retired marine surveyor

                          Comment


                            #14
                            My original distributor cap worked fine for 4 seasons and then the engine started to miss. Especially if it had been damp or raining. Run the engine for half hour; LET IT SIT and miss would diminish.

                            This year (one year after first cap replacement) BAD missing. I cleaned that cap so that it looked like new, but miss continued.

                            I'm on the third replacement cap (410 hours on engine) and this one is working fine.

                            Bottom line? Probably a good thing to replace at least bi-annually and keep a spare on board somewhere that it can stay DRY.

                            Here in Canada, cap and rotor run $130.00

                            (And BIII universals $300 but that is another story!)
                            2007 Discovery 246
                            300mpi BIII
                            Welcome island Lake Superior

                            Comment


                              #15
                              Thanks for that post.

                              I have a soft misfire that I haven't quite tracked down. The cap is 1-1/2 years old and needed a clean up of the terminals. It had some salts developed on it. I had put it out of the list of "possibles" but it is back in the list now (a new cap is on its way from my favourite online shop).
                              Terry (Retired Diving Instructor and Part Time IT Consultant)
                              1998 Bayliner 2452. 5.7l V8 - Edelbrock 1409 4bbl - Alpha1Gen2 - Solent UK.
                              MMSI 235061726

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