MarineEngine.com - Your online store for all types of marine engines and boat parts.
PHONE ORDERS
Monday - Friday
9:00 AM - 5:00 PM EST
Click for TOLL-FREE Number
Online Checkout
Special $9.95 Flat Rate Shipping
(800) 209-9624 | Home | Contact | Shipping | Returns | Cart View your shopping cart.
Part Number Search
Shop by engine/drive part number.
Original & matching parts for sale.
Manuals & Accessories
Shop by description, item number
or manufacturer's model number.
Boat Repair Forum Boat Repair Forum   Boat Video Gallery Video Gallery
   
Results 1 to 18 of 18
  1. #1
    Join Date
    Apr 2006
    Location
    Posts
    121

    Default "There is no OEM gasket. I wi

    "There is no OEM gasket. I wish there was. I have tried to make one w/ caulk gasket material and indian head, but the 'lip' is 1/16" or less - too fragile. I agree - there should be a gasket in a marine environment. I am playing w/ trying to make one with silicone.

    Be that as it may, every (2) months or so, my motor will misfire at higher RPM's - I remove the cap and see that the ignition contacts within the cap are 'fuzzy'. I clean it and am on my way.

    My dizzy is located right at the seam / opening of my i/o cover - not an ideal location. There is a 1" lip to prevent rain water from getting in, but spray must make it's way in and voila moisture. For example, right now the (2) screws that hold the rotor in place are pretty rusted - one has a stripped phillips head and I'll have to crack the rotor off to get the screw off...

    My mechanic says the 'fuzzy cap' has been an issue w/ many of these motors and although ideally it shouldn't happen, in reality there is a moisture problem. I know a couple of other guys who deal with it and just clean their old caps and re-install ( different model boats too )...

    So, I'd love advice on this and also where I might buy a aftermarket cap/rotor without losing QUALITY.

    The waxy water resistant stuff, is called 'cosmoline' - sounds like a good application, but some kind of mechanical gasket would be better. I do 665 lube the entire motor 2-3 times a season (7 months ).

    Thanks

    BTW: The motor is 8-9 years old and looks new. I maintain it myself."

  2. #2
    Join Date
    Aug 2006
    Location
    SW Ohio, USA
    Posts
    10,293

    Default Put some "never sieze"

    Put some "never sieze" on the screw threads and coat the screw tops w/clear nail polish. Check w/an auto/truck parts dealer to see if you can find a thin "O" ring.
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  3. #3
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    3,409

    Default What year is your motor? Yo

    What year is your motor?

    You could make a plastic cover that will go from the carb stud all the way back and cover the dist.

    Merc actually made a cover that way for a while.

    Every merc dist cap I have ever purchased had a gasket with it......

  4. #4
    Join Date
    Jan 2010
    Location
    Posts
    661

    Default "What is your engine serial???

    "What is your engine serial???

    Have your mercruiser dealer look up service bulletin # 2003-06, v6&v8 [GMEFI] NO START MISS FIRE OR ENGINE CUT OFF CONDITIONS. If you are within the serial number range, Then you will be in need of a new style distributor housing/Shaft with a redesigned vent screen to allow better air circulation inside the cap to prevent the accumulation of moisture. Engines with a higher S/N then the ending S/N listed have the new style HVS distributor. Models affected mcm 350 mpi OM320590-OM642305 Also MCM 5.0 MPI OM320415-OM642305. also MCM6.2 MPI OM320614-OM642305 and also MCM4.3 OM322781- OM645782 And some inboards also within that time frame.

    Now I'm not saying this is your problem just something to look into is all, Also if your S/N is within this bulletin Keep in mind you are way out of any warranty time frame and bulletins do expire and this would not be covered in anyway by mercruiser, I just posted this so you have something different to look at is all. Good luck to you with your engine problem."

  5. #5
    Join Date
    Nov 2006
    Location
    Posts
    119

    Default My 1994 thunderbolt IV has bee

    My 1994 thunderbolt IV has been trouble free. I even re-used it when I repowered. 1994 ignition with a 2006 vortec block. Spark plugs and replaced wires when I repowered is all that's been done to mine.

  6. #6
    Join Date
    Apr 2006
    Location
    Posts
    121

    Default THANK YOU BOAT TECH !!!!!

    THANK YOU BOAT TECH !!!!!

  7. #7
    Join Date
    Oct 2009
    Location
    archer city, texas, us
    Posts
    186

    Default hey everybody talkn about a th

    hey everybody talkn about a thunderbolt IV dist where can you get parts? can you test a ign module? do they go bad?

  8. #8
    Join Date
    Aug 2006
    Location
    SW Ohio, USA
    Posts
    10,293

    Default "Tests for Thunderbolt Ignitio

    "Tests for Thunderbolt Ignition:

    W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

    Check the kill switch first!

    #1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

    #2 - If 12 volts are present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

    #3 - If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

    #4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced."
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  9. #9
    Join Date
    Oct 2009
    Location
    archer city, texas, us
    Posts
    186

    Default thank you guy good info will t

    thank you guy good info will try

  10. #10
    Join Date
    Aug 2006
    Location
    SW Ohio, USA
    Posts
    10,293

    Default You're welcome. You can g

    You're welcome. You can get the parts from this site or any Merc. dealer or even eBay has good prices. Check your wiring and connections. If the optic sensor is rusted that could be the problem; fine wires corrode. Let me know what year and engine and what you find and I'll help you find parts.
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  11. #11
    Join Date
    Apr 2006
    Location
    Posts
    121

    Default "I want to thank you guys for

    "I want to thank you guys for helping out. I was able to get to the bottom of the problem - there is a Mercruiser upgrade for my year / serial # dizzy that is directly related to the moisture issue I have.

    So, hopefully, I will not need to be replacing caps and rotors anymore !!!!

    Now, I would love to get my hands on or make a rain / water diverter that connects to the flame arrestor bolt ( even though I have an FI ) and leads water aft, away from the ignition...

    Any takers on this ?"

  12. #12
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    3,409

    Default "I am not sure what you have o

    "I am not sure what you have on top of your flame arrestor now but this is what I have....

    It covers the distributor

    "

  13. #13
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    3,409

    Default You could also modify it a bit

    You could also modify it a bit so it goes further back and covers more of the distributor if you had to.

  14. #14
    Join Date
    Apr 2009
    Location
    New Zealand
    Posts
    22

    Default did the problem with the distr

    did the problem with the distributor affect 2001 350MPI or later model? I am having issues with misfire which I can't solve.

  15. #15
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    1,582

    Default "The water and/or moisture ins

    "The water and/or moisture inside the dist may not be related to anywater dripping on top of it.
    Given that the dist is essentially sealed, if you have normal temp variations in essentially a 100% humidity situation, i.e. in your boat in the bilge, then moist air gets sucked into the dist via the vent when the temp drops...it condenses on the inside of the dist/cap... temp rises, and the now less moist air is expelled out the vent... next evening same cycle repeats. Same process as that which makes your car windshield "fogged" in the very early am...except its inside your distributor and it does not dissipate."
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280
    1972 22ft Bristol
    Honda 7.5HP 4 stroke Long shaft

  16. #16
    Join Date
    Apr 2006
    Location
    Posts
    121

    Default I have a 2001 350 MAG MPI and

    I have a 2001 350 MAG MPI and it affects mine. Pull off dizzy and check the contacts ( be careful not to drop the torx head screws in bilge! ).

    It's been a real hassle and the above description of 'fog' in the dizzy seems like the culprit...

  17. #17
    Join Date
    Apr 2009
    Location
    New Zealand
    Posts
    22

    Default I did pull mine off the other

    I did pull mine off the other day. I noticed the black corrosion on some of the contacts and others were clean. I posted a photo on my thread with comments. what did you actually replace. the whole dizzy?

  18. #18
    Join Date
    Apr 2006
    Location
    Posts
    121

    Default "I was getting white and grey

    "I was getting white and grey 'fuzz', nothing black. I am going to replace the whole dizzy"

Similar Threads

  1. Aftermarket distributor cap rotor
    By abl1111 in forum Mercruiser Sterndrive Archive
    Replies: 11
    Last Post: 05-24-2009, 05:11 PM
  2. Mercruiser 50 LX AlphaOne Thunderbolt IV distributor question
    By kenmemphis in forum Mercruiser Sterndrive Archive
    Replies: 0
    Last Post: 04-15-2009, 09:57 AM
  3. Distributor for 1977 ford windsor mercruiser
    By riskcontrl in forum Mercruiser Sterndrive Archive
    Replies: 1
    Last Post: 01-18-2008, 07:25 PM
  4. Mercruiser 30L Distributor
    By snowcruiser in forum Mercruiser Sterndrive Archive
    Replies: 6
    Last Post: 08-23-2006, 04:11 PM
  5. Johnson 75 HP V4AV4AL16D Distributor Rotor
    By ko4nrbs in forum Johnson Evinrude Outboard Archive
    Replies: 0
    Last Post: 07-31-2006, 04:37 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •