Page 1 of 3 123 LastLast
Results 1 to 20 of 49
  1. #1
    Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978

    Merc 200 hole in piston

    As per my earlier post, I have a mid - late 80s Reman 200 merc on a 150 mariner 150 mid. 1.87 gear lower. It had the top starboard piston melted with a hole in the center. Got it split, and ready to rebuild, but cannot find a reason it blew. I expected to find plugged jets, stuck float.. something, yet I found nothing. I'm going to replace water pump as a precaution. I have the wh-39 carbs. Are these the proper jets?

    Any ideas as to why she blew? Other 5 cylinders look great. Perhaps old fuel and too far advanced timing?



    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #2
    Wrong spark plugs, timing not set correctly, switchbox bad (altering timing), poor or degraded fuel, or over-propped.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  3. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #3
    Quote Originally Posted by EuropeanAM View Post
    Wrong spark plugs, timing not set correctly, switchbox bad (altering timing), poor or degraded fuel, or over-propped.
    Would you recommend putting a new switch box in as a precaution?
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #4
    Really should only be replaced in PAIRS. Either replace them- or index the flywheel and check timing on ALL cylinders to make sure the timing is correct, stable, and not bouncing around (an indication of a bias circuit problem with the switchboxes).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  5. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #5
    Quote Originally Posted by EuropeanAM View Post
    Really should only be replaced in PAIRS. Either replace them- or index the flywheel and check timing on ALL cylinders to make sure the timing is correct, stable, and not bouncing around (an indication of a bias circuit problem with the switchboxes).
    Found tdc for piston #1 and the pointer is dead on 0 degrees. Can I check the timing at wot with the plugs pulled by jumping the starter or does it need to be in the water at wot with a load? I need to do break in on the motor and am wary about running it wot without checking everything first.
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #6
    Did you utilize the Service Manual and a Dial-Indicator to verify the mark at the .462" BTC (this is the CORRECT way of setting the point)?

    Also, the manual describes proper methods for setting engine timing (including at Cranking Speed).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  7. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #7
    I did not, I'll have to pick up a manual.

    Edit - I'm struggling to find exactly what I need for a manual since I dont have any consistent serial numbers to go by. The block is a 2.4 liter 200, on a 150 mid, with a 1.87 geared lower.

    Approx what years should I be looking for the block? Is it an equivalent to an XRI, xr6, mariner magnum. Etc? I've found some manuals and it appears that it should be set at 19 degrees cranking, 20 running.
    Last edited by JoshKeller; 11-06-2019 at 12:04 PM.
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #8
    I would recommend Part# 8140981 Service Manual (135-200 V6 Models). Have to be careful with those "XR" designations, which normally apply to Fuel Injected OR 150 Carb. models (ie: 150 XR4, 200xri).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  9. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #9
    Quote Originally Posted by EuropeanAM View Post
    I would recommend Part# 8140981 Service Manual (135-200 V6 Models). Have to be careful with those "XR" designations, which normally apply to Fuel Injected OR 150 Carb. models (ie: 150 XR4, 200xri).
    Yikes $100. Are there any digital online vendors?
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  10. Member
    Join Date
    May 2011
    Location
    Spangle, WA
    Posts
    6,180
    #10
    No there are not, Mercury's service manuals are copyrighted products and they do not provide them in any other form. You might find a good used OEM manual by searching/posting in the classifieds or searching a well known auction site.
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


  11. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #11
    Got the timing set and verified with the .462 mark
    I'm going to index all cylinders at tdc by marking the fly wheel. If I mark all 6 and test timing in each one at idle and wot and none fire oddly, is it safe to assume the switch boxes are ok, or are they more likely to develop issues under load at full rpm, and not just cranking rpm?
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  12. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #12
    I wouldn't trust "cranking RPM only testing" in this case.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  13. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #13
    little bit of time to work on it today - took it to a buddys private ramp so i could put a load on the motor. did not run very well. would bog down and shut off on wide open throttle, didnt want to stay idling. Put it back on the trailer and started diagnosing. good spark on all 6. compression test showed 122 - 126 on all 6 cylinders. pull wires off revealed cylinder 1 was dead. still getting spark, still getting fuel. compression is 124. plug is wet and oily. removed air box silencer. sprayed mixture of fuel/oil in each carb and the top port carb revealed no change at all - i believe this one feeds #1. i indexed the flywheel and all 6 seem to be firing at the proper time. Swapped coils and problem stayed on number 1. swapped switch boxes and problem stayed on number one. I can physically see fuel coming up through the venturing on the carb, so i believe its getting fuel, as well as the burned fuel oil mix on the plug. It even smokes when I take the plug out. any suggestions as to where to go now? reeds looked great when i had the motor apart also. also not sure if its pertinent or not, but the tach was working fine at idle, then bounced as the rpm increased, and finally just quit working all together.

    Top plug is #1. All the rest look like the bottom plug

    Last edited by JoshKeller; 11-11-2019 at 01:43 PM.
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  14. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #14
    I would try another PLUG before I spent a lot of time and money on that. If no improvement is noted, shut it down and check for either a flooding needle/seat/float, or a broken/chipped/damaged reed.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  15. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #15
    Quote Originally Posted by EuropeanAM View Post
    I would try another PLUG before I spent a lot of time and money on that. If no improvement is noted, shut it down and check for either a flooding needle/seat/float, or a broken/chipped/damaged reed.
    What I plan to do. Thanks so much for the continued advice. My service manual should be in at the end of the week.

    To verify, the plugs should be ngk buhw correct?
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  16. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #16
    Or BU8H (that would be my preference).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  17. Member
    Join Date
    Nov 2019
    Location
    Belpre Ohio
    Posts
    28
    #17
    As an aside check eBay for manuals. I picked up a dealer service manual those exact same years and models for 22 shipped like new condition..Mercury 90-97658–3 Service Manual models v-135 thru v-225 with serials 5464486 and up ... copyright 1988..

    I needed mine for a recently acquired 87 175hp mercury

  18. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #18
    new spark plugs and a few float adjustments and she appears to be running as it should. Cleaned all connections, replaced two rectifiers, but tach is still jumpy and fails after about 10 minutes of run time (the rectifier pops). Tried a second tach and same thing. am I looking at a charging circuit on the stator being bad as the most likely culprit?

    Also, setting the floats at 1/16" as in the manual results in the carbs flooding out. Replaced needle valves and seats and the same thing happens - they overflow. I set the floats to the highest point they can be without overflowing or leaking - ever so very slightly below level. Will this cause any issues? Ran about 20 miles saturday and no issues. all plugs looked the same.

    Last edited by JoshKeller; 11-25-2019 at 09:56 AM.
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

  19. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #19
    I know picture angles can look deceiving, but those floats look HIGHER than 1/16" below the gasket surface....

    What do you mean "specifically" by "popping the rectifier"?


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  20. Member
    Join Date
    Dec 2005
    Location
    Shepherdstown, WV
    Posts
    5,978
    #20
    Quote Originally Posted by EuropeanAM View Post
    I know picture angles can look deceiving, but those floats look HIGHER than 1/16" below the gasket surface....

    What do you mean "specifically" by "popping the rectifier"?
    my manual shows 1/16" below the bottom of the carb. perhaps im wrong? The rectifiers will charge for a bit (few minutes), tach jumps a few times, quits working, rectifier no longer charges.

    Last edited by JoshKeller; 11-25-2019 at 02:10 PM.
    2022 Hog Island Skiff
    Johnson 70/40 jet

    Bouncin' off rocks, and catching the smallies.

    Potomac River Smallmouth Guide

    Owner of Potomac Custom Tackle

Page 1 of 3 123 LastLast