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  1. #1
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    Jun 2017
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    Default 1971 Fastwin Gushing water out lower cowl.

    Been refreshing all the likely wear items on my 1971 Fastwin. Rebuilt carb, resealed the whole driveline, new points, fuel pump, water pump. Put it in the water and got it running (after 24 years hiatus). When it started the cowl under the engine filled up with water right up to the bottom spark plug. Figured it must be the head gasket, so changed that today and it is still leaking water It looked like it was coming out the head...but really can't see where it is coming from. I think I see some bubbling in the water by the spark plug. Anyway, is there something I'm missing or a likely gasket or or forbid a crack that an expert can suggest is causing this?
    BTW, I found evidence of a wasp nest in the water pump and all the way into the engine passages by the head.

    Thanks in advance.

  2. #2
    Join Date
    Nov 2011
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    2,593

    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Most likely the core plug in the bottom of the cylinder head. They rot away with age. Just replace it. Yeah, you gotta pull the head again.

    Item #15 in this drawing. http://www.marineengine.com/parts/jo...p%3B+Crankcase

  3. #3
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Will I need a new gasket in your opinion? Thanks for the reply.

  4. #4
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Probably not. Unless it sticks and tears when you remove it.

  5. #5
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Yeah, the freeze plug was the problem....it was missing. Haven't put it together yet, but did a compression test before pulling the head. Both cylinders were identical at 95 pounds.
    How does that measure up for a Fastwin?
    Also, should I use sealant on the Freeze plug??
    Thanks, Bob

  6. #6
    Join Date
    Dec 2015
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Is that with a rope pull or electric start on the compression?

  7. #7
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Yea put some permatex aviation gasket maker in the recess then use a socket half the width of the welsch plug and gently tap it flat using the bolt side of the socket not the flat side. You may have blockage going out of the head make sure the water circuits are open and then run it in a barrel with saltaway once you get it back together. Never reise a old head gasket lightly surface the head on a glass table with 220 grit in a figure eight pattern then pull the head down slow with a center out bolt pattern to spec.

  8. #8
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Rope pull, about ten pulls. Hope that is adequate pressure.

  9. #9
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    Quote Originally Posted by kimcrwbr1 View Post
    Yea put some permatex aviation gasket maker in the recess then use a socket half the width of the welsch plug and gently tap it flat using the bolt side of the socket not the flat side. You may have blockage going out of the head make sure the water circuits are open and then run it in a barrel with saltaway once you get it back together. Never reise a old head gasket lightly surface the head on a glass table with 220 grit in a figure eight pattern then pull the head down slow with a center out bolt pattern to spec.
    I did find a bees nest in the water pump area and signs of them when I removed the head. Bad news about the head gasket. The one in there was torqued down once and run for about two minutes. I did clean up the head just before installing it with sand paper on piece of glass.

  10. #10
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    If it is a new head gasket you should be OK 95psi is not that bad for rope start it should run just fine. Was there much carbon on the pistons.

  11. #11
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    There was some carbon on the pistons. I cleaned them up as much as possible. The bores looked fantastic though and the hatch marks were very visible. I buttoned it up this morning and took it for it's maiden test flight. On a Tin boat this thing flies. Leak is stopped, just needs the idle speed bumped up a bit to help with starting. It is also leaving a lot of fuel/oil in the water. Perhaps this is just blowing out a lot of oil used when I took it apart and stored it. Hopefully I get some miles on it before freezup.

    Thanks.

  12. #12
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    I would give it a good decarb now its running good. Get a can of seafoam spray and after the engine is fully warmed up take it to fast idle speed and spray the seafoam in the carb until it starts smoking real good and quickly shut it down. Fish for 1/2hr or so then start it up point to the big part of the lake and run it WOT for 15mins and the go back to slow and final the slow needle adjustment.

  13. #13
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    Default Re: 1971 Fastwin Gushing water out lower cowl.

    I spoke a little too soon. Running rough now. Idle seems low and intermittent. If I override the throttle I can get it to rev nicely. But this is tricky with the hood off and all that spinning flywheel. I changed the points and condensers when I had it apart, but the coils are originals.... Packing it up for today and hopefully get back to it next week. I also have a dead Yamaha 20 HP I will be tinkering with in the workshop. Powerhead is toast due to overheating, but I just bought one claiming to work very well for $75.

    I can't say I mind tinkering on outboards, because they seem quite well made.

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