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Thread: Tohatsu / mercury 3 cyl water on plugs.

  1. #31
    Team Member ice_spy's Avatar
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    Checked the reeds, they are ok, not broken and sealing pretty good.
    Called a boat mechanic and booked it in. I have to bite the bullet and leave it to the experts. Some things although seem simple enough to do myself, really need the expertise of mechs that have experienced the same problems with this model of engine. He said it is a common problem with this motor apparently. So if a new set of original factory gaskets fail ($$$) they will have to replace them at their cost not mine I would imagine.
    Can't say I didn't try. And at least all the bolts are free and easy to remove, no bolts to snap on them.
    Will post back with another compression test in about a week or two when they ring me and tell me it's ready to go. I don't trust the readings I'm getting at the moment. With a Skimmed head and block it should be around 130 psi I rekon.
    Thanks to all for your help and advice.
    The race never stops

  2. #32
    Team Member zul8tr's Avatar
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    Why not put some high temp sealant on that head gasket. Have you checked the flatness of the head and the block with a machinists rule and a backlight, could reveal low spot(s). Ex. I always check the split crankcase halves (I deal with Merc split crankcase engines) with that process and have found the lows and the highs especially around the bolts. Then fix them. Also came across this issue on the head and block of my Yamato, I wound up sealing the alum. gasket to solve it.
    " Three may keep a secret if two of them are dead" Ben Franklin
    " ------- well Doctor what have we got a Republic or Monarchy? A Republic he replies if you can keep it"
    Benjamin Franklin, 1787 Constitutional Convention, as recorded by signer James McHenry's in his diary at the Library of Congress

    Location: SW Orlando, Fl

  3. #33
    Team Member zul8tr's Avatar
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    Quote Originally Posted by ice_spy View Post
    Sorry missed the replys on last page. Zul8tr , TCW3 oil Castrol brand and premium 95 octain. 50:1 with a slight drop more for a little more lube.
    Dragracer checking my photos again to look for the leak. Thank you guys. Will let u know how I go.
    More oil wouldn't hurt for high rpm operation. I am sure you have seen the sticky thread in this section about 2 stroke oil see page 3.
    " Three may keep a secret if two of them are dead" Ben Franklin
    " ------- well Doctor what have we got a Republic or Monarchy? A Republic he replies if you can keep it"
    Benjamin Franklin, 1787 Constitutional Convention, as recorded by signer James McHenry's in his diary at the Library of Congress

    Location: SW Orlando, Fl

  4. #34
    Team Member ice_spy's Avatar
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    I'll have a read on that thanks Zul8tr, no I haven't seen that thread. Plea see e post a link if u can.
    So it was mentioned that I should check and or replace the bottom crank seal. When I dropped the motor off to the boat repair shop, we talked about the motor and he also informed me of the crank seal. I was not aware of water entry due to crank suction and water running g up the drive shaft. I thought being not near water ports and free to air it would not be a place of entry. There is an O-ring, and two seals. So highly possible this is the place of water entry, would make sense due to the bottom cyclinder being the wettest every time.
    Hopefully this is the problem. Will post back when I know for sure.
    The race never stops

  5. #35
    Team Member Roflhat's Avatar
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    hi mate, here's a link to the thread on oil and mixtures.
    I've been recommended to run 32:1 in my 70ces, it revs to around 7500
    Cheers
    http://www.boatracingfacts.com/forum...l-runnin/page3

  6. #36
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    Quote Originally Posted by ice_spy View Post
    I'll have a read on that thanks Zul8tr, no I haven't seen that thread. Plea see e post a link if u can.
    So it was mentioned that I should check and or replace the bottom crank seal. When I dropped the motor off to the boat repair shop, we talked about the motor and he also informed me of the crank seal. I was not aware of water entry due to crank suction and water running g up the drive shaft. I thought being not near water ports and free to air it would not be a place of entry. There is an O-ring, and two seals. So highly possible this is the place of water entry, would make sense due to the bottom cyclinder being the wettest every time.
    Hopefully this is the problem. Will post back when I know for sure.
    Yes what the mechanic has discussed is correct. The bottom seals on Crankshafts are either a double seal or two separate seals. One to stop any water entering and one to stop crankcase pressure escaping. When these are being replaced you have to ensure the each seal is inserted the right way. You will sometime come across the bottom of the crankshaft below the seal being a little bit rusty. With any motors being used for racing it is a common practice to replace seals and O-Rings within reason each time the motor is being rebuilt. The replacement of seals and O-Rings are as a precaution to prevent any possible issues.

    Stephen

  7. #37
    Team Member ice_spy's Avatar
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    Update.. bottom seals replaced, the motor has had all new original gaskets replaced also. Tested on the tap, the bottom cyc was still getting heaps of water. The point of entry was not the bottom seals as hoped. Compression seems to be correct at approx 105psi in each cyc. tested cold. We attained the idea that water entry is from the lower section of the leg as it could not be coming from any other point. removed sandwich plate, under bed pan and exhaust tube tuner. The top of the exhaust tube had rock hard gaskets, and upon removal the flat surface was not dead flat. Being pressurised with water at the top of the exhaust tuner tube, water could be drawing in to lower cyc if this is leaking. God willing, this will finally be the solution to the problem.
    The race never stops

  8. #38
    Team Member ice_spy's Avatar
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    Gaskets in lower leg top of exhaust tuner replaced and on the tap, a little bit of water. Too for a test run and plugs came back dry no water. Flushed on the tap with fresh water and bottom plug was wet again.
    Read a few posts about not running a thermostat. Bad news. 100% should always run a thermostat in 2 stroke motors. Replaced thermostat and no more water on plugs both on the water and flushing on the tap. Problem solved. Run a thermostat !! .
    Power is down significantly , only pushing 3 to 40000rpm
    I was hoping the lack of power was also due to not running the thermostat. I did however bend out the reed cage stoppers approx 4 mm thinking I would attain higher rpm. I'm confident that this has had an effect on performance and why the motor is now lacking power. The reeds were fibreglass but not the correct ones, they were 3 peddle off something else that were cut down to 2. Going to change them and bend back the stoppers to original postion. Oh the joys of a motor not running correctly. Missing driving my boat. Taking so long to get the thing running good again. At least the water in the cyclinders has been finally fixed. The only thing this motor hasn't had done will be a hone and a new set of rings.
    The race never stops

  9. #39
    Team Member zul8tr's Avatar
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    Do the reeds and test, then consider the rings if a compression and leak down test confirm they need fixing.
    " Three may keep a secret if two of them are dead" Ben Franklin
    " ------- well Doctor what have we got a Republic or Monarchy? A Republic he replies if you can keep it"
    Benjamin Franklin, 1787 Constitutional Convention, as recorded by signer James McHenry's in his diary at the Library of Congress

    Location: SW Orlando, Fl

  10. #40
    Team Member fs5's Avatar
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    Mate, give Scotty's mobile marine a call up here at brissy. He can line you up with a nice set of carbon ones.

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