Tohatsu M18d rebuild

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    Posted: 06 Jul 2024 at 4:54pm
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I scored a Tohatsu M18d outboard for free..........which may actually be more than its worth .
 After total dismantle  ( havnt done the gearbox yet )  I only broke 1 head stud   and 1 exhaust plate bolt . So I spends 1/2 a day  clamping the block to my drill press  , man there was some Kiwi ingenuity went into that Big smile , drilled and extracted both bolts without damaging the threads  and then found the block was #ucked anyhow Angry.  There is a lot of corrosion  on the head gasket surface in the ally surrounding the cylinder liner ,....... and there's another  thing , I got quoted 180 bucks per pot to rebore ( they are 12 thou barrel shaped ) and I can get brand new liners for $106  each .Any how the block was lookin repairable    untill I found a new one on fleabay  for $304nz   ( all prices quoted are in NZ bucks ) . The big ends are fine but the mains are a but rumbly ( you wouldn't re fit them  ) but that still means pressing the crank , but Mr Ching  also has a complete crank assy , with pistons . We haggled Ouchmight even have got a bit heated ( I had a ball LOL)   and agreed on a freight inc price  for a new  block  and crank assy inc pistons rings etc , on my door step  for $873.
 Apart from that I have bought a set of anodes from Eastern Marine  ( there wasn't one left on it  )  a gasket set  ( same set could be had  for either 55 bucks or 125  depending wether your lookin at Temu or Ali, got the reg/rect for the charging coil there too  (Ali ), new decals off fleabay  . Apart from all that  I have worn out a few elcheapo brass brushes  scrubbing corrosion offa it ...........which leads me to the real reason for the post 
 Can any of you recommend a decent paint to  paint the thing with ? I was planning to sand corroded bits back to metal and etch prime them , sand up the still good original paint and ......well some durable top coat . I wanna make a decent job of it as I will either keep it for ever  or ask fairly good money for it ( got receipts  and a few pix so far ).
 One more thing , how the hell do you manage to get water in the bottom cyl. A few of the ones on youtube did but Im buggered if I cant see how . Mine has a snorkel thing on the ex inside the lower leg bit . Apparently transporting it wrong can do it  but I don't think I could get water up that tube if I tried . The only way I could see is if one was to yank the motor up past horizontal real fast .... like so fast the water didn't have a chance to exit the leg and goes down that snozzle ...... beats me Smile
I wish I was young again .... Id be heaps smarter than this time
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Post Options Post Options   Likes (0) Likes(0)   Quote Pcj Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jul 2024 at 6:14pm
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youtube can be your friend

I scroll  Danger Marine(aussie) 
"Times up"
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Post Options Post Options   Likes (0) Likes(0)   Quote Mc Tool Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jul 2024 at 8:16pm
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Good lead Pcj , thanks . I got a feeling I may have flashed past him a few  times .  
 I got a bit of time tho ...... seee , after saying to myself and the Mrs  ( yeah , I still fill her with false hope LOL) that I must waterblast the path  for  oh  about 3 years  I arsed up on it this am and landed on my only knee  and I cant get pants on it now  , so Im anticipating a week swilling beer in front of my new smart tv ........welll  #uckit , silver lining an all that Smile
 Oh yeah , the old crankshaft out of the outboard  had a Fag bearing on it , on a Japanese motor ?  Im thinkin Im not the first peep in there Smile
I wish I was young again .... Id be heaps smarter than this time
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Post Options Post Options   Likes (0) Likes(0)   Quote Mc Tool Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jul 2024 at 5:07pm
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 bit of an update and a wee rave ....sorta mixed up Big smile
 After ordering a new block I found sleeves for 44 bucks , anyhow   the box of stuff  turned up   with one corner mashed in .
 . 
Inside I find a mashed piston 

  . I contact seller and they reply with a pic of a package  and tracking # addressed to me .... within a couple of hours , awesome 
But ! Shocked  after a few stellas that night ( been watching Josh James ) I decides to  have a fiddle  so I splits the crankcase  ( with her nail file Big smile ) and slots the crankshaft assy in there ........after a bit of head scratching and a couple more bottles of the main problem ....... the #ucking crankshaft is bent  ( pressed up  crankshaft ) and with the benefit of hindsjght I would say the ding in the bit of broken piston skirt  was done by the end of the crank  (they did line up in the box ) .  They were quite helpful .... as one can be  from China . Upshot is that I took it to a friend who builds his own race cranks   and he reckons an easy fix .... meanwhile  the chinese govern.......LOL  nah  ,  meanwhile the seller has offered me another crank ( long as the box aint made in China Tongue  if I pay the freight    which was to good to pass up  so its on the way . 
 Apart from all that   got some etch primer , a tin of polyester finishing putty  and a tube of  space shuttle anti seize ( 48 bucks for 1/2  a toothpaste tube    Ouch)  and its been brush painted at some point  so there's a bit of sanding going on too .
I wish I was young again .... Id be heaps smarter than this time
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Post Options Post Options   Likes (0) Likes(0)   Quote smudge Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jul 2024 at 8:27pm
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Dang! Is the crankshaft bent or just twisted?
Best gurnard fisherman in my street
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Post Options Post Options   Likes (1) Likes(1)   Quote Mc Tool Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jul 2024 at 9:44pm
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 Hopefully just twisted  , maybe a bit of both ,  but friend thinks it isnt much and can be fixed .
SmileSmilemeanwhile on the plus side  I have nearly enough bits to build another power head  .
I wish I was young again .... Id be heaps smarter than this time
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Post Options Post Options   Likes (0) Likes(0)   Quote Mc Tool Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 2024 at 10:55am
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Time for an update  , I have waterblasted the path LOL yep .... arsed up again .
In the end me and the crankshaft seller agreed that if I paid the freight ( 80 bucks ) they would send me another crank assy , and while Im thinkin that if they accept that the crank was damaged in transit  then they should pay the freight too , but  I was going to wind up with two new cranks  even tho one was bent  . When I say bent , for those who dont know , I really mean twisted out of line . These cranks are made up of several components that are pressed ..... like 12 tons of press , together . One then puts the crank on V blocks and using a dial gauge  you check the alignment , which is never spot on  after pressing , you then hold the crank in one hand and whack it with either a copper or ally hammer on the crank web  so as to get the assembled bits to twist  in the right place , in my case  pretty much reversing the misalignment caused by the transit damage .
Any how the new crank fitted perfect  so I got all keen and assembled the motor   .... and then pulled it to bits again coz I didnt check the ring end gaps ( they were ok ). Most of the new parts came from China  ( t/stat , waterpump , coil, gasket set ,  and a whole new carb assy  ). 
So  where Im at now is .......... there are some oil lines that  look like they are directing oil at the  3 main bearings  from the bottom of the transfer ports , and seeing as how the mains on the old crank were knackered I wanna verify the correct placement of these hoses as they were missing off the motor when I got it . Service and parts manual mention them but dont describe or show the correct placement . Any one here got a Tohatsu  9.9 to 18 hp  2 stroke twin cylinder motor they could take a pic for me please. The side opposite the exhaust  ..... starboard as it sits on the boat . 
 Thanks 
I wish I was young again .... Id be heaps smarter than this time
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Post Options Post Options   Likes (0) Likes(0)   Quote smudge Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 2024 at 6:36pm
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Crikey, bit of a mission. I think you will be lucky to get the info you need. You clearly have some knowledge about 2 stroke motors. 

If you can't get any info I'd go with how I thought it should be. Mind you that could cost you thousands. Sorry, I'm no help at all
Best gurnard fisherman in my street
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Post Options Post Options   Likes (0) Likes(0)   Quote Kandrew Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 2024 at 8:30pm
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Might be wrong but I thought the earlier ones were similar to merc mariner, haven’t had anything to do Tohatsu never been inside one but shouldn’t be too different.

Get onto one of the online Tohatsu forums, someone would know. There’s one on FB.

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Post Options Post Options   Likes (0) Likes(0)   Quote Mc Tool Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2024 at 6:46pm
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Here are the brass nipples  . I think I have sussed that the one  right above, under the carb .... that one goes to the middle nipple ( centre main ) , the bottom one on the crankcase ( from the bottom cyl transfer port ) goes to the top main bearing .  I think that this motor takes advantage of the oil that pools in these ports ( shoulda took a blimmin pic .... will get one tmoro ). On the bottom two mains there is a small gallery  that also connects these pooling areas to the adjacent main bearing as well as  the hose nipple .
 Oh yeah , the cleaver little Chinese  decided to change the factory  left hand thread on the crankshaft nose  to a right hand thread ..... which is fine if one just happens to have the correct nut ( m16 x 1.5mm ) lying about  ( one Censoreddidnt )Big smile ,  AND  I can absolutely guarantee  you that turning the engine over quickly by hand does produce a healthy sparkLOL
I wish I was young again .... Id be heaps smarter than this time
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