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Old 17 October 2008, 16:54   #1
Locozodiac's Avatar
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider Boats
Length: 4m +
Engine: Tohatsu 18 /30 HP
Join Date: Sep 2007
Posts: 1,706
30 HP Head Reconstruction Advise

Hello all technical gurus : Need a second opinion on this one:

A client's sailor flipped his 30 HP/380 sib, and did not say a word about to owner. Managed to start back the engine. Days latter when engine was used again went kaputt !! The complete engine head has been taken to pieces. What was found:

1-Mostly crankpin, piston pin, needles bearings are worn, 1 crankpin needle bearing outer collar is seized to rod, with needles missing.

2-All (3) crankshaft bearings with excesive play (craks when rolled)

3-Crankpins with middle scrapped 0.02 mm wear as to form a collar.

Have in stock :

3 main crankshaft bearings
2-piston pin needle bearings
2-rod needle bearings
2-piston pins
4-piston pin clips
2-connecting rods
1-cylinder Head Gasket
2-NGK Spark Plugs
Out of stock

2-standard piston rings set
Both connecting rods seems to be in perfect shape, are not bend, just need to pull out the seized left over of the needle bearing, and replace by 4 new needle bearings. Both front rods (piston bearing) in good shape

The engine needs to be working again, it's a surf towing sib, loosing cash at present times, the owner wants to close the engine head with used crankpins that are in not good shape, are a bit scrapped in middle where needle bearings will be running on. Question: is it possible to turn crankpin 180 so the neck faces the opposite side it was working when new so to work in this new position ? Untill new parts are imported, would it be advisable to increase a bit 2 strokes oil/gas ratio (30:1) to lube better new needle bearings working on scrapped crankpins ?

A friend of mine reconstructs all types on engine inside parts (incredible work) would it be better to reconstruct both crankpins untill new are available ? If impossible to reconstruct, will import including piston ring sets to change all.

Any ideas, thoughts are appreciated. See pics for better appreciation. As Arnold says..Hasta la vista baby...

Happy Boating
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Old 17 October 2008, 17:14   #2
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Country: UK - England
Town: The wilds of Wiltshire
Boat name: WhiteNoise/Dominator
Make: Ballistic 7.8/SR5.4
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Posts: 12,552
Don't mess around putting it together with the damaged pins in-it'll destroy the new bearings in hours if you're lucky-minutes if you're not. They can't be reused in that state.

I'd personally change the rods too-the one with the siezed bearing looks like it's got far too hot.
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Old 18 October 2008, 03:12   #3
Country: Other
Town: some warm anchorage
Boat name: depends how I feel..
Make: Honwave Air 3.2
Length: 3m +
Engine: Tohatsu 18 2 Stroke
MMSI: VHF 16 who wants DSC
Join Date: Sep 2008
Posts: 70
Hi Loco,
DONT put that pin back in in any form, it WILL screw the needle roller in minutes. I agree with Nos that the rod with the seized bearing looks to have got a tad hot, but would be tempted to reuse that if the bearing surface is clean when the old one is pressed out.
As for making another pin, would be tempted to avoid that and order the 2 pins dhl even if you dont get trade prices.

try this one. obviously you could pass the cost onto the owner.

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Old 18 October 2008, 09:11   #4
Country: UK - England
Town: cornwall
Boat name: nothing
Make: rib eye 430
Length: 4m +
Engine: tatsu 50
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Join Date: Mar 2006
Posts: 1,914
agree with above totally .

Can't you sell them a new engine Luis then rebuild that one later
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Old 18 October 2008, 10:44   #5
Locozodiac's Avatar
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider Boats
Length: 4m +
Engine: Tohatsu 18 /30 HP
Join Date: Sep 2007
Posts: 1,706
Originally Posted by ian parkes View Post
agree with above totally .

Can't you sell them a new engine Luis then rebuild that one later
Hello all, tech gurus!

Thanks for your worries, it was just a comment/discussion if possible, seems very loco, nuts, to rebuilt with used scrapped crankpins. The engine has only 400 hours use, was working as a clock when flipped at a surfing spot, guess why ? Ran out of cheap fuel with big monetary consequences. Have all spare parts except both crankpins and piston rings set. Will have to order from USA, found this nice place for Tohatsu brand and fellow brothers: Have purchased from them before, good prices and delivery to US destinations or worldwide by UPS if preffer.

Today will remove the remains of the broken rod needle bearing, if in good condition without excesive metal discoloration & fatigue can be used on the second hand spare market. Rudds, nice spare parts link sent, a bit complicated as they work with engine codes, the engine is a Mariner 30 Hp 2005, same 30 Toh parts for my peace of mind and everyone else involved in this dumb event. Fortunetely for them, have a same second sib configuration in use, so business still going on with just half profit.

Happy Boating
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