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09 December 2010, 01:59
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#1
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Member
Country: New Zealand
Length: 3m +
Join Date: Dec 2010
Posts: 2
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Tohatsu/Mecury/Mariner 25/30 2 strokes
Just a word of warning if you own or are buying a new Tohatsu, Mercury or Mariner 25 or 30 two stroke which are all in fact Tohatsu only the label is changed.
In my opinion they have a design defect that makes them prone to corrosion if you are using them in salt water. I have raised this issue with Tohatsu Japan and they disagree, so you can be the judge of the situation.
These engines all have a large aperture about the size of your fist under the carburettor in the bottom of the engine shell. This aperture is not at all obvious. This will allow salt spray and water to enter the engine bay. To make things worse the engine cover is also vented at the top so the spray can blow straight through around the engine.
This may mean your engine gets coated with salt over the summer season and may sit corroding over the winter months unless you have a serious desalting routine as part of your corrosion prevention.
In Australia, New Zealand, and the Pacific Islands these engines are sold with no mention of this serious short coming to unsuspecting purchasers like myself. I don’t know if this is the same elsewhere but I suspect so.
This problem has been recognised by Tohatsu Japan since 1985. I have their dealer maintenance bulletin (sent to me this month) of that year that states this. The bulletin shows that the engine cover was redesigned to incorporate a baffled air intake for the carburettor in the tilt hand grip at the top rear of the engine. A new grommet was designed and is available as an option ????? to close of the air intake under the carburettor and it notes that this helps stop corrosion.
The part number is Grommet D, Lower Cowl Part # 346-76161-0
In my opinion for salt water operation
1. All new Tohatsu/Mercury/Mariner 30 and 25 two stroke engines need to be fitted with the Grommet D, Lower Cowl Part # 346-76161-0 before they are sold in the Australia, New Zealand and the Pacific or anywhere else.
2. All such motors already sold need to be fitted free of charge with Grommet D, Lower Cowl Part # 346-76161-0 at their next service. All customers need to be sent a letter to inform them of this.
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10 December 2010, 15:18
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#2
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Member
Country: UK - England
Town: Looe
Make: Delta
Length: 4m +
Engine: Mercury
Join Date: Apr 2004
Posts: 1,409
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Interesting, i have seen this lots, although as far as know all the Mercury/ Mariner's have this grommet fitted as of abou 2 years ago, if not we fit the grommet when we PDI the engine.
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10 December 2010, 18:41
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#3
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Member
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,030
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Quote:
Originally Posted by Turbodiesel
Interesting, i have seen this lots, although as far as know all the Mercury/ Mariner's have this grommet fitted as of abou 2 years ago, if not we fit the grommet when we PDI the engine.
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No issues like this on my 50 is there?
I regularly spray my opti's with this stuff called "Shield", it's an oil that dries leaving a residue, going to put a good few coats on the 50 since it's brand new
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10 December 2010, 21:11
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#4
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Member
Country: UK - England
Town: Looe
Make: Delta
Length: 4m +
Engine: Mercury
Join Date: Apr 2004
Posts: 1,409
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Quote:
Originally Posted by martini
No issues like this on my 50 is there?
I regularly spray my opti's with this stuff called "Shield", it's an oil that dries leaving a residue, going to put a good few coats on the 50 since it's brand new
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No just on the 2 cylinder block engines.
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11 December 2010, 11:17
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#5
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Member
Country: Finland
Town: Helsinki
Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
Join Date: Oct 2009
Posts: 919
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Interesting. Not all seams to agree about this issue? http://forums.iboats.com/showthread.php?p=3042236
Haven't seen any water, excessive moisture or corrosion inside the hood or engine bay on my 25/30. The inlet in the cowling is pretty well protected, don't see any issues there.
Anyone have a picture of this mentioned grommet, maybe its already installed and that's why I haven't any issues?
What about the heat inside the hood from the engine, would not that dry things up pretty fast anyway?
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fun on a boat is inversely proportional to size...sort of anyway
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11 December 2010, 12:27
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#6
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RIBnet admin team
Country: Ireland
Length: 4m +
Join Date: Feb 2008
Posts: 14,910
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Quote:
Originally Posted by C-NUMB
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Always a bit worrying when a first post is a carefully scripted gripe on multiple forums
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12 December 2010, 20:57
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#7
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Member
Country: Finland
Town: Helsinki
Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
Join Date: Oct 2009
Posts: 919
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I was little curious about this so went to the garage to check the engine. Yes indeed, the mentioned aperture is there and its not obvious. Difficult to spot without knowing( i had no idea). Still dont know if there is any practical disadvantage of this design.
When the engine is running don't think any blow would go around the block, what ever air goes in will be sucked by the carb. Then again, when the engine is stopped warm air will go out from the upper vent in the hood and cold air will be going in through the aperture.
__________________
fun on a boat is inversely proportional to size...sort of anyway
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13 December 2010, 09:10
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#8
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Member
Country: UK - England
Town: Looe
Make: Delta
Length: 4m +
Engine: Mercury
Join Date: Apr 2004
Posts: 1,409
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Item number 10 on the attachment is the grommet!.
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14 December 2010, 22:44
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#9
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Member
Country: Finland
Town: Helsinki
Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
Join Date: Oct 2009
Posts: 919
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Quote:
Originally Posted by Turbodiesel
Item number 10 on the attachment is the grommet!.
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Thanks! Is this a metal part or rubber /plastic?
__________________
fun on a boat is inversely proportional to size...sort of anyway
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15 December 2010, 21:15
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#10
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Member
Country: UK - England
Town: Looe
Make: Delta
Length: 4m +
Engine: Mercury
Join Date: Apr 2004
Posts: 1,409
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Quote:
Originally Posted by C-NUMB
Thanks! Is this a metal part or rubber /plastic?
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Rubber grommet, Never seem to fit to well, so put some RTV on it!!
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22 December 2010, 20:45
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#11
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Member
Country: Finland
Town: Helsinki
Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
Join Date: Oct 2009
Posts: 919
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Quote:
Originally Posted by Turbodiesel
Rubber grommet, Never seem to fit to well, so put some RTV on it!!
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OK, Thanks!
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