Tohatsu 9.8 problems

[32511]

[32511]

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I seem to get no drive in either forward or reverse, although the splitpin looks and feels ok, and the prop seems tight on the shaft when waggling by hand. The strange thing is the motor jumps upwards when either forward or reverse are selected. There was certainly no rope round the prop or any apparent reason for shearing, and everything had been working fine until I needed a last burst of forward when mooring.
Bevel gears? or any other bright ideas?
SWMBO just managed to grab a dinghy with the boathook before we drifted onto the rocks when mooring last night, but that's another story.
 
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2 stroke, 4 stroke, year ?

However if you are referring to the split pin though the nut, that only stops the nut falling off!

The prop is driven by a hub which is probably "spun"

usually though it drives Ok at slow speed but slips when the power is increased

Mark a line on the end of the shaft and some marks in line with it on the prop.
Try it. If the marks no longer line up it is a spun hub.

If the propshaft does not turn when the engine is run then its probably an internal gearbox problem, broken drive shaft or gear shift problem

Is it still pumping water OK
 
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To make it completely obvious. The prop hub and the inner splined sleeve are joined by a rubber bonded insert.
The rubber will have torn from one or both of the surfaces it mates with.
It's not a DIY fix and will need a new prop. There are some businesses who re-bond props.

27084_L1.jpg
 
I think your more likely to find that the gear selector rod clamp is slipping. You should find a rubber grommet on the port side of the leg, about half way up, remove this grommet and peer inside.

You should see the clamp inside this hole, connected between two rods with a bolt head. When the eninge was last serviced, for the impellor change, this would have been disconnected. it is most likely that this has not been tightened up properly and so has slipped.
 
Still pumps water OK. Is a 2-stroke, probably about 8 years old, with remote throttle and gear linkages, plus electric start and alternator.
The rubber bonding scenario looks most likely. Looks like it is beyond me to lift the outboard out of the well, as I'm on a swinging mooring, and am the wrong side of 70, so I'll bite the bullet on Monday and get the local engineer involved.
It's all part of boat owning!
 
monkfish24 said:
I think your more likely to find that the gear selector rod clamp is slipping. You should find a rubber grommet on the port side of the leg, about half way up, remove this grommet and peer inside.

You should see the clamp inside this hole, connected between two rods with a bolt head. When the eninge was last serviced, for the impellor change, this would have been disconnected. it is most likely that this has not been tightened up properly and so has slipped.
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The diagrams I am looking at show spring pins through a joint collar to link the two parts of the shift rod but one could have come out broken ( or corroded if it had been replaced with an ordinary steel one) perhaps

The drawings dont show a rubber access plug. Are you sure that is how the joint is accessed on these Tohatsus?
 
probably about 8 years old, with remote throttle and gear linkages,
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Ah.
You sure there is not a problem with the remote gear shift sytem? Have you tried to operate the gearshift on the engine with the cable disconnected?
 
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VicS said:
The diagrams I am looking at show spring pins through a joint collar to link the two parts of the shift rod but one could have come out broken ( or corroded if it had been replaced with an ordinary steel one) perhaps

The drawings dont show a rubber access plug. Are you sure that is how the joint is accessed on these Tohatsus?
Click to expand...

Hmmmmm, It should be, like a rubber cap.

It is normally fixed with a single bolt through a clamp which holds each rod either side of the bolt.

I'm not trying to giff duff info, honest guv. :)

Yours
Slightly Perplexed
 
Gear shift seems OK- there is a clunk as it goes into gear, and the gear lever on the side of the engine seems to be in the correct positions.
 
tobermoryphil said:
Gear shift seems OK- there is a clunk as it goes into gear, and the gear lever on the side of the engine seems to be in the correct positions.
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Fair enough not the remote then!

Not 100% certain 'til you try the test I described but i'd still suspect the prop hub. Can't do that I suppose because you can't get the engine out of the well! :(
 
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As the motor kicks when engaging gear I think we can assume that it's selecting the gear and the prop is turning. It's just when he revs up that slip occurs. Even when the bonding goes they will still drive very gently, as a rule.
I've even had a broken shear pin that would drive under very low load.
 
No drive at all in either forward or reverse, and with the selector in neutral, the prop can't be easily turned by hand.
Suspect the pinion gear on the vertical shaft is chewed. Would this make the outboard jump up when gears are engaged?
 
With the selector in neutral the dog clutch should be disengaged so the prop and prop shaft should turn freely without the gears turning.

When the engine is running in neutral the drive shaft pinion should turn both gears freely on the prop shaft.
If you cannot turn the prop freely in neutral it sounds as though the shaft bearings may have seized. God knows what has happened to the gears

Dont know why it jumps as you try to engage gear. Maybe LS has some ideas.

I reckon the gear unit may be in for a major rebuild.

Maybe water has got into it. Presumably free of water when drained and refilled at the end of last season?
 
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