Yamaha Malta Shaft Seal

RJD393

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I am in the process of servicing my old(very) Malta. The prop shaft oil seals (2) have disintegrated and I have the replacements. According to the parts diagram these seals are inserted both the same way round - stopping water getting into the bottom unit. My limited knowledge suggests that the inner one should prevent oil loss and the other prevent water ingress so they should be inserted back to back. Anyone know the answer please?
 

VicS

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Mine are back to back in a Evinrude. The outer one is fitted to stop water entering and the inner one to stop the oil escaping. The Evinrude parts diagrams show them like that too .

The Yamaha diagram I have looked at ( 1984 4hp) does specifically show them both spring side facing out. Similarly for the drive shaft seals, spring side uppermost

More important I guess to prevent water entering than to prevent a little oil escaping!

Fit 'em as the diagram shows 'em.
 

West Coast

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Warning - old thread resurrection!

Am completing the same seal replacement for an even older malta outboard. Agree the diagrams suggest the prop shaft seals are the same way around, but noted the prop shaft has very small grooves where the original seals came against the shaft. So - concerned the new seals may not work properly.

Age of outboard etc means it is not really worth replacing the prop shaft.

So - considering reversing the inner seal so the lip comes into contact with an unworn part of the shaft ? Does this approach seem sensible, or am I missing something?
 

VicS

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Warning - old thread resurrection!

Am completing the same seal replacement for an even older malta outboard. Agree the diagrams suggest the prop shaft seals are the same way around, but noted the prop shaft has very small grooves where the original seals came against the shaft. So - concerned the new seals may not work properly.

Age of outboard etc means it is not really worth replacing the prop shaft.

So - considering reversing the inner seal so the lip comes into contact with an unworn part of the shaft ? Does this approach seem sensible, or am I missing something?

If the outer seal is not sealing properly then water will get past it. If you have fitted the inner seal so that the spring side is inner most water will easily get past that too
 

West Coast

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Thanks, new seals are not yet fitted - just thinking ahead before doing so. My experience with these types of seals is limited, but aware that fitting a new seal when the shaft has an even a small circumferential score (where the old seal made contact) the new seal may not work properly. Without changing or repairing the shaft, only option seems to be to get the new seal lip to bear on a different part of the shaft.

I will have a look in the housing arrangement, to see if I can perhaps displace the seals a small distance, so the lip bears on an unworn part of the shaft
 

CliveF

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The oil will naturally fall to the lowest point. and there are two bushings on the drive shaft above the oil to reduce any upwards migration towards the oil seals.

The oil seals are there to prevent water getting down into the lower case , which could float it up and out if enough water gets in.
I suggest altering the length of the upper bushing to move the seal off the worn bit of shaft is the way to go. However there will be little if any room to play with as they are all generally close fitting parts. lots of measuring with a vernier required methinks.

Good luck.

I had a 5c 6E32 which was the same series of engine. cracking little motor until the cows broke it off the transom!!!!!

Regards Clive
 

Sandro

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My Malta is from 1989. Also the part diagram I have shows both propeller shaft seals pointing the same side – outward.
On the diagram I can’t see which way round is the drive shaft seal turned. Surely, as VicS says, against water intake.

West Coast, I don't know how deep is the damage, not sure but polishing the shaft could improve the sealing; the spring action on the lip could compensate for the slight diameter reduction of the shaft. Don’t know if someone made this experience.

I wonder if you could displace the seals: a large distance would be needed (and room required) because, being two of them, the rear seal has to go beyond the actual position of the front one.

May be a modern gearbox would sustain working on an oil/water emulsion as was the rule for old Seagulls.

Are you sure the old Malta is not worth a new prop shaft? I would not swap mine for any new 4 stroke.

Sandro

While I was writing the Speedi Sleeve post arrived. New to me. Probably the most economical solution.

Sandro
 
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VicS

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My Malta is from 1989. Also the part diagram I have shows both propeller shaft seals pointing the same side – outward.
On the diagram I can’t see which way round is the drive shaft seal turned. Surely, as VicS says, against water intake.

West Coast, I don't know how deep is the damage, not sure but polishing the shaft could improve the sealing; the spring action on the lip could compensate for the slight diameter reduction of the shaft. Don’t know if someone made this experience.

I wonder if you could displace the seals: a large distance would be needed (and room required) because, being two of them, the rear seal has to go beyond the actual position of the front one.

May be a modern gearbox would sustain working on an oil/water emulsion as was the rule for old Seagulls.

Are you sure the old Malta is not worth a new prop shaft? I would not swap mine for any new 4 stroke.

Sandro
Old seagulls had bronze gears and bearings modern outboards have steel gears and steel ball bearings
 

West Coast

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New shaft is £146 + VAT and Carriage. So, getting on for 1/3 the price of a new 2.5hp 4 stroke. Yes, appreciate the issues with newer 4 strokes, and the Malta is a great engine, but won’t go on forever.

Speedi Seal looks an interesting option
 
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