Milky gear oil

[Matt]

The whole electrolytic thing is an odd one. It often appears to defy science - although it's of course not actually, it's just sometimes the circuit it ends up making isn't obvious.

[beamishken]

Originally Posted by Matt

Yeah, when I did the lower on my 2hp, it looked quite a bit like your right hand pic. So new casting from ebay.....

Did you also buy a case for the 5? I was wondering if there was a clone case to be had cheap. I've got at least 3 good engines with knackered boxes which is a shame as there damn good engines

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[Matt]

Actually yes - but my 5 isn't a yammie like the OP, my 5 is one of the last Johnson 2 strokes - single cylinder. Bit of a shame since I really like the Johnson twin cylinder engines.

Anyway, the last johnson & evinrude 5hp 2 stroke motors were single cylinder jobbies - a Suzuki DT5. So my replacement gearbox was a Suzuki. Bit of rattlecan paint and had to switch the driveshaft over from long to short and it's been great.

[Matt]

This was what the guts of mine looked like when I took it apart. So just replaced with a suzuki one.

I think Tommy is on the right track to repair sooner rather than later.

[Tommy c]

Originally Posted by TmMorris

Easy to be honest.

You'll have a pair of bearing seals around the shaft up the engine, under the water pump plate. Another pair of the same type in the prop shaft bearing. They need to be fitted the right way round as per the parts diagram.

The seal to the gearbox housing with the prop shaft housing is a large o ring but leaks there are a bit unusual but over time the two surfaces can oxidise and need a bit of emery to return to good form.

The gear leave has a rubber boot that is held against the gear stick with a retaining spring type washer and goes down to a nylon cam shaped piece that serves as the main seal. These are also unlikely to be the issue unless someone has failed to replace the nylon egg in the right position and the screw that exists to splay it out to form the seal isn't tight or able to do its job.

You can buy all of these bits from someone like BHG Marine and they're easy to fit.

It doesn't take much water to emulsify the oil but you do want to try and locate the point of ingress as you replace the seals, it usually obvious and if I had to rank the suspects then I'd start with the pair of bearing seals in the prop shaft, then the pair under the impeller. I think for the others to be candidates it would generally require a previous owner to have botched a rebuild etc.

I can feel what is supposed to be inside at the top of the boot and the retaining spring type washer is fitted to the top of the boot holding it against the inside part, but, with very little force this is able to slide on the shift rod.
Is this supposed to be able to slide?
Surely this won't hold a pressure test?
Due to it's height position, I can see that oil wouldn't leak but I can also see a potential access for water ingress??

[beamishken]

Originally Posted by Tommy c

I can feel what is supposed to be inside at the top of the boot and the retaining spring type washer is fitted to the top of the boot holding it against the inside part, but, with very little force this is able to slide on the shift rod.

Is this supposed to be able to slide?

Surely this won't hold a pressure test?

Due to it's height position, I can see that oil wouldn't leak but I can also see a potential access for water ingress??

They do seem surprisingly loose but do work, for what it costs probably worth changing it for peace of mind. I repair quite a few drives and gearboxes & rarely bother with a pressure test. If a box has water in it, it gets stripped & new seals then you know its good to go. All a pressure test is telling you is a cold box thats not turning might not be leaking, its hardly a guarantee of a good box imho.

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[Matt]

Now he tells me, after I've made my test rig

Actually, in general terms I agree with this. I've never pressure tested a drive/gearbox before across all the various gearboxes & outdrives I've had over the years. If there's been a leak, I just follow the trail.

The reason I've done it for this bravo I've just rebuilt (other thread) is it's at the expensive end of a fix - the new gearset and bearings cost thousands!
Don't want to be spending that again.

Originally Posted by beamishken

They do seem surprisingly loose but do work, for what it costs probably worth changing it for peace of mind. I repair quite a few drives and gearboxes & rarely bother with a pressure test. If a box has water in it, it gets stripped & new seals then you know its good to go. All a pressure test is telling you is a cold box thats not turning might not be leaking, its hardly a guarantee of a good box imho.

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[TmMorris]

Originally Posted by Tommy c

I can feel what is supposed to be inside at the top of the boot and the retaining spring type washer is fitted to the top of the boot holding it against the inside part, but, with very little force this is able to slide on the shift rod.
Is this supposed to be able to slide?
Surely this won't hold a pressure test?
Due to it's height position, I can see that oil wouldn't leak but I can also see a potential access for water ingress??

Yup. That's how it is. It's really a zero pressure system so the seal doesn't need to be as robust as you'd expect. I stripped a Mariner/Yam 15 earlier this year and had forgotten how bizarre that seal is as you just don't think it's good enough.

There's no real wear point in relation to the gear boot so I would guess that the only time a leak would occur there would be if someone failed to fit the nylon cam back in the right position.

I'll find the thread I ran on my Mariner as that was a bit of a horror show due to being left on davvits without an anode for a long time by the previous owner. A low hour engine but inside the lower leg was a mess.

[TmMorris]

https://www.rib.net/forum/f36/stuck-bolts-on-yam-15-2stroke-86074.html

The oil in this one was fine but the seals under the impeller in the bearing case were completely gone.

[Tommy c]

On face appearance I thought these look ok

[beamishken]

Originally Posted by Tommy c

On face appearance I thought these look ok

That whole box looks mint to be honest but if its letting water in somewhere its worth a set of seals for peace of mind, yam seals are just standard metric seals with stainless springs so can be bought from a bearing supplier if you dont want to pay yamaha prices. Iirc there about a tenner each from Yamaha so 4 seals wont break the bank. Definitely worth taking care of in that condition

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[Tommy c]

Yeah the engine is mint all over.
2005/2006 and hardly a sratch on it.
It came with the original handbook, maintenance sheet and toolkit.
I'm just going to replace the seals regardless. I'm ok with the lower seals but not sure how to remove the upper seals around the drive shaft.
Any instructions and advice please

[TmMorris]

You have to remove the gears and then you'll see a cog on the end end of the drive shaft that is held on by a C clip, just flick that off and then the drive shaft pulls out and you can get to the pair of seals.

When removing the main gears there is a little steel rod at the back that is what engages with the gear stick, it'll probably fall out at some point so keep your eyes and ears open.

There are two more seals the same as the drive shaft ones on the inside of the prop shaft that are probably worth doing at the same time.

The only fiddly bit I found was getting that nylon egg seal below the rubber gear stick boot into the right position before doing up the tightening screw that goes through it to wedge it in place.

[TmMorris]

I get the impression that this engine is new to you so you don't know the history? We're there signs that the bleed screws had been undone before? Do they have their washers etc?

The internals do look to be in great shape as someone earlier mentioned.

I've a 40 year old 4hp Yam that I decided I should give a service to at the start of this season because despite knowing it from new, knowing exactly when, where and how it has been used all its life and also knowing that it had never once been serviced it seems somewhat logical that at 49 years old it would be smart to check everything over.

Once inside the the lower leg everything was mint and zero signs of any perishing. I pondered as to whether the sensible thing to do was to replace all the rubber parts anyway but they were like news and I decided that disturbing things was more likely to cause trouble than leaving stuff be. I replaced the impeller but that really didn't need doing but they cost pennies and cooking a block while just out for day is far, far easier and more terminal than finding the gearbox oil is milky after a day out.

As you don't know the history it's plausible that a previous owner may have changed the oil and failed to tighten up a bleed screw correctly, found some oil after a trip and tightened it etc.

With the internals in such good shapes as yours it does suggest that human error is a bit more likely

Before stripping completely and replacing all the rubbers I think I'd be tempted to check the bearing seals on the prop shaft and if in the same condition as the ones on the drive shaft, clean up the gears in petrol, swill the case out with petrol, Emery the contact surface where the prop housing seals the gearbox if it doesn't feel nice and smooth which it probably does and put it all back together and fill with some cheap engine oil. Then a gentle pressure test to see any obvious leaks, if none, then stick it in a wheelie bin (sinking it nice and low in the water) and run it for an hour or so in gear then check the oil, just letting some out the lower bleed. If nothing then I'd top up and take it out for a bit of gentle work on the boat. If all fine then the water in the oil was almost certainly due to human error.

[Tommy c]

Yes the engine is new to me.
I purchased it from a retired gentleman who was the 2nd owner.
He knew the 1st owner and said it was always mounted on his yacht rear rail and never saw the yacht leave the marina.
The 2nd owner used it on his tender to his wet mooring and once on his yacht stored it below whilst sailing 2 to 3 weeks at a time.
The original service kit came with it. Gaskets,plug, impeller,float needle,fibre washers, split pins etc.
It definitely has had an impeller change as evidence of the needed bolt removal is evident.
When you say bearing seals on the prop shaft, do you mean just removing the gear housing cap shown in my last 2 pics of the 4?

[TmMorris]

In that cap, around the prop shaft should be a pair of seals identical to the pair under the impeller plate that seal the drive shaft.

[Tommy c]

Well I've got it all back together, refilled with gear oil and ran it for a few minutes.
I dropped the oil and it's definitely getting water in.
My problem now is the bearing carrier is corroded stuck to the back of the housing cap. I've removed the o ring but not sure how to now split the cap from carrier.
It's currently sat in a jug of petrol.
I'm presuming that the corrosion that's 'glued' it all together is responsible for the water ingress corroding the seals
Any ideas please

[Matt]

I appreciate this doesn't help you - but on the old British Seaguls NOT finding any water in the gearcase was a worry - it meant you hadn't been using it.

[babbot1]

That stinks. Turning into a project.
I would hit it with penetrating oil like pb blaster if you have that stuff over there. Then gently tap it. Maybe with a wood block on the edges not to hit the bearing seal. Keep gently tapping every so often and letting it soak with penetrating oil. Hopefully the wood block will break the corrosion.
These corrosion stuck things generally take patience, which I don't have, so it doesn't often end well for me.

[Matt]

Do you mean getting that bearing out? A bit of heat'll do it. Or a cheap slide hammer kit off ebay - I'll linky you up if you wish.

Gave my 5hp a good run at the weekend. Think I need to richen it up ever so slightly. https://youtu.be/AkgCOOZb34Y