aaarggghh.... the outboard - again!!!!

[VicS]

That link to iBoats is to a question about a Nissan. Are they the same?

Regarding the comment about not touching the seal. In my book if the lower unit is off especially if the impeller is being changed it makes sense to replace all the seals.

 

[misterg]

Sorry, hadn't realised that this was a Nissin - my search was on Honda. They are grouped together in the Iboat forums, so maybe relevant?? (maybe not).

I would be inclined not to do more work than absolutely necessary, so I wouldn't do the gearbox seals unless there was evidence that they were leaking (water in g/box, etc.). But then I'm a lazy git! IMHO, you do have to draw the line somewhere, or you end up spending a fortune on rebuilding the whole thing with new parts. If it's broke - fix it. If not, leave well alone. Understand the sentiment, though.

Andy

 

[jonathankent]

I have blown compressed air down the engine from the water outlet, and there wasn’t any resistance as it came out the exhaust perfectly, so no blockage there /forums/images/graemlins/smile.gif. There wasn’t anything coming out of the water inlet – is this because the water impeller will not allow the air to pass and will not rotate, in which case a good thing that the impeller is OK, or should the air have forced the impeller to rotate? My next job is to use fresh water and leave to stand and run in a tub of fresh water.

I remember a mention of the thermostat – how do these work with the water control, and how do I test this?

 

[Lakesailor]

If air forced the impellor to rotate it should be turning the motor as well. I wouldn't expect that to happen.

 

[jonathankent]

Well, alls well now..... managed to get it all cleaned through and running fine, in actual fact running better than ever - and thats after it had been to be serviced and water system checked!

After blowing compressed air down from the outlet, and then using a hose pipe into the inlet, using a fair pressure, it is all clear and flowing freely. I'm almost certain it was the inlet and strainer - once taking the hose pipe away the water ran back rather whitey cloudy in colour and you could smell the sea, so salt seems to have been the route cause.

Thanks to all for suggestions... I'm just glad it wasn't internal and had to strip it apart.

 

[VicS]

Lucky you. Glad to hear it is now all sorted and thanks for letting us know.

You will have to think of a way of preventing it happening again but leaving it in the water is always likely to cause problems. The white cloudy appearance of the water which ran out suggests corrosion of the aluminium, aluminium oxide causing the milkyness.

You should check/ renew the sacrificial anode assuming it has one.

 

[jonathankent]

There is an anode and it was replaced a couple of months ago…. I had thought that it may have been a salt type build up? The anode is bolted to the plate above the exhaust/water intake… normal place I think? I had noticed the start of corrosion on an unpainted part of the tip, but didn’t think too much of it… assumed must be OK as there is the anode. Just a thought, where the anode has been fitted there has been a welded join in the plate… would this do anything to stop the remainder of the outboard from being protected? Should I have a bigger anode fitted to the other ‘good’ side?

 

[VicS]

Salt, sodium chloride, is readily soluble so as such I would not expect it to cause problems. But it does need a water flow to remove it so it could build up once the water flow becomes restricted I suppose. The enemy in my opinion is corrosion. the voume of aluminium oxide that is produced always seems out of all proportion to the amount of metal lost so can easily block small passages. If that leads to salt build up then the rate of corrosion will increase so the whole process spirals out of control unless you regularly clean things out. Personally I would not leave an outboard in the water.

You've done what you reasonably can regarding the anode, and no a weld should not affect the perfomance but there must be good electrical contact between anode and structure. Ckeck it with a multimeter set to the lowest ohms range. Unless it's a "quality instument that can be zeroed compare the reading you get with the reading with the clps shorted together. (Check the continuity across the weld as well just to be sure about it.)

One of the troubles is, I suspect, that the anode on the outside gives virtually no protection to the insides. The general advice is that anodes should not only be close to what they are protecting but in "line of sight" of it as well. Just one of the reasons that outboards should not be left in the water IMHO.

 

[jonathankent]

Thanks for the advice. Ideally I wouldn't keep it in the water all the time, but.... it lives in the well as I didn't want to put one of the transom bracket jobs on (I think my boat looks better without it, and I get very good handling when under power with the prop right in front of the rudder). It is also quite a lump to start lifting in and out and moving each time. I have thought that all would be OK.... I have seen quite a few other that also leave them in continuously, and I would have thought that if it were going to be a serious problem then they wouldn't... maybe I am wrong. You begin to see my dilemma....?

I now also need to paint the lower half of the leg and tip. What paint is best for this, before applying the special antifouling? Would normal car paint be OK?

 

[VicS]

[ QUOTE ]
You begin to see my dilemma....?

[/ QUOTE ]

Oh yes I understand perfectly. You just have to live with the downsides in order to enjoy the benefits.

Re repainting the leg. The most important thing is the preparation as with all painting jobs. You must remove all the unsound paint, salt and corrosion products (aluminium oxide) The ideal way to do that is grit blasting with a soft grit. Then apply a suitable primer for aluminium. Followed by something like a chlorinated rubber paint. I'm a bit out of touch with that sort of thing now but at one time the group I worked with included a small paint technology section. That was good for getting small objects grit blasted and the supply of small quantities of specialist coatings as well as sound advice.

I'm not so sure about car paints. Hammerite may do the trick and they do a primer for aluminium, I think. I'm not madly keen on Hammerite although some people seem to be in love with it and I have mixed some to match the colour of my Evinrude. I know the paint technologists were unimpressed when they tested it. If you use it put on more coats than Hammerite suggest!