brown 'sludge' in outboard gearbox - how to clean?

[guyd]

I have been asked to service a mariner 4hp - it turns out the gearbox has never had an oil change - or not for a very very long time....

upon removal of the prop back plate and shaft, there is a coffee coloured (light brown) sludge, with bits in it of porridge consistency

1st thing I tried - which works for most oily stuff - diesel. No effect at all. Second, industrial thinners (proper Gunwash - not B&Q rubbish) - no effect at all - which is a bit scary. That cleans off all oily stuff that I have ever come across.

What the hell do you use to clean off emulsified EP90 marine grade?

 

[sarabande]

dunno what time schedule you have to complete this work, but it sounds as if your only option apart from blasting it out with a water jet, may be get hold of some biological oil cleaner, or enzyme based household cleaner, and leave it in the box for a while.

Heat might be useful as the melting point of emulsions is quite low. Pour v hot water on the casing gradually ?

 

[Anthony]

Try Jizer, best degreaser I have ever found.

Ants

 

[guyd]

personally I have had poor results with jizer / gunk - but maybe this time is different. Is it enzyme based <does google search> ah - not really - but washing powder is...

<scurries off and nicks the wife's powder>

lets see how good this is then!

thanks

Guy

 

[grumpy_o_g]

A steam cleaner may be worth a try - even the domestic ones are alright if you can get the nozzle right up against the crud. It don't half make a mess of everything within range though....

 

[markdj]

WD40, result!

 

[VicS]

I'd try paraffin first but then an emulsifying solvent such as Jizer or Gunk or even Polyclens.

Then drain and fill and run briefly with a cheap automotive engine oil before finally draining and filling with the correct outboard engine gear oil.

However it sounds as though the cause of the water ingress should be investigated. Could be as simple as the sealing washers on the drain and level screws. It could be that the propshaft seal has been damaged (Fishing line a suspect there) or it could be the drive shaft seal or even the seal on the shift rod.

The only way to identify the source of the leak is with a pressure and vacuum test.

If it were mine I would be replacing all the gearbox seals and renewing the waterpump impeller at the same time.

 

[guyd]

there was a fishing line wrapped round the propshaft. new seal there then.

The bearing housing / seal housing under the impeller is quite corroded - to the point where the metal base plate / gasket was slightly 'domed' up by the aluminium oxide, bu66ering the impeller. New impeller installed as a matter of course (dangerous tides here, you don't take chances). I reckon I can repair the corrosion with chemical metal or similar (1985 4hp isn't worth that much) - and yes - I know those last two statements are contra-indicatative....