How best to flush out a gearbox/ overdrive

[Tipidave]

I am making progress with my three rail d type overdrive that will go into my Herald 1200. 

I have drained out the old oil and it looked reasonably clean with no nasties in it. The magnetic sump plug had scavenged just a very few bits of fine metal adhering to the magnet.
 

I have removed the overdrive filter and cleaned both it and the magnetic rings. It did have small amount of grey sludge no sign of black clutch material so I am guessing not significant and nothing untoward. 

so… my question is do I need to flush both through with either duck oil or paraffin or similar? To be belt and braces, Or just refill with EP90 when the time comes? 
 

[Clive]

26 minutes ago, Tipidave said:

I am making progress with my three rail d type overdrive that will go into my Herald 1200. 

I have drained out the old oil and it looked reasonably clean with no nasties in it. The magnetic sump plug had scavenged just a very few bits of fine metal adhering to the magnet.
 

I have removed the overdrive filter and cleaned both it and the magnetic rings. It did have small amount of grey sludge no sign of black clutch material so I am guessing not significant and nothing untoward. 

so… my question is do I need to flush both through with either duck oil or paraffin or similar? To be belt and braces, Or just refill with EP90 when the time comes? 
 

I would just refil with some ep80/90 GL4. If worried, drain it after a few runs

I would also store it with at least some oil in it. 

[johny]

yes its not an engine where sludge from combustion products or emulsified oil can build up👍

[DVD3500]

Always get the box nice and hot before  a drain... that should get most stuff out... Use a magnetic drain plug to keep chunks out of meshy parts...

[johny]

Trouble is, this box isnt in the car yet😁

[Colin Lindsay]

I usually wash out gearboxes with petrol. Maybe it doesn't need it, but it sure brings the gears up nice and shiny.

[NonMember]

Nice shiny gears are great for if you're going to be working on the box, but if you're betting on it being OK as is and just fitting it, then I'd go with clive's advice.

[Colin Lindsay]

Sometimes, having seen the outside, I take no chances with the inside either...  But store with oil, never dry.

 

[Pete Lewis]

you could check th baulk rings are not bottomed out  by just lifting the top cover 

i would go with clive  just fill with ep90 GL4 oil and see how she runs 

best not to store a box up ended any debris goes into the input bearing 

the awful gunge on the filter rings is pretty normal 

 

Pete

 

[Tipidave]

Thanks for the info. It was sold as a working concern so I think I will fit a new end seal on the overdrive and a couple of new gaskets and fill up with oil. 👍👍😀

[johny]

Yes maybe the front seal as well (if its not a scroll type) as its very easy to do and only needs the bell housing paper gasket to finish. Also dont forget to check the wear of the input shaft support bronze bush tucked in the end of the crankshaft...