SAE 140 Gear Oil

[Gannet]

With the unsealed early gearboxes and by now with worn bearings, oil leaks out and water seeps in to produce the custard colour emulsion with which we are familiar.
With the small unsealed 10:21 boxes used on the FVs and SJMs, the small quantity of oil, relatively quickly becomes custard colour and often with water droplets as well. So I always drain the oil after every outing and refill the gearbox. I used to keep the emulsion in a jar so that if it separated out into oil on top and water underneath, l could reuse the oil. However natural separation often didn't occur.
What l now do is to boil the emulsion in a saucepan. (Its best if the woman of the house is away at this time!) The process seem very successful in that the water appears to be driven off to leave good looking reusable oil. I have found that a temperature of about 125/130deg C seems to be required. An oil of a similar viscosity from the same manufacturer had a flash point of 260deg C, which gave me a bit of confidence that the house would not be a charred ruin when she retuned!
I know SAE 140 is available and is not really expensive, but this reuseability encourages me to ensure that l refill these small gearboxes after every outing.
I always fill them up in the sensible manner recommend by BS for the FV, which is to lay the unit down horizontally and fill the box right up to the filler. The oil capacity is only about 70cc.

Jeremy

[headdownarseup]

Certainly some food for thought there Jeremy.

To keep things simple for now let's try to keep any comments to this topic within the scope of the "classic" non-sealed gearboxes.
Keep it old skool.

I do similar things with my old 102's as well. Fill them right up till you can get no more in them just like the smaller gearboxes. According to some old paperwork i have, with a 102 gearbox it makes no difference to whether it's a clutched or direct drive box. FILL THEM TO THE TOP. All of mine are just fine like this, no trouble with them at all. Depending on how worn the bushes actually are will depend on how quickly a water/oil emulsion will take place. My thinking with this is that with an oil quantity that is equal to the available space within the gearcase (in other words NO AIR GAP for expansion or contraction) there's less of a chance that water will mix with the oil as quickly as if the oil were only half filled. These gearboxes both big and small under normal operating conditions are fully submerged under water with all the cooling they're ever going to need, so it's hardly like they're going to get hot.
Another basic maintenance requirement that often gets overlooked is the length of time that oil has been inside the gearcase. From memory BS recommends every 10 or so hours before an oil change is required. Why then do so many people (not including the regulars of course) neglect to do this! Oil is definitely cheaper than a replacement set of gears and/or bushes. Most people these days change the oil in their car's engine every 6-12,000 miles (depending on what you drive i suppose) but the dear old seagull seems to get nowhere near as much attention and it's still expected to perform without fault???


I wonder why then in later publications up into the late 60's the recommendation was to only half fill the gearbox, as if to only cover half the prop shaft and half the gear surface? This never made any sense to me, and still doesn't!


Jon

[Charles uk]

Jon I agree that in the case of grease nipple gearboxes "fill to the brim" was Seagulls instruction, even though this left large air voids inside the box, I've only ever seen 1 FV series owners manual & don't remember noticing a fill with the motor horizontal instruction, it would be nice if Jeremy could post a picture of this page.

Though I'm not sure I'd agree will filling unsealed oil cap boxes right up, I can see no benefit unless replacing your bearings are beyond your abilities.

It's really a matter of personal choice.

[pat777]

Jeremy

Can you describe in more detail what actually happened when you heated the emulsion up in the saucepan.

Did you have the hob ring on full heat?

Obviously I'm familiar with a deep fat fryer and the bubbling effect when loading wet chips in to hot oil as the steam evaporates.

I guess you had a lot of steam, once the oil heated up, and did you end up with the oil looking the same colour as new oil?

[headdownarseup]

Sorry Charles, my older 102 boxes don't have any "air gaps". No sir. No way.With or without nipples. Right to the brim. Firstly i fill them with the end cap removed (pain in the .... if it hasn't been removed since the year dot) and then refit the end cap. Then i squirt a bit more oil into them with a gun (sometimes with the box on its side with 1 nipple removed so the air rises to the top, keep pumping till i can see some oil oozing from the prop shaft bush. Basically what it says in the older operating instructions. Word for word. No air gap, just oil.


Now, what you're forgetting Charles is that not every seagull user on the SOS site is as mechanically minded as some of us on here. Some people's pockets are deeper than others and so a more sympathetic approach is needed for those with shallower pockets. Some people can carry out their own repairs, a LOT of people can't for whatever reason. Fast forward 30 or 40 years and things aint what they used to be. And let's face it, some folks just can't be bothered.
Just keeping it in the real world.

Jon

[Charles uk]

Sorry Jon I wasn't talking about filling them with straight SAE 140 but with something with a similar viscosity to the Castrol K70 they were meant to be filled with.

The bearing clearances were designed for something around SAE 420 when they were new, that's why many users use 140 thickened with a suitable low additive grease to a cold tinned custard viscosity.

This only refers to the lower units fitted with oil/grease nipples.

[Gannet]

Pat,

The emulsion heating procedure was quite straight forward. I heated it up on full heat, but keeping the saucepan moving all the time as well as stirring it at the same time. The emulsion level rose up at one stage, probably when the water content started to boil. Then after a few minutes this subsided and I was able to see the neat oil. At this stage, all the water appeared to have been driven off. After letting it cool, I poured it into a jar. The colour of the oil was slightly darker than the original oil. I now reuse this 'reclaimed' oil in my gearboxes.
It is a very simple procedure and is it does not involve throwing away oil, it should encourage us to drain and refill after use and before engines are stored for their next outing.
I have seen too many small (10:21) gearboxes ruined by inadequate attention to keeping them full of oil.
Please let me know how you get on with this procedure. I have only carried this procedure out on one specification of Gulf 140 gear oil, but I would expect other manufacturers 140 oil to probably behave in a similar way.

Jeremy

[Nudge]

The emulsion heating procedure was quite straight forward. I heated it up on full heat, but keeping the saucepan moving all the time as well as stirring it at the same time. The emulsion level rose up at one stage, probably when the water content started to boil. Then after a few minutes this subsided and I was able to see the neat oil. At this stage, all the water appeared to have been driven off. After letting it cool, I poured it into a jar. The colour of the oil was slightly darker than the original oil. I now reuse this 'reclaimed' oil in my gearboxes.

This works ok, But... Only if the motor has been used in fresh water! If you try it once the motor has been in salt water you end up with a large build up of salt in the oil. Not so good!

[Gannet]

A salt build up?

An interesting point. But will a few molecules of NaCl in oil really make the mixture corrosive? Corrosion is complex in a gear box. With the wrong mixture of metals - bronze, steel and aluminium for electrolytic corrosion. Then add water and oxygen for steel to rust. I am really not sure how it exactly works - its complex that is for sure. Perhaps the NaCl might counter the acidity (?) of used oil?
I will have a think plus some tests.

Jeremy

[Keith.P]

I think we have all seen the large salt crystals in gearbox's and the pitting that goes with it, which I think points to the motor being used in salt waster, obviously, as the gearbox is getting refilled with water every time the motor gets used and then the water is evaporating when the motor is not in use, this will build up in to salt crystals over time, so with reusing gear oil and evaporating the water content off every time, over time you will have a very high salt content in your oil, will it start to crystallise at some point? or will it increase the rate of corrosion and pitting in the gearbox?

[Nudge]

Here is a photo of some gear oil that has been sitting on the window sill in the garage for a month

it is quite easy to see the good unemulsified oil on the top

Now take a look what has dropped out!

Do you want that back in your gearbox? I don't!

I can only guess that the black dots are water drops.... but then again who knows.

If I get time, I will give this oil a cook up just to see what it does. Then I will put in back on the window to settle so we can have another look.

Don't know why all of the pics are 90 deg? but you get the idea!

[Gannet]

Keith,
I think that you have raised a very fair point. I think repeated boiling up would eventually produce a salty oil mix, which is something not required! Its back to the drawing board for me! Although I think the occasional boil up will do no harm. Thanks for pointing out the obvious to me!

Nudge, I was not suggesting reusing the contaminated very awful oil that you have shown. That is just fit for throwing away. Thanks for making the comment about the eventual salt build up. I hadn't fully considered that aspect.

Jeremy