How to you get a felicia 1.3 gearbox breather out ?

and

Can oil go through the middle of the speedo drive or is it confined to forcing its way past the drive's outer o-ring?

Any thoughts gratefully received

Do you mean the speedo drive when you say breather? AFAIK the breather (small plastic piece on the top of the 'box) doesn't come out.

To get more oil in you need to remove the speedo drive - remove the cable, remove the 9mm headed bolt that holds the square C-washer in place, and you can then pull the drive out; sometimes you need to rotate it in the housing (use the C-washer to do this) to get it freed up as they can stick in place. Then it's easy to fill, although using a long-necked funnel makes it much easier.

Thx. I've done what you said and still have the leak.

Either ...

a) there's some residual oil behind the speedo instrument panel

(How do you get the instrument panel out to check ??? )

or

having a floppy mushroom on top of the gearbox does not necessarily clear a block beneath it

(Although there was nothing wrong with the oil removed other than there being only 1 litre of it).

or

c) there's a perished seal in the speedo drive body + cable that allows the smallest amount of pressure to drive oil up.

(Skoda UK couldn't tell me about any seal in the drive+cable assembly and referred me to a retailer. I find it strange that retailers should know more about the internal composition of parts than the manufacturer of those parts. Perhaps its me??)

Incidentally I read about there being a seal on this forum. Was it in the drive assembly or in the cable?

Note: The plastic drive wheel easily separated from it's metal housing.

Is that normal?

Any help with this problem would be most appreciated.

Edited 7 September, 200916 yr by fpga

Where is the oil coming out of?

Its leaking down the back surface of the dash in line with the headlight adjuster knob and the radio i.e. its just dropping onto the left edge of the driver's rubber mat and into the square box molded into the transmission tunnel plastic ie under the dash and in line with with gearstick and I don't seem to be losing any brake or radiator fluid ie the levels haven't changed. However there was only 1 litre of gearbox oil in the box?

It's only supposed to be filled a few mm off the bottom of thhe drivegear used as a dipstick. The breather also needs to be clean and free to move up and down. I used WD40 with a cloth to clean mine up and it worked a treat.

You would be surprised at the amount of oil that the foam sound proofing under the dash can soak up.

Yeah, but I'd also be surprised if the speedo cable managed to pump 1.4 litres of oil out of the gearbox and into the passenger compartment. I can't see a way that this is physically possible.

That is certainly possible, I've seen it happen on more than one occasion. Warm gearbox oil, under pressure due to a stuck breather, gets pushed up the speedo cable (also the cable acts like an Archimedes screw and pumps the oil) and gets soaked up by the foam under the dash, only when the foam is completely saturated does it start to drip, by that time a lot of oil has left the gearbox.

Where is the pressure coming from?

The pressure comes from the heat generated within the gear box.

Your comments are very interesting

I've just removed the instrument panel and disconnected the speedo cable at the top and can confirm that cable is very oily at the top as is the back of the speedo clock and below.

The breather was stuck but was very easy to twist free and I have wd40'd it too.

When I twisted it it felt like I'd cracked a very weak "crust".

In my favorit manual it said oil 4 to 11mm up the speedo drive gear/dipstick.

I took this to mean from the the bottom of the cog bit of the plastic drive not from the bottom of the thing cos it looks like that bit sits in a hole. Is that right.

As the cog is about 11mm this suggests that you can just about cover the cog doesn't it?

By the oil at the top of the cable it looks like my speedo drive + cable still offers an easier root for pressure to escape than the breather suggesting that either

a) my now free running breather doesn't automatically mean its unblocked.

or

there is a seal in the speedo drive + breather that is broken and easier to get past than the breather.

How do I test the breather if its still coming up the cable instead or how to I ensure it's free?

I'm going to clean the cable and behind the clocks first.

If that doesn't work I'm going to get a "new" drive and cable from a scrap yard.

Any thoughts would be most appreciated. Its only cos of this forum that I'm this far!

Er, I'm not going to do the calculations precisely, but given the coefficient of expansion of air and an increase of 100 degrees C (which a gearbox goes nowhere near), then it would need to have an air volume of around 5 litres to displace 1 litre. And that's a worst-case scenario, giving a generous extra amount to the coefficient of expansion and also an over-the-top temperature rise. I don't think there's 5 litres of space inside that gearbox when it's got gears, etc., in it and also 2.4 litres of oil.

Secondly, the normal oil level in the gearbox is BELOW the speedo drive bushing. - I fail to see how the oil would then be able to get up through the speedo drive shaft as a result of this. An increase in air pressure wouldn't lead to that situation changing. It might happen with a design of box where the speedo drive is immersed in oil, but that's not the case here. So I'm surprised that this is happening, to say the least.

I take "bushing" to mean the guide hole that the smooth cylindrical bottom part of the plastic speedo drive (below the cog bit) sits in.

If the oil level is below this I'm not sure...

a) how the drive itself is used as a dipstick as per the Haynes manual for Favorits?

and

what lubricates this relatively "deep hole" bearing arrangement, since its only plastic and not something like phosphor-bronze?

I could do with knowing from where the 4mm to 11mm is measured if not from somewhere on the drive?

Your grasp of air pressure calculations is impressive and based on this alone I too would dismiss the leak's cause as speedo/gear oil too. I would add that the gearbox oil was also leaking through the linkage under the car. I cleaned it but have not checked since.

The position of the continuing leak once I had cleaned up what I could suggests something high and right in the dash.

I had no preconceptions about the leak's cause and simply monitored the fluid levels to see what went down.

Nothing did suggesting something hidden like gearbox oil which in turn suggested that levels would be low and that there would be oil running down the back of the speedo clock.

Both are now a reality.

There is a potential route up through the centre of the drive, which spins, and therefore must have a seal, of sorts.

If damaged/worn why couldn't this offer less resistance than the breather?

Someone above commented that the pressure is due to heat and I can confirm that very short journeys don't cause the leak whereas longer journeys, when everything is hot, do.

The scrapyard I was going to has got rid of their Felicia so I'll clean things up and watch for a while. Thanks for your thoughts and I'll keep you posted.

Edited 10 September, 200916 yr by fpga

Gearboxes run at temperatures approaching 80 deg C, this heat is dissipated by the oil, as the oil level reduces it can't dissipate so much heat, therefore the gearbox temperature will rise, leading to increased pressure if the breather is blocked. Also there is movement within the box which will physically move the oil closer to where the speedo drive/cable is.

Thank you for the info.

I've just come back from a scrap yard having failed to get the engine end of a cable off a scrapper which was up in the air. The engine was dead dry apart from a sooty deposit around the breather which my car doesn't seem to have. I got the rectangular locking plate off but the drive housing was solid in the gearbox, even after I "tapped" it! If I go again I'll take a chain wrench and a small right-angled nail pulling crowbar that i think might lift it in these tight working conditions if hit on the side.

Before I went I put the top of the speedo cable into a bottle. After 10+ miles nothing has come out and nothing dripped on the driver's floor mat. Theres a small drip in the square box under the radio so its still happening but at a seemingly reduced rate.

There's foam on the bulkhead where the speedo cable passes through and it's wet with the stuff. Now I can get at it I'll "lose" this foam as well and brake cleaner the area. I've got to do about 20 miles tonight so hopefully things will become clearer in the morning.

The possibilities are

Not enough pressure built up to cause the leak (I was doing 25-50 mile trips involving the motorway for bad leaks).

Breather is now clear and has solved the problem.

Its not a leaking speedo cable after all.

I'll post what I find.

Edited 10 September, 200916 yr by fpga

I've removed the foam I can get at ie there's still a bit behind the heater but if feels dry. I also removed the headlight adjuster system. Most of the fluid was gone but the drip that was left was blue and seemed like antifreeze. The leaking fluid is yellowy brown.

Gearboxes run at temperatures approaching 80 deg C, this heat is dissipated by the oil, as the oil level reduces it can't dissipate so much heat, therefore the gearbox temperature will rise, leading to increased pressure if the breather is blocked. Also there is movement within the box which will physically move the oil closer to where the speedo drive/cable is.

How is "heat dissipated by the oil". Where does the heat go? And given that 100 degrees isn't enough to make the magic pump work, how on earth would 80 (more like 60 given ambient temperature) do so? Do you really think that the speedo cable attachment to the drive on the fel/fav box is airtight? Etc... the list goes on!

fpga:

I'll save you some time: It's option 3.

Ok then genius... where else is all this gearbox oil making its way into the car then? And conveniently round the speedo drive cable?

Phil

Yeah, but I'd also be surprised if the speedo cable managed to pump 1.4 litres of oil out of the gearbox and into the passenger compartment. I can't see a way that this is physically possible.

i hate to say this darren, but you are wrong mate:O

i've had it happen on a few of mine too, i should imagine it's caused by convection of air with the gears and shafts turning at high speeds and oil being thrown up by the gears.

i've even disconnected the speedo cable before now and watched oil dripping out the end whilst the engine was revving hard

You might get a few little 'bubbles' of oil if you span the crownwheel hard - the speedo drive gear shaft has a spiral flute on it for lubrication. Just revving the engine up wouldn't do anything with that though, the crownwheel (and therefore speedo drive) wouldn't be turning.

Is it -actually- gearbox oil in the car? Unless the OP is olfactorily challenged, then I'd be surprised, as EP80/90 STINKS. Really badly. If I had 1.4 litres of it inside a car, I'd not be able to sit in it for long. And if it was actually coming out of the speedo cable, then it would like as not be dripping onto the feet/shins of the driver. And given that the OP also put a bottle over the speedo cable end and drove the car, and had no oil out of the cable, that doesn't seem to tie up.

Given your hypothesis, how does the air in the gearbox cause the gearbox oil level to rise above the normal level? Not just a bit, but by about 15mm - where it would need for this pumping action to occur? And then provide such a consistent pressure that it pumps this oil out of the box? Bearing in mind that you're saying that the gearbox is a sealed unit, so therefore the air needs to get back into it when it cools down.

You're talking about having lost 1.4 litres of oil. Get hold of that amount of liquid, and think about where it would be - it's a LOT of liquid to have in the car - especially of stinky EP90. Given the arrangement of the gearchange shaft on the Fav/Fel box and the way the seal works, plus the action of the shaft in the 'box, I'd say that's a far more likely area to check than thinking it's all being pumped out of the speedo cable. Every Skoda fav/fel gearbox I've had (and that would probably be about 30 of these) has leaked to some degree there. Several have leaked significantly, and only on long runs in two cases - one to the point of losing around 1.5 litres in 4000 miles. Why? Because the box is aluminium, and the shaft is steel.

If the oil level is below this I'm not sure...

a) how the drive itself is used as a dipstick as per the Haynes manual for Favorits?

and

what lubricates this relatively "deep hole" bearing arrangement, since its only plastic and not something like phosphor-bronze?

I could do with knowing from where the 4mm to 11mm is measured if not from somewhere on the drive?

Put the oil in until you see it at the bottom of the hole where the nylon gear will go. The oil level is right it it's just touching the bottom of the nylon gear (the plain bit).

guess i´m lucky, i put 3 litters of oil on the change 75W90 and have not got a problem, lubricated the speedo cable with ax grease and i gess it works to keep the presure in the gearbox.

by the way, taking a wack at how oil disipates heat, it spreads the heat throug a lot contact area that then disipates heat with the surrounding air (VW Beetle cooling system)

oil has 4 funtions one is cooling the system.

I couldn't believe it so I've held fire for a few days.

After 130+ miles I can neither see nor smell any leak whatsoever.

All I have done is

cleared the breather,

refilled the gearbox with oil and

cleared the sodden foam from behind the dash.

Either this cured the problem or the problem was cured before I bought the car and the foam was just acting as a reservoir for the leak, that was previously repaired.

The old lady I bought the car off told me that she thought she may have overfilled "the oil" because it only started a few days before I bought it. I struggle to see her topping up the gearbox oil and there was only 1 litre in it when I drained it?

Thanks everyone for your contributions.

I hope I don't need to come back on this one.

Edited 14 September, 200916 yr by fpga

How is "heat dissipated by the oil". Where does the heat go? And given that 100 degrees isn't enough to make the magic pump work, how on earth would 80 (more like 60 given ambient temperature) do so? Do you really think that the speedo cable attachment to the drive on the fel/fav box is airtight? Etc... the list goes on!

fpga:

I'll save you some time: It's option 3.

The heat is dissipated by the oil by conduction and convection. As the cold oil passes over the moving shafts and gears heat produced from the friction and the kinetic energy in the movement is conducted into the oil. As the oil is moving around the gearbox, it comes into contact with the metal gearbox casing. As the casing is cold and oil hot, a temperature gradient is set up, with heat from the oil getting conducted into the casing. The outside of the gearbox casing is exposed to the air to which the heat is transferred by convection.

If the gearbox breather is blocked there is no room for expansion, so the oil takes the easy way out, which in the these gearboxes is up the speedo cable. I am not saying that it makes its way all the way up the speedo cable solely by means of the pressure, but that the pressure starts it off at the bottom of the cable and the spinning cable acts as a mechanical pump similar to an Archimedes Screw.

I shouldn't think that the speedo drive is totally airtight (it does have an O ring seal), but it has less clearance than the inner speedo cable has with the outer speedo cable, thus providing an easier route for the oil.

What's on the rest of the list?

The heat is dissipated by the oil by conduction and convection. As the cold oil passes over the moving shafts and gears heat produced from the friction and the kinetic energy in the movement is conducted into the oil. As the oil is moving around the gearbox, it comes into contact with the metal gearbox casing. As the casing is cold and oil hot, a temperature gradient is set up, with heat from the oil getting conducted into the casing. The outside of the gearbox casing is exposed to the air to which the heat is transferred by convection.

If the gearbox breather is blocked there is no room for expansion, so the oil takes the easy way out, which in the these gearboxes is up the speedo cable. I am not saying that it makes its way all the way up the speedo cable solely by means of the pressure, but that the pressure starts it off at the bottom of the cable and the spinning cable acts as a mechanical pump similar to an Archimedes Screw.

I shouldn't think that the speedo drive is totally airtight (it does have an O ring seal), but it has less clearance than the inner speedo cable has with the outer speedo cable, thus providing an easier route for the oil.

What's on the rest of the list?

thank you, not only did you explained it perfectly but i guess now some people will apreciated how thermaldinamics play a role in all engine parts and funtions