Technical Changing Clutch Fluid

[s130]

Well almost at the end of my 50K mile service. Today was new front discs and pads AND brake and clutch fluid change.

Clutch fluid change has a BIG gotcha which took me ages to figure out.

eLearn would like you to use a power/pressure bleed process for both brakes and clutch. Personally I and many others (Fiat technicians included) prefer the old manual pump and bleed.

Brakes went fine. However the clutch fluid came out of the bleed nipple OK and the fluid in the back reservoir dropped BUT DID NOT fill again. Meanwhile the reservoir was still full of fluid. :bang:

It took a long time to work out that the clutch fluid reservoir WILL NOT self fill until the brake pedal is pumped! :yuck:

Needless to say in finding this all out the clutch master cylinder got air into it.

When I get a few hours to spare I'll Google this little 'problem'. This is the fist time I've ever come across this peculier behaviour.

Hopefully my experience and solution will save others a shed load of time, brake fluid and sanity.

 

[Radlet6]

Having an auto this really is not my worry, but I am intrigued to know why the clutch won't refill until the brake pedal is pumped - they are totally separate systems - aren't they?

 

[s130]

Well totally separate is what one normally finds/expect. A common fluid resevoir is pretty normal but for safety there is usually a "titanic" type vertical bulkhead/separator so that should say a clutch hose burst then only the clutch compartment would be drained. When topping up the fluid can flow over the bulkhead to fill the compartment.

(I gather on the Fiat 500 there is a really small separate fluid resevoir for the clutch hidden below/behind the main brake fluid resevoir)

The Croma resevoir appears to be totally different. Things I see are:

1) The filler opening has an internal wall/spout that goes below the fluid level
2) This down facing spout also has a divider wall sectioning it into a 1/3rd & 2/3rd sections
3) The clutch feed comes of the lower back right corner of the resevoir
4) The overall resevoir appears to be sectioned into 3 comparments. These comparments are roughly as follows
a) Front (a little over) half is for the brakes
b) The rear half is spilt into two. The rear left is about 2/3rds of the width of the resevoir and the back right the remaining 1/3rd.

When you bleed the brakes it appears that only the front half comparment drains. When you bleed the clutch only the small back right compartment drains. The back left remains steady.

When you press the brake pedal the back right compartment fills again, and I'm assuming it does this from the rear left compartment which is then back filled from the front main compartment.

I'm just wondering if this strange setup is some form of advanced safety feature although if it is I can't figure out what this feature is.

 

[Radlet6]

Well why have two separate systems like they did in the 1950's when you can complicate it like this?

It seems that not every innovation is progress - I take it this is yet again some weird GM thing?

I'm off to see how this works on the auto.

 

[s130]

It seems that not every innovation is progress - I take it this is yet again some weird GM thing?
/

Yup

 

[Radlet6]

It seems that not every innovation is progress - I take it this is yet again some weird GM thing?
/

Yup

 

[Radlet6]

I have had a look on the one on my auto and it seems to be a simple split 50/50 affair suggesting the reservoirs for the manual and auto are different.

Addendum:

Right, having looked at e-per: a closer inspection of my car reveals that the reservoirs for the manual and auto are indeed the same, but the tube that would feed the clutch from the rear section is crimped off.

So I am carrying a whole load of clutch fluid around for nothing. Everything makes sense now.

 

[s130]

Everything makes sense now.

Glad you think so!

Not sure where you saw the 50/50 split. Yes there are internal divider walls but filling the resevoir only fills the front half and nothing spills over to the rear 1/4 section.

Well least we know how odd this setup is and hopefully your MPG will no fall too much by having to carry that excess fluid :yum:

 

[Vento]

Not sure where you saw the 50/50 split. Yes there are internal divider walls but filling the resevoir only fills the front half and nothing spills over to the rear 1/4 section.

Non auto Croma. If I look into the brake/clutch fluid reservoir, there is a partition in longitudinal direction that divides the round fill opening in 2 identical parts. The fluid level is slightly under the top of the divider but in both halves the same. Does the level drop in one of the halves if bleeding the clutch by pumping the brake? BTW where do I find the clutch bleed nipple?
Thanks in advance

 

[s130]

What you see re: filler hole with longitudinal partition/wall is what I see/saw.

When I was bleeding the clutch the fluid was brimmed to the top of the filler hole and thus much higher than the longitudinal partition.

As for in which half the fluid dropped I can't recall. I was just so happy I was finally getting fluid into the rear clutch resevoir compartment and thus able to get the clutch working again.

The clutch bleed nipple is on top of the gearbox/bell housing but hidden by the air intake hose from the intercooler to the throttle body. This is the hose (humped shaped) directly to the right of the cylinder head between the head and the battery. You have to remove this hose to get access from the top. Unless you have a vehicle lift then access from beneath is not an option and even if you did have a lift I would still access from top down.

Note! The bleed nipple and combined quick connect union is all made in plastic and is delicate in that the whole assembly 'floats' around the connection union between the feed hydraulic pipe and the interface into the gearbox bell housing (the clutch slave cylinder is a co-axial unit fitted inside the gearbox bell housing). Two spanners will be required and a delicate method!

from the