I've just completed the purchase of a 1.6TDI 2012 Yeti Greenline that has a very heavy clutch pedal. There's a story behind this - three weeks ago the owner was driving the car and without warning the master cylinder 'went' and lost its fluid. He had it towed to an independent repairer who fitted a new master cylinder. Prior to the moment it failed there was no warning and the clutch pedal had always been fairly easy to operate. The heavy pedal was noticed immediately when he collected the car and he took it back to complain. The garage said it was bled properly and there isn't a problem.

 

However, the pedal is ridiculous and it's not possible to drive the car very far. I've got a good discount on the asking price and now need to get to the bottom of the problem. I have a vehicle inspection pit so can get underneath the car to work on it. I don't intend to take it back to the people who changed the cylinder.

 

Is there anything that I should be looking for that a garage could have done incorrectly, or any steps I should take to diagnose the problem? I did notice that when the clutch is operated there's a creaking noise in the engine bay. I'm new to the Yeti, but have worked on quite a lot of vehicles over the years.

 

Thanks,

 

Mick

I am sure you appreciate that the clutch hydraulic system obtains its fluid from the brake master cylinder reservoir.  The clutch action is normally quite light, so if it is at all heavy then something is wrong.  You say that the original brake master cylinder lost all its fluid.  Sudden failure is rather uncommon, unless a seal gets "flipped" and distorted. Where did the fluid go to, remembering that it acts as a paint stripper ? Check that the air vent in the master  cylinder reservoir cap is functioning OK and you are not getting a partial vacuum.

I didn't know they were shared so that's useful to know. I only collected the car today and the seller had organized in advance for the garage to take another look at it. They agreed the pedal was way too heavy but insisted it was normal when it left them and the problem is a seized clutch, which they also said was the reason for the master cylinder failing in the first place and it must have been heavy prior to it failing. It's not their responsibility. The seller disagrees, so I'm still going to have to sort it  out. I did ask the seller again for a more detailed account and he's 100% adamant that there was nothing wrong beforehand and he replied;

 

"I recall the breakdown incident very well. Had driven normally for half an hour then in slow moving traffic pushed the pedal down to disengage the clutch, which I assume it did but the pedal never returned. I was stuck. The AA man recovered the pedal back and pushed it down while I was looking under the bonnet to find hydraulic fluid leaking out behind the brake fluid reservoir. He topped up this reservoir and towed me (to the garage)"

 

He re-confirmed that the clutch pedal was behaving normally immediately prior to the breakdown.

 

The garage did say that the slave cylinder is external and they'd removed it to check it and then refitted it.

 

My next stage is probably to inspect the work that's been done to see if a mistake was made - could the slave cylinder be incorrectly fitted or a pipe kinked? I don't have a workshop manual right now and access is really tight and I'm not yet familiar with the layout or what needs to be removed to get access. I did give the area another wash off with traffic film remover then fresh water but I'll need to remove the undertray to get a better look to see if there;s any paint damage.

 

The car drives and I got it home (18 miles). There are no  unusual noises whilst driving, other than the creaking sound that appears to come from beneath the battery /air filter when the clutch is operated (no engine running).

12 minutes ago, Mickeyluv said:

The garage did say that the slave cylinder is external and they'd removed it to check it and then refitted it.

 

They were not looking at a Yeti if that was the case because the slave cylinder is in the bell-housing so needs the gearbox and bell-housing removing to get access to it.

I've taken a look at what work has been carried out. It doesn't look good. The master cylinder is dripping with fluid and there's a large tie-wrap around it. The corrugated feed pipe from the reservoir is leaking at both ends and needs replacing. For some reason the 'new' cylinder is smeared with copperslip when viewed from the pedal side within the car. In fact, given that the cylinder is supposed to be fitted less than three weeks ago there's a lot of caked-on crud around it. The feed pipe to the bell housing is unclipped and loose and the bleed screw cap is missing. It;s also soaked with fluid in that area.

 

On this car there's an external plastic cylinder attached to the bell housing with a bleed screw on top and clip-connected pipe from the master cylinder.  If I put my hand on it when the clutch is operated I can feel it as it makes the groaning noise. Either its transmitting this from elsewhere, or it's making the noise itself. I would have said this was the slave cylinder, but I've never worked on a car with a concentric actuator within the housing. if the  slave cylinder is inside the housing, what's the purpose of the plastic cylinder and is it likely to be a source of the problem? To the touch it feels very creaky and rough as the clutch is operated.

 

 

 

 

 

 

What you are describing sounds like bodgery.    On a modern car there should be no trace of leaking fluid or dampness. I have never heard of Copaslip being used in that area, it's principally meant as a high temperature anti-seize measure for metal-to-metal joints.  The reservoir and fluid is also part of your braking system for heaven's sake. The last thing on the car you want doubts about. 

 

If the slave cylinder piston is partially seized, or the clutch itself has a fault, then the clutch pedal action will become much harder, and heaving down on it will raise the pressure in the clutch hydraulic circuit to higher than normal levels. I don't know what these pressures are, but I would imagine normally a few hundred PSI i.e. considerably lower than in the braking circuit.  So it's possible that the elevated pressure is overcoming a seal somewhere, leading to the fluid leakage.  Suggest you find an independent VAG specialist who knows what they are doing.

Edited 26 July, 20196 yr by Austin 7
additional info

Agreed. Does anyone know of a good and trustworthy independent specialist in North Staffordshire? 

 

What I would usually do in this situation is remove the slave cylinder and set it up so the travel can be limited to prevent the piston being ejected and see if it operates smoothly away from the housing. Urrell says the slave cylinder is in the bell housing but after looking at the parts list It looks to me like what I have is a regular external cylinder that can be removed once the battery tray, air filter assembly and gear linkages are removed -I may be wrong. The master cylinder also looks straightforward to remove - disconnect hoses + wiring, release the rod from the pedal and twist to unlock and remove. I've recently overhauled a Mistubishi Pajero clutch hydraulics and the Yeti looks a lot more straightforward.

 

I think at this stage I'd like to establish whether the slave cylinder is binding or not then consider which way to go. If there's a good garage nearby I'm happy for someone else to do it. Sometimes working on cars gets to be a bind.

 

No doubt others have more detailed knowledge, but given the variety of different transmissions used in the Yeti (Is yours 5 speed ?) it wouldn't surprise me if some had internal slave cylinders and others had external.  I think your plan of action is on the right lines, but you might need a glamorous assistant !

Just an idea, some old 70s cars I've worked on had different master cylinders (mc's) available depending  on the engine  type fitted. The bore size of the mc varied. Fitting the wrong one would result in either a very heavy clutch or that the clutch wouldn't dis-engage. 

 

Is there a way of checking if there are alternative mc's, and that you have the correct one?

I would want to see the receipt from when the garage that fitted the master cylinder to see exactly what they did do.

It just says 1 m/cylinder + labour. It's interesting that the mechanic said he'd removed the slave cylinder to check it. It is external on this car, but I can easily see that it's never been removed and the rest of the work shows they aren't trustworthy or competent. If the weather clears up today I'm going to remove it and see if it's the problem. In any case, I'd need to replace the allegedly new master cylinder, supply hose, and o-rings as well as the connector or section of harness (they levered it out and broke it).

 

There are different part numbers for what externally appears to be the same master cylinder as they're used in many different vehicles. I suppose the best way is to go to a main agent and buy the parts because at the moment I can't be certain which part is correct, as I don't have the specific parts list for this car. It could be that they fitted a used master cylinder off another vehicle and the bore size is incorrect and any part number present could be misleading.

 

The creaking from the slave cylinder is perhaps my main concern, though there are so many problems the whole lot should perhaps be replaced.

If the Master cylinder bore is too large, not only would the pedal be harder, but the slave would be travelling farther than normal (more fluid being forced in) and that could be the cause of the creaking?

 

It could be. I'm unsure about the master cylinder - to me, the more I look at it, the more it looks like a second-hand part. I removed the air intake assembly yesterday to get a close look at the slave cylinder. There's no way the garage had removed it (as they stated) - nothing had been touched around this area, other than there was a puddle of fluid on top of the gearbox. It points to them bleeding it with a socket on a long extension and just letting the fluid pump out. That's why the bleeder cap had not been replaced.

 

I did unscrew the cylinder to the the extent where I could manually compress the piston. I had a helper just apply general pressure to the pedal and when the piston extended i could easily push it back.  I'd previously attached a length of bleed hose to the opened bleed screw and the pedal easily went to the floor, so no resistance in the pipework and the master cylinder is operating smoothly.

 

Overall then, apart from the leaks and bodges, there's free movement in the hydraulics. There is however a very good chance that the master cylinder is incorrect. I can't see a part number on the body but It needs replacing anyhow.

Hi Mickeyluv.

 

I'm not convinced by the theory that the Master cylinder has been replaced by an incorrect one with a much bigger piston area, but I guess anything is possible given the standard of work you are reporting.

 

It would seem from your tests that the Master cylinder, pipework and Slave cylinder all work together OK when not being asked to generate any appreciable force.  This leaves the possibility that something in the clutch mechanism from the slave cylinder onwards is faulty and offering abnormally high resistance to movement, especially as you earlier noted creaking noises from that area. So it could be that the garage were barking up the wrong tree and looking at the wrong part of the system. I just wonder if you could rig up some sort of temporary manual lever in place of the slave cylinder and see how much force is needed to release the clutch, though even a normal clutch might need a fair old push at that point.

 

In the past I have had an instance of a clutch driven plate on a Polo wearing abnormally such that one of the coil springs suddenly broke free of its stamped retainer and jammed the mechanism so that the (cable) clutch couldn't be released.  The drive to the garage was "interesting" !

I've been attempting to cross-reference master cylinders to see if there are any bore differences. There are different bores for different models other than the Yeti, but then again it's difficult to tell from the pictures whether any of the larger ones could fit the Yeti. Within the confines of the model-specific types by different manufacturers there are only fractional differences of a few 1/10ths of a mm. not enough to make any difference. 

 

Something doesn't add up. The garage claims it replaced the master cylinder, but to me it looks used. The AA man looked under the bonnet and saw fluid leaking from behind the brake fluid reservoir. Now, if the clutch cylinder had failed any external leak would be on the pressure pipe connection or inside the car. If it was an internal leak past the seal then there's often no external sign of leakage. Given that the master cylinder is not readily visible without removing the heat insulation (almost impossible with a hot engine) and there was visible sign of fluid leaking from behind the brake reservoir, this points to the supply hose leaking. It still is leaking. Who knows what happened. Maybe it leaked anyhow and the seal went inside the cylinder but the leak didn't cause the fault. Maybe the clutch failed simply because the fluid leaked and it fell to a critical level and pulled in air? Against this is the description by the owner that the clutch behaved fine right up until it failed, with no harder feel or prior warning.

 

Fully removing the master cylinder is more involved than the weather is permitting at the moment - there's a gearbox support in the way amongst other things. It was originally my plan to get some leverage on the clutch fork to see if it moves. 

 

 

 

Well, this is not Yeti-specific, or even VAG-specific, but my experience of vehicles with shared hydraulic reservoirs is that the clutch (and PAS, suspension) takeoffs are higher up the reservoir than the brake takeoff, so that you get some form of "elegant degradation" in the event of a leak because the brakes lose hydraulic assistance last.

 

So I'd suggest checking the "brake fluid" level and if it's low check the reservoir and brake master cylinder for leaks.

I mentioned in an earlier post that the clutch cylinder supply pipe is leaking at both ends. New parts on their way. Rather than being a regular hose and clips, this one is a corrugated plastic pipe with rubber fittings at either end. It looks like its designed to be a quick fit at the factory, but I can't see it being as good as a regular hose. The manual also warns against pinching it off when working on the rest of the system as it will be destroyed.  Brake connections and the rest of the system are fine.

An update on this - I just noticed that the over-centre spring assembly is missing from this car. I'm not sure how much this helps with pedal effort - on Landrovers that i've had it makes a massive difference.

 

It's shown on the parts list for 2009 onwards, but this doesn't necessarily mean it wasn't deleted by 2012. I wonder If I may trouble someone with a 1.6TDI to take a quick look at their pedal  from inside the car and see if there have this spring fitted? It's located above where the piston rod connects to the pedal. 

Edited 2 August, 20196 yr by Mickeyluv

I don't suppose there is an over centre spring still rolling around on the floor of the original repair garage is there ??

I thought of ringing them, but I wondered if they'd see this as an admission that the clutch was not right when it left them. I do';t really want to have anything more to do with them as they're incapable of either doing a good job or telling the truth.

 

I did confirm this model was fitted with the spring. I wonder if out local TPS has one?

An update to this saga;

 

I did as much as I could to diagnose the issues and everything pointed to a sticking clutch release mechanism. I took the car to a transmission specialist and they replaced the clutch and any worn components, using LuK parts. They saved everything removed for me to inspect. The clutch was completely worn out right down to the rivets and the friction material badly glazed. There was a large quantity of dust and this was tightly packed in the splines (and a total absence of any lubrication). In addition they said when they came to remove the gearbox they found the gearbox mount was loose.

 

The car is utterly transformed.

 

The clutch is now really smooth and light - especially now the over-centre spring is installed. The bite point is closer to the floor and the progression is excellent.

@Mickeyluv- Well, it's possible that $vendor had just got used to the heavy clutch. What sort of mileage has the car done?

180,000 miles  - most of this over the past three years. Otherwise well-maintained. I think it would have progressively got heavier and if he could have done an A-B with how it was three years ago and how it was before it failed, he'd notice the difference.

Cheers; I'd say that really is "one of those things" then. On the plus side, the replacement might do a similar mileage.