Lupo 3L 1.2 Tdi hydraulics issue

Good evening all, I lurk around here a lot looking for glimpses of help for my Lupo 3L I belive is shares its engine with the A2 3L. Anyway, im hoping someone on here can back up a theory i have about an issue wiht my 3L. I am struggeling to find info becuase most of the owners sites are in German or Dutch.. Anyway, here goes,

This week my lupo started using a lot of hydraulic fluid, it was leaking out at quite a rate. On investigation today it appears that the fluid is being forced out of the expansion tank relief hole. I have removed the expansion tank and the oil is weaping from the connection to the clutch slave solenoid valve. Marked as "T" on Pg 10 of this pdf.

http://www.volkspage.net/technik/ssp/ssp/SSP_221.pdf

Video of my leak. Hardly any pressure in the system, most of the oil has been purged.
https://www.youtube.com/watch?v=5JijG30LJIM


Does anyone know what could cause this, under pressure a lot of fluid is being forced out of the relief hole in a pulsating motion. I have developed a theory, but id like someone with expertise to confirm or call me a idiot.


I have a feeling that all of this can be traced back to the door switch. The one that detects if the door is open. It also acts to start the hydraulic pump so that the pressure is built up by the time you start the car.
*My switch failed a couple of months ago. My pump only initialises now with the ignition going on. This means you can start and potentially drive away with low pressure.
What happens is that you select a gear, release the brake and press the accelerator. With low pressure the gear hasn't been selected but the car tries to move. When nothing happens the car thinks the clutch hasn't bitten. So it adjustes the bite point. *The problem is that it was wrong, and the clutch is now incorrectly adjusted. The car is violent to pull away or in the worst case stalls.

So. According to page 10 of the PDF. The connection in my video that's leaking goes to the clutch slave solenoid valve. If you read on it says that it can have a position that's 20% clutch bite.
Now, I think my car has potentially adjusted itself so that this solenoid is not fully closing and allowing constant pressure back into the expansion tank

If I'm right, I wd40 a switch in the door lock, refill with oil, and perform a basic gearbox setting and all should be ok in the future.


sorry for the long post, im kinda lost in a sea of German and Dutch forum posts

Cheers

Kieran
 
Oh, one more thing. When the fluid was pulsating out of the expansion tank, i noticed the clutch slave cylinder was also pulsating in and out slightly.
 
The system will work without the door switch; you'll just have to waiit longer to start. It will make no difference oherwise. Your leak out of the expansion tank is caused by over-filling. Disconnect the hydraulic unit electrically and loosen accumulator half a turn. Oil level should then be within the rectangle on the reservoir. Re-tighten the accumulator and re-connect the hydraulic. Give the car a basic setting (and every 30,000km) and everything should be OK. A new door switch will be resquired; WD40 will not solve the problem.

RAB
 
If the reservoir was correctly filled (as above), the leak from the reservoir cap would be caused by a failed non-return (check) valve between the pump and the reservoir.

RAB
 
Good Morning Rab,

Thanks for your quick response. Just to clarify and to add all the details i know. I have been losing hydraulic oil all week. This only started since i was a bit impatient and tried to drive off before the gear had engaged causing to creep point to be adjusted. The car is just about drive-able with the current creep settings.

Can you confirm that the car will not start with low hydraulic fluid? This was my first issue last Monday. I put some more fluid in and the car starts fine. Or did i just get lucky?

Do you not think my theory about the creep point / clutch adjustment being modified is correct?

I have just ordered some more oil. Ill try and do the basic gearbox setting this week (my first ever) and also order a new door micro switch.

Thanks once again for taking the time to reply.
 
If the reservoir was correctly filled (as above), the leak from the reservoir cap would be caused by a failed non-return (check) valve between the pump and the reservoir.

RAB


I also suspected this. Is the non-return valve replaceable? It appears to be a solid block of aluminum when i inspected it last night. I removed the pump motor but couldn't see how to get any deeper into it all.
 
The car will not start with insufficient pressure. The creep point and clutch adjustment only occur at a basic setting as far as I am aware. If it was self-adjusting there would be no point in a basic setting. There are two seals between the reservoir and the hydraulic station and O-rings on the underside between the tubing and the body; these are likely leak points.

I don't think that the non-return valves are replaceable but they should be removable. There is probably some debris holding it open.

RAB
 
Update.

So, i finally got around to putting the hydraulic unit back together and ordering the unlock code for VCDS. I also replaced the door lock so that the car knows when the door is open.

I ran though the basic gearbox settings and it immediately fixed the cars violent creep/clutch bite issue. And since then it has not lost any oil or failed to start like it was before.

So, all i can say is that i am convinced that the faulty door lock switch started the issue which meant i could attempt to drive off with low pressure, this made something adjust that only the basic gearbox setting could resolve.

Ill report back if anything fails again but its looking like the Lupo will live on a little longer

Big thanks to RAB for your help.
 
The door switch only starts the pump earlier so you don't have to wait so long (or not at all) when you switch on. It doesn't allow you to drive off with insufficient pressure. You just needed a basic setting (and every 30,000km).

RAB
 
Good morning all (especially RAB :) ),

So, its been over a month since i repaired the door lock and did a basic setting. since then, i have had to do a basic roughly every 1.5 weeks (1000km's). I cant explain except it seems like the car loses calibration of the clutch position or creep . It gets gradually more violent until it simply wont engage a gear the next time i try and drive it. This morning it lost all drive while on the autobahn. A quick basic setting after i coasted into a service station as fixed everything again.

The oil level is fine. all the measurements when doing the basic gearbox setting are correct. I also get 7 shifts in tiptronic mode before the pump kicks in. Any ideas whats going on?
 
You might need a new clutch actuator. It sounds as though the actuator potentiometer (which measures position) is faulty. Look on the German site for possible repair. Otherwise replace.

RAB
 
Thanks RAB,

just to be sure, by clutch actuator do you mean the slave cylinder? Part number 6N0142063D ?. If so ill try to find one over lunch and fit it at the weekend
 
Correct. However you mentioned an unlock code earlier. Genuine VCDS doesn't have an unlock code; anybody can download the software but it requires a genuine lead. So you are presumably using something else. Somebody else on here, possibly using the same software, claimed that early 1.2Tdi PD's didn't have creep adaptation. We have a very early Lupo 3L which most definitely does have creep adaptation. Not so long ago it somehow lost its creep adaptation and was completely unusable; a basic setting restored it. So your problem might be software related but more likely a faulty clutch actuator.

RAB
 
Back
Top