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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 20396
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 2005 VW Passat 1.9 TDI. I have just fitted new

Customer Question

Hi. I have a 2005 VW Passat 1.9 TDI. I have just fitted new brake pads to the front only but now the peddle keeps dropping to floor when the engine is running. When the engine is off there is a peddle. I removed the vacuum pipe from the servo, started the engine & there is a peddle but as soon as fitted the pipe back the peddle dropped to the floor again. I have bled the system although it didn't need it but still the same problem. I know that if you put pressure on the peddle & start the engine it should just drop away slightly but this one drops right to the floor. If there is a direct link from the peddle to the master cylinder how is this happening. Many thanks & looking forward to your reply.
Submitted: 1 month ago.
Category: Car
Customer: replied 1 month ago.
Hi its been 24hours since I sent my email but have had no reply!!!! Please advise
Customer: replied 1 month ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Matt replied 1 month ago.


I'd next try removing the master cylinder again and have your assistant push down onthe brake pedal to expose the pushrod as it exits the servo

on the end of the pushrod there should be a little adjustment nut

try screwing thisin a turn or two and put it all back together

this adjustment takes out free play at the pedal so its better to have a little bit of playr ather than too tight

Customer: replied 1 month ago.
There is no free play at the peddle, at least no excessive play. As I have explained there is a solid peddle when the engine is off but when I start the engine with my foot on the peddle it drops to the floor, when I pump the brake peddle it just slowly drops to the floor again. It's not air in the system & it's certainly not free play on the peddle. By the way there is no adjuster on the push rod in the servo.
Expert:  Matt replied 1 month ago.


OK as the next step I'd say to try is that its possible that you need to run the ABS pump to move any trapped air inside

the dealer method is to use the diagnostic tool to cycle the ABS during bleeding

however I've had good results buy just taking the car for short drive and stamping on the pedal at low speed to lock the brakes and trigger the ABS

and then re-bleed

Customer: replied 1 month ago.
Already done that, the brakes were power bled & still the same problem persists.
Expert:  Matt replied 1 month ago.


Ok in that case I'd say you may have an issue with the master cylinder leaking internally

So I'd suggest that this needs replacing as the next step

Expert:  Matt replied 1 month ago.


do you still need help?

Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

Customer: replied 1 month ago.
I replaced the master cylinder just after I changed the pads as I thought that by pushing the pistons back in the callipers I may have upset the seals in the master cylinder. That's when I power bled the system after bleeding the ABS unit. So no, that's not it. Sorry but you have been no help at all. I think it best that we leave it at that & I'll try to sort it myself. I've got a few things I can try, I'm not a fully trained mechanic but I do know how to use a spanner. Just for your future information the adjuster for free play on the pushrod is at the peddle. Thank you for trying to help. If I finally find the problem I will let you know for your records. So that's now 40.00 euros wasted & unless I receive a refund this will go to all the social media sites.
Regards, *****
Expert:  Matt replied 1 month ago.

hello Terry

you can request a refund like this

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