06 S60 R non-responsive brake pedal at startup Topic is solved

[oragex]

Good to know about the pump. Not sure but I think some years the S60 didn't got a pump?

My booster went at around 110K miles so pretty low. But they go bad simply because the lube for the seal dries out.

Mercedes and other european cars have the same booster (and same issue), Ate is a pretty common provider for these brands.

[cn90]

- Thanks jimmy57 for the info on electric vacuum pump, all these years I could not figure out why these mfg's installed the electric vacuum pump.

- I did a quick search for my 2004 V70 2.5T (car runs fine but just want to list the PNs in case others need them later):

1. ATE Brake Booster 30793673 (w/o DST) vs 30793674 (with DST).
About $140 at rmeuropean dot com etc.

2. Booster Seal Kit PN 308477016 about $30 for URO.
I don't know about the quality for these seals, but seeing URO name...hmmm.

3. Brake Booster Switch PN 31400692, about $65 at rmeuropean dot com etc.

[mrbrian200]

Ok, so the booster piston seal silicone-teflon grease dries out eventually causing a seal failure (due to friction between the seal and the piston). Can the back of the piston (behind the brake pedal) be accessed without removing the booster from the firewall? IE long term preventative maintainance = rub some fresh grease on the piston once in awhile assuming as you use the brakes it would work itself into the seal.

Being a rubberized seal one would absolutely not ever use lithium, petrol, or petrol-like synthetic base greases as that would risk swelling/softening near guaranteed destruction of the seal.

I noted that Jimmy57 mentioned the pump should run momentarily, but turn off after several presses of the pedal in KPII. If it runs a little with each brake press, but doesn't otherwisse run if you leave the pedal alone or while the engine is running, and does appear to hold vacuum in the system overnight, this seal is still working but--- has seen better days in that it's letting a little more air slip past when pressing the pedal than when new. In this very early wear stage, maybe fresh grease is all it needs to stay 'happy' for several more years?

[oragex]

I think the seal takes some time to fail, when it runs out of grease. So yes, greasing the white plastic (with the correct grease) it's a good practice and even if the seal is not in the best condition it will certainly extend it's life - even in terms of years. A must do on all cars.

[erikv11]

However, the white piston on my car's booster has a shiny grease film on it, I confirmed that with my finger, yet the seal is clearly failed.

I'll try it since I'm not going to replace the booster now anyway, does this grease look good (Super Lube 92003 Silicone Lubricating Grease with PTFE)? https://www.amazon.com/Super-Lube-92003 ... 0081JE0OO/

Here is a potential hangup to greasing the piston periodically: the dust boot on my car tore very easily when I tried to re-seat it yesterday. Unless that boot is replaceable - anyone have a part number? I only saw it as part of the booster.

[erikv11]

The car is fixed. No more brake pedal issues, the pump comes on if I bleed down the vacuum with the key in position 2 or disconnect a brake vac line, etc. . Here are some final details to close it up:

- Intstalled a used brake booster vacuum pump from the junkyard, from an 08 V50, same item.

- When removing the pump frmo the S60, just unhook the bracket (2 bolts, 10 mm socket) and drop the pump down attached to the bracket. The bracket on the V50 pump was different, I had to swap the replacement pump over to the S60 bracket.

- To release the vac line on the brake vacuum pump, press on the green connector tab while pulling the hose off the pump nipple. To reinstall the hose, just push it on until it clicks.

- All works great except for the leak in the booster seal. This weekend I will re-grease the piston for good measure (I bought the grease from Amazon), but as I mentioned the piston is already/still greasy from the factory - the seal failed without ever drying out.

- I'm expecting the replacement pump will eventually fail, at which point I will either fix the booster seal or just put in another sacrificial pump - it is a super easy install.

- Here is a super useful link with clear and simple instructions for testing the booster pump switch: viewtopic.php?t=43817 . The switch on my car tested out fine so I left it in place.

[oragex]

I don't have a part no. for the grey cover, but it's easy to replace with a used one off the junk yard, maybe have a look here @2:30 when disconnecting the brake pedal www.youtube.com/watch?v=jKcDOLIYR3A

Here's how I greased the seal, it may help a little even if it's already damaged a little. It is very possible that the old original grease will lose its properties after several years, causing the seal to not get lubricated as it should which gets it to fail. I think this will happen on all cars after 8-10 years.

www.youtube.com/watch?v=TuA8nuIeQb8