vacuum leak hiss from the brake booster v70 2.4t

whaleplane · Post by **whaleplane** » 29 Aug 2010, 19:30

I did a search for hissing noises and found a thread that mentioned a problem that I think I have. Is this something that can be fixed at home or is this a shop job?
Funny thing is that it doesn't make the noise all the time but it's enough that I have started to notice it.

jda2000 · Post by **jda2000** » 30 Aug 2010, 14:19

yes, you can fix it yourself if you are the DIY type.

You need a new brake booster. Don't buy used or rebuilt.

Use the link above for FCP and buy new with the 10% off coupon and free shipping. The new unit comes complete with new vacuum valve and new pedal position sensor. Remove the old parts from the old booster and save them.

Also, you don't need to disconnect the ABS hydraulic lines, just loosen the ABS pump and push to the side when you replace.

Post by **JRL** » 30 Aug 2010, 15:13

I'm assuming this is a 2001?
Along with everything else wrong with 01's, they have bad brake boosters, most fail

whaleplane · Post by **whaleplane** » 02 Sep 2010, 19:16

It's a 2001....

tuplip_73 · Post by **tuplip_73** » 25 May 2011, 17:07

Thank you for the post. A certified tech dx this problem and now you confirm it. I will have the work done. Thanks.

tuplip_73 · Post by **tuplip_73** » 25 May 2011, 21:38

tuplip_73 wrote:Thank you for the post. A certified tech dx this problem and now you confirm it. I will have the work done. Thanks.

I have a mechanic that will do the replacement for the brake booster, do you have a diy tutorial? I am having a hard time locating it. Your assistance will be appreciated. 2002 s60 55,000 miles. Thank you.

Post by **oragex** » 09 May 2018, 18:56

Pulling this thread from the dust, as I just went through this issue on my 2003. I will soon upload a DIY video on my channel with repairs .

The brake booster has a seal where the rod from the brake pedal goes into the booster. This seal is covered with a grey bellow. The seal needs lubricated with a special silicone grease that is applied on the white cylinder that is sliding on the seal. After several years, the special grease dries out, and the rubber is no longer lubricated. The rubber then gets torn and the brake booster starts loosing vacuum and will hiss when the brake pedal is released. Moreover, the brake booster electric vacuum pump can start running after the engine is shut off to compensate and the pump will wear after a while.

The faulty seal can be bought separately plus the white cylinder needs lubricated: don't use any silicone grease, many of the silicone greases on the market get stiffer in cold weather which will damage the seal. I will try the Volvo silicone grease for the caliper pins (part #1161688).

As for the seal, it's part # 03.7718-5018.1

URO has a kit - Carefully with the white cylinder, it should not be scratched with the tools when replacing the seal

This is another brand https://picclick.co.uk/Brake-Booster-Se ... 00600.html
https://www.ebay.ie/itm/282046759411

There may be other brands out there.

The big problem is replacing the seal as this normally will require to remove the brake booster from the car. On the cars with right hand driving, this is terrible as the whole engine needs to be lowered several inches to clear the booster. Even on the cars with left hand driving this is not the easiest task.

I don't know if it's doable to replace the seal without removing the brake booster from the car. Not sure if someone already succeeded this way.

But at least if the booster is removed from the car, it doesn't have to be replaced, just the seal.

Also, even if the booster isn't hissing yet, I would recommend tossing the grey bellow, and applying a quality silicone grease on the white cylinder - again, the word quality is essential here as this may rather damage the seal instead of extending its life. Don't forget to place the grey bellow properly secured back in place to prevent any dirt from getting to the seal.

Hopefully this helps.

Post by **precopster** » 09 May 2018, 19:59

Sage advice ^^^ !!

I found the same seal with postage to Australia: https://www.ebay.co.uk/itm/MERCEDES-W16 ... Sw5cNYU6CE

When the booster type is a DSTC as on my T5 it is worth a try even if I need to drop the engine assembly (you use extender bolts which you can fabricate from M14 thread bar) because the booster is around $400 AUD landed

Don't forget there is also a seal between master cylinder and booster. This can fall off when the MC is removed.

Post by **oragex** » 10 May 2018, 09:45

Great find, it's a seller from Poland so he will ship worldwide. The quality is still to be tested, but it's great to have the option of replacing the seal instead of the whole booster.

Post by **oragex** » 10 May 2018, 09:54

Small update, and hopefully some good news, there is a owner who managed to replace the seal without removing the brake booster from the car, Mac940 in this thread https://www.volvoforums.org.uk/showthre ... ost2402215