S80 2000 2.0T Problem (noise) from Vacuum hose / Brake booster check vale Topic is solved

vetjugote · Post by **vetjugote** » 30 Nov 2020, 15:45

Hi,

Suddenly (on my Volvo S80 2000 2.0T) i heard a noise from the engine bay. It was similar to a "knocking" sound, but seemed to be related to the vacuum hose from the intake that goes to the brake booster.
I was thinking it might be a vacuum leak, or can the check valve be broken?
See video below:
https://files.fm/f/2ma4cs5d9

Thankful for any help!

Post by **ndphotonl** » 01 Dec 2020, 15:55

Yes the valves can break. How do the brakes feel?

If you remove the check valve, you can check them by simply blowing in them. One side should be easy to blow air through, the other side should block completely. If you have compressed air, you can test them better, but dont overdo it with the pressure

There is a simple spring in there, which might loose its stiffness over time.

vetjugote · Post by **vetjugote** » 03 Dec 2020, 14:52

If I pump the brakes with the car being turned off, it gets stiff after 2-3 times.
I removed the check valve and tried to blow through it, and it does let through air on one side (blew with my mouth and it wasn't very strong), and blocks from the other.
I will order a new check valve and hose and replace them and hope it solves it. If that doesn't solve it, I guess look into the vacuum pump/brake booster?

Post by **ndphotonl** » 03 Dec 2020, 15:50

Also use hose clamps

vetjugote · Post by **vetjugote** » 09 Dec 2020, 07:09

I haven't been able to diagnose yet but will do this week.

I was planning to order a new hose/check valve to replace it, and while looking closer, I found another check valve and a hose in bad shape.
Due to delivery time, I wanted to order both at the same time.
I was looking through diagrams (volvoparts online) and vida diagrams, but I can't seem to find these specific pieces (neither the t-pipe/hose or that check valve) anywhere.

Seems to come from the air intake to a t-pipe and on to this valve. Is this also related to the brake booster - vacuum hose/check valve?
Attached pictures,

Appreciate if anyone has any suggestions here.

Post by **ndphotonl** » 09 Dec 2020, 09:37

Its also a check valve. You can disconnect it without issue and do the same test as you did with he brake booster check valve

[edit]
Where is the bottom part of the hose going? On my 2.4T it goes to the left under the intake manifold.

Volvo S80 2.4T PCV Repair by Andy Ramdin, on Flickr

Tip: also replace the hoses, as they look very brittle in your case. I used some silicone hose to replace it (barely visible in the picture below)

Volvo S80 2.4T Forge FMDV006 by Andy Ramdin, on Flickr

vetjugote · Post by **vetjugote** » 09 Dec 2020, 14:53

Thanks for the reply,

The bottom part of the hose goes along the engine (straight instead of down like yours) to another check valve, I couldn't see really well since it's hidden under the intake.

I measured the hoses to order new, and the smaller ones are ~7-7,5mm inside diameter, and I couldn't find any silicone hoses in this size (only 4,5 and 6mm, https://www.partsforvolvosonline.com/pr ... 22cc3689e3)
They are too small right, or will they expand enough when mounting it?

The check valves seems fine also. I managed to find the source of the noise, it's coming from this hose ino the front (which was loose, and no idea where it should go?) I put my finger against the opening (red circle) and the noise stopped (not completly, but almost silent).
The hose (blue circle that is coming from under the engine?) is also not going anywhere. Should they be connected together?

The hose that goes to the right of the red circle, goes to the T-Pipe as shown before in this image (coming from the front of the car).

I checked diagrams again, but can't find what the disconnected hose is from.

Post by **ndphotonl** » 09 Dec 2020, 15:37

I checked in VIDA for you and its part of the EVAP system (a emissions system)

https://www.aa1car.com/library/evap_system.htm

vetjugote · Post by **vetjugote** » 09 Dec 2020, 16:47

Thanks for that, much appreciated!
After some research seems like the hoses that are disconnected should be connected together. And I presume the canister purge valve (for the evap system) where the hose should go is not working properly. I'll order new check valves, canister purge valve and vacuum hoses and hope for the best!

Thanks again for the help!

Post by **ndphotonl** » 10 Dec 2020, 05:10

Fyi, EVAP system does clicky noises, so you should have found the root cause of the issue.