vacuum check valve

Mar 31st, 2005, 08:34

I have, what our American cousins would call, an "issue" with the ABS system. I have been told that it could be the vacuum check (non return) valve. I've looked in the book and can find no reference to it. Can anyone tell me where to find it please. G.

Peter Milnes · Apr 1st, 2005, 00:35

As it is a purely mechanical device, basically a one-way valve, it is dificult to find it in the handbook. However it features in the "Brakes" Green Book (produced by Volvo). If you look at the servo on the driver's side bulkhead (firewall) at it's top rhs there is a black or white plastic elbow with a hose attached from the vacuum source. The elbow sits in a rubber grommett. That is the "check" valve. Gently ease it out of the grommett and see if there is the sound of air movement. If you hear a fairly loud puff of air then the valve is OK. Be careful when re-inserting it as the grommett can be pushed into the servo, from which it will be expensive to remove. On some models particularly those with air-conditioning, the vacuum hosing is quite complex. A leak in any one of those will cause lack of vacuum when braking. One model has a second check valve included in the vacuum line. This one is a straight component with a wide portion in the middle. It is usually black at one end and white at the other.

All the best, Peter.

Apr 3rd, 2005, 08:08

Thank you for your help

Mar 31st, 2005, 08:34	#1
apostle Guest Location:	vacuum check valve I have, what our American cousins would call, an "issue" with the ABS system. I have been told that it could be the vacuum check (non return) valve. I've looked in the book and can find no reference to it. Can anyone tell me where to find it please. G.

Apr 1st, 2005, 00:35	#2
Peter Milnes Premier Member Last Online: Apr 10th, 2014 00:01 Join Date: Feb 2002 Location: Tonyrefail	RE: vacuum check valve As it is a purely mechanical device, basically a one-way valve, it is dificult to find it in the handbook. However it features in the "Brakes" Green Book (produced by Volvo). If you look at the servo on the driver's side bulkhead (firewall) at it's top rhs there is a black or white plastic elbow with a hose attached from the vacuum source. The elbow sits in a rubber grommett. That is the "check" valve. Gently ease it out of the grommett and see if there is the sound of air movement. If you hear a fairly loud puff of air then the valve is OK. Be careful when re-inserting it as the grommett can be pushed into the servo, from which it will be expensive to remove. On some models particularly those with air-conditioning, the vacuum hosing is quite complex. A leak in any one of those will cause lack of vacuum when braking. One model has a second check valve included in the vacuum line. This one is a straight component with a wide portion in the middle. It is usually black at one end and white at the other. All the best, Peter.

Apr 3rd, 2005, 08:08	#3
apostle Guest Location:	RE: vacuum check valve Thank you for your help

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