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What is this black and white check valve for

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
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dcmike
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What is this black and white check valve for

Post by dcmike » Sat Aug 11, 2018 7:52 am

I have a 98 v70r. This little black and white check valve keeps coming off and my mileage drops. What does this valve do and why?

Mike
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jsloden
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Re: What is this black and white check valve for

Post by jsloden » Sat Aug 11, 2018 8:41 am

If I remember correctly that's actually part of the EVAP system. So I would assume that it could definitely effect mileage. You can buy those little rubber pieces at ipd fairly cheaply. I replaced all of mine when I did the PCV system. There are actually several of them throughout the system.



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misha
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Re: What is this black and white check valve for

Post by misha » Sat Aug 11, 2018 10:58 am

It is one way valve for SAS solenoid on fan shroud.


'97 850 2.5 20v /fully equipped/ Motronic 4.4 / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

dcmike
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Re: What is this black and white check valve for

Post by dcmike » Sat Aug 11, 2018 11:08 am

Why does the valve keep coming off the line from the SAS? Is their to much pressure?



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misha
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Re: What is this black and white check valve for

Post by misha » Sat Aug 11, 2018 11:50 am

Could be that SAS valve is stuck open and recirculating exhaust gases via vacuum line....i had this problem.
Check the air filter for water from exhaust condensation and carbon from exhaust gases.
If so....it will kill your MAF.
It killed two of mine...brand new from Volvo a long time ago.

EDIT***

I mixed this line with purple vacuum line from SAS valve....there is no danger of exhaust gases here nor for the MAF sensor.
This line goes from vacuum tree to sas solenoid at fan shroud.
Purple one goes directly from SAS valve to a vacuum tree.
Last edited by misha on Sat Aug 11, 2018 3:47 pm, edited 3 times in total.


'97 850 2.5 20v /fully equipped/ Motronic 4.4 / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

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Re: What is this black and white check valve for

Post by scot850 » Sat Aug 11, 2018 11:53 am

Could just be vibration and a really worn out rubber elbow. Not sure if that part of the system is under pressure or vacuum. Remove one en of the pipe with the engine running and stick your finger over the end of the valve and the end of the pipe and see if it is sucking or blowing form one or other to determine if the system is vacuum or pressure.

If it is vacuum then I can only believe it is the vibration that is causing it to work loose. If it is under pressure then the worn out rubber is probably to blame. If a new rubber elbow does not fix it the valve may be partially blocked or there is too much pressure in the system. When was the PCV system last serviced?

Neil.


2000 V70 R - still being an endless PITA
2006 XC70
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold

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