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98' S70 - Direction Arrow on the gray 1-way check valve on evap hose in engine bay

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
1997 - 2000 V70-XC
1997 - 2004 C70

S7turbo
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S7turbo

98' S70 - Direction Arrow on the gray 1-way check valve on evap hose in engine bay

Post by S7turbo » Fri Aug 12, 2016 12:12 am

While finishing up some other repairs I noticed that the arrow on 1 of the 2 check valves in the engine bay could be pointing in the wrong direction. Can someone assist? The main evap line comes from the canister under the car back by the gas tank, routes underneath and up into the engine bay to the side of the fan, then heads toward a T. One direction from the T goes to the intake manifold -I know the arrow is correct on this on- it points to the intake manifold. The other direction at the T i can't figure out which is the correct direction to point. The T goes straight back tiward the firewall and down, attaching to the turbo tube.

Is this one pointing the right direction? In this pic it points to the firewall, but car runs with it in either direction. I thought it was supposed to route air up to the T and then over to the intake manifold , which is not what's in the pic... ?? :
checkvalve_ed2.JPG
This one is ok: this check valve at the front of the engine bay on top of the fan points and goes right into the intake manifold, which is correct. Difficult to see the actual on the check valve, but the arrow does points left.
checkvalvefrontB.jpg
Thanks everyone.
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1998 S70 T5 Auto - current
1993 850 Manual - previous

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chrafael
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Re: 98' S70 - Direction Arrow on the gray 1-way check valve on evap hose in engine bay

Post by chrafael » Fri Aug 12, 2016 8:23 am

That's right. One flows to the intake when it is under vacuum. Under boost it shuts off then the other one takes over and flows ahead of the turbo back to the intake. It's one or the other but never both.

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rspi
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rspi

Re: 98' S70 - Direction Arrow on the gray 1-way check valve on evap hose in engine bay

Post by rspi » Fri Aug 12, 2016 8:31 am

Also, they are check valves, so, if you can blow through it in the wrong direction, it is bad and can cause a P04xx code.
'95 855 T-5R M, Panther - 22/28 mpg
'98 S70 GLT, Lil' Red 25/32 mpg
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S7turbo
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S7turbo

Re: 98' S70 - Direction Arrow on the gray 1-way check valve on evap hose in engine bay

Post by S7turbo » Fri Aug 12, 2016 3:00 pm

Thanks for the replies chrafael and rspi. So, I will leave it with the arrow/flow pointing back to the turbo tube near the firewall (hose in the top picture). Also, after stuyding the checkvalve itself and trying to match it up with new hose, I noticed that the "in" direction has a larger opening than the "out" direction. Say what? The smaller diameter in the "out" direction seems to match up more with the size of the nipple it fits on back on the turbo tube than it does to the thicker hose coming right off the T. So I guess my mystery is solved (and I wont have any evap codes from the wrong direction), one arrow points to the IM, the other points directly back to the firewall.

The diameter is different...
evap 1w cvalve 33.jpg
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1998 S70 T5 Auto - current
1993 850 Manual - previous

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