Rollover Valve Topic is solved

Post by **GlennG2759** » 04 Sep 2018, 10:08

Yesterday while replacing rear endlink bushings on my 1994 850 NA 172K I broke and end off what I found out to be the rollover valve. Can I scrap this valve and just connect the inlet and outlet hoses together? Will it affect antything? Tip. I used a 3/16 2 flute x-long end mill in a drill to hog out the rubber and plastic, no heat, each side took about 45 mins. A couple shots with a hand sledge and pipe from behind on lower lip of bushing and they dropped out. Any input on rollover valve would be greatly appreciated. Thanks

Post by **misha** » 04 Sep 2018, 10:53

Yes you can,but you will not have a roll-over protection from fuel escaping anymore.

Post by **abscate** » 04 Sep 2018, 13:43

More importantly, it stops this from happening - wear your seat belts too...

Post by **Clemens** » 04 Sep 2018, 16:36

Third time's the charm

Post by **JimBee** » 04 Sep 2018, 21:43

I don't understand how the rollover valve actually works, since it's not on the fuel line. I replaced the decayed hoses on mine (1/4" ID silicone fuel line for small engines from O'Reilly Auto), but can somebody explain how it stops the flow of fuel.

Related, there's another small device just ahead of the rollover valve on my 96 850 NA that seems integrated in the fuel line and has a short "J hose" connection to what I assume is the vapor line. What is that device?

Post by **GlennG2759** » 04 Sep 2018, 21:59

After just taking mine out today and replacing with hose, it seems to be a very simple check valve. When turned upside down (in case of a rollover) I believe it interrupts the flow of fuel by way of the fuel tank venting system. Just a guess though. That other device on your 96 could be the purge valve. My 94's located above radiator fan in shroud. Although I've done a lot work to my 94 850 in short time I've had it , I'm a newbie to volvos. I find their engineering amazing.

Post by **jreed** » 05 Sep 2018, 04:58

I think the rollover valve is designed to close when the car is tilted or upside down. The closing prevents liquid fuel from the tank from escaping through the vent tube, which could happen when the tank gets tilted or flipped upside down in an accident.

Post by **JimBee** » 05 Sep 2018, 12:56

I had mine off, so I could hear the ball valve inside when I tilted or inverted it.

It makes sense that it somehow would create a vacuum, but if the tank isn't full, would there be enough negative pressure on that line, from the valve to the tank, to pull a vacuum on the empty space in the fuel tank and preventing fuel from finding an outlet?