leebar Posted July 11, 2006 Share Posted July 11, 2006 Hopefully one of the forced induction guys may be able to help! Dumb question which probably explains why I've moved to a NA car !! On my fiat coupe (20v turbo, hybrid turbo, unichip, drilled airbox, decat, BMC filter, Bailey dump to air Dump Valve) the dump valve is occasionally sticking open on full chat and then free's if you back off. Valve is only 8 months or so old, could this mean that I need to adjust tighter as boost is forcing open or could it just be knackered?? Has anyone had a similar problem? Wanted to try here first before resorting back to the Fiat Coupe Forum. Thanks in advance Quote Link to comment Share on other sites More sharing options...
M13KYF Posted July 11, 2006 Share Posted July 11, 2006 On the Audi TT they used to rip/perferate as they were not of the best quality. It was a common fault with them. Seem to remember a replacemnt was £40 plus labour. Quote Link to comment Share on other sites More sharing options...
leebar Posted July 11, 2006 Author Share Posted July 11, 2006 Thanks Mike, the original plastic Bosch unit went some time ago, I'm (the wife now) currently running a upgraded dump to atmos unit that shouldn't face the same issues of the diaphram failing that OEM units do. Long way of saying already changed it and it's the new one that's playing up Quote Link to comment Share on other sites More sharing options...
bernmc Posted July 11, 2006 Share Posted July 11, 2006 I think the baileys are piston-type BOV's. You need a stronger spring, I suspect. Spring too soft - valve opens under boost. Spring too hard, valve won't open or 'chatters'. If it's an adjustable valve, then you need to increase the tension by twiddling the adjusting nut. You want to use as light a spring (tension) as possible without the valve opening under boost - remember, you want the valve to open and dump extra boost as quickly as possible to prevent the turbo stalling. Quote Link to comment Share on other sites More sharing options...
Hope4sun Posted July 11, 2006 Share Posted July 11, 2006 I'd go with bernmc in saying it sounds like the spring, though if its not a year old, ask about replacment anyway Quote Link to comment Share on other sites More sharing options...
lomoto Posted July 11, 2006 Share Posted July 11, 2006 A quick fix that worked on a twin piston dump valve on one of my old cars, is to stretch the spring and / or put a couple of packing washers under to help the seal Is yours the twin piston type? if so these suffer from the smaller piston sticking, dismantle it and make sure it is free Quote Link to comment Share on other sites More sharing options...
leebar Posted July 11, 2006 Author Share Posted July 11, 2006 Thanks everyone Looks like I've got a few things to try this weekend (unless it's sunny and then I'm off for some top down fun!!) Cheers Quote Link to comment Share on other sites More sharing options...
Yorky Posted July 14, 2006 Share Posted July 14, 2006 I believe the piston type dump valves are prone to sticking, and should be stripped and cleaned regularly. There was lots about this on the seatcupra.net site. Quote Link to comment Share on other sites More sharing options...
bernmc Posted July 14, 2006 Share Posted July 14, 2006 I believe the piston type dump valves are prone to sticking, and should be stripped and cleaned regularly. There was lots about this on the seatcupra.net site. Mine sticks a bit because of oil buildup in the intake system (from the crankcase breather) - thin film of oil on the top of the piston makes it stick to the housing by capilliary action. Tends to make it reluctant to open coming off boost. Need to install an oil catch tank. Leebar's problem is that the valve is too willing to open, not that it's sticking. Quote Link to comment Share on other sites More sharing options...
leebar Posted July 14, 2006 Author Share Posted July 14, 2006 I believe the piston type dump valves are prone to sticking, and should be stripped and cleaned regularly. There was lots about this on the seatcupra.net site. Mine sticks a bit because of oil buildup in the intake system (from the crankcase breather) - thin film of oil on the top of the piston makes it stick to the housing by capilliary action. Tends to make it reluctant to open coming off boost. Need to install an oil catch tank. Leebar's problem is that the valve is too willing to open, not that it's sticking. Cheers bernmc, sould that also cause a small amount of oil bleed out of the valve, if so I think you've hit the nail on the head Quote Link to comment Share on other sites More sharing options...
bernmc Posted July 14, 2006 Share Posted July 14, 2006 Cheers bernmc, sould that also cause a small amount of oil bleed out of the valve, if so I think you've hit the nail on the head yes. Just be careful if you disassemble and clean the oil out - the piston does need some grease in the right places (it's usually red in colour), so don't just chuck the whole thing in some degreaser unless you've got some spare grease. I usually just wipe the top of the piston off carefully, as well as the surface it closes against. There are often oil catch cans on fleabay, and they're easy to install - I just haven't got round to it yet. Quote Link to comment Share on other sites More sharing options...
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