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View Full Version : volvo says i dont have a B.O.V ?? help.



blackbooty
Monday 25th April 2005, 21:04
Hi guys n gals,can any1 tell me if i have a recirc valve,bov,dv on my 96 T5 auto?
im sure im supposed too as my other turbo auto's all have,but after 20 minutes of parts searching,my volvo main dealer in norwich told me that no such part could be found.
on leaving i asked the mechanics who were on lunch break for the correct part name and they also told me it doesnt exsist???
i keep reading about blanking plates and recirc valves and have looked at pics of Bracers blanking plate,in situ,but im real confused now.

Ross9
Monday 25th April 2005, 21:11
pardon my french, thats ****ing nonsense.

T5 with no standard BOV, hmmmm.

Don't go back there, all turbo cars have BOV's, if not, where does the pressure go when you let off. Sounds well dodgy that they are telling you you dont have one.

Ross

blackbooty
Monday 25th April 2005, 21:27
pardon my french, thats ****ing nonsense.

T5 with no standard BOV, hmmmm.

Don't go back there, all turbo cars have BOV's, if not, where does the pressure go when you let off. Sounds well dodgy that they are telling you you dont have one.

Ross
confirmed what i thought bud,started doubtin myself in the end.
gotta go back for some trim i orded tomorrow,whats the correct part name so i can spell it out for the fools.

Wobbly Dave
Monday 25th April 2005, 23:59
I would just say CBV or Recirc valve - vents excess air pressure in a loop back into the turbo
BOV (Blow Off Valve) aka Dump Valve - vents excess air pressure into the engine bay.

Here is the extra techincal info, for those that want to know -

Essentially we consider 2 states of the engine (for simplicity) - wide open throttle and closed throttle.

During the WOT state, the boost pressure builds on the clean air side as compressor spools up - driven by the turbine on the exhaust side. These two fans are connected by a shaft. The more revs - the faster the turbine spins (connected by the spindle shaft) and the harder the compressor pushes the inducted air. Air is pushed through the intercooler and into the inlet manifold to be mixed with fuel and burnt. And so the cycle continues.

When the throttle is closed - by releasing the accelerator pedal - the excess pressure in the clean air side will have a tendancy to wash backwards into the compressor, stalling it, because the engine will not be using all the air being pushed towards it. This at least adds to turbo lag or at worst can damage the blades in the compressor. To combat this all mitsibushi turbos fitted to Volvos have a Recirc valve or CBV. During WOT this is held shut by the pressure generated on the compressor side. When the throttle shuts this pressure is lost and the recirc valve opens allowing excess pressure to escape & recirculate around the clean air side. The advantage is that it maintains the spin on the compressor blades until the throttle is opened again. As such it prevents the stalling action of the backwash of pressure.

A BOV will prevent stall but it will not maintain the compressor spin in the same manner - which from a performance aspect is not so good.

Wobbly Dave
Tuesday 26th April 2005, 00:03
Oh yeah and another thing - as the turbo/induction system on a T5 is metered on its way in and on its way out - if you vent air into the bonnet space the measurements with a BOV will become confusing to the ECU, as effectively you have fitted an air leak.

volvotuning
Tuesday 26th April 2005, 09:07
Just so you know, on the T5 the recirc dump valve is built into the turbocharger, which is why most Volvo mechs won't know it exists as a seperate part, because it always comes with the turbo.

Adam.

blackbooty
Tuesday 26th April 2005, 10:14
thanks Dave,i originally asked them for a new recirc valve,and even explained its funtion accurately.
im not too impressed to be honest.
ill put them right with your and V.T's comments.

blackbooty
Tuesday 26th April 2005, 10:21
Just so you know, on the T5 the recirc dump valve is built into the turbocharger, which is why most Volvo mechs won't know it exists as a seperate part, because it always comes with the turbo.

Adam.
cheers V.T,worrying to think that a main dealer doesnt have any one on staff that knows their turbo's inside out.
im in the know now and ill share your knowledge with them.
at main service milage,ill bring her to you guys.
ta wayne.

Wobbly Dave
Tuesday 26th April 2005, 10:41
Pictures...

http://stealth316.com/images/18t-1.jpg

18T as found on the S70R
The CBV is that shiny think with the small pipe outlet on the bottom LHS of the pic, bolted to the induction side of the turbo.

blackbooty
Tuesday 26th April 2005, 11:33
Pictures...

http://stealth316.com/images/18t-1.jpg

18T as found on the S70R
The CBV is that shiny think with the small pipe outlet on the bottom LHS of the pic, bolted to the induction side of the turbo.
ta mate,i couldent open your link but i have looked at Bracers pics of his blankig plate and just looked at mine so i know where it is now ta.

should i be able to hear it releasing pressure back into the air intake?
on all my 9000 turbo's it was a distinctive whoosh as pressure was released back into the intake(many people thought id fitted a atmostpheric DV) but its normal for them to sound loud.
i cant detect any dumping sound, she boosts halfway into white section but seems to take a long time to spool up.
does this sound consistant with a tired or dead recirc valve to you mate?
wayne.

Wobbly Dave
Tuesday 26th April 2005, 11:51
Here is the pic!

Wobbly Dave
Tuesday 26th April 2005, 11:57
ta mate,i couldent open your link but i have looked at Bracers pics of his blankig plate and just looked at mine so i know where it is now ta.

should i be able to hear it releasing pressure back into the air intake?
on all my 9000 turbo's it was a distinctive whoosh as pressure was released back into the intake(many people thought id fitted a atmostpheric DV) but its normal for them to sound loud.
i cant detect any dumping sound, she boosts halfway into white section but seems to take a long time to spool up.
does this sound consistant with a tired or dead recirc valve to you mate?
wayne.

Wayne,

I doubt the recirc valve is at fault (though I do get it wrong occasionally). It is more likely to be a tired wastegate actuator. Your boost levels seem about right to me - though I'd have to see it first.

I have never been to Norwich? If you go halves on petrol I will see if I can find the time.

Laters

Dave

volvotuning
Tuesday 26th April 2005, 13:42
Yeah it's either a tired wastegate or a boost leak somewhere.

Adam.

pault5
Tuesday 26th April 2005, 16:58
hello,
i replaced my cbv with one from forge.
http://www.partsforvolvosonline.com/default.php?cPath=28_168
it was a pig to fit with the turbo in situ.
i dont think you can buy the part from volvo.
paul