Volvo Community Forum. The Forums of the Volvo Owners Club

Forum Rules Volvo Owners Club About VOC Volvo Gallery Links Volvo History Volvo Press
Go Back   Volvo Owners Club Forum > "Technical Topics" > 850 / S70 & V70 '96-'99 / C70 '97-'05 General

Notices

850 / S70 & V70 '96-'99 / C70 '97-'05 General Forum for the 850 and P80-platform 70-series models

Information
  • VOC Members: There is no login facility using your VOC membership number or the details from page 3 of the club magazine. You need to register in the normal way
  • AOL Customers: Make sure you check the 'Remember me' check box otherwise the AOL system may log you out during the session. This is a known issue with AOL.
  • AOL, Yahoo and Plus.net users. Forum owners such as us are finding that AOL, Yahoo and Plus.net are blocking a lot of email generated from forums. This may mean your registration activation and other emails will not get to you, or they may appear in your spam mailbox

Thread Informations

Loss in boost

Views : 9011

Replies : 129

Users Viewing This Thread :  

Reply
 
Thread Tools Display Modes
Old Feb 29th, 2008, 17:24   #121
PNuT
MaDMaN
 

Last Online: Nov 26th, 2022 19:47
Join Date: Sep 2006
Location: Red Lodge
Default

Quote:
Originally Posted by ovlov25 View Post
850, why what you thinking???

My gut feeling is BCS or actuator.
i have a spare bcs that i promised to someone else but realised they had an me7 car which would have been useless.....

the spare one i have is from a 70 series car but i have heard a rumour it will fit an 850.... your welcome to give it a try if you want.....

as far as the actuator itself is concerned, i would be very surprised if it would fail & become inconsistent from one day to the next..... they are quite sturdy bits of kit!! if the diaphragm(sp?) splits it will stay closed & you will have megaboost!!

another overlooked item IMHO is the inlet gasket.......
__________________
PNuT is offline   Reply With Quote
Old Feb 29th, 2008, 17:28   #122
irf
Member
 
irf's Avatar
 

Last Online: Jan 1st, 2014 14:05
Join Date: Sep 2006
Location: nw london
Default

Quote:
Originally Posted by PNuT View Post
the spare one i have is from a 70 series car but i have heard a rumour it will fit an 850
yep, they fit and work fine. actually cheaper from Volvo as well. the 850 bcs is about £70 from Volvo whereas the later ones i have been told are about £40.
__________________
irf is offline   Reply With Quote
Old Feb 29th, 2008, 17:30   #123
PNuT
MaDMaN
 

Last Online: Nov 26th, 2022 19:47
Join Date: Sep 2006
Location: Red Lodge
Default

Quote:
Originally Posted by dooby View Post
I'd forgotten about that :-) Fancy dropping it off sometime, or I can pick it up if we're both at a meet? I seem to remember you said it was quite weak, no stronger than the one on your car but I might like to have it as a pattern for an after-market one or something... No rush obviously, since it's taken me this long to remember it's away!

Cheers, Pete

will drop it off a week on tusday when im round your way..... some of the actuators have different opening pressures & i have a feeling the 15g is less than the 16t
__________________
PNuT is offline   Reply With Quote
Old Feb 29th, 2008, 17:30   #124
PNuT
MaDMaN
 

Last Online: Nov 26th, 2022 19:47
Join Date: Sep 2006
Location: Red Lodge
Default

Quote:
Originally Posted by irf View Post
yep, they fit and work fine. actually cheaper from Volvo as well. the 850 bcs is about £70 from Volvo whereas the later ones i have been told are about £40.
they are about 52 quid
__________________
PNuT is offline   Reply With Quote
Old Feb 29th, 2008, 17:48   #125
ovlov25
Premier Member
 
ovlov25's Avatar
 

Last Online: Aug 2nd, 2022 00:02
Join Date: Nov 2007
Location: Antrim
Default

Quote:
Originally Posted by PNuT View Post
i have a spare bcs that i promised to someone else but realised they had an me7 car which would have been useless.....

the spare one i have is from a 70 series car but i have heard a rumour it will fit an 850.... your welcome to give it a try if you want.....

as far as the actuator itself is concerned, i would be very surprised if it would fail & become inconsistent from one day to the next..... they are quite sturdy bits of kit!! if the diaphragm(sp?) splits it will stay closed & you will have megaboost!!

another overlooked item IMHO is the inlet gasket.......
I'll be having a proper jeff duke tomorrow to see if i can diagnose the problem, the inlet gasket is fresh maybe 6 weeks ago from when i did the PCV refurb.

Will PM you at the start of the week if i need a lend of the BCS

Thanks

William
__________________
I want I want I want!!!
ovlov25 is offline   Reply With Quote
Old Feb 29th, 2008, 21:09   #126
bb54
diy bhp
 
bb54's Avatar
 

Last Online: Apr 7th, 2011 20:38
Join Date: Jun 2006
Location: great yarmouth
Default

[QUOTE=PNuT;377822]
i would concentrate on investigating the recuirc valve if you havent done already..... lost boost that way is more or less undetectable & unhearable.....

hi, i recently changed a good recirc for a recirc with a massive split in the diaphram because i liked the chopping sound when the un recirculated air was trying to stop the compressor wheel.
there was no drop in boost pressure at all with the damaged recirc in place.
a split in the recirc to inlet manifold hose could bleed boost pressure off but id have thought this would happen consistantly rather than here and there.

meter of 4mm bore fuel line and 5 minutes work eliminates the possibility of this.

wayne
__________________

auto 96 T5
tweaked n ratted
bb54 is offline   Reply With Quote
Old Mar 1st, 2008, 05:28   #127
PNuT
MaDMaN
 

Last Online: Nov 26th, 2022 19:47
Join Date: Sep 2006
Location: Red Lodge
Default

[QUOTE=bb54;378002]
Quote:
Originally Posted by PNuT View Post
i would concentrate on investigating the recuirc valve if you havent done already..... lost boost that way is more or less undetectable & unhearable.....

hi, i recently changed a good recirc for a recirc with a massive split in the diaphram because i liked the chopping sound when the un recirculated air was trying to stop the compressor wheel.
there was no drop in boost pressure at all with the damaged recirc in place.
a split in the recirc to inlet manifold hose could bleed boost pressure off but id have thought this would happen consistantly rather than here and there.

meter of 4mm bore fuel line and 5 minutes work eliminates the possibility of this.

wayne
the split in yours would have been leaking boost directly into the inlet manifold, thats were its going too anyway so technically its not lost boost, just taking a different route

but how do you know the valve is seating properly after its lifted? or if the boost pressure is pushing the valve off its seat?

all the split in yours confirms is that the depression from the inlet isnt going to open it in the correct way

having suffered lost boost in the past & silcon sealing my blanking plate the boost loss disapeered..... the blanking plate already had two rubber seals on! which in theory should be enough to hold the pressure????

i personally dont believe the reciurc valves are that reliable especially on high milage motors....
__________________

Last edited by PNuT; Mar 1st, 2008 at 05:30.
PNuT is offline   Reply With Quote
Old Mar 1st, 2008, 08:28   #128
stusT5
850 t5 and r owner
 
stusT5's Avatar
 

Last Online: Aug 21st, 2014 08:28
Join Date: May 2007
Location: epsom
Default

had to seal my blank plate too mate due to loss in boost in fact i think it was yourself that gave me the idea
__________________
www.t5d5.org the no nonsense free speech performance volvo site
stusT5 is offline   Reply With Quote
Old Mar 1st, 2008, 15:04   #129
PNuT
MaDMaN
 

Last Online: Nov 26th, 2022 19:47
Join Date: Sep 2006
Location: Red Lodge
Default

Quote:
Originally Posted by stusT5 View Post
had to seal my blank plate too mate due to loss in boost in fact i think it was yourself that gave me the idea
did it improve things?
__________________
PNuT is offline   Reply With Quote
Old Mar 1st, 2008, 17:59   #130
bb54
diy bhp
 
bb54's Avatar
 

Last Online: Apr 7th, 2011 20:38
Join Date: Jun 2006
Location: great yarmouth
Default

[QUOTE=PNuT;378174]
Quote:
Originally Posted by bb54 View Post

the split in yours would have been leaking boost directly into the inlet manifold, thats were its going too anyway so technically its not lost boost, just taking a different route

but how do you know the valve is seating properly after its lifted? or if the boost pressure is pushing the valve off its seat?

all the split in yours confirms is that the depression from the inlet isnt going to open it in the correct way

having suffered lost boost in the past & silcon sealing my blanking plate the boost loss disapeered..... the blanking plate already had two rubber seals on! which in theory should be enough to hold the pressure????

i personally dont believe the reciurc valves are that reliable especially on high milage motors....
hi, i just started to write a "i beg to differ" reply and thought id better go and get my split recirc valve to make sure i understand how it works before i gob off he he.
good job i did cos your bang on the money.
id always presumed a damaged recirc was always in the "closed" position because the split diaphram didnt allow the inlet manifold depression to suck the valve open thus not allowing a dump and causing the audiable chopping sound associated with a faulty recirc.

how wrong i was... a faulty recirc is always "open" because the pressure in the inlet manifold cant close the valve due to the split diaphram.

as soon as i worked that out i started thinking how the hell does the chopping sound occur then if i was always dumping air through the recirc ???
your sentance... "the split in yours would have been leaking boost directly into the inlet manifold where it ultimately goes anyway" answerd that one

your smarter than me he he

wayne
__________________

auto 96 T5
tweaked n ratted
bb54 is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 09:20.


Powered by vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.