V6 Exhaust Flexi - Alfa Romeo Forum
You are currently unregistered, register for more features.    
 1Likes
Reply
 
Thread Tools
(Post Link) post #1 of 44 Old 25-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
V6 Exhaust Flexi

Hi all

I have searched and searched and can't seem to find the answer, but does anyone know what size the exhaust flexi bit is on the v6 busso? In one post someone suggested 6x3" but it was never confirmed.

How hard is it to replace the whole section of pipe with the flexi in? Or is it worth just buying a replacement flexi and cut the old one out?

My car is idling really rough like it's misfiring and sometimes struggles to start, it is fine when it's being driven it's just on idle.
It did have an error code for cylinder 6 misfire but since changing the sparkplugs and the coilpack on number 6 the code has gone and it isnt showing any at all, but still at idle it sounds like a dog.
My Flexi has a huge great hole in it I have since noticed. Do you think this could be the cause of the rough idle, throwing a lambda sensor out? Either way it needs replacing.

Thanks in advance guys

Dom
dominic2115 is offline  
Sponsored Links
Advertisement
 
Status: -
AO Member
 
lizard's Avatar
 
Join Date: Oct 2010
Location: Slovenia
County: -
Posts: 363
Downpipes have external diameter of around 50mm (around 2"), so you should be good with flexis of 50x150 mm (2x6" right?), but measure the diameter before you buy them, just in case I'm wrong.
lizard is offline  
(Post Link) post #3 of 44 Old 25-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Thanks mate
dominic2115 is offline  
 
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
I think the OEM downpipes are made from 54mm OD tube. 2 & 1/8th inch.
Pud237 is offline  
Status: -
AO Member
 
lizard's Avatar
 
Join Date: Oct 2010
Location: Slovenia
County: -
Posts: 363
Quote:
Originally Posted by Pud237 View Post
I think the OEM downpipes are made from 54mm OD tube. 2 & 1/8th inch.
I stand corrected, I have mine made out of OD 50mm stainless pipes (which I believe have thinner walls than OEM). Would you perhaps know the inside diamater of downpipes, perhaps of those made by Wizard?
lizard is offline  
(Post Link) post #6 of 44 Old 25-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Quote:
Originally Posted by Pud237 View Post
I think the OEM downpipes are made from 54mm OD tube. 2 & 1/8th inch.
Also looking at it, it looks like it's longer than 150mm and there isn't much room to play with before it clamps to the CAT
So think I may have to go for this and replace the whole pipe

http://www.cats2u.co.uk/product_info...ducts_id=28335
dominic2115 is offline  
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
Quote:
Originally Posted by lizard View Post
I stand corrected, I have mine made out of OD 50mm stainless pipes (which I believe have thinner walls than OEM). Would you perhaps know the inside diamater of downpipes, perhaps of those made by Wizard?
The original steel is probably 1.5mm, something like that. Maybe a bit more. We use 1.2mm wall thickness for all our stainless steel exhausts.
Pud237 is offline  
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
Quote:
Originally Posted by dominic2115 View Post
Also looking at it, it looks like it's longer than 150mm and there isn't much room to play with before it clamps to the CAT
So think I may have to go for this and replace the whole pipe

BM70446 | ALFA ROMEO 156 2.5 (AR32405 engine) 06/00 on Front Pipe | Buy Catalytic Converters Online
They do fit & work, but they're about as poor quality as any pattern part I've ever seen. But that is why they are only forty odd quid each. Our flexis alone cost us almost 20 pounds each and we buy them 20 at a time.

My preferred solution is to find a good local fabricator, buy some high quality flexis and get them welded in to the original downpipes. That will cost a good bit more than those cheap downpipes though.
Pud237 is offline  
(Post Link) post #9 of 44 Old 29-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Ok compression test carried out by myself on cylinders 4, 5 & 6.
Results were 170psi across all 3.
I did remove the front bank pre cat lambda it looked like this below. New genuine bosch part is on its way. I hope this is causing the misfire.
I have now changed.
Sparkplugs
Coil pack
Compression tested.
Ecu reset and throttle reset.
And new Lambda on the way.

Any thoughts appreciated.
Attached Images
File Type: jpg IMG-20160828-WA0005_1472483044023.jpg (42.7 KB, 9 views)
dominic2115 is offline  
Status: V6 Inside
AO Silver Member
 
ransoman's Avatar
 
Join Date: Jan 2007
Location: United Kingdom
County: Aberdeenshire
Posts: 4,771
Images: 1
Check the timing. My v6 has a rough idle too. I cleaned the lambda's - No change. replaced the spark plugs - No change, cleaned the throttle body - No change, compression test - Perfect

Doing the timing belt job I found that both rear bank cam's were out. The exhaust by a little, the inlet by a lot. You don't really need camlocks to check but you do neet a TDC guage. The cams have a very fine groove at the end. Set the engine to TDC on the compression stroke (so the inlet cam on the rear bank is pointing to approx 10 o'clock, you MUST set tdc by the crank though). Place a thin feeler gauge flat on the casting on the cylinder head and slide toward the camshaft. It should meet a tiny slot in the cam.

The cam position sensor is on the rear exhaust cam so if that one is out (and it often is) then it can cause idle problems.

You must compression test the rear bank as 9/10 this is where you will find poor compression.

Alfa GT 3.2 V6 - Daily Driver.
Alfa 145 QV ph1 in green (Death by rust project) For Sale.
Alfa GTV TS ph2 in blue
ransoman is offline  
Status: -
AO Member
 
Join Date: Apr 2006
Location: Switzerland
County: Zürich
Posts: 49

Member car:

AR 156 3.0V6

Quote:
Originally Posted by dominic2115 View Post
I did remove the front bank pre cat lambda it looked like this below. New genuine bosch part is on its way. I hope this is causing the misfire.
Unlikely. Most of the time the wrong timing is responsible for misfires.
alterro is offline  
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
Quote:
Originally Posted by dominic2115 View Post
Ok compression test carried out by myself on cylinders 4, 5 & 6.
Results were 170psi across all 3.
I did remove the front bank pre cat lambda it looked like this below. New genuine bosch part is on its way. I hope this is causing the misfire.
I have now changed.
Sparkplugs
Coil pack
Compression tested.
Ecu reset and throttle reset.
And new Lambda on the way.

Any thoughts appreciated.
Did you compression test the rear bank?
Pud237 is offline  
(Post Link) post #13 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Quote:
Originally Posted by Pud237 View Post
Quote:
Originally Posted by dominic2115 View Post
Ok compression test carried out by myself on cylinders 4, 5 & 6.
Results were 170psi across all 3.
I did remove the front bank pre cat lambda it looked like this below. New genuine bosch part is on its way. I hope this is causing the misfire.
I have now changed.
Sparkplugs
Coil pack
Compression tested.
Ecu reset and throttle reset.
And new Lambda on the way.

Any thoughts appreciated.
Did you compression test the rear bank?
I didn't, purely because the fault when the MSCF light finally came on was showing as misfire on cylinder 6. Also I couldn't be bothered stripping it back down at the time.
Worth doing?
dominic2115 is offline  
Status: V6 Inside
AO Silver Member
 
ransoman's Avatar
 
Join Date: Jan 2007
Location: United Kingdom
County: Aberdeenshire
Posts: 4,771
Images: 1
Have you done anything to the injectors for cyl no 6?

Shotgunning replacement parts must be costing you a fortune. Don't spend any more money untill you have checked the timing and compression tested the rear bank.
ransoman is offline  
(Post Link) post #15 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Quote:
Originally Posted by ransoman View Post
Have you done anything to the injectors for cyl no 6?

Shotgunning replacement parts must be costing you a fortune. Don't spend any more money untill you have checked the timing and compression tested the rear bank.
Nope but I have ruled out injectors as it is misfiring if run on LPG or petrol. It doesn't seem to make a difference
dominic2115 is offline  
(Post Link) post #16 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Quote:
Originally Posted by dominic2115 View Post
Quote:
Originally Posted by ransoman View Post
Have you done anything to the injectors for cyl no 6?

Shotgunning replacement parts must be costing you a fortune. Don't spend any more money untill you have checked the timing and compression tested the rear bank.
Nope but I have ruled out injectors as it is misfiring if run on LPG or petrol. It doesn't seem to make a difference
I will try to compression test the rear bank later, time permitting
dominic2115 is offline  
(Post Link) post #17 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Rear bank compression tested, cylinder 1 and 3 were 170 psi.
Cylinder 2 made 90 psi on dry test and only 70 psi on a wet test.
This also pulled out of cylinder2 when I removed the tester after the wet test.
Again any help appreciated
Attached Images
File Type: jpg 20160830_181726_1472577771697.jpg (70.2 KB, 18 views)
dominic2115 is offline  
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
You have a problem on cylinder 2 - when you say a 'wet test', did you just drop in something like 10ml of engine oil, or something else?

That looks like silicone, is that what it is?
Pud237 is offline  
(Post Link) post #19 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
10ml of engine oil.
It looks like silicone to be honest. What's you thoughts on the problem?
Thankyou by the way
dominic2115 is offline  
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
Whats the size of it? It could be that someone has siliconed down the rocker cover and that bit was excess which squeezed into the spark plug hole?
Pud237 is offline  
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
To be honest even from your first post I thought it sounded like the beginnings of HGF or a burnt exhaust valve maybe. You can run these engines for months or even years sometimes with half a cylinder's worth of compression on the back bank and they perform OK, its just idle where they show trouble.
Pud237 is offline  
(Post Link) post #22 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Quote:
Originally Posted by Pud237 View Post
Whats the size of it? It could be that someone has siliconed down the rocker cover and that bit was excess which squeezed into the spark plug hole?
A pic for you is probably easier
Attached Images
File Type: jpg 20160830_204308_1472586220407.jpg (56.6 KB, 8 views)
dominic2115 is offline  
(Post Link) post #23 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Quote:
Originally Posted by Pud237 View Post
To be honest even from your first post I thought it sounded like the beginnings of HGF or a burnt exhaust valve maybe. You can run these engines for months or even years sometimes with half a cylinder's worth of compression on the back bank and they perform OK, its just idle where they show trouble.
So either way I'm looking at head off?
dominic2115 is offline  
Status: Busy busy busy!
Club Member
Membro Premio
 
Pud237's Avatar
 
Club Member Number: 71
Join Date: Apr 2006
Location: United Kingdom
County: Cumbria
Posts: 42,282
Quote:
Originally Posted by dominic2115 View Post
So either way I'm looking at head off?
I would think so, yeah.. What mileage is the car on out of interest, and how many has it done on LPG?
Pud237 is offline  
(Post Link) post #25 of 44 Old 30-08-16 Thread Starter
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Wiltshire
Posts: 277
Quote:
Originally Posted by Pud237 View Post
Quote:
Originally Posted by dominic2115 View Post
So either way I'm looking at head off?
I would think so, yeah.. What mileage is the car on out of interest, and how many has it done on LPG?
It's on 125k and was converted to LPG at 77k
I have sent you a PM

Last edited by dominic2115; 30-08-16 at 20:44.
dominic2115 is offline  
Reply

Go Back   Alfa Romeo Forum > Supported Alfa Romeo Models > Technical & Vehicle Assistance > Alfa 147, 156 & GT

Tags
exhaust , flexi

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome