Technical Mk2b Exhaust blowing - but not?

[xFaz]

Sure my exhaust was blowing, friends confirmed this yesterday, you can just hear it, burbling when the revs cut down, it sounds like it has a custom backbox but it doesn't.
Only thing is, I just took it to an exhaust garage, they checked it over and said it's fine, no blowing. Bloke said it could be something rattling, but he couldn't hear that either. He agreed with me in that it sounded as though it was blowing.

It's a brand new exhaust since Feb 2011, so I was suspicious when it started 'blowing' anyway. I am uploading a video so you can hear the noise, as I type.

Other things I have noticed - I have lost 2 mpg , but I am sure my driving technique has barely changed. Also, when I leave the door open and rev the engine, a cloud of warm air comes up next to drivers door just after revving, smells a bit exhausty (but more like general engine smell), and I have no idea if this was here before.

The place was seriously understaffed so I can take it in next week and he said he would have a proper look, but they couldn't today.

To clear things up, I don't dislike the noise, it sounds quite cool, but I am worried about the hit on MPG (is this related at all?!), and also the fact it started making a noise at all. As well, when I stop at a car park or something, you get out and you can smell exhaust a little bit. It's odd.

Any ideas?

thanks

(will post video when it finishes uploading)

 

[DaveMcT]

It sounds like there is a blow so go back when they are less busy. Or jack up the car onto proper stands and get under the car yourself.

Its unlikely to affect the fuel usage.

 

[xFaz]

Ok, so say there isn't a blow, then what else could it be?

I have had the car on stands myself, and had a look in the garage, neither time I could feel any air leaving the pipe at any joint or at the backbox at all. It's extremely odd.

edit: damn video won't upload, upload speed here is terrible. Will set it to do overnight tonight, if anyone really wants to hear it.

 

[SamuraiDragon]

could it be anything to do with the cat dying? can u pin-point where the "blowing" is coming from, front, back, middle? when u were checking, did u put ur hand or something over the tip to restrict the flow out the back to see if its leaking from a join or something? having a 2nd person may help there. any smoke from the back? has the car had a service recently? could drop in mpg be from a blocked air filter for eg? just throwing random ideas in really.

 

[xFaz]

Random ideas are good!

The noise actually sounds as though it's coming from the backbox or rear tip itself, although if you stand on the left side of the vehicle, it sounds like it's at the front too, like under the passenger seat. There's no smoke, nothing visual at all, just the noise and the smell.

Think the best idea will be to take it in monday/tuesday and leave it with them, they can give it a run around and see what is up. If it is blowing, I would have thought it would be very noticeable, as it's such a new exhaust it could only be on the joints where, for example, a joint may have come loose. But nothing !

Very strange, definitely will do some further investigation.

 

[MrChris]

could it be anything to do with the cat dying?

Random ideas are good!

Faz he means the Catalytic Converter, not a domestic animal! Haha


Chris

 

[SamuraiDragon]

Faz he means the Catalytic Converter, not a domestic animal! Haha


Chris

do i? :devil:





thanks for clearing that up tho..... although im not sure anyone would think otherwise being a car forum and all that

 

[xFaz]

Hehe

But going onto the cat, I read that one guy had a reduced power like, a lot, i.e. he couldnt move the car, changed the cat and it fixed it. He also had the blowing exhaust sound.

I will take it to the garage on monday and leave it there for them to have a play around with.

Would you have any idea if the cat would be changed with the exhaust? or are they seperate units?

 

[SamuraiDragon]

puntos use a manicat... its part of the manifold and not a pretty price new either, prob about £200 give or take. other option is run a 4-2-1 manifold and decat.... or add a sports cat to the 4-2-1 which will add to the costs....... BUT in the extra expense or a 4-2-1 set up is a nice noise and more performance. if u went down this route u may even find a 2nd hand 4-2-1 off fleabay etc which may be cheaper.

 

[xFaz]

thanks for the info. £200 does sounds quite dear, but let's wait and see what the verdict actually is because I haven't a clue.
Will see if I can upload that video tonight, might give someone some clues.

thanks Samurai

 

[D4nny8oy]

You sure its not just the condensation drainage hole at the lower-front edge of the rear silencer? They tend to create a 'burble'/exhaust blow noise (and is normal).

 

[xFaz]

Sounds plausible

How would I go about checking or emptying this?

 

[D4nny8oy]

It's a hole- its self emptying, as is the nature of holes in metal with them not holding things in, like condensation.

New owners used to freak out all the time and we were forever having to show people its a design feature of the rear silencer and not a defective part. Just get under the car and have a look.

 

[Focus Owner]

best way i have found to see if my exaust is leaking. (dunno if its good or bad)
get a rag and block the end pipe hissing is bad.
i just fixed a crack around my cat flange to main exaust pipe.
and a small hole in back box which i may change later

 

[dave]

if the exhaust fitted in Feb 2011 was a pattern part it probably has no hole

 

[xFaz]

It's a hole- its self emptying, as is the nature of holes in metal with them not holding things in, like condensation.

New owners used to freak out all the time and we were forever having to show people its a design feature of the rear silencer and not a defective part. Just get under the car and have a look.

Ok, so if I had this then surely it shouldn't be burbling as it would be emptied? Im so silly

best way i have found to see if my exaust is leaking. (dunno if its good or bad)
get a rag and block the end pipe hissing is bad.
i just fixed a crack around my cat flange to main exaust pipe.
and a small hole in back box which i may change later

I read this was a good idea to block the end, as it then obviously forces it out of the hole if there is one. I am going to drive it today, going to see some friends, so I am just going to really see if I am losing any power, or if the noise gets any worse, and then I will drop it into the garage tomorrow and ask them to find out.

if the exhaust fitted in Feb 2011 was a pattern part it probably has no hole

It was fitted smack bang in the middle of feb 11, receipt says "EXHST CTRE" and "EXHST", the first costing £67, the second costing £61. That might help?

 

[dave]

It was fitted smack bang in the middle of feb 11, receipt says "EXHST CTRE" and "EXHST", the first costing £67, the second costing £61. That might help?

if it wasn't done at fiat it will be a pattern part.

 

[xFaz]

Ok been out all day, but yes it wasn't done at official fiat.

Here is the video!!



Any new ideas?

 

[Benjy911]

Sounds lovely, take the cat out and it'll be spitting flames too :devil:

 

[D4nny8oy]

if the exhaust fitted in Feb 2011 was a pattern part it probably has no hole

Good quality pattern ones will.

Ok, so if I had this then surely it shouldn't be burbling as it would be emptied? Im so silly

The burbling isn't the water- it's the 'built-in' exhaust blow created by having a hole in the rear box. They make the noise all the time.