Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6

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Tue 3 May 2011 21:51
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - squibsquib

The downpipe gasket is slightly blowing in my Brova. Would this effect the MPG by much? MY car seem to be going through a lot of fuel.

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Tue 3 May 2011 22:04
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - unthrottled

Possibly, but probably not. When you mean 'downpipe gasket' I take it you aren't referring to the exhaust manifold gasket but the inteface between after the collecot where the pipe joins the cat?

A breach at the exhaust manifold itself could let air in to the exhaust system during the partial vacuum that occurs during valve overlap. This air will obviously contain oxygen which will be detected by the lambda sensor which would cause the ECU to think that the mixture was lean and add fuel.

Further downstream, the exhaust pulses even out and there is little/no vacuum even at idle. The leaking of exhaust gas in itself will make an annoying blowing noise but won't adversely affect fuel economy. It will adversely affect you next MOT though!

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Wed 4 May 2011 01:52
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - squibsquib

Its the gasket between the outlet manifold and downpipe. Since its the 1.6 model the exhaust is at rear of engine and access if difficult to see if its a missing bolt or blown gasket. I seen to be getting no more than 40 MPG city driving/slight MW driving.. I've serviced the car and its only done 30,000. The MPG seens a little high. Do you think I could seal it bu exhaust paste?

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Wed 4 May 2011 09:37
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - unthrottled

That's about on the mark for a simple 1.6 Engine-what were you expecting? The leak is downstream of the lambda sensor so it wouldn't have any effect. You could try exhaust paste if you can get to it. The leak might be in the flexi section rather than the gasket itself-in which case exhaust paste probably won't do much good.

If you do use paste-don't paste up access to the bolts!

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Wed 4 May 2011 19:37
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - sb10

Depends on the engine,some dont like exhaust leaks and cause performance problems,though your fuel figure is not bad for yours the leak will have to be fixed anyway they get very noisy otherwise, and performance drops .

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Wed 4 May 2011 20:23
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - squibsquib

Sorry. I made a mistake in my MPG. I meant to say 40 miles from £10 worth of fuel. So I am getting around 20 MPG The car passed the emission test no prob in MOT and I can't smell any fuel etc? Is this correct for a car this size? Thats me even driving like Miss Daisy

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Wed 4 May 2011 21:23
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - unthrottled

You can't make a meaningful measurement of economy over £10 worth of fuel at today's prices! The margin of error is huge.

At the downpipe gasket, the leak is downstream of the lambda sensor so it shouldn't affect fuel trim and this is the only way it could get affect fuel economy.

I don't buy the 'exhaust leaks cause a loss of performance' line. There's no thermodynamic reason for it. I think they just say that to make people more inclined to fix them. As an extreme example, think of an engine with the ultimate exhaust leak ie running through open headers-does it suffer from a loss of performance? Not likely!

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Fri 6 May 2011 00:29
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - squibsquib

Fair enough on the fuel prices but that was based on £1.36 per litre or £6.18 per gallon. The gasket is before the lamda sensor so would this not effect the reading? Thanks

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Mon 9 May 2011 14:44
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - sb10

I don't buy the 'exhaust leaks cause a loss of performance' line. There's no thermodynamic reason for it. I think they just say that to make people more inclined to fix them.

Not knowing the car I cant say for sure,but I am not in the habit of advising people to change an exhaust unless I think its going to make a difference,regardless of your reasoning for it,it has been known,and fixing a leak does help but I suppose it depends on whether you are a college/university taught fitter or taught the practicals of mechanics

If the leak is before the sensor usually it does make a difference to economy but you wont find out till its fixed which it will have to be anyway

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Sat 7 May 2011 08:16
Blowing Gasket. Will this effect my MPG - FIat Bravo 1.6 - logic0104

What are you using to judge your MPG, Dont rely on your fuel metre as they are usually inacurate, Fill ya car to the brim, reset the trip counter do a couple of hundred miles the fill to the brim again the use your receipt and calculate your mpg against your trip reading to be exact its 4.54 litres to a gallon, then you can acurately determine your mpg. I have a 1.4 astra 06 and average around 42 MPG howerver that seems to drop as i near service times ?

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