Broken Exhaust & Fuel Eeconomy

Thunderbird_2

Hi

I wondered if a broken exhaust will affect the fuel economy, and if yes, How? And how significant would the diffference be?

Your thoughts will be highly regarded.

Thunderbird

tomstickland

Depending on where it's broken, yes it can.
If the break is very close to the engine then it can affect the gas flow and back pressure in the exhaust manifold, which in turn will affect the exhaust gas flow out of the combustion chambers.

iltisman

Yes it could affect fuel economy as the setup of the timing/mixture is affected by the back pressure from the exhaust system.Its not a good idea to drive with a shot exhaust because of noise and the risk of fumes entering the vehicle causing injury to the folks inside.

Inactive

As well as the fact that it is illegal.;)

anewman

When my centre exhaust was knackered it failed emissions tests suggesting to me it was running rich as a result. I agree with all other comments. In fact I just took my car in to get a leaking exhaust sorted today

Thunderbird_2

Thank you all for your replies.

The thing is, the lower end of the catalyst converter is leaking.

The story is back to October. After two weeks of passing the MOT, I started to hear a bit louder than usual noise from the exhaust. I closer inspection revealed a leak from the front end of the centre section of the exhaust.

I took it to the garage and they had look and said I need to buy a new middle section. I was fine with it and they replaced it. Later in the week, I started to notice that there is a bit of leaking noise from the same area.

I took it back to them and they sorted it and said it needed some paste under the joining bracket (between the cat and the middle section) and it will be ok. Two months later, I started to hear it again, not that loud, but, not perfect ( the exhaust noise that is).

I took it to another garage and they said it needs a new catalyst converter as the lower end is rusty and uneven and that's why the other garage needed to use some putty to keep it quiet and they will do the same.

Now, I can hear it a little bit, not that loud, but it is there. I was asking the question above simply because I wanted to know how much does it affect the fuel economy. I don't want to replace the cat now and I will try to leave it ( or extned its life by using exhaust putty from Halfords) till October when The MOT is due and see what the car will fail on ( other than the exhaust, of course) and then if there is nothing serious, I will replace the cat with a new one and change the timing case belt.

Thank you for your time

Thunderbird

anewman

You can get relatively cheap aftermarket catalytic converters so do call around the exhaust places. I have no doubt a genuine one from the dealers would cost a bomb.

You *may* even get away with having it replaced it with a straight pipe. AFAIK so long as it passes emissions tests, it is legal - although please don't quote me on that.

tomstickland

I drove around for 4 weeks with no exhaust beyond the start of the centre section. Ear plugs necessary. It did sound rather impressive for the first day.

Pew_Pew_Pew_Lasers!

There is no requirement on the MOT for a catalytic converter. It simply has to pass the emissions test.

Thunderbird_2

anewman wrote: »

You can get relatively cheap aftermarket catalytic converters so do call around the exhaust places.

I found this website which sound ok. I have not used it yet, but, I plan to do so in October. My catalytic converter came to £50 something, not that bad!!

I drove around for 4 weeks with no exhaust beyond the start of the centre section. Ear plugs necessary. It did sound rather impressive for the first day

This must have been fun!

I fixed the exhaust by using exhaust wrap GUN GUM plus exhaust paste. It looks ok this morning and the car back to normal. How long this will last? I have no idea!!

Thank you all for your replies.

Thunderbird

Thunderbird_2

anewman wrote: »

You *may* even get away with having it replaced it with a straight pipe. AFAIK so long as it passes emissions tests, it is legal - although please don't quote me on that.

But you have got to remember to tell your insurance company about this modification as it might increase your BHP, so the insurance might go up as a result.

There is no requirement on the MOT for a catalytic converter. It simply has to pass the emissions test.

This is true, but, my worry about failing the MOT is due to the Cat leaking, not because of a possible emissions test failure. A leaking exhaust can be a failing point.

Thunderbird