Faint hissing noise from engine and terrible economy

[Number Six 10]

My car (Mondeo mk2 automatic) makes a slight hissing noise when under load.

 

The catalytic converter disintegrated some time ago and so I had that replaced - is it possible some bits of the old one are stuck in the pipe somewhere and creating a bit of back pressure? I suppose this could explain it's poor fuel consumption - it was never great, but it seems to be worse now. Will brim it and check at some point.

 

Or is there something else obvious on these cars I should check that might cause the hissing? The car drives fine - it's always been slow, and it still is.

 

Cheers.

[DragonofAna 10]

I've owned several mondeos but never an automatic one. None of the cars I have had have made a hissing noise though - even when the Cat has gone so do not think this is anything obvious. It could be that there's a leak in the exhaust somewhere.

Where abouts is the hissing coming from?

[Number Six 10]

Sounds like it's coming from the engine - not been and checked to be honest as it only seems to do it under load. Pretty sure it's from in front of the driver rather than somewhere down the exhaust.

 

Don't get an automatic one, btw. Slow and thirsty, and the boxes only last 60 to 90k apparently.

[DragonofAna 10]

Would not dream of getting an automatic. Takes the fun out of driving for me.

 

Just done a check and someone suggests a split induction pipe. Could be a split anywhere - or perhaps as simple as the replacement cat was not fitted properly and there is a gap in the housing.

[Number Six 10]

I think the cat was fitted properly - it was done at Hawleys who are very good in my experience. Will check the pipe - thanks.

 

(I was given the car btw - an auto wouldn't be my choice either!)

[exCrossLad 10]

Would not dream of getting an automatic. Takes the fun out of driving for me.

 

Just done a check and someone suggests a split induction pipe. Could be a split anywhere - or perhaps as simple as the replacement cat was not fitted properly and there is a gap in the housing.

 

An air leak seems the most obvious cause of the problem to me too. But I disagree on automatics. Who needs to be changing gear endless times, and slipping the clutch in traffic, for God's sake?

Give me an auto any day!

[Number Six 10]

An air leak seems the most obvious cause of the problem to me too. But I disagree on automatics. Who needs to be changing gear endless times, and slipping the clutch in traffic, for God's sake?

Give me an auto any day!

 

I have a manual as well - this is the only automatic I've ever had. It is good when you get stuck in traffic, but as I try to avoid that as much as possible it's not a benefit I appreciate very often. In normal driving it's slow, unresponsive and not very efficient. I've been driving more years than I didn't drive, and I've never felt the need to slip the clutch in traffic.

 

I'll definitely have a look for pipes that might be split. I suppose when the cat disintegrated the increased back pressure (it blocked the exhaust) could have caused something to split.

[exCrossLad 10]

I have a manual as well - this is the only automatic I've ever had. It is good when you get stuck in traffic, but as I try to avoid that as much as possible it's not a benefit I appreciate very often. In normal driving it's slow, unresponsive and not very efficient. I've been driving more years than I didn't drive, and I've never felt the need to slip the clutch in traffic.

 

I'll definitely have a look for pipes that might be split. I suppose when the cat disintegrated the increased back pressure (it blocked the exhaust) could have caused something to split.

 

Maybe its because I havent driven in the UK for some years and my memory is fading but I remember going home to Crookes every day from work and having to slip the clutch all the time in bumper-to-bumper traffic from Redhill up past the Children's Hospital to Crookes. I've been driving automatics for six years now and my mpg is no worse than an equivelent manual, and its far more driver friendly. I drove an artic for a living up to a year ago, and changing up and down through 18 gears all day is hard work. I had a friend who drove an auto artic, got the same mileage (about 3.5 mpg), and didnt have left leg twice the size of his right!

[PaymePal 10]

Sounds like it could be the plastic/rubber pipe that goes into the air box.

It could be split or i think theres a jubilee clip that holds it on that can come loose.

It happened to me but on an Escort and was fixed in seconds.

I had exactly the same symptoms.

[Rupert_Baehr 10]

I have a manual as well - this is the only automatic I've ever had... In normal driving it's slow, unresponsive and not very efficient...

 

It's also a Mondeo - perhaps that has something to do with it?

 

My wife's car is an automatic with a 6-speed box. It's quick, responsive and efficient. - You can also select the gearshift to the 'tiptronic' side of the box to 'lock up' the transmission or if you don't want to drive in full auto.

 

It's not a Mondeo.

[exCrossLad 10]

My wife's car is an automatic with a 6-speed box. It's quick, responsive and efficient. - You can also select the gearshift to the 'tiptronic' side of the box to 'lock up' the transmission or if you don't want to drive in full auto.

 

Exactly! Ferrari use two clutch "automatics" now with paddle shifts on the steering column because its simply impossible for a human to change gear fast enough! The transmission bangs off gear shifts in thousands of a second. It also ensures that the drivers hands are on the steering wheel all the time, where they should be.

Manual trans are old school. I dont own a Ferrari, of course, but my Chevy pick up truck with a 5.3 V8 is a pleasure to drive, tons of acceleration, and returns 20mpg.

Give me an automatic any day!

Edited March 24, 2010 by exCrossLad

[DragonofAna 10]

My wife's car is an automatic with a 6-speed box. It's quick, responsive and efficient. - You can also select the gearshift to the 'tiptronic' side of the box to 'lock up' the transmission or if you don't want to drive in full auto.

 

Exactly! Ferrari use two clutch "automatics" now with paddle shifts on the steering column because its simply impossible for a human to change gear fast enough! The transmission bangs off gear shifts in thousands of a second. It also ensures that the drivers hands are on the steering wheel all the time, where they should be.

Manual trans are old school. I dont own a Ferrari, of course, but my Chevy pick up truck with a 5.3 V8 is a pleasure to drive, tons of acceleration, and returns 20mpg.

Give me an automatic any day!

 

You prefer automatics because you didn't have the intellect to pass a manual test? Just joking before you get your nickers in a twist.

 

If automatics were so superior then how come my licence - taken in a manual, allows me to drive and automatic, but the reverse is not true. Autos are too easy to drive. You do not have to make judgements of when to change gear and which gear is the best to be in. Just stick it in drive and forget about it. Boring.

 

Nothing wrong with Mondeo's. Know lots of people who have them, including me. They are a poor mans everything car - quick; nice to look at; cheap to buy; easy to learn to fix; cheap parts; plenty of leg and head room; and so on. Okay they are not fararris or lambourginis or jags but they aren't intended to be, and they far outclass blooming vauxhall astras.