Exhaust Smell in car, how to solve it?

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
begins
Posts: 230
Joined: 11 Sep 2012, 13:06
Location: Malaysia
My Cars:

Exhaust Smell in car, how to solve it?

Post by begins »

Hi all,

I have a headache here. My year 2007 C5 would give out exhaust smell inside the car when driving hard or running quickly to 4K RPM. If I run beyond 180Km/h, It will give rotten egg smell intermittently. I used internal air circulation so it should not have let in the fumes from the outside.

The moment the speed is reduced, the smell would go away. If the RPM is below 4K, I will not have this problem.

When I described the problem to the workshop, they have no clue on how to solve it.

Can any kind souls and experts here advise me on how to tackle this one?

Thank you very much.

Regards,
User avatar
mooseshaver
Posts: 886
Joined: 27 Apr 2006, 10:50
Location: Cumbria
My Cars:

Re: Exhaust Smell in car, how to solve it?

Post by mooseshaver »

I've had this with with fire rings not done up properly. Was a 1.4 hdi. A friend has had the same issue with his focus 1.6 hdi. Think same fault really but it was injector seals. Think fire rings and injector seals are the same thing. I think you can look around where injector is visible and check for carbon.
C5 III Tourer 2.0 HDi 163 Auto Exclusive
Gone cars.
C5 2.2 HDi Exclusive Estate auto 57. Awesome car. Sadly Could not be fixed by Citroen.
C5 1.6 HDi VTR Estate 56. Traded in.
C5 2.2 HDi SX Estate 02. Drowned in the floods of 09.
C3 1.4 HDi 92 SX 52.
Saxo 1.1 East Coast.
begins
Posts: 230
Joined: 11 Sep 2012, 13:06
Location: Malaysia
My Cars:

Re: Exhaust Smell in car, how to solve it?

Post by begins »

mooseshaver wrote:I've had this with with fire rings not done up properly. Was a 1.4 hdi. A friend has had the same issue with his focus 1.6 hdi. Think same fault really but it was injector seals. Think fire rings and injector seals are the same thing. I think you can look around where injector is visible and check for carbon.
Hi there, Thank you very much for the tip! Will get the mechanic to check on that.

Regards,
Gibbo2286
(Donor 2020)
Posts: 7171
Joined: 08 Jun 2011, 18:04
Location: GL15***
My Cars: 2006 C5 2.0 Litre HDI VTR Automatic Estate.(now sold on)
Currently Renault Zoe 2014 ZE
x 2500

Re: Exhaust Smell in car, how to solve it?

Post by Gibbo2286 »

You could also check that the tailgate/boot lid seals are in good condition, exhaust fumes can be drawn in through there.
Man is, by nature, a lazy beast, he does not need twice encouraging to do nothing.
User avatar
blackbeard
Posts: 24
Joined: 13 Jan 2013, 16:54
Location: Chorley, Lancashire
My Cars:

Re: Exhaust Smell in car, how to solve it?

Post by blackbeard »

Fumes inside a modern car are very rare. From my experience of 'Rotten egg smells' it was the result of one of the following:

1) Cat fault / failure: Sulphur 'rotten egg' smell on start up (and then clearing a few seconds later) is the classic symptom of a catalytic converter on the way out. This is not just a 'Citroen thing', it effects any make model with a standard Euro approved cat. Loads of info on the net about this if you want to do some independent research.

2) Dirty and damp air-con internals and filters. Rotten egg smell can come from bacterial growth in the air con system (which will come through into the cabin with recirculation on or off). If you are getting a damp smell / condensation in addition to the egg smell you may want to try replacing your pollen filter and getting the air-con professionally cleaned / decontaminated and see how you get on.

Hope the above helps.

PS, dont drive if you really do suspect fumes are coming into the cabin - they sneak up on you and they will put you to sleep. I drove a car with a faulty exhaust system (a 1970's VW Beetle) in my younger days. The old VW and ended up in the scrap yard and I ended up in a hospital bed (the Beetle was rolled onto the roof after bouncing off a tree, sliding through a fence, accross a field, still on the roof, and then sliding upside down an embankment into a water filled ditch).
Current French machine:
2002 Citroen C5 2.0 16v Automatic (petrol)

Previous French machines (all auction finds):
2000 Citroen Xantia 1.8 16v (petrol)
1999 Peugeot 206 'Roland-Garos'
1998 Renault Laguna 1.8 8v (petrol)
1992 Renault 21 2.0 8v (petrol saloon)
Peter.N.
Moderating Team
Posts: 11563
Joined: 02 Apr 2005, 16:11
Location: Charmouth,Dorset
My Cars: Currently:

C5 X7 VTR + Satnav Hdi estate Silver
C5 X7 VTR + Hdi Estate 2008 Red

In the past: 3, CX td Safaris and about 7, XM td estates. Lovely cars.
x 1199

Re: Exhaust Smell in car, how to solve it?

Post by Peter.N. »

I assume from the 4,000 rpm and rotten egg smell that yours has a petrol engine, in which case its more likely exhaust gasses getting into the car from outside, running the ventilation on 'recirculate' will make matters worse as you have no internal air pressure, as suggested, check the tailgate seals.

Peter
begins
Posts: 230
Joined: 11 Sep 2012, 13:06
Location: Malaysia
My Cars:

Re: Exhaust Smell in car, how to solve it?

Post by begins »

blackbeard wrote:Fumes inside a modern car are very rare. From my experience of 'Rotten egg smells' it was the result of one of the following:

1) Cat fault / failure: Sulphur 'rotten egg' smell on start up (and then clearing a few seconds later) is the classic symptom of a catalytic converter on the way out. This is not just a 'Citroen thing', it effects any make model with a standard Euro approved cat. Loads of info on the net about this if you want to do some independent research.

The strange thing is the problem is not upon startup. It happened when driving hard and at high rpm, in excess of 4K.

2) Dirty and damp air-con internals and filters. Rotten egg smell can come from bacterial growth in the air con system (which will come through into the cabin with recirculation on or off). If you are getting a damp smell / condensation in addition to the egg smell you may want to try replacing your pollen filter and getting the air-con professionally cleaned / decontaminated and see how you get on.

Initially suspected that too but I have changed the aircon filter just a few days ago. Cleaning the entire aircon system will take a few days to do, need to schedule for it

Hope the above helps.

PS, dont drive if you really do suspect fumes are coming into the cabin - they sneak up on you and they will put you to sleep. I drove a car with a faulty exhaust system (a 1970's VW Beetle) in my younger days. The old VW and ended up in the scrap yard and I ended up in a hospital bed (the Beetle was rolled onto the roof after bouncing off a tree, sliding through a fence, accross a field, still on the roof, and then sliding upside down an embankment into a water filled ditch).
Thank you very much for the pointer. I need my car for work and I drive about 100km each day nowadays. I suppose so long I stay below 4K rpm, I should be ok.

Regards,
begins
Posts: 230
Joined: 11 Sep 2012, 13:06
Location: Malaysia
My Cars:

Re: Exhaust Smell in car, how to solve it?

Post by begins »

Peter.N. wrote:I assume from the 4,000 rpm and rotten egg smell that yours has a petrol engine, in which case its more likely exhaust gasses getting into the car from outside, running the ventilation on 'recirculate' will make matters worse as you have no internal air pressure, as suggested, check the tailgate seals.

Peter
Pardon my ignorance, if the car is running fast, the wind should have dispersed the exhaust away while on the move right? How could the fumes be entering from behind?

I read further from the net and have gathered that the following items have to be checked:

1. As you said, check the tailgate seals,
2. Check spark plugs,
3. Check spark wires,
4. Clean the injector,
5. Check that the ventilator is enable to close properly,
6. When all else fail, check for leaky catalytic converter.

Today, I went to a workshop and they found out that all the 4 plugs have been drenched by oil. So I have changed the spark plugs but was advised to change the plug seal (I wonder what is the root cause and what is that seal by the way?) ASAP. I only managed to hit almost 4K rpm for a short while today and I’m quite surprised that smell is much more faint now. I need to find a chance to try again next week. May be will try cleaning the injector the next round.

Thank you very much for your advice.

Regards,
Gibbo2286
(Donor 2020)
Posts: 7171
Joined: 08 Jun 2011, 18:04
Location: GL15***
My Cars: 2006 C5 2.0 Litre HDI VTR Automatic Estate.(now sold on)
Currently Renault Zoe 2014 ZE
x 2500

Re: Exhaust Smell in car, how to solve it?

Post by Gibbo2286 »

begins wrote:
Peter.N. wrote:I assume from the 4,000 rpm and rotten egg smell that yours has a petrol engine, in which case its more likely exhaust gasses getting into the car from outside, running the ventilation on 'recirculate' will make matters worse as you have no internal air pressure, as suggested, check the tailgate seals.

Peter
Pardon my ignorance, if the car is running fast, the wind should have dispersed the exhaust away while on the move right? How could the fumes be entering from behind? Regards,
The car moving forward through the air creates a partial vacuum behind it which sucks in the exhaust fumes, you will see it most prominently on vans etc. where that rear doors are covered in road dirt that's been sucked up. Watch formula one cars getting a tow from the vehicle in front to see the same effect.
Man is, by nature, a lazy beast, he does not need twice encouraging to do nothing.
begins
Posts: 230
Joined: 11 Sep 2012, 13:06
Location: Malaysia
My Cars:

Re: Exhaust Smell in car, how to solve it?

Post by begins »

Gibbo2286 wrote: The car moving forward through the air creates a partial vacuum behind it which sucks in the exhaust fumes, you will see it most prominently on vans etc. where that rear doors are covered in road dirt that's been sucked up. Watch formula one cars getting a tow from the vehicle in front to see the same effect.
Thank you very much for the explanation.

For now, it seems to me that solving the problem is like tackling an art subject:-D How do I check for a leak in the tailgate seal? I can’t find any break nor crack lines?

By the way, I attempted high speed today (i.e. >4K RPM), the smell still comes on so it means it is not the spark plug problem.

Regards,
User avatar
SaabC5
Posts: 765
Joined: 01 Aug 2011, 23:18
Location: SW London
My Cars: 09 C5 X7 2.0Hdi Exclusive
x 1

Re: Exhaust Smell in car, how to solve it?

Post by SaabC5 »

Check all hoses that deal with gasses under the bonnet are intact. Common fault on the Saab 9-5 having exhaust gasses in the cabin is a small vent hose on the cam cover perishing allowing exhaust smell to enter cabin.
09 C5 X7 2.0Hdi Exclusive in Perla Nera black (the best colour) :wink:
begins
Posts: 230
Joined: 11 Sep 2012, 13:06
Location: Malaysia
My Cars:

Re: Exhaust Smell in car, how to solve it?

Post by begins »

Hi all,

Strange, I just realized that if I switch off the Fan to “OFF”(Air-con off), I will not get exhaust smell in the car at all.

So I can now rule out tailgate seal and spark plugs issues. I wonder if it helps to refresh the air-con gas in the car?

Regards,
Post Reply