Thread: Strong sulphur smell in TD5 ventilation system

Any ideas what could be causing a strong sulphur smell coming through the air vents?

It's been happening for around 2 weeks now.

I searched for this and a previous post suggested in cabin battery to blame - I don't have this though.

Any ideas?

Originally Posted by akula

How do I check this? I don't know where that is located.

Hi Akula,
The heater matrix (or core, like a small radiator) is located behind the dash panel (roughly in the centre), inside the passenger compartment.
Hoses come from the engine bay, through the firewall, to connect with the heater matrix.

To establish whether your smell is due to leakage from the heater core, I think a couple of things are worth checking.

1. Monitor coolant level in the radiator expansion tank. If the heater core is leaking, then the level should be going down (but it might only be slow, so far).

2. Put your head down into the front passenger footwell and driver's footwell, and use a small torch look for any sign of dampness and odour above the hump in the middle.

3. Have you noticed a gurgling sound coming from behind the dash-panel, inside the passenger compartment? This is a symptom of heater-core leakage.

If the cause of the smell is exhaust gas, then the exhaust manifold or pipe must be leaking, and you could probably hear this when the engine is running with the bonnet up. You could get someone to place a folded rag over the rear end of the exhaust pipe for a few seconds, and see if there is a hissing sound that would indicate a leak. I think such a leak would need to be in the engine bay for it to result in smell coming through the air-vents, so an exhaust leak much further back is probably not the culprit.

PhillipA's suggestion of a dead mouse is quite a real possibility.
The blower motor for the ventilation system is behind and under the glove-box.
If you remove it, anything that is in the pipe that brings air into the cabin from an intake under the plenum cover at the bottom of the windscreen may drop out. If not, but there is a bad smell from the blower, the blower needs to be opened!

bblaze's offering about windscreen-washer fluid/additive reminds me that I have sometimes experienced a noticeable odour in the cabin immediately after using the windscreen washers. It might be worth using the washers for a few seconds while you are driving, and seeing if you notice any smell that correlates with doing so. The intake for cabin air is located in front of and below the passenger's-side windscreen, just under the black panel that runs along the bottom of the windscreen. Water that drains off the windscreen can easily run underneath that black cover ("plenum"), into drains that carry it to either side. Without going down the air-intake pipe, the washer-fluid might impart an odour to the air being drawn in over it.
IF WATER DOES GO DOWN THAT AIR-INTAKE it will DEFINITELY show up on the carpet in the passenger's footwell (so long as there is enough of it).

Good luck,
Andrew