Fumes in cabin - 850 T5 ?

[Stu B]

Hi All,

Over the last week or so during commuting (heavy-ish traffic and cold weather) I’ve noticed a slight smell of fumes in the cabin of my 850 T5 leading to a moderate headache / light headed feeling on one occasion.

I’m going to investigate in daylight tomorrow but wondered if anyone else has experienced this or has any pointers? Car is performing normally, doesn’t smell overly rich, no warning lights illuminated so I’m thinking perhaps fuel tank breather blocked, maybe exhaust leak in engine bay contaminating heater air intake? Missing pollen filter maybe? I changed all the PCV gubbins not too long ago so that should be fine unless something is dislodged.

The tailgate and doors all seem to seal ok, fresh air vents don’t seem contaminated...? I’ll block the tailpipe temporarily with a rag tomorrow and see if I can see any exhaust leaks to start with I suppose.

Any pointers appreciated before the thirsty old girl tries to poison me?

Cheers
Stu

[Cookeh]

Think you've already identified the main probables. Could also be seal on the pump, but you said it wasn't particularly petrol-y smelling, so most likely something exhaust related.

Here's a couple more suggestions borrowed from other forums:

link, link.

Looks like you might want to add the intake manifold vacuum elbow, gasket from mani to downpipe, leaky flex-pipe, and fpr lines. A lot of posts also seem to suggest PCV, so perhaps your breather/flame trap is a bit blocked again?

Alterntively its something much simpler and its just a bad/missing pollen filter that is sucking in plenty fumes from the traffic around you - especially in the cold where fumes dont dissipate as well as on a sunny day. Could try putting climate control on recirc and seeing if it helps.

[Stu B]

Cheers, Cookeh - appreciate the info and links. I checked yesterday and found I have no pollen filter or housing, doesn’t look like there was ever one fitted. Minty has a spare so I’ll fit that when it arrives with a new filter to help.

I checked blocking off the tailpipes temporarily and couldn’t see any exhaust leaks, no apparent fuel leaks and all obvious vacuum pipes etc appear seated correctly. I’ll investigate in more detail over the weekend time and weather permitting. Recirc helps a little I think but without recirc and ‘air mix’ to fresh air that seems fine too though I haven’t been in heavy traffic since Thurs.

I notice if you remove the petrol cap with the engine running there is quite a bit of pressure built up in the tank. Not sure if that’s normal or a sign of a partially blocked breather?

Sure I’ll get to the bottom of it but any further ideas appreciated while I check all the various possibilities

[klausc]

A cabin filter will not keep smells out of the system, but it is good that you are installing one because it keeps the dirt out.
Do you have the driver's window open at all during your commute? That will draw air from the rear of the car to the open window. Heavy traffic, light wind, and cold temperatures will tend to keep the exhaust fumes in the travel lanes.

If your engine uses a lot of petrol, check for vacuum line leaks as well as the engine temperature sensor next to the thermostat. The seal under the bonnet and on top of the firewall is supposed to keep engine fumes from entering the fresh air intake.