Smell of engine/oil with air con on

colm_c · 30-07-2014 10:57pm #1

Recently when I have the aircon on in the car, I get a faint smell of the engine -- oil or fumes. It takes about 5-10 mins from starting off for this smell to be noticeable. However once I put it in re-circulation mode (and open the windows to let the air out), smell isn't there. I'm now keeping it in re-circulation mode until I get this sorted.

I'm thinking there's a leak in the aircon input pipe somewhere, any ideas how to track this down or is it a specialist job?

Car is a BMW 5-series (e60).

Thanks.

corglass · 02-08-2014 2:52pm

colm_c wrote: »

Recently when I have the aircon on in the car, I get a faint smell of the engine -- oil or fumes. It takes about 5-10 mins from starting off for this smell to be noticeable. However once I put it in re-circulation mode (and open the windows to let the air out), smell isn't there. I'm now keeping it in re-circulation mode until I get this sorted.

I'm thinking there's a leak in the aircon input pipe somewhere, any ideas how to track this down or is it a specialist job?

Car is a BMW 5-series (e60).

Thanks.

Been there. I presume you've a diesel?

If so, I'd guess its the injectors. The seals have failed in one or more of them resulting in "blowback / blowby" at the injector. If you lift your engine cover you'll probably find some lovely gunk around the injector area.

It's no big deal to fix. Just remove ALL injectors and remove the seals beneath each. Replace the seals, then clean and refit the injectors. It takes about 4 hours if the injectors and seals aren't too stubborn.

Hope this helps

colm_c · 03-08-2014 3:31pm

corglass wrote: »

Been there. I presume you've a diesel?

If so, I'd guess its the injectors. The seals have failed in one or more of them resulting in "blowback / blowby" at the injector. If you lift your engine cover you'll probably find some lovely gunk around the injector area.

It's no big deal to fix. Just remove ALL injectors and remove the seals beneath each. Replace the seals, then clean and refit the injectors. It takes about 4 hours if the injectors and seals aren't too stubborn.

Hope this helps

Nope, not a diesel, petrol. Having my mechanic have a look this week.

Alanstrainor · 03-08-2014 4:07pm

colm_c wrote: »

Recently when I have the aircon on in the car, I get a faint smell of the engine -- oil or fumes. It takes about 5-10 mins from starting off for this smell to be noticeable. However once I put it in re-circulation mode (and open the windows to let the air out), smell isn't there. I'm now keeping it in re-circulation mode until I get this sorted.

I'm thinking there's a leak in the aircon input pipe somewhere, any ideas how to track this down or is it a specialist job?

Car is a BMW 5-series (e60).

Thanks.

Is it only with the A/C on? Or does it come through with just the blower?

Could be the rocker cover gasket failing. That's exactly what symptoms I would get on my 2001 e46, and the engines are very similar. It would only happen after 5/10 minutes after things have warmed up you would get the smell of oil through the vents due to the oil leaking onto the manifold on the drivers side of the engine. Very common issue on these. It can be hard to see properly if this is the case, but taking a look under the bonnet when you get the smell and you may be able to see the steam coming from that side of the engine where the drips of oil hit.

colm_c · 03-08-2014 4:21pm

Alanstrainor wrote: »

Is it only with the A/C on? Or does it come through with just the blower?

Could be the rocker cover gasket failing. That's exactly what symptoms I would get on my 2001 e46, and the engines are very similar. It would only happen after 5/10 minutes after things have warmed up you would get the smell of oil through the vents due to the oil leaking onto the manifold on the drivers side of the engine. Very common issue on these. It can be hard to see properly if this is the case, but taking a look under the bonnet when you get the smell and you may be able to see the steam coming from that side of the engine where the drips of oil hit.

Comes on with both the AC or the blower.

Symptoms do sound similar alright, might have a poke around later on to see if I can see any leak.

DublinDilbert · 03-08-2014 6:23pm

What engine is in these? Is there a Vac pump driven off the back of one of the CAMs? If there is, this is probably leaking onto the exhaust causing the smell your getting.

if its the vac pump leaking the easy fix is to take it out and replace the o-ring in the cover, with one from a new oil-filter, same size and works a charm.

PeteK* · 03-08-2014 10:49pm

I mentioned this when my card was being serviced a few weeks ago.
It was the pollen filter(?) apparently.. which they replaced but I think I have since smelt the same smell.. not entirely sure just yet. It's generally when I'm not moving and the engine is off.
I don't smell it when air con is on.

My oil wasn't low at the beginning and now it's at five litres (Which is more than I'd prefer).

antodeco · 03-08-2014 11:56pm

When mine is running on low on oil, I notice the smell coming through. Top up with oil and it goes. Bizarre "self diagnosis" on the car

JohnCleary · 05-08-2014 6:05pm

Happened on my 320d, it was a leak in the exhaust. IIRC it was the join between the manifold and the downpipe. Basically the blower was sucking in exhaust fumes. Mechanic fixed it promptly, wasn't a big deal

Smell of engine/oil with air con on

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