Diesel smell in engine bay and cabin

KFed · 05-11-2024 10:41AM #1

Hi there

I have a bmw e92 320d which has the timing chain replaced a few years ago. Since then, there has been a persistent smell of diesel in the cabin from time to time. Normally it is most noticeable when the air con is on.

The timing chain was done by a bmw independent specialist and has been back to them since for services etc and Its been looked at but no resolution.

I have had the flexi pipe replaced.

There are no errors on the dash.

But it is quite noticeable from time to time. This morning on start up I popped the bonnet and there is a quite noticeable smell of unfiltered exhaust in and around the engine bay (this shouldn't be normal?)

Any thoughts on what it may be?

The car is passing the nct with no issues and no apparent issues with emissions etc so I don't think it's any sort of filter issue.

The car is running well otherwise and I like the car so I'd like to hold on to it but can't seem to solve this problem.

antodeco · 05-11-2024 12:33PM

DO you notice any whine/squeal/hiss when you accelerate at all?

KFed · 05-11-2024 01:50PM

No I don't notice anything on acceleration.

The car seems to be driving normally, but does just seem to be an issue with gases accumulating / escaping.

Lewis_Benson · 05-11-2024 01:54PM

Check to see if the egr valve had any leaks around it, get someone to rev the engine while shining a torch around that area, I had a similar issue on a mk4 Ford Mondeo years ago, turns out when getting the EGR replaced, the gasket was put in arseways on the join to the exhaust, and was leaking exhaust fumes, and was being tucked into the car by the AC.

MustangMick · 05-11-2024 04:45PM

Any leaks around the injectors or loss of performance?

Atlantic Dawn · 05-11-2024 04:53PM

Any sign of any diesel spillage under the engine bay when the car is parked up after a drive?

KFed · 05-11-2024 09:35PM

No sign of any diesel spillages under the car.

And there doesn't seem to be any loss of performance. I'll see can I get someone to rev it while I look around with a torch.

It's definitely noticeable though, very distinct smell of diesel fumes in the engine bay that hasn't gone back through the exhaust and filters. As in, the engine bay smell is much more distinctive (dirtier of that makes sense) so I'm assuming it is escaping somewhere...

No loss of performance in the car and no lights on so it's fine to drive. I'm just worried about my lungs tbh!

KFed · 24-12-2024 03:57PM

I am wondering if it's a cracked exhaust manifold. I had a look around with the engine cover off and can see smoke (trace amount) coming up from where I think the exhaust manifold is fitted to the engine.

Does anyone know roughly how labour intensive a replacement that would be?

The car is in very good condition so just want to get it sorted.

I'm looking to move it on in the new year and apart from this issue the car is perfect.

mk7r · 24-12-2024 07:58PM

The exhaust downpipe Flexi is a common failure on them

KFed · 24-12-2024 10:49PM

Thanks,

I've had a new flexi pipe installed and that hasn't solved the problem.

I have a video, not sure how to link to it, but inside the engine bay can see thin wisps of smoke coming up from what I think is the exhaust manifold.

The car is running fine, no fault or error codes, but very noticeable smell in engine bay and getting sucked into the cabin then also.

I assume some level of leak from exhaust and based on what I can see I think it may be the manifold.

Anyone had a similar issue, similar repair?

I'm wondering is this a 1k euro issue or much simpler?

I'd look for an indie.

magicbastarder · 25-12-2024 09:55AM

Not diesel, but a few years ago (in my petrol car) I hit a huge pothole and afterwards sporadically got what smelled to me like a two stroke engine smell in the car - turns out the impact had broken the oil breather pipe and oil was slowly dropping onto the engine block. Generally the smell was only noticeable if I was sitting at lights for a while - when moving there was obviously enough airflow to carry the fumes away before they were sucked into the cabin.

BlakeS94 · 25-12-2024 08:36PM

Next time it's in at the garage ask them to smoke test it, should find any little cracks in the manifold,if there are any.

Exhaust fumes into the cabin will make you feel ill,you'd have a headache after a few minutes of breathing it in, if its just a noticeable unpleasant smell it could be unburnt diesel, have you checked around fuel connections, injector leak off pipes?

deandean · 26-12-2024 11:11AM

I had that same problem a few years ago on a 530d (6 cylinder). One of the injectors had loosened.

Take off the top engine cover and look around the injectors while the engine is running.

I had all six injectors pulled and re-seated, problem sorted.

colm reilly · 28-12-2024 03:39AM

So new cooper seals ,ye ?

Diesel smell in engine bay and cabin

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