Hello all, over the past couple of months we've had a smell of engine/exhaust fumes coming from the heater vent of our 2013 Ford S-Max 2.0 TDCI 140bhp Powershift. When it started I did a search and a few people fixed the problem by changing the injector seals.

 

So I had a look and sure enough two of ours were leaking combustion gasses. I replaced these two, (just two, im reluctant to disturb the other two if they aren't leaking) and the heater definitely got a lot less smelly, but there was still fumes coming in. I changed the pollen filter just to be sure, and that made no difference.

 

I triple and quadruple checked the injectors, and no leaks, I also sprayed soapy water on them when hot, and cold, and no bubbles and no leaks.

 

So I moved my attention to the exhaust, I connected the workshop vacuum (outlet) to the exhaust to pressurise it, and found two small leaks, one on the gasket between the Cat and DPF, the other on the flex joint, so I replaced the flex joint and the gasket and no more leaks… we still have a smell from the heater though!

 

I cant see any leaks on the EGR, exhaust, or injectors, all double or quadruple checked with soapy water at different temperatures.

I cant see any diesel or oil leaks, it smells like exhaust rather than fluids anyway.

 

The smell is at its worst when sitting in traffic, and I cant smell it at all once moving. The smell is there from first start in the morning when the engine is cold, and when its hot. One more thing to mention, the smell started around the same time the top engine mount failed and collapsed, this was replaced shortly after it failed. It could be a coincidence that both started at the same time. (The powershift failed around the same time too… its been an expensive few months!)

 

So has anyone any ideas what to check next?

Is the engine/injector cover damaged, leaking or missing ?

https://www.ebay.co.uk/itm/285538012993

 

On 12/3/2025 at 7:26 PM, unofix said:

Is the engine/injector cover damaged, leaking or missing ?

https://www.ebay.co.uk/itm/285538012993

 

 

Sorry for the slow reply on this, i got distracted with work and the christmas rush.

Thanks for the suggestion Unofix, to answer your question yes the injector cover is completely intact, and as far as i can tell well sealed, i wouldn't say its 100% hermetically sealed, the gasket/seal is 12 years old after all, does it need to be completely airtight?