Help Needed - Diesel Fumes

[JEZ.S320L]

My ML270 has suddenly started to pull diesel fumes in through the heating system. All is OK at motorway speeds, but is definately pulling fumes in when stopped - and no, there is no other vehicle in front.

Any ideas, please?

 

[JEZ.S320L]

My ML270 has suddenly started to pull diesel fumes in through the heating system. All is OK at motorway speeds, but is definately pulling fumes in when stopped - and no, there is no other vehicle in front.

Any ideas, please?

Any suggestions/advice please?

 

[Jensen]

Mine too C250TD. There is a smell like fuel and had problem starting last week when only had quarter of tank. Once filled up started no problem.
Indie advises might be a fuel connection pipe in engine or something like that, sorry I'm not a techy. Also manafold needs replacing as oil residue present.

 

[JEZ.S320L]

Mine too C250TD. There is a smell like fuel and had problem starting last week when only had quarter of tank. Once filled up started no problem.
Indie advises might be a fuel connection pipe in engine or something like that, sorry I'm not a techy. Also manafold needs replacing as oil residue present.

I had filled up and almost completed a 225 mile trip. By this time I was down to just over half a tankful left. It was only when I stopped at the top of the slip road that I noticed the smell. Upon joining another motorway - the smell disappeared - only to return again when I pulled up outside a Hotel. The smell was definately coming in throught the heating vents.

p.s. I have had no starting problems whatsoever (touch wood.!!)

 

[hawk20]

I'm not a techie- not even half a techie. But I had this awful smell problem every now and again on the S320cdi. A technical expert at Mercedes said it is the particulate filter burning off surplus something or other that does it. Not every time you stop. Just sometimes. Do you have a Particulate filter?

 

[JEZ.S320L]

I'm not a techie- not even half a techie. But I had this awful smell problem every now and again on the S320cdi. A technical expert at Mercedes said it is the particulate filter burning off surplus something or other that does it. Not every time you stop. Just sometimes. Do you have a Particulate filter?

I am not 'techie' either. I wouldn't know if I have or have not. :roll: Fortunately, I am off to Egypt on Wednesday morning - and have it booked in for a mega-service/health check, the week after I get back as I'm driving to Spain on the 22nd. It's just that I don't want the smell of diesel fumes to spoil the journey. Is it something I should leave for the dealer to sort out, or is it a DIY 'quick fix'?

Thanks.

 

[hawk20]

I am not 'techie' either. I wouldn't know if I have or have not. :roll: Fortunately, I am off to Egypt on Wednesday morning - and have it booked in for a mega-service/health check, the week after I get back as I'm driving to Spain on the 22nd. It's just that I don't want the smell of diesel fumes to spoil the journey. Is it something I should leave for the dealer to sort out, or is it a DIY 'quick fix'?

Thanks.

I think you must get it checked. You don't want to be asphyxsiated and until you know the cause I would be concerned.

 

[Xtractorfan]

I had this from my S320 CDI driving thru town, my missus mentioned it first and the blame was immediately apportioned to a lorry just in front... but sometime later whilst traffic warden spotting on double yellow lines, engine running for a quick get away and no lorries or diesel fed vehicles around I still noticed the fumes.. and as I had already removed the engine cover previously I had a quick look and nothing immediate but on a second look ..later.. It turned out to be a leaking injector..blowing past.. and fitting a new copper washer/seal cured the problem..tho i did have to use the 'old' bolt again. and refitting them can be a bit of a problem as apparently they do stretch when tensioned /torqued

 

[JEZ.S320L]

I had this from my S320 CDI driving thru town, my missus mentioned it first and the blame was immediately apportioned to a lorry just in front... but sometime later whilst traffic warden spotting on double yellow lines, engine running for a quick get away and no lorries or diesel fed vehicles around I still noticed the fumes.. and as I had already removed the engine cover previously I had a quick look and nothing immediate but on a second look ..later.. It turned out to be a leaking injector..blowing past.. and fitting a new copper washer/seal cured the problem..tho i did have to use the 'old' bolt again. and refitting them can be a bit of a problem as apparently they do stretch when tensioned /torqued

Thanks - I shall put it in the hands of the Dealer when I get back.

 

[Ellsy Tanners]

Hi mate, a few possible cause'es could be a blowing injector as said, a slightly blocked cat causeing a leakage of exhaust gases through one of the joints, or simply a fuel leak from the engine, most commanly around the filter on the top right of the engine, a few things to check and i hope points you in the right direction

 

[JEZ.S320L]

Hi mate, a few possible cause'es could be a blowing injector as said, a slightly blocked cat causeing a leakage of exhaust gases through one of the joints, or simply a fuel leak from the engine, most commanly around the filter on the top right of the engine, a few things to check and i hope points you in the right direction

Thanks very much - I will get it into the Dealers when I get back. I discovered on my way home last night, that as a purely temporary fix, if I put the recirc on - no smell of fumes

 

[panason1c]

A common area where the exhaust fumes leak from on a ML270 is the joint between the turbo and the exhaust downpipe .... the clamp that holds the joint together is of a 'sprung' type and can occasionally weaken and fall off. (That is what happened to mine) If you watch this joint whilst someone floors the throttle from tickover you will see a puff of black smoke come from it if it is leaking.

There is also an issue that affects some vehicles where the cat becomes blocked and the resulting back pressure forces the gasses out from the aforementioned joint, this is not such a common problem.

Here is a pic of the area of the joint and you can just see one of the forks of the clamp...(just below the air box)

Access to the joint is very easy, just remove the air filter box and heat shield assembly to expose the area.

 

[BlackC55]

Remove the engine covers and check the injectors. They tend to leak combustion gasses and it does get into the cabin.

 

[JEZ.S320L]

BlackC55/Panason1c

Thanks for your replies - you have put my mind at rest. I will certainly get it checked out when I get back from Egypt (I go tomorrow for 2 weeks )

Have a Happy Christmas and a Healthy and Prosperous New Year. I'll be back on the Forum in the new year.

 

[Winslow]

I have had the same problem with my C250. The local MB dealer thought it was a leaking heat exchanger then the fuel shut off valve but have now just traced it to the joints where the high pressure fuel pipes come off the pump. I think these pipes take the fuel to the injectors. They had to send the car to a specialist as they didn't have the tool to undo the thing but [touch wood]it seems ok now. I am guessing what was happening was high presure diesel was being sprayed out in to the engine bay and finding it's way to the air vents when the car was stationary in traffic. MB were pretty good about it and only charged me for the specialists time and parts. Hope this helps.

 

[JEZ.S320L]

Update

Remove the engine covers and check the injectors. They tend to leak combustion gasses and it does get into the cabin.

I have just had my car returned from the main dealers, and your diagnosis was spot on.! Leaking seals WERE the cause.

Thank you.