Stinky Diesel Leak

[Winslow]

Had my C250TD [1979] serviced by the local MB dealer 2 months ago - I had previously gone to an independent. About a week after the service I noticed an increasingly strong smell of diesel and one morning the car refused to start. The AA man said the fuel filter has not been fitted properly or was leaking allowing air into the system. The AA chap got the car started and I drove it to MB. MB said the filter was ok but there was a diesel leak coming from one of the lines and they wanted to change some washers [ which were not in stock] Went back after the washers had been delivered and another mechanic decided the original diagnosis was wrong and they changed the heat exchanger. The smell didn't go away and I took the car back to MB - this time they thought it was the fuel shut off valve which was replaced. In fairness they were getting pretty embarrassed and waived the labour charges. The car continued to coat itself in diesel and I found the only relief from the stench was to constantly drive with the aircon on recirculating mode. I went back and they said they would like the car for two days to get to the bottom of the problem. I left the car with them – 2 days later returned to find no change but the problem was now thought to be some seals which were not in stock I was now beginning to get a whiff of déjà vu as well as diesel. They said they would like the car back for an extended period and offered a courtesy car. I picked up a A170 2 days ago. The latest update is that they have sent the car to a specialist engineering firm as the leak is in the injection pump and they do not have the tools to replace the washers. Has this happened to anyone else? They anticipate I will get the car back in a couple of days. So far the MB boys have been really good about this and the sense of corporate embarrassment is overwhelming. I still have an uncomfortable feeling as the car had been fine up to the service and the thought that I may need to sell a kidney before I get it back. My car has done 110,000 miles [ran my previous c250 to 120k with none of this nonsense]. Any thoughts would be appreciated.http://forums.mercedesclub.org.uk/images/smilies/confused.gif

 

[mercedes13156]

Have you looked at the braided rubber hose which goes from the heat exchanger under the filter, under the engine cover and loops from injector to injector from front to back. Mine had perished at the filter end and at Nr 4 injector. A new hose might do the trick. I cut an inch off the filter end, but the injector end is a bit of a bugger to replace, so I'm still leaking a bit of diesel which gets drawn in through the grille just behind Nr 4 at the back of the engine and comes into the cabin. I can only smell it when I've been sitting for a couple of minutes at the idle. In my case the hole that the injector site in was full of fuel. I hope this helps. Let me know if it does.

 

[Parrot of Doom]

Do a search of this forum for 'fuel leak', you'll find plenty of info on your situation.

The easy thing to do would be to wipe the fuel pump and all the lines clean (with a rag), take it for a drive, and then shine a torch down there to see where its leaking. My guess would be the fuel lines, or the delivery valve seals, or the shutoff valve.

Another method is to put the car on ramps, remove the plastic undertray from beneath the engine, and run the car to see where it's dripping from.

 

[hmang]

dry everything off with brake cleaner and an air line.
then dust all the suspect areas with talcolm powder.

 

[Winslow]

Hi All,

Thanks for the suggestions - will try a combination of Parrot and hmangs ideas and look for these braided pipe. Will keep you posted.

All the best.

 

[Daeths]

dry everything off with brake cleaner and an air line.
then dust all the suspect areas with talcolm powder.

Gr8 tip, one for the memory banks !!

 

[Winslow]

Hello,

Got the car back this afternoon It seems it was the joints on the high pressure side of the injector pump that take the fuel to the injectors - I'm told this is very rare. Only done a few miles since the repair and so far it smells much better. Thanks for all the helpful suggestions above.

Merry Christmas
John

 

[dieselman]

Hello,

Got the car back this afternoon It seems it was the joints on the high pressure side of the injector pump that take the fuel to the injectors - I'm told this is very rare. Only done a few miles since the repair and so far it smells much better. Thanks for all the helpful suggestions above.

Merry Christmas
John

They are the 'delivery valves'. Unusual to leak but not unheard of. You description suited this fault. Tying a bit of paper towel around parts of the pump would've told the story.

If a diesel leak is difficult to spot on these engines run the engine with the inlet manifold off for better access and vision.