cdi fuel pump leak

[williamuk21]

Hello I am new to the forum. Always wanted a mercedes so took the plunge and bought a s320 cdi 2003 with 120k on the clock. I really love the car but I've only done a couple of thousand miles and already had the MAF replaced at £200 and recently it has shredded its fan belt. I took it into quick fit as I was nearby and didn't want to risk the belt breaking, they fixed it for £80 and a week later I was back to them with the belt going again, they investigated and said there was fuel leaking onto the belt and it would be £700 to fix. I asked them to just do the belt again which they did but without the warranty this time of course. So although I love the car I am getting a bit worried about reliability and not sure what to do next about the fuel pump, could really do without a £700 repair bill and still be worried about what might go next. Any ideas would be appreciated.

 

[mersum1es]

If diesel leak will damage the belt so fast, you should observe quite amount of leak...? Mine leaked also about one week (several liters!) and no (more than in the beginning) visible damage in the belt. Is the belt running smoothly, not vibrating on the run?
Often culprit are o-rings of the low pressure connection on the side of the pump, shows like leak comes between pump head and body. Inner seals can be changed, cheap 'nothing to loose' try if pump need to change anyway:
http://forums.mercedesclub.org.uk/showthread.php?t=105316
http://www.mbclub.co.uk/forums/engine/136662-e320-cdi-fueling-problem-3.html
Refurbished pump will cost 500€ most, W210 rather easy to change DIY, W220 access may be slightly different (fan removal etc.)?

 

[williamuk21]

Fuel leak?

To be honest I didn't even smell diesel but I don't think Quickfit would lie about the leak. I heard a chirp chirp from under the bonnet after the first belt change so I sprayed it with some belt dressing, the next day it started to strip again. I think I will take the car to the local Merc specialist and see what they suggest.

 

[rpe2]

Haven't we covered this already in post #12?

http://forums.mercedesclub.org.uk/showthread.php?t=113643&highlight=junking&page=2

 

[williamuk21]

Hi Richard.yes I did post it before but as part of my post about keys,thought I would try it in the right section and hopefully get more response. I want to get as much info and help as possible before I decide how to procede. I am new and really enjoying this excellent forum. Hope I didn't break any rules covering the same subjet.

 

[mersum1es]

And diesel on the belt will damage it in the long run...
I just wondered if the belt is vibrating, there are problems with tensioner pulley or alternator free wheel. Did they change tensioner or other pulleys when the belt was changed? 120k is not much but pulleys are not expensive. Is there visible polished sections either side of the belt? Water pump of my colleague W211 failed, and caused extra torque (pump was still rotating) so that the belt started slipping.

 

[bigtwin]

Just picked up same car this morning from having this fixed. Was 5p O ring on feed pipe that was leaking. Full seal kit for pump is £30 anyway, and exchange ECP unit is £400. No need to stupid dealer prices.

Replace the serpentine belt - mine was half destroyed (not visible in situ) after not many miles of leak. You have to take the rad off to access the pump anyway, so you may as well - it's another 10 mins and £25 or so.

 

[Silver_Star]

You need to clean the pump and area up, then find out where the leak is coming from. It will either be the O rings in the low pressure lines, the seals in the pump (either in the heads, input shaft or both). Even if the pump seals are shot,, you can but a rebuild kit for £20. There is a guide on the DIY section HERE .

 

[williamuk21]

You need to clean the pump and area up, then find out where the leak is coming from. It will either be the O rings in the low pressure lines, the seals in the pump (either in the heads, input shaft or both). Even if the pump seals are shot,, you can but a rebuild kit for £20. There is a guide on the DIY section HERE .

Thanks for the practical advice Dan and a big thanks to everyone who has helped me on this one, much appreciated.

 

[williamuk21]

And diesel on the belt will damage it in the long run...
I just wondered if the belt is vibrating, there are problems with tensioner pulley or alternator free wheel. Did they change tensioner or other pulleys when the belt was changed? 120k is not much but pulleys are not expensive. Is there visible polished sections either side of the belt? Water pump of my colleague W211 failed, and caused extra torque (pump was still rotating) so that the belt started slipping.

Thanks for your input I think my first job this weekend is to give a good clean around the diesel pump area and try to see where the leak is.

 

[bigtwin]

Thanks for your input I think my first job this weekend is to give a good clean around the diesel pump area and try to see where the leak is.

You can't. You can't see anything useful at at all without dismantling. And you can't run it then.

Strip down, for access, and see where the diesel lines go in. Take them out, and note the condition of the o ring seals. If they are at all aged/hard/flat and/or the lines come out as if they were not snug, this is your favourite for cause. Put new rings on anyway before re-assembly.

If there are iffy - replace and re-assemble with new belt, and see if the leak is gone. If your luck's in, it will be. If not, you know it's the pump, and you need to do the seal kit re-build, or pay silly money for a "new" one.

 

[williamuk21]

diesel leak s320 cdi (update)

Took the car to the Merc specialist near my home on Saturday morning.
He was kind enough to have a look for me straight away.
Opened the bonnet there was a smell of diesel and in the torch light we could see a small leak coming from where the clear pipe on the left enters the pump. He said he was pretty sure it wasn't the pump. Fingers crossed it is just a matter of replacing the pipe and of course the belt again and I can get back to enjoying this amazing car.