Diesel leak

Robin_Cox

Member
Up until now I thought the diesel leak on the project car Cosmo was just a knackered pump that needed to be replaced with a Bosch with better gasket. However, since I detected the leak to begin with, there was always a small pond of diesel on the floor roughly by the passenger side rear wheel - I assumed this was where pooled diesel running down onto the engine bay subframe was pouring off when reversing out. However, I haven't moved Cosmo this last 10 days and the pool by the rear wheel has been getting slowly bigger.

Had a good look underneath just now and there is a regular (~ every 10-15 seconds) drip coming from the space just above and in front of the rear axle, around halfway between the centreline and the passenger side of the car. Is that where the fuel filter is? Can't think of what else is above there apart from the fuel tank itself. This is an 02-reg AMF with probably the old-style diesel filter, although I assumed that was on the driver's side just ahead of the wheel.

Any thoughts?
 
Does sound very much like the diesel filter or one of its connections. If the leak is that bad you should be able to see exactly where it is coming from.
 
Thank you for confirming likely suspect. I'm just back after a 20 hour 1100 mile round trip to Plymouth and back and that side of the car is next to the hedge at the moment so I can't get it on an axle stand right now to look properly - at least I've got an idea where to look though. Was wondering why it only went 84 miles on the last (34L) tank.
 
I could always get a 25L badge made up for the tail gate? :)

Luckily the two rear wheels on it are a garage spare pair with heavily worn old continentals on. The actual rear wheels are off to have the valve seats and rim edges cleaned up as they don't hold pressure more than a couple of weeks but the tyres have plenty of good tread on them. Unfortunately it is raining here this morning so grovelling on the ground under the car for 10 minutes isn't happening.. will come back with photos and questions once I've had a chance this week.
 
Fuel filter casing is heavily corroded and saturated down much of its length with diesel either through the surface or draining down from the upper end where the pipes attach. The wet patch visible on the bodywork there is at the top end suggesting the seepage is up there and then working its way down by surface tension and gravity wherever it can run. I'm still struggling with the orientation (had my arm under the car taking photos from various directions) so apologies for being a bit vague.

Bunch of naive questions now :

With these older model fuel filters, is it a case of undoing the bolted bracket (silver strip 3/4 way up the casing), then dropping the casing down on the hoses to look at it?

Are these replaceable by unclipping the hoses and plugging a new one in? Is the pipework otherwise compatible with the newer plastic casing version? (there is a Webasto so I assume there are some extra pipes involved judging by the 7zap).
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I'm not that tech savvy but that looks nothing like the diesel filter housing on my A2. Its plastic for starters. I'd get that whole thing replaced. Mine was replaced about 2 years ago after the garage over tightened the bleed nut. Quite a common error it's only meant to be nipped up finger tight or 2Nm. Memory serving the entire unit was about 70 pound from Audi so you'll get it cheaper or perhaps one of our parts traders has one. Hope you get it sorted soon. My leak was also causing starting problems.
 
Yup earlier filters are all metal Murdo and replaced as a single unit. I made the mistake a while back of ordering a couple only to find they were completely different and they ended up with Depronman....and yes I'm also on my second housing but I've bought the replacement nut from Paul so hopefully wont be an issue in the future
 
Yup earlier filters are all metal Murdo and replaced as a single unit. I made the mistake a while back of ordering a couple only to find they were completely different and they ended up with Depronman....and yes I'm also on my second housing but I've bought the replacement nut from Paul so hopefully wont be an issue in the future

Eek and shiver ??. Does the filter rust like that with the heat shield in place.
OP needs a new yin methinks
 
Few tips on changing the metal fuel filter -

(only second link in post 7 still works)

Cheers Spike
 
New filter is already ordered as even with my mechanical expertise (nil) it looked bu**ered.. The various heat shield panels that the workshop manuals instructs you to remove to get to it are long since gone. Car spent 12 years in an Aberdeenshire fishing village and did around 280k up and down the A90 in all conditions (a road that is notoriously heavily-salted) so needless to say almost anything that is ferrous and in a vulnerable place is badly surface-corroded and even some Aluminium bits (window frames, some small bodywork locations) have signs of corrosion where the paint had been chipped at some point so some (driver door) are due for replacement or tidying at some point. Pristine set of early-style control arms though - the previous owner Luke did a great job of sorting out some seriously expensive mechanical stuff (belts, gearbox/clutch etc. ) before it was my turn to take on mostly small fiddly things (number plate light fittings, steering error, thermostat, air-con sensor, ARB bushes, front struts, various diesel leaks etc. that are just down to age).
 
Make sure you mark the various hose locations before removing them from the filter. That way there should be less chance of an issue when the filter is replaced, and clamp off all hoses. Not much you can do about the dreaded salt other than regular washing and good quality "wax". It may be worth wire brushing and protecting suspension parts with Hammerite assuming not already too far gone. Certainly protect anything new going on. Any signs of the filter being changed in the service record? Fuel filter IIRC gets changed every 2 years or 20000 miles - that make 14 filter changes!!!!!!! If the car still drives on heavily salted roads I would check it more frequently for signs of deterioration and replace more frequently as required. You really should also replace the heat shields as they do offer some protection.
 
I'm confused. :oops:
Help me figure it out. It seems to me that the scheme is not correct ....

Is a blue hose or a black hose put on a red filter inlet?
 

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Based on the photo - does it look like the black hose (in the diagram) is wearing a filter inlet?
 

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How is your rear axle (eg fixing points to strut) and front wishbones if your dieselfilter looks like that?
 
How is your rear axle (eg fixing points to strut) and front wishbones if your dieselfilter looks like that?

This is a photo of the author of the record ... I decided to transfer the filter from the engine compartment to my native place .. But I got all the hoses mixed up and a little cut off o_O
 

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