Audi A6 2.5TDI 2000reg intermittent start problem

[Khi]

Hi,

I'm a newbie to this forum, but I'd really appreciate any advice or help you knowledgeable people could give me.

I've recently bought a 2000 reg Audi A6 estate, and it's pretty obviously I've been done by the last owner. I'll try to describe the syptoms as best I can.

When I met them to buy it, the engine was running, so I turned it off to let it cool for a bit. Started and stopped it while I inspected the vehicle but could find nothing too untoward. I then drove 5 hours from Wales back to Brighton with no issue (I once stopped and turned the engine off to refuel at a fuel station).

We drove it on and off the next couple of days with no issue, then suddenly one morning it wouldn't start. It turned over repeatedly, however wouldn't fire. The battery eventually ran pretty low so I had to stop trying. A few days later we hookep up the jump leads to a mates car, and it turned over for aaages, then suddenly fired! I turned it off, then started it again no worries. I waited till late that night to go out and start it once more, and again it started no problem. A couple days later we drove it around, put loads of diesel in it, filled the screen wash etc, then parked it again. The next day, once again it wouldn't start.

It is booked to go into the garage, but I'm trying to think of everything I could to help the guy find the fault.

There is a clear line that connects to the pipe from the tank, and is before the fuel filter, this showed occasional bubbles going through it, which made me think there was an air leak in the pipes coming from the tank. I looked all over the pipes but couldn't find any diesel weeping out of any joints. I filled the car with diesel, and the bubbles appeared to stop, which made me think maybe it was something in the tank causing bubbles (apparently the tank is split into two, and a small pump balances the levels in the two tanks, sometimes an issue with this pump can cause the side that feeds the engine to run dry). However the day after filling the tank is when it wouldn't start for the second time.

Other factors include:
- There is white smoke coming from the exhaust when it does run, I don't know if diesels are the same, but it makes me think it's running lean (again fuel supply issue?).
- There is a high pitched whine coming from the engine when driving around - I can't figure out if that's just the turbo or something else
- There doesn't appear to be any power issues when driving, it seems pretty pokey and drives ok when it's going
- On the two occasions it refused to start, it happened when starting from cold (ableit it's mid summer at the moment). The first time it ticked over for a couple of seconds, then shuddered and stopped. The next time it was ticking over for a while, while I faffed around with seatbelt etc, then when I went to pull away it stopped
- Both times it failed to start the car was facing uphill - although it did start on other occasions in the same spot
- I have a receipt from the last owner saying the fuel pipes, fuel filters and oil filter were recently changed (makes me think they were trying to eliminate air leaks)

Reading all around the forums etc I've found many suggestions as to possible causes, including:
- Faulty coolant temperature sensor
- Faulty fuel pump (although why would it run fine sometimes but not others?)
- Air leaks in the pipes
- Faulty immobiliser

The car doesn't go in to the garage until the 6th July, so anything you guys could suggest beofre then would really be appreciated.

I've obviously been royally done over by the last owner. http://www.audi-sport.net/vb/images/smilies/unhappy.gif

Thanks in advance for taking the time to read this! Any other info I can give I'm happy to crawl around the car/engine and find out for you if it helps you to diagnose.

Cheers guys

[NickPicks]

I'd say the first thing to do is to get a fault code read.

The double sided fuel tank, I thought was only for the Quattro versions.

How much white smoke? Is it smoke or steam? What's happening with the water in the cooling system?

Also, let us all know what engine code it is (sticker in service book or spare wheel well)

[Khi]

I'd say the first thing to do is to get a fault code read.

The double sided fuel tank, I thought was only for the Quattro versions.

How much white smoke? Is it smoke or steam? What's happening with the water in the cooling system?

Also, let us all know what engine code it is (sticker in service book or spare wheel well)


Thanks for taking the time to reply Nick.

You're probably right about the dual sided tank being on the Quattro - our mechanic at the garage was suggesting that over the phone, just from his memory of that model of car.

I couldn't say if it was smoke or steam to be honest, I'll probably need to run it again to check - I'll do the same and monitor the coolant, while it's running. Will get engine code - all of this I'll need to do when I get home this evening. Are you thinking it could be the head gasket? I did check the oil repeatedly and haven't found any white blobs (water ingress), however the level does seem fairly high - unable to say whether that's because it was overfilled or not.

Unfortunately I don't have any VAGCOM software or hardware, and I fear that taking it to the local Audi dealer will probably require me remortgaging the flat. I do have a mate who races cars professionally so maybe he knows someone with a cable and the software, I'll drop him a line.

Thanks again

[Peter D]

After a fail to start, when it does start does it start up normally or chug, chup, splutter in to life.
Can you hear the lifter pump in the tank run for 2 seconds when you turn the ignition on.
Try the secong ignition key. It could be the coolant temp sensor lying to the ECU. Regards Peter

[Khi]

After a fail to start, when it does start does it start up normally or chug, chup, splutter in to life.
Can you hear the lifter pump in the tank run for 2 seconds when you turn the ignition on.
Try the secong ignition key. It could be the coolant temp sensor lying to the ECU. Regards Peter


Hey Peter,

When it does finally fire up it seems to start pretty promptly, no stuttering or chugging. It takes a lot of turning over before it does start though. I still haven't yet ascertained a clear pattern as to when it does or doesn't.

I can just about hear something when the ignition is turned on, (while I'm waiting for the coils to heat). I also see on the voltmeter on the dash that there's a load on the battery for a few seconds (lasting longer than the coils heating), once I see the needle jump up a volt or so then that's when I try to start it. Maybe it's the lifter pump imposing the load on the battery?

Unfortunately I only have one key - yet another sign that in hindsight I should have avoided the purchase of that car with a barge pole!

I'm more and more tempted to replace the temperature sensor, since it's such a small item...

[Peter D]

As it start cleanly then I suspect a fuel/immobiliser.
We need the engine code like, ABF. It is either in the service book or in the spare wheel bay. Regards Peter

[Peter D]

If it was the temp sensor then it would not start cleanly as it would be overfueled during all the cranking. Regards Peter

[Peter D]

Do you have a multi meter. Regards Peter

[NickPicks]

With the talk of engine coolant sensors, it hasn't got a "Tuning Box" installed has it? These are the cheap things from ebay which cause the ecu to think the engine is colder than it is, and overfuel. They're a cause of trouble.

[Khi]

Do you have a multi meter. Regards Peter

I haven't got one but I can get a hold of one.

[Khi]

As it start cleanly then I suspect a fuel/immobiliser.
We need the engine code like, ABF. It is either in the service book or in the spare wheel bay. Regards Peter

Yeah that seems to be where most people are leaning - fuel/immobiliser.

I have to wait till I'm home again to get to the car and I'll post that code as soon as I've got it.

[Peter D]

Do you have a meter. Regards Peter

[Khi]

With the talk of engine coolant sensors, it hasn't got a "Tuning Box" installed has it? These are the cheap things from ebay which cause the ecu to think the engine is colder than it is, and overfuel. They're a cause of trouble.

No tuning box that I know of - not sure how to check for that. Looking up some pictures on google to see what to look for.

[Peter D]

Do you have a meter. ?????

[Khi]

Do you have a meter. ?????

Sorry Peter I did reply to this already but it disappeared off the page when the thread went to a new page.

I don't have a multi-meter but could get a hold of one. Am emailing my friend now to see if I can borrow his...

[Sparky Charlie]

What I pick up on is " failed to start when parked nose up hill".

That is classic for an air leak allowing all the diesel to drain back to the tank. On starting it injects the last bit of fuel in the pump and it will fire but imediately stop.

Don't forget, air can leak in to a pipe that diesel cannot leak out of.

I'd be starting with a fuel filter and change any o rings, then I would be suspecting the injector bleed off pipes. In the mean time park nose down hill.

Charlie

[Khi]

What I pick up on is " failed to start when parked nose up hill".

That is classic for an air leak allowing all the diesel to drain back to the tank. On starting it injects the last bit of fuel in the pump and it will fire but imediately stop.

Don't forget, air can leak in to a pipe that diesel cannot leak out of.

I'd be starting with a fuel filter and change any o rings, then I would be suspecting the injector bleed off pipes. In the mean time park nose down hill.

Charlie

Hey thanks Charlie, I did wonder that. This most recent occasion when it wouldn't start, I checked the clear bit of hose (the intake to the fuel filter) and it was full of diesel, no bubbles. It was also the highest point of all the hoses. Admittedly there could still be a big air pocket that went into the pump, but I'm still very confused now in that sense, as for a while I was convinced it was air leaking into the pipes.

I will definitely be parking nose downhill in future. To be honest we don't currently use the car much as it's too unreliable, don't want to end up stuck somewhere!

[Peter D]

Well spotted charlie, I missed that. There have been several of the nose up issue on here as as you say it is a common sign of an air leak. The engine code will tell us if it has leak off pipes and/or a self bleeding system. OP, do you now if your engine has distributor type injector metal pipe to each cylinder or electron injectors. Regards Peter

[Khi]

OK I've got the code after having another look tonight. Biggest thing to note is I think the clear hose leading to the fuel filter is completely empty of diesel - just air in there! I'm sure that is not supposed to happen when the car has been sitting, the fuel lines just emptying themselves! Points again to leak in the system somewhere I guess?

Anyway as requested the code for the engine is AFB - I've attached a photo of the sticker (although I've removed the chassis number) in case there's more info needed from it.

I also attached photos of the metal pipes going to the cylinders, since that was requested as well. Also one photo showing the empty clear hose above the (pre) fuel filter.

Still working on VAGCOM software/hardware or getting a multimeter!

Thanks once again all of you for the suggestions so far

[Peter D]

Those pipes have been changed to may be stop the leak. Check the connection on the tank under the rear drivers side seat. Regards Peter

[Khi]

Those pipes have been changed to may be stop the leak. Check the connection on the tank under the rear drivers side seat. Regards Peter

Yeah I have checked that one - under the panel just behind the rear drivers side seat. It looks like that pipe coming off the top of the tank has recently been changed too. Obviously someone's been through a lot of these motions already trying to get rid of the air leak. My only thought is now the pipes along the bottom of the car? Unless the replacement pipes/pipe clamps that have been put in are not adequately air tight.

[Peter D]

PM me your email address, I have some diagrams for you. Regards Peter

[A62.5TDIV6]

Hi Guys,

Really glad I found this thread.

I have a '98 A6 2.5tdi AFB. It is doing pretty much the same thing.

I'm on the key for about 10-15 seconds before it reluctantly chugs into life, white smoke appearing from the exhaust (unburnt fuel?)

It only does it the first time I start it, usually in the morning leaving for work. Then the rest of the day it starts on the button.

When I park on my drive way the car is facing slightly uphill..........it doesn't cut out once it's running.

Any thoughts anyone?

Not trying to hijack the thread, but it sounds like we have the same problem........

Cheers,

Will.

[s8utt]

looks like there are a few people with this problem

Me too :(

I've got a 51 plate passat v6 tdi.

Will I have exactly the same thing, first startup in the morning 10-15 seconds.

Just changed the fuel filter and tee piece not holding my breath.

Thanks
S8utt

[Khi]

Just to update everyone on the original car problem.

Just before I took the car to the garage, it would not start at all. We had to tow it there in the end. The clear hose leading into the fuel filter was completely empty of diesel. So in the case of this car it is pretty obvious the main issue is air getting into the fuel system. 'Peter D' who replied on this thread, very kindly sent me some diagrams of how to pressure test each individual section of the fuel system - which I passed on to the guy at the garage to look at.

What he found, was that the fuel filter fitted was the incorrect filter (it was originally meant for a Ford, which are apparently cheaper (talking £10 instead of £20!!), the main problem with this being that the fuel pipe diameters were larger than the diameters of the inlet and outlets to the fuel filter. I've attached a picture below (also posted earlier in thread). This difference we think could have been where the air was managing to seep in.

He had to replace all the T piece, hoses and filter (since whoever had bodged this before had thrown all these parts away) - and it seems to be starting and running fine. He's left it parked uphill for yesterday and today, and we'll have a look this afternoon, if all looks ok fingers crossed that's the issue taken care of.

The only thing I could recommend is to fit a bit of clear hose so you can see if air is actually getting into the system, as well as whether bubbles are streaming into and/or out of the fuel filter.

I'm happy to forward on the pressure testing instructions that Peter kindly sent me if you need them, just pm me your email address.

All the best hope you find the issue. I'll post again in a month to confirm I haven't been left stranded somewhere due to not having found the real root cause!!

[GeeCee]

Hi

Dont know if you have your prob fixed or not. I had starting issues with my 2.5 also. Looked at all the major things even got the fuel pump tested. Turned out to be the two hoses which exit the right hand side of the fuel filter and run to the fuel pump. One is a feed and one is a return. I think they are supplied as a set. Changed them and prob was away. Hoses were porous with age. Not leaking fuel though. Try this first before delving deeper.

Hope this helps

[s8utt]

Well looks like I'll have to look further into this.

I'll have a go over the weekend as it still aint running right

Thanks

[s8utt]

GeeCee, do you know the cost of these hoses, maybe worth trying my car seems a bottomless pit of expense at the moment.

[Khi]

GeeCee, do you know the cost of these hoses, maybe worth trying my car seems a bottomless pit of expense at the moment.

I know that through our local garage guy, when he tried to source the hoses from VW, they were about £90 for the pair including VAT. He sourced a slightly alternate pair instead from a different source.

[Khi]

Just to update everyone on the original car problem.

Just before I took the car to the garage, it would not start at all. We had to tow it there in the end. The clear hose leading into the fuel filter was completely empty of diesel. So in the case of this car it is pretty obvious the main issue is air getting into the fuel system. 'Peter D' who replied on this thread, very kindly sent me some diagrams of how to pressure test each individual section of the fuel system - which I passed on to the guy at the garage to look at.

What he found, was that the fuel filter fitted was the incorrect filter (it was originally meant for a Ford, which are apparently cheaper (talking £10 instead of £20!!), the main problem with this being that the fuel pipe diameters were larger than the diameters of the inlet and outlets to the fuel filter. I've attached a picture below (also posted earlier in thread). This difference we think could have been where the air was managing to seep in.

He had to replace all the T piece, hoses and filter (since whoever had bodged this before had thrown all these parts away) - and it seems to be starting and running fine. He's left it parked uphill for yesterday and today, and we'll have a look this afternoon, if all looks ok fingers crossed that's the issue taken care of.

The only thing I could recommend is to fit a bit of clear hose so you can see if air is actually getting into the system, as well as whether bubbles are streaming into and/or out of the fuel filter.

I'm happy to forward on the pressure testing instructions that Peter kindly sent me if you need them, just pm me your email address.

All the best hope you find the issue. I'll post again in a month to confirm I haven't been left stranded somewhere due to not having found the real root cause!!



Aaaaarrrghh the garage guy phoned up and after the "hill test" where he left it parked uphill yesterday and today, there is once again a bubble in the clear bit of pipe. He said there are a couple of other fuel pipes that look like they've never been replaced, so he's going to try them first (since it's relatively low cost). If that doesn't work, the only thing left will be fuel pump, which = muchos £ for pump and £ for labour =(

Will keep posted of what progresses

[Khi]

No-one knows about price of fuel pumps for these cars do they, as well as a good place to source them from?

I know reconditioned ones would be cheaper but have probably come off a high mileage vehicle, vs new ones in perfect nick but phenominally expensive...

Would really appreciate some guidance if you can help.

[GeeCee]

KHi and s8utt

Hope this description helps. i will try and post a photo tomorrow. Your fuel filter should have 4 pipes attached to the top the 2 pipes on the left of filter are: LH TOP - supply from tank. LH BOTTOM - return to tank. RH TOP - feed to injection pump, RH BOTTOM - return from Injection pump to filter.

The two hoses I had to change were the two which attach to the RH side of the filter. The original hoses have crimped fittings to ensure no air leaks.

They are around £90 for the pair but I wouls strongly advise spending the money on them before starting to look for a bigger problem. I have been down the road you've been down trying everything possible. You could both have a bigger problem but it would be worth doing these pipes 1st.

They are easy enough to replace. 2 hose clips at the filter end and two banjo bolts at the injection pump. One of the bolts at the injection pump has a small check valve inside. Worth changing this at same time

Hope this helps and I'll get a photo of fuel filter

Cheers

[A62.5TDIV6]

Last night I parked my car facing DOWNHILL on the driveway, and guess what it started perfectly......

I'm assuming I must have the same problem..........

[Peter D]

Yep you have an air leak in the fuel line somewhere. Regards Peter

[All-rod]

Here are some pics of what oem fuel lines look loke:

http://www.vwaudiforum.co.uk/forum/showthread.php?t=76207&highlight=crankcase+breather

There is a chance you need a non return valve put on just before filter to stop fuel running back to tank, not sure if there is one already.

Mine is not as bad, but simillar animal....:drive:

[s8utt]

Right sorted mine, did the pressure test turns out it was a defective fuel filter. I put the old one back on and everythings fine again.

[Khi]

Hey S8utt,

Glad to hear you got it sorted.

We've been through the same steps now, pressure tested all the system and the only thing to be leaking air is the fuel pump itself. Hence I think there must be a seal gone in the pump, meaning it needs to be overhauled - which is not good!

We face a choice of buying a second hand pump, or paying to get ours overhauled - I would appreciate any advice anyone can give around this, the problem we face is secondhand pump will probably have been to the sun and back already, vs getting our own pump overhauled and we don't know if once it's opened it could be deemed unrepairable.

Second hand pump does look like it could be a cheaper option, but you'll get what you pay for.

Khi

[A62.5TDIV6]

Update......

My fuel pump is all but dead. Being tested tomorrow but it's 90% certain it's failing.

Replace or repair..........?

Starting to fall out of love with this car...........

[mickmcvw]

Update......

My fuel pump is all but dead. Being tested tomorrow but it's 90% certain it's failing.

Replace or repair..........?

Starting to fall out of love with this car...........

I'd say contact bba-reman and ask them. They seem to be pretty decent from reports on here.

From your engine code, I'd guess the part number you'd need is 059 130 106D (with or without an 'X' at the end).

[shabazmo]

These guys are just down the road and very experienced. about £600 for an exchange
http://www.pbasher.com/automotive.htm

[fjtwelve]

I had mine done by dieselbob.co.uk, very good.

[carcav]

Hi check the steel pipes back to the tank, mine were rotten. replaced with 8mm plastic, had no more trouble.

[Khi]

Update......

My fuel pump is all but dead. Being tested tomorrow but it's 90% certain it's failing.

Replace or repair..........?

Starting to fall out of love with this car...........

My advice would be to repair. Diesel Bob has our pump at the moment, he's managed to find the fault and is repairing it for us, expecting a call from him today hopefully confirming it's done.

If you get it reconditioned, at least it will be the shell of the pump with all new parts in it, rather than a second hand one which could have taken the car to the moon and back. Also second hand pump you won't know if it really is 'plug and play', since the ECU and car need to be compatible. It's pretty difficult to find the right matched pump.

Second hand pump: £150
Recondition existing: £500 - £700
Buy new pump: £1500

With our pump it was the strangest thing - Bob said it had been reconditioned, but only half of it!? the bottom half of the pump has seized, so he did a partial rebuild to replace the old bits.

[A62.5TDIV6]

My existing pump has actually been reconditioned before, but it was about 2 years ago. It was guaranteed for a year, but that has obviously expired.

The car has pretty high mileage (179k). Is it worth another repair? (The fuel pump that is...)

[Khi]

My existing pump has actually been reconditioned before, but it was about 2 years ago. It was guaranteed for a year, but that has obviously expired.

The car has pretty high mileage (179k). Is it worth another repair? (The fuel pump that is...)

I would say it depends on the rest of the car. If it's in really good nick, and there's nothing else wrong with it then maybe yes get the pump repaired. You kind of need to weigh it up though, removal of pump and reinstallation labour + pump reconditioning will be £900 - £1000

Weigh it up against what you can buy out there second hand car wise? Also how emotionally attached are you? SOme people pump loads into their cars because they just love them!

Sorry to hear yours is playing up, we've only just literally this afternoon got ours back from the garage, been a nightmare! Hope you find a solution that won't cost you too much.

[A62.5TDIV6]

I would say it depends on the rest of the car. If it's in really good nick, and there's nothing else wrong with it then maybe yes get the pump repaired. You kind of need to weigh it up though, removal of pump and reinstallation labour + pump reconditioning will be £900 - £1000

Weigh it up against what you can buy out there second hand car wise? Also how emotionally attached are you? SOme people pump loads into their cars because they just love them!

Sorry to hear yours is playing up, we've only just literally this afternoon got ours back from the garage, been a nightmare! Hope you find a solution that won't cost you too much.

Well, I really like the car when it's running well. I like everything about it. But at the end of the day it's a car, so no I'm not emotionally attached to it.

But I do really like it, the power, the luxury, the massive boot for weekends away (avant)......LOL. It is a great family car (2kids).

My cousin's boyfriend works on it so he does mates rates, but its not in really good nick. It's an S reg 1998, with the normal amount of scratches etc and would benefit from having 1 new front wing.

I'm just starting to wonder what's gonna go next.

I'm sure it'll be worth something as "spares or repairs"..........

[A62.5TDIV6]

The A6 has gone........sold for spares. Replaced with an Alfa 156........

[Sparky Charlie]

Frying pan......Fire..

[A62.5TDIV6]

Frying pan......Fire..

LOL.....yeah maybe, we'll see.

It's got FSH from main dealers, in mint condition. The car is spot on really.

I couldn't justify spending more money on the A6. Shame really but it had become a money pit.

In my experience of owning an A6, I must admit I was surprised how problematic the cars seem to be.

I probably would have another one though....;)