A4 2.5TDi Quattro opinions...

[mboy]

Have owned a couple of vehicles with the 1.9tdi engine in now (a mk3 Golf with a 1Z and now a Passat with an AHU), looking at getting an A4 Avant with the 2.5 V6 TDi.

Opinions on this engine? As good/solid/reliable as the 1.9?

What to look for?

Any advice etc. will be gratefully received...

[adamss24]

What year and model ? b5 is better put toghether than b6 but the b6 rides better and came with the engine in different state of tune (163 Bhp and 180 Bhp in the quattro). Wichever you go for make shure they have not been kept on Longlife Service as they used to service the engine every 2 years or 25k wich will wear the engine down-mostly the top end suffers ! Front wheel drive will struglle to put the power on the road in the b5 (poxi ASR) and the b6 gets ESP. The quattro b6 responds less well to tuning than the b5 but they do remap trough the OBD port. The b5 is a chip job only or you can fit a decent tuning box: Steinbauer, PSI Motorsport,etc. The b5 is dated now but the quattro's came much better equipped than the equivalent b6. Leather is a must in these and help with the re-sale. Injector pumps ECU are known failure and they cost about 600 quid to rebuild. They are brilliant motorway cruisers and do not be fooled by the tdi badge as they can give many petrol "sports" cars a good run for their money ! Push them and they get thirsty but so it will be ANY v6 engine with 180 Bhp. On a motorway run at legal speed limits expect high 40's Mpg, in town high 30's. Front wheel drive fare better however the quattro is brilliant in snow and wet wheather ! Pretty much bulletproof engine apart from the cams issue and injector pumps. Cambelts will be pricey as not many "grease monkey's" feel confortable on working on vee engines and they are fairly involved jobs. If the car you after had cambelts done recently, make shure the water pump has been replaced as well, allong with the vibration damper, the tensioner and relay roller (they are important as the belt runs on them and the dealer only checks them visually ?! All in all much more rewarding (in my honest oppinion) than the 1.9 tdi engine as they have masses of torque available from allmost tickover and a very broad, smooth power delivery curve wich means the engine pulls the same in any gear ! It might not give a wiplash but find a good one and you'll smile every time ! If you close to london, i could take you for a drive in me a4 tdi quattro...so you will have a refference on how a sorted motor should run !

[spartacus 68]

I'll add my tuppence worth.

The B5 2.5TDi avant quattro is a great car. Compared to the newer models, it doesn't have the same aggressive stance. However saying that, a good example, in avant guise, with nice alloys and a roof spoiler, then it holds its own. The engine is silky smooth, has a satisfying growl from a standing start, and pulls like a locomotive. The 6-speed manual box is perfect. My only criticism is 1st is simply too short, and it peaks in next to no time.

Engine wise the (AKN) engine 2001-2005 (150bhp) is perfect for the car. Like all V6 blocks, it's thirsty if driven hard, and you can almost see the fuel gauge drop in a traffic jam.

Go for sport suspension. The uprated springs and marginally lower ride height means you can take corners with confidence.

Quattro-drive comes into it's own at this time of year. We've had temperatures as low as -19 this year and over 3 feet of snow and it simply ploughs on!

It's a heavy car, so expect the usual suspension woes. Upper control arms, springs, tie-rod ends, and ARB drop-links to name but a few.

Mine was on a long service interval, which I've kept, but I don't leave the oil in longer than 15k. I personally prefer Castrol Edge fully synthetic 5w30 oil. It takes around 6 litres, so it's not cheap. Timing belt and water-pump need to be done every 80k (including tensioner). Worth doing the auxiliary belts for piece of mind too.

Brakes are adequate, given Audi's poor track-record on B4s. I fit Brembo rotors and Bosch pads. Any heat spots you can normally attribute to a sticky caliper. Strip down and use Lockheed red grease to lubricate.

One last thing. Change the rear diff oil after 100k if you intend to keep it. I drained mine and it was like Mellowbirds coffee! Use genuine VAG gear oil to top up (takes just under 2 litres).

Enjoy.

[mboy]

Thanks very much to you both for such comprehensive replies, you've been a great help.

The car in question is a 2000X plate B5, with the 150bhp engine and a 6spd manual box. Don't know whether or not it has been on longlife or normal service intervals, but I do know it has only had one owner and has got a full service history and lots of bills, including recent new brakes all round and all the important stuff (belts etc.) done on time.

Good to hear about the economy on a run edging up into the 40's, I suppose that was my main concern. Suppose a tall 6th gear and lots of torque low down will help with the economy on the motorway, I can live with mid 30's for local driving as long as I can get into the 40's on a longer run... I'm only getting 42-45mpg out of my B5 Passat 1.9TDi average at the moment anyway, but then it is only a 90 and the gearing is quite short, so it's working its balls off keeping me at 85 on the motorway I suppose. Thinking about it, borrowed my Dad's 3litre TDi A5 a couple of years ago when it was only 3 months old, did a trip to the Lakes and back in it. Despite 255 wide tyres on 19" rims, and me cruising at speeds that were not strictly legal, it averaged almost 40mpg that trip and the engine was only a few thousand miles old. He got 48mpg out of it on a steady 65mph run one day! I'm sure a B5 A4 on relatively skinny tyres can come close...

How well do they respond with a Tuning Box? I can get a PSI Motorsport one for trade+VAT through work... Are the PSI boxes any good? Their site says it should be about 185bhp with it fitted, so not a bad claimed gain if it is to be believed.

And as far as oil and other consumables are concerned, again not too worried, can get them all for trade+VAT through work (though trade often isn't as cheap as you might think!) so not too concerned... I used to run a 540i Beemer a couple of years ago, which took almost 8 litres in its sump, and averaged 24mpg. As long as the running costs are nowhere near what the Beemer was (though surprisingly I managed to keep it on the road pretty cheaply through 2nd hand bits off ebay), I don't mind too much as I expect it would be a bit more expensive to run than my 1.9TDi Passat.

adamss24, where exactly are you? I don't live near London, but I might well be popping down that way between Christmas and New Year...

[adamss24]

North london mate and i might be having a car or two for sale if you pop in ! I have 3 v6 tdi quattro's, 1 b5 tdi avant wich started as a 150 Bhp(has a little bit more than that now !), 1 a6 tdi avant wich is 180 Bhp quattro sport (this is for sale!) and a allroad. The b5 has a PSI tunning box (worth its weight in gold and it really does what it claims !) and the allroad has a Steinbauer P-Box. The PSI one is not smokey at all even at full throttle, the PSI one is a bit... I do use Castrol Edge 5w30 too and mine take little over 5 L so with a trade card from Halfords the oil cost me 36 quid for 4L and the filters are 15 quid at Euro Car Parts. I allways buy 2x 4L cans of oil as it works cheaper than buying individual 1L cans + i save it for later so it gets used pretty quick ! User good quality parts and the car will reward you with reliability and thrills ! I drive me b5 hard (within reasonable limits) and it never let me down...+ if you drive a souped-up diesel engine you'll wonder why you drove petrol for all these years ! Give us a ring on 077 899 12128 when you nearby !

[spartacus 68]

Thanks very much to you both for such comprehensive replies, you've been a great help.

The car in question is a 2000X plate B5, with the 150bhp engine and a 6spd manual box. Don't know whether or not it has been on longlife or normal service intervals, but I do know it has only had one owner and has got a full service history and lots of bills, including recent new brakes all round and all the important stuff (belts etc.) done on time.

Good to hear about the economy on a run edging up into the 40's, I suppose that was my main concern

If you drive like Miss Daisy and don't have a heavy right foot, you should see 45mpg on motorway.

How well do they respond with a Tuning Box? I can get a PSI Motorsport one for trade+VAT through work... Are the PSI boxes any good? Their site says it should be about 185bhp with it fitted, so not a bad claimed gain if it is to be believed.

I'd be very careful regards chipping the car. This may not be an issue with the AKN engine, but I've heard horror stories with the B6 (180bhp) upgrade, with poor running, etc.

[adamss24]

The b5 responds very well to chipping and it will transform how the car feels: 30Bhp min and loads of torque(running mine for a few years with no ill effects) ! The b6 does have sneaky limiters built in the pump ECU and as such is not as easy to tune as the older AFB engines. One thing to note is the quattro AKE pumps had 3 plungers in the pump, the AFB only had 2 so getting your hands on a quattro pump will be better for the tuning part. The quattro engines tune easy to 300 Bhp/600Nm with just a GTB2260VK turbocharger, Bosio race 683 nozzles and custom remap. You can get the parts cheap on ebay nowadays for less than a grand all in and it will transform the humble mile muncher into a fire breathing engine while still returning 27Mpg driven flat-out ! As with any turbocharged engine the first 50 Bhp only cost a few hundreds but the next 50 runs into thousands ! The AKE 180Bhp engine has a stronger bottom end (beefy rods, forged pistons and a stronger crank), a bigger turbo and reduced CR with larger injector nozzles for the extra 30Bhp and 40Nm of torque. The limiting factor is the clutch but the Sachs Racing Engineering clutch can take 30% more torque but at a price ! The bottom end is very strong and will take 500 Bhp and there are VP44 pumps fitted on Cummins engines able to fuel over 1000Bhp available in the states ! Thing is in Uk there are not many that can modify the pumps-they just put them back to Bosch spec ! Bosio race nozzles are the largest available off the shelf and will make the engine shudder at tick-over as they are too big but thats ok to sort out in the tune. There are also injector nozzles available from Iveco/Man/Daf and JCB lorries wich will fit the AFB injectors with similar spray pattern and up to 80% more flow than the AKE nozzles but they are difficult to source as they never been intended for passenger cars... Rule of thumb: more air and fuel in the cylinders + bigger bang !

[mboy]

Thanks again guys

Interesting to know the V6 has quite a bit of tuning potential, I didn't know that! To be fair, as good as 300bhp sounds too, I'd be more than happy with 180ish from the standard car with a PSI box fitted...

adamss24, could you PM me with more info on the cars you've got, including prices etc... I've not got a huge amount to spend, but if the car and price was right then I could be interested...

GOT TO BE an Avant though... I know they're not very big for an estate, but I need a 5 door. I can't be dealing with Saloon cars any more... And preferably V6 TDi with Quattro and a manual box...

[techfreak]

I've been looking into changing my tt as need a bigger motor.
Was looking at b6 v6, this has been a great help , thanks guys

[dan2802]

Dont know if anyones interested but our 99V A4 2.5 TDI Quattro Avant will be up for sale soon.
Its just gone through its MOT with minimal expense which considering its 11 years old with 150k on the clock, I dont think is bad.
Its a 6 speed manual with cream leather.
It had a new fuel pump last year so you shouldnt have to worry about that.
We also had the cams replaced 3 years ago.
Car has FSH.
Reply for more info.