decrepit A4 2.5 Quattro. Options?

[mikeburton_2000]

Hi all
I recently bought an old (2002 Y) A4 2.5 quattro. It seemed pretty good when I bought it - on a Sunday night after spending 4 days dragging the wife and kids round the country looking at some of the most atrocious things you could ever hope to see.
Any way, I noted it had a bit of tap in the top end of one bank but given the FSH and dash both indicating it was a couple of thousand miles passed due a service I thought it probably just wants a service.
I've had the car a couple of weeks now and concluded it has way more issues than I thought and have to wonder about my judgement and ability to avoid lemons!
I now see The AC belt appears to have been removed, assuming the pump is knackered. The tapping top end is more akin to the tin man falling down an escalator and there is significant fuel leak on the same side. After a couple trips around the high passes near my home I hear a thump from the back end when setting off with any enthusiasm. The thump is recurring and changes with road speed under acceleration in first/second.
I don't think I'm going to throw the car in the bin. I'd like to bring her back from the brink and mod along the way. I love torque and have read some of impressive posts about molding and improving the 2.5 V6 tdi.
I wonder if you could recommend a sequence of jobs, mods, improvements to help me drag this crippled senior citizen back to its prime and beyond.
I'm pretty competent and work as an electro-mechanical engineer but it's been a long time since I tackled anything as meaty as this project. If I could bring the std 180bhp to around 220-240 and gain a good bit more torque without shredding clutches flywheels diffs etc I'd be a happy fella.
Any thoughts n ideas greatly appreciated
Mike

 

[mikeburton_2000]

Ps I'm not a millionaire!!

 

[Mike B]

You might need a lot of time and money to sort this.I am on my 2nd but have been lucky .The tapping could be the cam shaft cos early ones wore easily and the knockingmight be the diff or something in the drivechain.Fuel could be just the spill pipes.There are learned types on here who know much more than I do who will be of more help

 

[abyrne153]

Most likely the diesel leak is from the flexible leak off pipes the loop from one injector to another. These perish and need to be renewed periodically. They are cheap and available from most motor factors and simply push into place. The belt similarly may have been lost due to a stone being picked up or maybe a tensioner failing. It the pump pulley spins then it would be worth sticking a belt on and trying it out as these are cheap and again are readily available. The top end tapping is a worry though as it could indicate worn cams. The 2.5 cams and rockers are prone to wear particularly on high mileage and cars on long life service cycles. It is an expensive fix as there are 4 cams , 24 rockers and 24 lifters to replace. The kit alone will cost the most of £600 plus the labour to replace them. The only way to check the condition of the cams etc is to remove the rocker covers and inspect them carefully. If you are fortunate that the cams are good then these engines can get some serious power by using a hybrid turbo, bigger injector nozzles and a custom remap. A simple remap will get you close to 210bhp without further modifications and the standard clutch is well capable of taking much more power than that. Check out Adamss24 posts as his knowledge of these engines is second to none. Thump from rear may be a diff mounting. Get it on a ramp and check as these are not particularly expensive.

 

[mikeburton_2000]

Got the leak sorted, as you guys identified it was the leak off pipes. Found a worn out drop link bush on the rear anti roll bar which cleaned up some of the back end noise allowing me to hear that the thump under acceleration is accompanied by similar thud when throttle is shut-off. Would this suggest a bit of slop in the prop shaft Uj?
I'll try a belt on the pump as I can turn it by hand. I had the system degassed this morning so no worries if I need to remove the pump, pipes etc.
Might get the local indi audi guy to have a listen to the top end and give his best guess.
Thanks for your input guys. If there is a problem with the diff, will any other unit fit? Is the 3.0 or TT unit similar?

 

[abyrne153]

It's much more likely to be a bush or mounting at fault, drive shaft cv joint or maybe the centre bearing on the prop. The diff is unlikely to be at fault itself and is a big money item. There are a lot of links , bushes and mounts on the rear of these so it may take a bit of work to find the culprit. Stick at it and you will eventually find it. Good luck with the engine top end but don't leave it too long to get it checked as worn cams can lead to rockers falling off and jamming valves open, meaning piston contact and a smashed engine. Not nice.

 

[AudiLeon]

Get the rocker cover off on the side making the noise and check the cam lobes and that all rocker arms are all there.

 

[Ovid]

if you have vcds then you can check fuel trim on each bank if its a cam issue you will see it.

 

[mangolo]

Im having the same issue with my 2.5 2002 V6 Auto Quattro, previously had a big loss of power which i'd originally attributed to a possible Turbo failure (however this seems to not be the route of the problem).
Would cams cause a considerable loss of power?
I will investigate as most of you have already pointed out - Just weighing up if its worth repairing and replacing specific parts, or maybe starting over with a donor engine with lower miles...?

 

[Ovid]

Best man to talk to is adamss24 he knows the engines better than anyone .

 

[adamss24]

If you can drive to Chingford, N. London i would have a look at your car, it's very difficult to troubleshoot issues on a car without looking and driving it...

 

[mangolo]

Unfortunately its currently Sorn and im based in north oxfordshire so it'd be a propper trek to tow it!
Anyone on here based in or near oxfordshire that might be able to help?
(ill post a thread shortly with videos of my engine running from cold and warm to show noises)
Cheers