80, 'N' reg - acceleration and smoke problems

[xylophone]

I have an Audi 80 1.9 TDi, 1995, 90bhp, 222, 000 miles. Serviced and maintained on the dot, latterly by an excellent Bosch franchise, Volksparts, Durham. Never had what I would call major problems. Next major service due about now.

During last 7 days touring Scotland, heavily laden. Checked oil beforehand, level above line, topped up with small amount. Noticed she was not accelerating properly up steep hills. This got progressively worse, ending with same symptom on any hill, and sometimes on the flat. I put in Reddex thinking of the injectors, but no discernible improvement. Sometimes she would go up any hills without a problem, 75 mph, say, but that rare.

Coincidentally, perhaps, she has been emitting smoke in a manner I have not experienced before. Started with occasional cloud of dense black smoke we are all used to, which appeared to happen also at times when changing gear. Difficult to be sure in rear view mirror. That stopped, then noticed a thin, vapoury, whitish/darkish smoke, and that this happening when going up hills. This got worse. Not belching smoke, just thin clouds.
Exhaust is the original. Volksparts said several years ago, outer skin perished, but inner ok. They have only ever replaced a clip.

I am a member of the IAM, so I don’t drive fast or, I hope, badly so far as the car is concerned.

Re the lack of acceleration, I had the same problem, more or less with the car, five years ago, when I kept a record of what happened, as follows:

“Car not accelerate beyond 70

Main dealer advised as follows:

1. Turbo valve sticking - £35 valve + 20 minutes. Mechanic can tell just by taking on road

2. Cat - £100 - £300 + 2 hours (I think he said 2 hours) Diagnostic while on road

3. Flow meter -£100 + 2 hours. Diagnostic machine would tell, expensive

They leaned towards 1. Seemed confident that was it. If 2, would lose power across range, i.e at any speed.

In end, Volksparts, Bosch people, fixed - pipe/hose frayed so hole, stopping enough air into engine, you understand. To look at, hose very similar to bicycle pump connector. Car transformed. Might not be answer, they said, but seems so. £62 including £40 diagnostic test.”

Car not losing power at any speed, so not 2.

So seems this hose business may be the answer. I seem to recall being advised this is a known problem with the car.

On that basis, I am more concerned about the smoke. Volksparts, I assume, will do a smoke test. But I would appreciate any thoughts/comments from you guys here.

This has been a wonderful car. I intend to replace it with another one, an A4 Avant of some kind.

[jonathan_dyane]

Hello,

OK, simple things first. How bad was the car smoking? If the car is generally used fairly gently, soot will lodge in the cat and intake system. A long trip with lot's of hills will serve to get the car good and hot, and it would be perfectly normal to see this soot expelled as smoke; it's almost like the car giving itself a decoke!

On the power issue, you are quite right in that a split hose would cause these symptoms. If I were you, I would buy a couple of yards of 'diesel injector leak off pipe' and use this to replace all of the old vaccum piping you can find under the bonnet. Cost is pennies, and you may find the problem will be solved. The large diameter piping can be checked physically, but splits here may also be betrayed by whistling or sucking noises as the engine is revved...

Good luck,
Jonathan.

[xylophone]

Thanks, Johnathan

Its the whitish/darkish smoke that worries me. Personally, no idea what that might be - broken exhaust, broken cat, cylinder head gasket (God Forbid!)

Re the lack of acceleration, the damaged hose must be a candidate.

I think I'll get Volksparts to do a diagnostic test, their forte, which should indicate the true problem/problems. Could be any of a number of things.

If the hose is shown to be a problem, couple of quid and Bob's Your Uncle.

Wish me luck

[jonathan_dyane]

Don't worry about the grey smoke at this stage; if your problem was caused by the head gasket permitting water to enter the cylinders you would certainly have noticed either coolant loss or pressurisation.

Grey smoke can be caused by poor combustion which could well be caused by perished or damaged vaccum piping...

The cat *could* cause lack of power, but I too would expect this to manifest itself gradually and progressively rather than on an intermittant basis. Incidentally, the car does not need the cat to pass the MOT, so if it was to need replacing due to blockage I personally would cut it out and replace it with a straight piece of pipe. This has the added benefit of making the car slightly more responsive, and improving the MPG...

Good luck,
Jonathan.

PS, other than blockage in the cat as discussed above, it is unlikely in the extreme that the exhaust is at fault; as the silencer is behind the cat and obviously is less restricted the cat would choke first... The EGR can and does cause the inlet manifold to choke up, but again I would expect it to manifest itself gradually and progressively.

[xylophone]

Jonathan

Thanks again. You know your stuff!

Will keep you posted as to how I get on, as you have been good enough to help.

Do you say what you say as you are perhaps a mechanic or otherwise a car person of some other sort?

[jonathan_dyane]

No problem! I'm not a trained mechanic, just a keen amateur, who takes pride in the fact that he has never yet had to pay anyone to fix his car! (Fitment of new tyres excepted...)

[fenboyandy]

[quote=jonathan_dyane;157936]

Incidentally, the car does not need the cat to pass the MOT, so if it was to need replacing due to blockage I personally would cut it out and replace it with a straight piece of pipe. This has the added benefit of making the car slightly more responsive, and improving the MPG...

Good luck,
Jonathan.

Hi,

Found this really interesting - is that 100% right? I've got a '94 L-reg and would like to ditch the cat, but assumed the car wouldn't pass MoT without one.... Is it due to the age of the car that it WILL pass MoT without a cat? Does lack of cat not mess up the emissions??

Cheers

Andy

[jonathan_dyane]

Found this really interesting - is that 100% right? I've got a '94 L-reg and would like to ditch the cat, but assumed the car wouldn't pass MoT without one.... Is it due to the age of the car that it WILL pass MoT without a cat? Does lack of cat not mess up the emissions??

All the diesel smoke test used for MOT does is test the opacity (density) of the smoke emitted by the vehicle. Diesel catalysts of this generation allowed manufacturers to meet EU emisision standards for *new* vehicles, although VAG prempted this legislation, bringing the cats in in the early 90's.

A TDI powered car will easily pass the MOT smoke test *without* a cat provided it is not smoking excessively due to being in poor condition or badly setup, indeed my father runs a 80TDI which has had the cat removed, and it passes the test by a large margin.

However, I have known over-zealous testers to fail diesel cars when they have realised that a cat has been removed, despite the emissions being within acceptable levels. This is IMHO a dubious interpretation of the MOT regulations. I have heard of people avoiding this by removing the cat and setting to it's innards with a masonary drill which causes the brittle subdstance within to break down and be easily tapped out. This leaves the tester unaware that the cat is empty as the external apperance is as normal. The position of the 80 cat may make this difficult to acheive however, due to the length of the pipes which are attatched to it...

The bottom line is that very few diesel vehicles had cats in the early 90s, and the tester is unlikely to spot the fact that it is not present, and the car *will* pass the smoke test, provided it does not have any faults (which would probably cause the car to fail *with* cat too) and you will gain an MOT with no problems on this score...

Hope this helps,
Jonathan.

[moaning]

Just reading through some of these posts, and very heartened by the mileages these cars can clock up. I love my 80 TDI, but the economy just won't get better than 40 mpg. It starts on the button, pulls very well but does smoke a bit, especially when pulling away. the car seems very smelly compared to our 4 year old Fabia TDI. As its only done 119K what's the best thing to investigate first? Diesel Bob said they would overhaul the injectors and reset the pump timing. I thought the pump timing couldn't be adjusted, and can't think that there's much wrong with the injectors. Is it not more likely to be just coked up on the inlet side from the EGR system? If so can this be sorted without dismantling? I've run a couple of tankfuls of fuel treatment through replaced on the bleed off pipes, changed the thermostat and air filter.

Is it a good idea to remove the EGR pipe to inlet manifold and squish some kind of decoke spray in?

[xylophone]

Hi,

I'm the originator of this thread. My 1995 80 TDi Avant. Had to replace turbo recently. Volksparts, excellent outfit in Durham, did the job. £700. First 'big' part have had to replace. Now on 235,000. Still on original gearbox, clutch, exhaust, engine.

Time, I think, to replace car with an A6 Avant, say 2-4 years old, for greater comfort, capacity. Second hand prices at all-time low. Any comments, anyone, on this car?