Club 80-90 Forums

Thought I would take the opertinity to show some of the common tdi issues that can afflict these actually very reliable engines if maintained badly...first of all is the EGR system build up or Black Death to give it more dramatic name...not really caused by poor or lack of basic maintainance but certainly not good for the engines breathing abilities, or for emissions/mpg...

Note the reduction in size of the port, valve backs are piled high with carbon too..inlet is heavily clogged though not as bad as some I have seen..

Not pleasant to remove but very worthwhile doing...the valves are the biggest issue as it means head off and in bits..

Next issue is cambelt related, having a recent belt fitted is not always a good thing when buying an engine, if the fitter decided it wold be a good idea to remove the center bolt on the crank pulley is 99% certain it won't of gone back tight enough and with a new bolt...these leads to to pulley fretting on the crank nose untill something wears out and the timing starts to retard...this leads to gradually causing the valves to hit the pistons...and eventually the tappets start to break up or the pulley spins and valves get bent..here's the pulley when damaged.

Notice no locating "D" remains at all...the crank has nearly survived this time..

But still needs facing off on a lathe to ensure the pulley will run true...so crank out, new shells and bolts etc.. Also
Also..never assume anything was fitted right either..here's something I see very regularly...tensioner turned in wrong direction causing the self tensioner to be damaged and solid...leads to belt becoming loose over time..

Note the bent tag...this engine still ran and went well in fact...but may have valve gear damage...will,see soon but just a bit of a heads up on what can go wrong and can be expensive to fix...check your bottom pulleys for wobbles and correct ASAP if you have even a slight hint of wobble.

AFN from a shazza per chance?

How can you tell what way is the right way for the tensioner?

what mine looked like

The tensioner on these engines is turned clockwise with the peg spanner untill the notches align...often folk turn them anticlockwise, damage them, then turn clockwise and lock them up solid...the roller should be spring loaded when in use, if it ends up solid the belt goes loose over time and things go wrong.

jes*b wrote:AFN from a shazza per chance?

Yep, that's the Afn out the shazzer, got a A4 tdi engine as well now to meddle with! That's 4 tdi engines and a AAZ now at this address! all proper ones with distributor pumps too.

Will second the bit about the centre bolt needing to be tight and to check for any wobble if you're in the engine bay for any reason.

These are similar pics of the crank and pulley of my old 1Z engine. Once again little left of the locating D on the pulley. Previous owner ran a garage and had done the conversion and fitted new belt at same time. Let go cruising down the M2 at about 50 to 60 mph no faster and under little load. One minute OK, next a loss of power and white smoke out the back.


In this case the bolt itself finally sheared most likely down to the wobbly pulley.



I scrapped the engine and found another to refit but pulled the head off to check the damage. Pistons seemed good enough to reuse if I wanted to go that way but the most obvious internal damage was to a few of the cam followers which were well mashed.

That's a bad one...most go unnoticed in fact for ages but the engine runs with the piston just touching the valve every turn...it wears a pocket into the piston crown even...but then one day a tappet top fall apart and wrecks the head, camshaft and whatever else it decided to take with it...grim but quite common, and all because that center bolt is just abit loose..if in doubt check it.

I've just had the cambelt go on my TDi - play in the intermediate shaft, moving in and out. As the pulley is driven by the back of the belt it just wore the belt out and it eventually let go.

bugger

monsho wrote:I've just had the cambelt go on my TDi - play in the intermediate shaft, moving in and out. As the pulley is driven by the back of the belt it just wore the belt out and it eventually let go.

bugger

Are you sure? The intermediate shaft is not renowned for excessive end float! Was the belt worn at its sides? As in narrowed?

Yep, about 2 mm of end float on it, Baxter has seen it before he said, edges of the belt were chamfered but the back of the belt was worn, just reduced the strength of the belt till it went