TDI-1Z: Partial Engine Repair Guide

Hi,

Since the head gasket in my Audi 80 TDI 1Z is starting to fail after 270,000 kilometers, the question arises as to what else could be replaced at the same time. All original parts (hydraulic lifters, ESP, etc.) are still installed.

I will definitely replace the shaft seals and sealing rings. I'm not sure if it would be worthwhile to install a replacement cylinder head plus a replacement pump, so that I don't have to take everything apart again after 30,000 km . The car has been driven gently, starts immediately, consumes little fuel, and easily reaches 200 km/h... maybe the parts will last another 100,000 km . What would you do ?

I would be grateful for any tips .

Hello Christian,

"A new pump should only be considered if there is a strong suspicion of a defect. I would rather replace the injectors (if they are as old as the engine), because with that mileage, I wouldn't trust the pump anymore."
Shaft seals are not as critical today as they were with the 827 models from the early 1980s. However, if the head is already removed, it's worth investing those few cents and replacing them.

Bertil wrote:

I would rather replace the nozzles (if they are as old as the engine), because with that mileage, I wouldn't trust it anymore.

Hi Bertil,

Thank you for the tip! The nozzles are new , and there are no air bubbles in the lines leading to the ESP. However, I was thinking about maybe replacing the oil seal on the ESP shaft anyway (it was completely worn out in my Passat) . Well, perhaps it will be an interesting experiment to see how long such an engine can last .

It would also be interesting to know why the shaft seals now last much longer . Besides a larger inner diameter, I haven't been able to visually identify any other differences compared to the old TD shaft seals... but it is probably because the material is different than before (it doesn't harden as quickly anymore) .

Hello!

If you already have the ESP unit accessible, also check the condition of the drive shaft. It's only equipped with a plain bearing, which usually lasts around 300,000 km if the timing belt wasn't too tight. Otherwise, later on, you might end up with a timing belt that wants to slip outwards.

HENZO can equip these injection pumps with a new sliding bearing at an affordable price. A new seal made of Viton is also included.

Best regards, Tom.

Hi Tom,

aaaah, another one who had their pump done at Henzo. I sent the pump from my Passat 1Z to Henzo and afterwards, I no longer had any air bubbles in the lines (the seal was defective). Of course, it's an idea .

However, I have a hard time believing the theory that the timing belt runs outwards due to slack. Even after installing new bearings, the ESP unit still had quite a bit of play (although it's still a good idea to replace them). If the shaft has some axial play, perhaps the ESP wheel moves out just a tiny bit during operation... but why would the timing belt also run further out ? I've replaced several timing belts, and one ran far inside, while another ran far outside, and they all held up .

Hello Christian!

I didn't buy my pump from Henzo. We are very good friends.

Regarding the externally mounted timing belts:

After high mileage, the drive shafts of VE pumps tend to tilt inwards, as viewed from the direction of the belt's tension. Any play is then only in that direction, and it's minimal. However, if the timing belt tries to move outwards due to this tilting, it will rub against the edge of the tensioner pulley and the intermediate shaft. This causes the belt to slowly fray. Often, this is what happens before a timing belt skips or breaks.

So, always pay close attention to the timing belt tension and don't blindly trust any workshop.

There was certainly no obligation; it was just a well-intentioned piece of advice.

Best regards, Tom.

Tinkatom wrote:

So, always pay close attention to the timing belt tension and don't blindly trust any workshop.

Hi Tom,

Anyway, not.....and if I have to work on it in deep snow...Your theory sounds plausible . So, the important thing isn't determining the axial play, but rather the tilting play . I have the old bearings from the ESP here and now (I think) understand which play is meant: only a narrow strip has been worn in the axial direction, meaning that the shaft tends to "come loose" in the radial direction, and as a result, the ESP wheel eventually tilts...if the wheel tilts, it's definitely conceivable that the belt tends to "come loose" outwards .

Hello Christian!

Sure, here's the translation of the text from German to English:

'Delete: Theory'

Set: Practice.

As a theory, it feels too unstable to me.

Good night!

Tom.