Passat 3B AHU won't start

Hello,

After hours of searching through various listings and trying to get in touch with the seller, I'm completely stuck and can't proceed any further!

Vehicle data:
VW Passat 3B TDI, 90 horsepower, automatic transmission.
MKB: AHU
Mileage: 360,000 km
Former taxi (family-owned, well-maintained).
Timing belt replaced approximately 10,000 km ago at a VW authorized service center.
Always use VW for service.


Okay, let's talk about the error:
The vehicle simply stopped while driving (the driver unfortunately couldn't say whether it was accompanied by sputtering or not), and it hasn't started since!

Error memory is empty.

Checked so far:
- diesel engine running without filters, etc. -> fuel is being drawn in.
- Diesel fuel, pre-pressurized with a hand pump towards the VEP intake, is being injected -> engine does not start.
- If you loosen the fuel injection lines, diesel fuel will leak out (it might seem like a small amount, but I don't really have experience with how much/how forcefully diesel fuel should come out).
- The ELAB is foreign-made, it makes a clicking sound, -> but it still doesn't start! I wanted to remove it, but unfortunately, it's stuck in there really tight right now!

I've been looking for the relay 109 that has been mentioned several times, but I can't find it on the relay carrier located under the dashboard. Where is this thing located?


And now I'm unfortunately stuck and can't seem to move forward, I hope you can help me!

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

"Hello,"

Robert.

Quote:

The vehicle simply stopped while driving (the driver unfortunately couldn't tell me whether it was with or without sputtering) and hasn't started since!

Did the aforementioned driver perhaps not refuel with diesel?

If so, what do the timing marks and the error memory say?

Hello,

If the problem is caused by a lack of power supply from the engine control unit (e.g., a faulty ignition switch, wiring, or relay "109" - note that this relay may not always be labeled "109"), you will not be able to access the engine control unit via diagnostics.

Similarly, for example, loose connections could have been created in the engine control unit due to soldering work or cheap socket adapters (tuning).

Best regards, Rainer.

hello,

@R.M.
The error memory is empty.
There's no gasoline or anything like that in the tank, just regular diesel, so it shouldn't be the cause!


@ dieselschrauber
I can access the engine control unit!
Can this be used to identify the aforementioned sources of error, such as relay 109 or similar, and the contact part of the ignition switch?
highly likely to rule out? I think so?

I really can't imagine that anyone has soldered anything onto the control unit or modified the software. Both people are retired, and the vehicle has always been in their possession.

I've finally found some time again to dedicate to my Passat.
I actually wanted to check the valve timing, but when I removed the valve cover, I discovered a piece of a hydraulic lifter inside the cylinder head. I then stopped turning the engine with the wrench because I was afraid of causing further damage!

After that, I disassembled the cylinder head because I was already fearing a major engine failure.
When I disassembled the head, it didn't initially appear that the valves were colliding with the pistons. However, upon closer inspection, one might possibly imagine that to be the case, but it doesn't actually look that bad.

After disassembling the camshaft, I noticed that all four intake valves have defective hydraulic lifters (see pictures).

Okay, so my question is, the timing belt was properly tensioned, so I think we can rule out the possibility of it skipping a tooth!
Ultimately, there are only two possibilities: either the camshaft and camshaft sprocket are misaligned (since the sprocket is conical), or the crankshaft sprocket is misaligned.
Can someone tell me where the small pin on the KW wheel needs to be positioned when the first cylinder is at top dead center (TDC)?

Is it very likely that the camshaft is damaged (e.g., bent)?
The valves don't seem to be bent, can I leave them in?
Furthermore, I've noticed that a wastegate turbo is installed. Shouldn't the AHU engine actually have a variable geometry turbocharger (VTG)? Is there also a motor code letter to be found anywhere on the engine block?




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

"Hello,"
Robert.

Hi,
The AHU engine has a wastegate turbocharger.
Here's what I would check on the valves:
- Inspect the valve stem for damage due to the failed hydraulic lifter, and replace if necessary.
- Check the cylinder head, especially this valve, for damage to the guide for the valve stem.
- Check all valves for leaks by pouring solvent into the inlet and outlet channels. Where it leaks, you'll need to remove and re-grind the valve anyway, and you can check it for warping at the same time. If it's tight, it's not warped. I wouldn't expect it to happen, anyway.
If you want to do it properly: remove all the valves, check the cylinder head for warping, verschandeln all the input/output channels, re-grind the valves, and install new stem seals.
Do you have any reason to believe that the valve timing was misadjusted?
You should carefully examine the cam lobe on the camshaft, specifically the one that drove the damaged lifter. If there are any signs of wear, replace it.
All the hydros have been replaced.
The timing of the camshaft on cylinder 1 of the AHU automatic transmission should be determined in the same way as on the 1Z automatic transmission: Look through the inspection hole on the transmission; in the area of top dead center (TDC), you will see a "0". Turn the engine over in the direction of rotation using the crankshaft until the "0" is centered directly below the reference mark. You can easily check that right now, while the ZK is expanded.
In this position, you will be responsible for hiring NW employees.
The "Nase" (nose) on the KW front strut is for the vibration damper.
Okay, I understand. Please provide the German text you would like me to translate into English. I will only provide the translation.
Herbert.

Regarding the mileage, I would probably just install a used replacement engine right away. It might end up being cheaper. They probably aren't that expensive anymore.

I once had a 1.4-liter engine that suffered a similar damage after a timing chain failure, where the hydraulic lifters were pushed through the valve guides by the piston. It was a classic timing chain rupture.

Thanks for your replies!

I will double-check that again tonight!
My question about the kW wheel was related to whether I wanted to check if the wheel might have become twisted or misaligned on the kW axis.
Is it conical, or is there a keyway in it?
If a wedge is inserted, I'll be able to see if it's twisted.
I don't want to install a replacement engine because it's also a complex job, and it will cost significantly more than a completely reconditioned cylinder head!
But I think I'll check the valves and then see if it would be cost-effective to repair the old one with a few spare parts. If that doesn't work, I suppose I can always install a used engine!

Regards,
Robert.

Hi,
The timing gear is held in place on the flattened crank shaft journal by a tight fit, as long as the central screw is tightened. If the central screw is tight, then it hasn't twisted.
Check the cylinder head with the valves; you'll see more then.
hg
Herbert.

I took a closer look at the cylinder head again yesterday. The exhaust valves seem to be sealing properly, but when I filled the exhaust manifold with brake cleaner, only a very small amount slowly leaked out of the valves, which I don't think is a major issue considering the mileage.
However, something came out of the intake valve when I was filling the intake manifold! I disassembled and inspected the Dan valve; it doesn't appear to be bent, at least not visibly, but the valve guide seems to have a lot of play.
If you let the valve protrude about 2cm, it will have approximately 1-2mm of clearance.
Since the contact surface of the head also has some damaged areas on the collapsed hydraulic lifter, I don't want to do any further repairs in that area!
The camshaft is also broken!

Therefore, my question is: besides the cylinder head for the AHU engine, which other cylinder heads might fit? Would the 1Z engine's cylinder head be compatible? Or not? Are there any other available sizes?
Does anyone happen to have anything lying around that they might want to get rid of?

Best regards,

Hi,
The exhaust valves seem to be leaking.
"As you mentioned, one of the intake valves is clearly leaking. The valve clearance is likely too large." I only have the values for the 1Z. In this case, the wear limit is 1.3 mm. During the measurement, the valve must be loose in its guide, and the valve stem must make contact with the guide on the NW side.
The complete cylinder heads appear to be different for certain vehicle models (Passat, Golf, Audi), but sometimes this is independent of whether the engine code is 1Z, AHU, or AFN. The Passat should originally have a cylinder head with part number 028103265P. Part number 028103265HX (which appears to be the AT version) should also fit, or possibly 028103265BX. These part numbers also appear in the A4 catalog. Perhaps other ZK models will also fit, but I can't say for sure.
Okay, I understand. Please provide the German text you would like me to translate into English. I will only provide the translation.
Herbert.

Hi,

If needed: I still have an AHU cylinder head lying around from my Golf 3 days. Back then, I bought a complete replacement engine that had a seized piston. I still have some ZK, ESP, and Turbo components, as well as a few small parts.

If you are interested, please send an email with your realistic price expectations to my diesel mechanic username AT gmx.de.

I can look up the part number over the weekend. If you know the differences between the heads, I'd be happy to take photos of the relevant areas so you can see if it fits. So far, I've always thought that only the blocks would be different (different motor mounting points for transverse and longitudinal installation). I can also gladly double-check which vehicles each part number was used in.

Greetings.
Guste.

Okay, sure.
Part numbers also appear in relation to Volkswagen Golf vehicles. The AHU, however, doesn't appear until 1996.
hg
Herbert.

The crankshaft pulley was stuck, so I unscrewed it and removed it to take a closer look, but the problem wasn't there!

What still surprises me is that there's another roller located between the K-Wert sensor and the fuel injection pump. What is its purpose?
Is this just a redirecting roller? It feels like there's some kind of "whirring" sound coming from the engine when it's revving high.
Does it have axial play? Is that normal?

I might be able to get a used AHU cylinder head from an AHU engine that was installed in an Ibiza. Do you know if there are any differences between them?
The part number should be: 028103373N.

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

"Hello,"
Robert.

Hi,
You must install the KW wheel according to the regulations using a new screw (torque plus angle!).
The idler pulley, located between the crankshaft pulley and the ESP pulley, is mounted on the intermediate shaft, which also supports the oil pump and the vacuum pump.
The Tl. The number is likely the one from the "body" of the ZK (Central Committee), and it's the same as mine (1Z).
The complete ZK (likely referring to a part number or code) from the Ibiza AHU engine has the same numbers as mentioned above, so it should also fit.
Okay, I understand. Please provide the German text you would like me to translate into English. I will only provide the translation.
Herbert.

Thank you for your help.
Is it a problem if the intermediate shaft has axial play? Or is that normal?
I will definitely install a new screw!
I have one more question: How do you lock the motor in place when tightening it? "That screw is definitely being tightened with well over 100 Nm!" (tightening torque +)
I still need to find out about the angle.

Best regards,