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Hello,
Here's a sad update on the condition of my ARL engine after 65,000 km (approximately 40,000 miles) of use.
Originally, I was planning to replace the timing belt because the head gasket was leaking a little oil, so I decided to replace the head gasket at the same time.
The problem became apparent when I removed the cylinder head. The piston in cylinder 3 shows significant signs of impact damage (presumably from something that was ingested...). The same marks are visible on the cylinder head. Cylinder 4 also exhibits this damage, but to a much lesser extent. Furthermore, there are two grooves in the cylinder liner of cylinder 3, which are clearly noticeable and run from bottom to top.
"Regarding the head, I'm wondering if it's possible to have it machined. I'm thinking about 4-10mm needing to be removed. Would that still allow for the use of the pre-compression device (PD) and glow plugs, or are there thin adapter plates available for installation?"
The defective piston will be replaced. For cylinder 4, new piston rings will be installed (there are two visible wear marks, but they are minimal and only about 2cm long).
The valves for cylinders 2 and 3 are no longer sealing properly (pressure test with soapy water on the valves) and therefore need to be replaced.
I hope you can help me with something.

Hi,

Whatever went in, probably came out – whatever it was. Therefore, it might not be a bad idea to take a look at the turbine wheel of the turbocharger.

Best regards, Rainer.

I disassembled the charger, and it looks good (though a bit dirty). Once, a hose (on the pressure side) near the LLK (low-level coolant) inlet tore, and I drove a few more kilometers before noticing. There might be a foreign object inside.
Can you get a head transplant?

Well, it's possible that a small stone might have been sucked in... who knows.
Regarding planning: 0.4mm seems like quite a bit to me, but then I see how some people force the nozzle holders in place or cram two gaskets instead of one – so it probably can't be that dramatic.

If I were you, I would only plan the head so that it is straight overall. Those few small marks from the foreign objects don't matter.

Best regards, Rainer.
PS: I'm looking for a defective PD cylinder head for my latest toy .

Hi,

my opinion:
Just make sure the head gasket sealing surface is clean. The minor imperfections (as long as they're not too deep and don't cause leaks) will hardly affect the combustion process in the engine. Since the valves need to be removed for grinding anyway, maybe... Check the seating rings for damage.

Best regards,

So, you're saying that if the head is already flat, it's not necessary to re-grind it. That actually sounds good to me. I wasn't entirely sure, but I definitely want to prevent the piston from hitting the "crater bumps."
Can the camshaft, valves, and PDE (high-pressure diesel injection pump) be removed and reinstalled on a PD TDI engine without special tools? If so, are there any things to be aware of, or any helpful tips on how to avoid using certain specialized tools?
Should I replace all the valves while I'm at it? Can I reuse any parts of the "valve system," or do I need to replace components like the lifters and springs?
Thanks in advance for your (as always) valuable tips.

PS: Are forged Mahle pistons used in the ARL engine? VW offers pistons from several manufacturers, and I would be surprised if they were truly identical, especially considering the weight. Has VW made any changes since model year 2002 regarding pistons or piston rings, including the oil scraper ring?
"Does anyone have a contact for valves and pistons at a reasonable price? I'd prefer not to have to go back to the VW dealership (pharmacy) to buy them..."

Quote:

So, you mean that if the head is flat, it's not necessary to re-grind it

?

At least on the surface, the head appears to be in good condition. If I'm not mistaken, VW specifies the tolerance limit based on length as 1/10 mm.

I think you should be able to sand it down with a grit of 1-2/10 mm.

If it were my car, I would first thoroughly verschandeln it using a cleaning stone. If he doesn't have any excavations or noticeable flaws, I would reassemble him (but only for myself).

If you're not willing to take risks, it's best to let him do the grinding.

Regarding the leaking valves, you should check if there are any contaminants lodged between the valve seat and the valve itself.

You only need one tool to remove the PD elements; otherwise, you'll need a good set of Torx drivers (or whatever those multi-tooth fasteners are called). You'll need one for securing the PD elements and another for the upper parts of the bearings on the camshaft.

Okay, thanks for the helpful information. I'll replace the valves and valve stem seals, and then have the cylinder head machined (maximum 2/10mm). There's no warping present; it was checked with a (specialized) ruler. The piston for cylinder 3 has already been ordered; hopefully, that's all that's needed.

Zak1976 wrote:

Sad update on my ARL engine after 65,000 km of mileage.

Hi,

Even if it doesn't directly help you, I have a question:

To what extent are you familiar with the history or origin of the engine?
Or did you install it as a new engine in your G3, and the problems must have arisen while you were using it?

Zak1976 wrote:

Once, the hose (on the pressure side) near the LLK inlet got a tear, and I still drove a few kilometers. There might be a foreign object that got in there.

"I'd bet my life on it, Ulf, that's what happened, because when you're unlucky, you're really unlucky, right?"


Okay, when you're using the Torx/star bit for the camshaft bearing caps, make sure it's a longer one, not a short one with a socket attached. Otherwise, you won't be able to reach the screws, as they are recessed a bit deeper in the bearing blocks. And, new screws wouldn't hurt!

matthiasTDI96 wrote:

Quote: Once, a hose (on the pressure side) in front of the LLK inlet got torn, and I still drove a few kilometers. Possibly, a foreign object got in there. I would bet on it, Ulf, that something happened there, because when you're unlucky, you're really unlucky, right?

According to Murphy's Law, it's likely to happen... but for a foreign object to get in there, it would first have to overcome the intake pressure (at least in the double-digit mbar range) and enter the intake path against the "outflow" current.
And that's something I can hardly imagine...

I've also been racking my brain (my actual ) trying to figure out how this could have happened. That would be the only possibility that seems plausible to me.
I opened and cleaned the charger on both the exhaust and compressor sides. There is no visible material loss or wear on the nozzle. I also always covered the openings with a verschandeln cloth after removing parts, but it's possible that some dirt or a small stone may have entered the pressure system. Fortunately, no cracks have formed in the head.
Thanks again for the tips regarding the keys I need.

The engine came from a VW test vehicle and was one of the very first ARL engines ever produced (engine number 80, which can be seen on the upper timing belt cover). If there was no material defect, then it likely happened during my time working on it. However, I am not aware of any fault on my part, and I always take a careful and thorough approach when performing repairs, especially in the engine area. If anything is unclear, I prefer to ask questions.

Here's what I was also thinking: it could be a tiny piece of metal from the piston ring, even though there are no visible cracks on the piston. The pistons will be removed later, and if there's interest, I'll post some pictures of the removed pistons later.
Do connecting rod bolts actually need to be replaced?

Hi,

Connecting rod bearing bolts should always be replaced. Don't ask me how they are put on.

Best regards,

"Hmm, I'm curious, but those marks don't look like piston ring fragments. It must have been a really large piece. Since you also have minimal traces on another cylinder, I think it's rather unlikely. It's also quite unlikely that something like this would happen while driving with the defective hose. If it came from the turbocharger, I'm sure you would have more obvious signs." "Now that the cylinder head is on the workbench, maybe something has broken off on the intake side or near the EGR valve in the intake manifold. Let's take a close look at everything."

I'm curious to see.

Did that part need to be removed again?

What causes such impacts, and how can they pass through the turbine without causing any problems?

Does it still depend on VTG?

On the intake side, something might have dissolved out of the coolant. Because the damage is also seen on the Z4, it must have happened suddenly, in the short term, but *before* the cylinder head. With the ignition sequence 2-1-3-4, it occurred on cylinder 3 and took some time before affecting cylinder 4. Then it was gone.

Already hunting for phantoms, Martin.