VW T4 2.5 TDI AFB: Sawing Noise When Accelerating?

Hello,

I recently had a V6 2.5 TDI engine with an AFB motor. As soon as you press the accelerator in this vehicle, the engine starts to vibrate back and forth. However, this only happens under load. As soon as you slightly lift your foot off the accelerator, the vibration disappears. It immediately starts again when you press the accelerator. This happens regardless of whether the engine is warm or cold. The vehicle has a manual transmission and has a mileage of 293,000 km (and still has the original turbocharger).
"I've also noticed that when the engine is cold, it makes a relatively loud clicking sound for about 10 minutes. Then it disappears. Also, the vehicle's acceleration is quite sluggish, especially in the lower RPM range. It's very slow until about 2800 RPM, and then there's a significant turbo boost, and it really takes off! The turbocharger and mass airflow sensor were replaced about 20,000 km ago."

I personally suspect it's related to worn-out glow plugs. What do you think? Could it also be caused by the fuel injection system or something else?

luiggi wrote:

Hello, The vehicle has a manual transmission and a mileage of 293,000 km (and still has its original engine). What I also noticed is that the engine makes a relatively loud clicking sound during cold starts, for about 10 minutes. I personally suspect a problem with the engine's lubrication system! What do you think? Could it also be caused by the fuel injection system or something else? Best regards

Perhaps you could also tell us what your side effects look like?
I'm 99% sure it's the NW engine, because I don't know of any AFB engines that have lasted longer than 300,000 km before failing.
They might be sawing because the valves can no longer open sufficiently.
It's also possible that a tow release lever has already failed.

Hi,

Next week, I'll remove the VD and let you know how it looks. It's probably not going to be good. Considering the mileage, the NWs (presumably referring to "Nockenwellen," or camshafts) should probably be replaced for the second time.

HELLO;

This afternoon, I had some time and removed the right valve cover. I was quite surprised when I saw the shafts. You can barely see anything on them – only the faintest traces of wear. It's not the kind of damage you usually find. Based on this, I suspect (or am almost certain) that something was already done to them by previous owners.
"But what I've noticed is that several of the hydraulic components seemed quite easy to compress. These will probably fail soon. Could the noise my saw makes, and the power loss when starting, be related to the hydraulics? And one more thing: Didn't Audi issue some guidelines regarding the acceptable amount of wear on the hydraulic components (i.e., how much they are allowed to compress)?"

According to Audi, the valve clearance should be checked and adjusted when it reaches 0.5mm, measured at the lowest point, specifically on the camshaft lobes.
Have you removed both valve covers?
It's quite possible that they've already been replaced, but probably with the bad ones. Since your car has quite a few miles on it, it might have had the problem with the worn-out glow plugs early on. After all, the faulty parts were installed until the end of 2002.
It's plausible that the vibrations and lack of power are caused by the pistons not fully opening.
What kind of oil are you using?
If you have the LLII password, then share it!
LL3 is significantly better, especially regarding the valve clatter.

If the hydraulic lifters remain soft even during operation, which is a concern, it will have the same effect. Furthermore, this increases the stress on the valve stem. The 0.5 mm thickness from Audi is a joke, just like an oil consumption of 1 liter per 1000 kilometers.

Hi,

The vehicle is currently running on 10w-40 oil. I agree with Christians about the hydraulic lifters (and the Audi joke!). I'm now in a state of indecision. On the one hand, the vehicle has a very high mileage. On the other hand, it might last another 100,000 km if I replace the internal components (e.g., valve lifters, pushrods, etc.). But what about the condition of the valves and the engine block? Should you consider removing the cylinder heads given such high mileage? What would you do?

luiggi wrote:

Hi, The vehicle is being driven with 10w-40 oil. I agree with Christians about the hydraulics. (And also about the Audi joke!) I'm now in a state of indecision. On the one hand, the vehicle has a very high mileage. On the other hand, it might last another 100,000 km if I replace the internal components (NW, hydraulics, lifters, etc.). But what about the condition of the valves and the engine block? Should you consider removing the cylinder heads with such mileage? What would you do?

If you say the camshaft looks surprisingly good, why do you want to replace it?

When I discovered that the camshafts were worn out in my AKE (presumably a specific vehicle model), I decided to sell it. In my opinion, it's simply the most cost-effective solution.
That won't work for you, though, because it's not running properly.

"Regarding our two A6 vehicles with AKN engines, I purchased them after they had already experienced engine damage."
With 256,000 km, the camshafts were surprisingly good. I only replaced the lifters, rocker arms, and shims, and the engine has been running like new ever since.

Hello,

After some consideration, I've decided to replace the hydraulic lifters and rocker arms, along with other related components. I'll leave the other parts alone for now, as they look good. Hopefully, this will allow the car to run for another 50,000 kilometers. After that, I'll probably sell it and send it to Bulgaria.

I just hope that this will also improve the lack of power and sluggishness in the lower RPM range.
Regarding Steffarn: How did the engine damage manifest itself in the Audis you purchased? Is the vehicle still running, or did the defective hydraulic lifters cause the rocker arms to fall out?

Wouldn't you like to try it with a good oil first?
It might be cheaper than taking the entire engine apart.
And: The timing belt replacement alone costs around 800 euros.
Replacing the hydraulic fluids will probably cost around 1200, just for the labor.
A used NW (presumably referring to a specific type of equipment) with a sliding lever and hydraulic system, priced between 800 and 1000 euros.

I think that if your new car gets a new engine, it will easily reach 300,000 kilometers.
The V6 engine is virtually indestructible.
With the exception of the ESP, NW, and Turbo models, these engines rarely experience any major issues.

I've only heard about camshaft wear when the engine is run with long-life oil. I've never heard of it happening with the standard 15,000 km service interval.

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

'MFG' is an abbreviation for 'mit freundlichen Grüßen,' which means 'with kind regards' or 'best regards' in English.

Hello,

I also need to briefly comment on this.
It's been a while since I worked with those specific models (NW and V6 TDI).
aber ich kenne da einen A8 eines bekannten, der mittlerweile über 400tkm drauf hat und immer noch den ersten Turbo hat, die ersten NW's, den 3. LMM und die 2. Clutch.

Year of construction: 02/1998...
Apparently, they were still using 'good' parts back then.

Regards,
Marcus.

EMSimASZ wrote:

I've only heard about camshaft wear when the engine is run with long-life oil. I've never heard of it happening with the "normal" interval of every 15,000 km. MFG

I already have one. LL didn't even exist back then. But there were many defective units, just like with mine.

Tagessuppe wrote:

Wouldn't you like to try it with a good oil first? Replacing the hydraulic fluids will probably cost around 1200, just for the labor.

It didn't help with mine. But it's not that much work, especially when you combine it with the ZR.

It probably won't do anything with the new ones. But maybe it will help with the older models.

I had a very significant experience last summer.
And I thought I was doing something good for my A3 by doing this in the summer.
I'm going to put Castrol RS-0W40 in instead of SLX 0W30.
As a result, the hydraulic components started making a lot of noise, even when the engine was warm.
It was used and driven for some time.
During the next oil change, I added LL3 for the first time.
And then, after about 100 kilometers, the valve ticking disappeared, and the engine was running smoothly.
softly and gently again.
Although one might think that RS 0W40 is not a bad oil either .

And some people claim that the viscosity of the base oil doesn't matter.
it's going to be thick anyway! so, like a 30, but I don't want to start a new oil discussion .
If the lifters are making noise, I would add some cleaner to the oil.