Burnt Piston 1.9 TDI AFN Golf 3

Hello, dear community!

I'm having the following problem...

"On my Golf 3 with a 1.9 TDI engine (AFN), which currently has 345,000 kilometers."
"These are the piston rings from cylinder number 2."
(not the 3rd one with a needle lift injector) was burned out.
The one cylinder had a compression of 10 bar, while the other three cylinders had a compression of 30 bar.

The cylinder head had been completely overhauled before.
The injectors were already refurbished by Bosch 2 years ago.
After the damage, the injectors were re-examined by Bosch-Meyer Hannover, and according to their report, all four injectors were in excellent condition (opening pressure and spray pattern were all within acceptable limits).

Now I am at a loss...

Could the damage to the pistons, specifically cylinder 2, also be caused by the VEP injection pump?

Thank you in advance for your help.

Best regards, Matthias.

Hello,

Quote:

Could the damage caused by burned pistons in cylinder 2 also be caused by the VEP injection pump?

Yes, this happens when the injection start control of the fuel injection pump is no longer functioning correctly, and the actual injection timing is too late at high engine speeds and high load.

Furthermore, if the engine is improperly tuned or the piston cooling system is no longer functioning.

Generally speaking, I would like to point out that such damage can also be considered normal wear and tear at 345,000 km. After all, how long is a motor supposed to last?

Best regards, Rainer.

Hi.

I'm familiar with this type of issue; it doesn't always have a direct cause. Things like age or overload can also lead to it.

The advantage is that these motors can be purchased for relatively small amounts, often in the low three-digit euro range. Alternatively, you can opt for a more traditional solution and continue to save on fuel costs.

Best regards, Rüdi.

Okay, I'm going to have the engine rebuilt, so new oversized pistons will be installed.

I will send the VEP (likely referring to a document or report) to Bosch-Meyer on Monday for review.

Regarding durability, I've had enough experience with 90hp and 110hp engines over the past 12 years, as well as the early 1.9 TDI pump-injector engines (AJM and ATJ). With normal use and the original cylinder heads and pistons, these engines often lasted between 480,000 and over 500,000 kilometers.

Therefore, it's not standardly plausible to me why 3-cylinder engines are considered normal, especially when they appear almost new, have a compression of 30 bar, and everything looks fine, yet this one specific piston in cylinder 2 suddenly breaks down after just one hour of highway driving and is completely destroyed.

Therefore, I wanted to get some more expert opinions to see if, given that the injectors are supposedly excellent according to Bosch, the cause might be related to the VEP (Valve Electronic Pressure) system.

Before I push the new pistons back in.

P.S. The engine is not tuned!

However, it's still a significant amount of money to spend on a car that's worth between 500 and 1000 euros, but that's your decision .

Engines can fail after 100,000 km (or even sooner), while others can last over 500,000 km; eventually, materials will always give way. I don't see the ESP as the cause if the engine has been running smoothly so far. For the cost of this inspection, you could just buy a refurbished pump.

As I mentioned, I've seen this type of damage in several TDI engines over the past 20 years. The usual solution was to replace the engine with a used one, re-seal it, and replace the timing belt. Then, the engine would last until the car was sold.

My suspicion, which would fit very well with the overall picture: The corresponding injector nozzle was leaking towards the cylinder head and overheated. This caused the injector needle to jam, leading to uncontrolled fuel injection. This can quickly damage a piston, especially at high speeds on the highway.
The critical thing is that the nozzle doesn't necessarily have to sustain significant damage, and therefore, after it cools down, it can often function perfectly normally again.

I would take another close look at the nozzle and the seat in the cylinder head, but the image of the nozzle is probably already distorted due to cleaning after the initial inspection.

Hi!

Well, I don't know if it's worth it either?
What does a new piston actually cost? That includes the piston itself, plus machining (x 4), boring, grinding, honing, gaskets, stretch bolts, timing belt, etc.

My Golf 4 TDI needs a new timing belt, the front brakes are rusty, the windshield is worn, and the battery is old.
"I also usually need to get some new summer tires, and I have to go to the TÜV (technical inspection) in March."

I've been thinking about whether I should continue doing all of this, but honestly, it's not really worth it anymore.

The cost of new pistons, bearings, etc. is relatively low for this AFN engine. Therefore, a used engine with under 200,000 km is not a viable option, even if it costs around 600 euros.

Since the car has already been completely rebuilt, including new tires, brakes, radiator, wheel bearings, dual-mass flywheel and clutch, timing belt, injectors, and a completely overhauled cylinder head, approximately 4000 euros have been invested.
I'm not going to get rid of the car; I'm going to keep it and have the engine block rebuilt now.

My sole focus was on identifying the cause of the sudden failure of the piston in cylinder 2.

The fact is, there was too much diesel fuel involved, which caused the piston to melt.

The initial assumption, without further testing, was whether the error might be related to the VEP (visual evoked potential).
The cylinder head had been previously refurbished, and as a result, the injectors were properly seated in their housings.

No, I'm not a complete beginner; I've been working with engines and transmissions in the VAG and Opel sectors for over 10 years.
"Previously, piston failures in common rail or pump-nozzle diesel engines were always attributed to faulty injectors or defective oil pumps."

However, we weren't sure about these issues, as I've never had problems with the air intake on older TDI engines in Golfs or Passats, except for things like old nozzles or leaky pumps.

Good evening, and thank you all for your answers.

Best regards, Matthias.

@Micha-VAG: You can safely disregard the fuel injection pump at that mileage, and you don't need to use a dynamometer for testing.
Because every (!) modified car with this engine that I've ever had experience with has had its catalytic converter fail, at the latest after 300,000 km, and sometimes as early as 220,000 km.

"Of course, there are probably some people who have driven over 500,000 km with these engines, but they are invariably doing so on French highways with speed limits or as a mobile obstacle that regularly gets its high beams flashed by following trucks."
Just because these vehicles are still running doesn't mean everything is working as it should, and that you can set the cruise control at 180 km/h. Otherwise, things can quickly go wrong, as with the damage you described.

I wish you all the best for your car, but I agree with what was said above.

"Just wonder how long the following would last for you:"
- Transmission (is the first oil still in, or is there sludge?)
- Starter motor
- CAT/Exhaust
- Electrical components, including light switches and ignition systems.
- Wheel bearing
- Power steering
- Shock absorbers and springs.
- Heat exchanger for heating.

... at that mileage, you can expect any of the above issues to occur daily, and I'm sure I've forgotten some others.

I would either export the item to the highest bidder or, if the price is bad, scrap it and sell the parts.
Take a look at what a Skoda Fabia costs on Autoscout, check out the prices of similar cars in your area, and then decide whether you want to continue investing money in your current car.

Best regards, Rainer.