Jet Engine Noise: What to Expect After Replacement

Hello everyone.

"My friend's AFN-G3 probably exhibits the same symptoms with the new 216 injectors as described in..."
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.
was was described:

A faint, metallic clicking sound (roughly like a small hammer hitting a small anvil) during the working cycle of a cylinder – you know the rhythm of a valve with excessive clearance at idle speed.

After a cold start, you can't hear anything, but when the engine is warm, the noise is clearly audible near the car.

Inside, you really have to pay attention. During the thrust cutoff, the noise disappears, and otherwise, it's not clearly load-dependent.
It is most noticeable in the lower RPM range under partial load; at higher loads, it is often masked by the louder engine noise.

With the hood open and the engine cover removed, the noise from the machine is just barely masked. When the hood is closed, the sound becomes audible again.

When listening to all the nozzles and injection lines with a wooden stick held to the ear, the noise cannot be located.

Die Leerlaufruheregelung liefert mit Werten bis max. 0,9 mg auch keine eindeutigen Hinweise auf den betr. Cylinder.

@ chris: Do you recognize these symptoms? How is your engine sounding these days?

@ everyone: Who else can make sense of this?

hi ulf

As described in the other post, I also experienced a changed soundscape with my 1Z after the injector replacement, similar to your description. Can you remember that I once mentioned, in an email, having heard louder combustion noises?! I've tried everything. The noise hasn't gone away to this day. The idle speed is also around -1 on all cylinders. I've tried adjusting the fuel pump. Nothing has helped. Bertil also mentioned a changed soundscape after the injector replacement. He also couldn't find the cause. For my part, I've learned to live with it.

Deleted upon request.

Looking at the design drawings of the nozzles, both with and without the NBF (Nozzle Flow Booster), I can already imagine that the NBF nozzle would produce more noise. There's simply a lot more movement involved.

Otherwise, Gustav is naturally right; the problem is: what constitutes a 'good' sound and what constitutes a 'bad' sound. My mechanic has a total feel for this thanks to 30 years of experience. What would be needed is a sound database. However, creating good recordings would require an enormous amount of effort...

CU Gremlin.

joergs wrote:

As described in the other post, I also experienced a changed soundscape similar to your description on my 1Z after the nozzle replacement. Do you remember that I once mentioned, in an email, having heard louder combustion noises?! I've tried everything. The noise hasn't gone away yet.

I, for my part, have learned to live with it.

Hi Jörg,

Here's a thought of mine: perhaps an injector nozzle ignites "noisily" against one of the glow plugs (which protrude into the combustion chamber).

"I think it will likely start showing signs of wear within a few thousand kilometers. It's probably too early to see that kind of issue with the G3 engine, but maybe you could check the spark plugs from the 1Z engine and inspect them if it has already accumulated enough mileage since the injector replacement?"

Deleted upon request.

diesel.gustav wrote:

What exactly should "ring" in a TDI engine? The injector, if it's in good condition and correctly installed, sprays slightly downwards into the combustion chamber. But not upwards onto the glow plug. Or what exactly do you mean with your approach?

Hi Gustav,

When I removed my spark plugs, there was a small deposit of carbon buildup on each one, in a spot that looked like it was being hit by a jet of something.

And aligning a beam of energy towards the candle as a "hot spot" would make sense to aid in ignition.
I think so, at least.

And aligning a beam of energy towards the candle as a 'hot spot' would make sense to aid in ignition.


Okay, here's the translation:

'Yep. The candle is positioned such that the outer edges of an injection stream just barely graze it...'

individual droplets from the edge of the area hit the candle, NOT the entire beam.

CU Gremlin.

Deleted upon request.

Hello.

It has since become apparent that the "ting ting ting..." noise no longer occurs after a warm start, provided the car has been standing for about 5-10 minutes – meaning the inside of the engine block is still barely cool overall, given these outside temperatures.

Shortly after a restart, it reappears.

Could it be that, according to my opinion, there's actually a connection to a "hot spot" in cylinder 1 that cools down so quickly after a short period of inactivity that it initially becomes "inaudible"?

Hello again.

So, it seems that a TDI engine is truly a precision machine... The mystery surrounding the engine sound is probably largely solved (in this case).

In the hope that it might help other TDI drivers with keen ears (no, I don't mean Vulcans ), I've added something to the error database.

Okay, I'm ready. Please provide the German text you want me to translate.

So, it seems that a TDI engine is really a precision machine.


Yep, I was just reading something about exhaust gas composition. The result: even deviations of just 2 degrees in the injector installation angle can cause significant, measurable changes.
and 2 degrees is really not that much...


Hoping that this will also be helpful to other TDI drivers who are paying attention .

live long and prosper

CU Gremlin.