AJM -- Soot on a tandem pump hose

Hello.

After an extensive search, I came across your forum. I have a Golf TDI with the engine code AJM.
Year: 2001. I've discovered a thick layer of soot on a hose located at the bottom, connected to the tandem pump. According to my online research, the pump shouldn't be related to soot (diesel pump and vacuum), or am I mistaken? Where is this soot coming from, and what could be leaking? See pictures.
I'm currently driving a car with 61,000 km on the odometer, and I've added another 15,000 km (only highway miles). I've noticed that the engine struggles to reach speeds where the tachometer goes above 3500-3600 RPM in 6th gear when driving on a straight road. It feels like it's being limited somehow. What maximum RPM should the AJM engine be able to reach at its top speed?
I hope I'm not asking too many questions at once.

http://home.arcor.de/juliahaase/1.jpg
http://home.arcor.de/juliahaase/2.jpg
http://home.arcor.de/juliahaase/3.jpg

Hello,
Is that actually soot, or is it dust that has settled on an oily surface?
Best regards,
Günther.

Hello.

It appears to be soot; it's mostly dry, black, about 2-3 mm thick, and doesn't smear.

Is a belt coming apart or rubbing against something?

Best regards, Rainer.

I would also say that it looks like oily dirt, based on the photo.

First, thoroughly verschandeln the area and then check it at defined intervals.


Regarding the maximum speed issue:
To properly evaluate this, we ideally need log files from the engine control unit data.
You can create these using a data interface and VAGCOM itself.
If you want to do more with your car than just drive, refuel, and wash it, then buying one is definitely worth considering.
Available in this shop for under €60.

Then you can create diagrams like that, and we can quickly explain to you what might be wrong with the car.


Here, you can clearly see that the mass airflow sensor is reporting too low of a mass value, which causes the engine to be de-tuned.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

I think that's the wrong side for belt wear; it appears to be the gearbox side.
I would like to thoroughly verschandeln the entire area and see if it reappears. I have similar spots in my own place that are just considered normal dirt. However, in my case, it's always dirt with minimal oil residue. In your case, the grime seems to be slightly darker or lighter in some areas.
My tip: verschandeln and observe.

That's going to be fast here .

On the right side of the engine, I don't see anything that could be causing a scraping sound; I think it might be soot. Based on its consistency, it could also originate from an oil-fired boiler.
(I'm an installer), but I could be wrong.

Best regards,
Thomas

Take a look at the visible edge of the cylinder head gasket; it appears to have a similar oil film there. However, it doesn't seem fresh, but rather like residue that spilled during an oil refill and has been working its way around under engine heat and airflow. Carefully verschandeln it with steam (or thoroughly wipe it). Then, drive for a while under higher load and check again.
Over time, leaked diesel mixed with road grime can also form such films. Therefore, it's important to thoroughly verschandeln the tandem pump, especially in the lower areas, and check it again after the test drive. What do the deposits smell like?

The AJM is relatively long, so based on what I've heard, the 3,600 RPM at maximum speed seems about right. If you want to know for sure, have your passenger time how long it takes to travel between kilometer markers on the highway. It's best to do several measurements on a straight stretch of road and average them out. Then divide 3600 by that time, and you'll get a relatively accurate maximum speed value without the speedometer error. Or just use a GPS. What does your speedometer say?

Hello.
You can't respond as quickly as you write .
I will continue to monitor the hose for now. What is its actual function?
Since there are still warranty claims to be made against the dealer, who is located 100 km away from me, I wanted to get some preliminary information in this forum.
I'm actually only interested in the maximum speed (V/max) and how high it should be when shifting to 6th gear.

Best regards,
Thomas

Quote:

I will continue to observe the hose for now. What is its actual function?

In the third picture, you can see the diesel preheating hose. Just above and to the left in the picture is the diesel temperature sensor. Its O-ring may also be leaking.

Quote:

It's impossible to respond as quickly as you write...

Regarding the maximum speed, I'm actually only interested in knowing how high the RPM should be in 6th gear.
You need to read faster , it's already stated there .

Hello,
Scrape off a little of the 'soot' and rub it onto a piece of paper. If it's real soot, you'll get a 'black spot,' but if it's oily dust, you'll get a 'greasy spot' on the paper.
Best regards,
Günther.

Hi.

wutz wrote:

I think that's the wrong side for belt wear; it appears to be the gearbox side.

Sure, unless it's somehow transported there by an air current.
I'm trying to say that it could be something other than soot, and that something might be rubbing or causing friction somewhere. It could also just be oily grime; you would have to see it in person and examine it closely to know for sure.

Best regards, Rainer.

The AJM is relatively long when translated. From what I've heard, the 3,600 RPM at Vmax should be approximately correct.

Hey guys.

My AJM doesn't rev higher even with the chip disabled. According to the speedometer, it then shows approximately 195 on the dial -> however, it's a 6-speed 4Motion, so it's originally somewhat clunky .

Regards,
Best regards,
Greetings,
Cheers,
Warmly,
Sincerely,
(or simply)
Best,

Hello,

For the Golf IV AJM with a 6-speed transmission (not all-wheel drive), 3600 RPM is the absolute maximum it can reach on a straight road. Mine usually stopped at around 3400 RPM and only managed to reach 3600 RPM after a long run. According to the speedometer, 3600 RPM was just over 200 km/h. I then installed a power box from PSI, which allowed it to rev between 3800 and 3900 RPM depending on the situation, sometimes reaching 4200 RPM going downhill, but that was on a long hill.

Your dirt isn't soot either; it's just regular oily grime. Mine had the same thing in that spot.

By the way, this box is for sale because I'm switching to a Volkswagen Golf V 2.0 TDI; see also under 'For Sale.'

Hello.

I give up; it's just oily dirt and smells like motor oil.
I took another photo today from the other side after removing the cover. I found more of that substance on the head gasket.
http://home.arcor.de/juliahaase/4.jpg
Due to the maximum speed, according to the speedometer, it's just under 200 km/h at 3600 RPM (it's a Variant). So, it's normal; it just worried me. It is said that TDI engines reach their maximum speed at 4000 RPM. Since the speedometer is supposed to have a tolerance, I thought I was only going 185 km/h or so .

I have a service appointment in two weeks anyway, so I'll bring it to the attention of Volkswagen then.

AAAHHH

Are there still such unsightly cable connections on the G4?

I thought they would have installed the protective housings all the way up to the connector by now, as it's supposed to be done.