Polo 6N: ESP Gearbox - 3rd/4th Gear Shift Problem

Hi!
"My Polo has been giving me trouble since yesterday. After driving about 400 km on the highway at a higher speed, I tried to shift from 5th to 4th gear, but it wouldn't go in. The gear lever wouldn't engage in the 4th gear position. Neither would 3rd gear. I managed to get it into 2nd gear after braking, and then the other gears worked again."
Today was the same. I couldn't get it into 3rd gear. Neither could I get it into 4th. I then braked all the way down to a standstill with the clutch depressed, repeatedly trying to get it into 3rd or 4th. No luck. Then, while stationary, I briefly released and then pressed the clutch again, and everything worked perfectly.
What could be the reason for this? If it were only one gear, I would suspect a synchronizer ring. But two gears at the same time?!

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

"Further:"
- No grinding or scraping when shifting gears quickly.
-So far, only problems with downshifting, never with upshifting.
-also started today even when cold.
- appears and disappears seemingly randomly.
- Front mechanism operates smoothly.
- TAF-X was added over 100,000 kilometers ago.
-The entire transmission housing is completely dry on the outside.
- no unusual noises.


Do you have any ideas?
Thank you!

Sure, here's the translation:

"Small addition:"

Habe heute die Schaltzüge nochmal neu eingestellt und den Getriebeölstand kontrolliert. AEverything's okay.
However, I caught a few drops of the oil in a glass, and under sunlight, I could clearly see metallic particles (looking like brass). Is this normal after 100,000 km, or is it another indication of a defect?


Dirk.

I was just thinking that it might be a clue related to your synchronization rings...

Hi!

Can synchronous rings sometimes work and sometimes not? I have a complete old synchronous body here in front of me, but I can't explain it.

Dirk.

With 6-speed transmissions, it's not uncommon for them to occasionally malfunction, but this is often temperature-dependent and can be resolved by using a different type of oil.

"Noise in the oil is a bad sign, and in relation to your problem, it strongly suggests the synchronizer rings. Whether it's constant or only happens sometimes..."

However, it's unlikely that anyone can answer your question with 100% certainty.

Since the other gears work, it's not the clutch. And since you've adjusted the cables and the 1st and 5th gears are working, it's also not the cables. That leaves the synchronizer rings. I think the wear in the oil can only be caused by the synchronizer rings.

If you're installing new synchronizer rings, I'd also like to investigate what might be causing the problem. 100,000 km is quite low mileage for that to happen...

Quote:

After driving for about 400 kilometers on a fast highway, I wanted to shift from 5th to 4th gear, but it wouldn't go. The gear lever wouldn't go into the 4th gear position.

It's possible that something is not quite right with the 5th gear engagement or shifting mechanism, which might be preventing the other gears from engaging properly within the transmission. Try making sure you fully disengage the 5th gear when shifting, so that the shift lever moves all the way to the rear stop.

A small amount of brass shavings is normal for a used speedometer.

Even if the connections seem loose to you...

Please spray some WD-40 or a similar product into the mechanism where the ropes are attached.

After a spring engine flush, the problem simply disappeared for me and another forum member. Your issue, where the gears wouldn't engage, was completely resolved. In both cases, the dealer would have diagnosed a new transmission or synchronizer rings, with a hefty price tag. However, the intermittent problem was solved by greasing the connection mechanism.

Good luck, and don't forget a little bit of bearing grease and penetrating oil.

Hi!
Thanks for the tip, but unfortunately it didn't help me:-( I made sure to highlight everything again, but there's no difference...

Let's consider something completely different: Could a similar or even identical symptom also occur with a defective (worn) clutch? In other words, is it possible that it's not slipping, but still exhibiting a similar problem?

Best regards,
Dirk.

Try running it with a leaner air-fuel mixture. If that works, then the synchronizing rings are probably worn out.

Okay, a brief conclusion. So, over the course of another approximately 3,000 km, shifting became increasingly difficult. In the end, all gears (except reverse ) were affected by significant shifting problems. I then decided to replace the transmission. Now it's running smoothly again. By the way, the clutch was only about half worn at 137,000 km – I expected more! Nevertheless, we replaced everything.
Since I have to return the old gearbox completely empty, I took a closer look at the drained oil. If someone unfamiliar had seen it, they would have undoubtedly thought it was a metallic paint. It's incredible... although the noise during driving didn't seem to have changed. I would have expected the gearbox bearings to fail more quickly under the stress, especially since it was mostly driven on the highway.
Okay, thank you again to everyone who helped me. Unfortunately, I can't say exactly what broke inside the transmission, as it's an automatic transmission component. It's a shame; I would have been interested to know...


See you later.
Dirk.