ATF auto transmission fluid change

Chat about your 9n Polo (inc GT and Fun)
4aceman
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Posts: 8
Joined: Mon Oct 03, 2022 7:23 pm
Drives: Polo 9n 1.4 auto BKY
Location: London

Re: ATF auto transmission fluid change

Post by 4aceman »

Sounds good, I’ll try that trick to get the filler seal off without breaking, if not I’ll see if I can seal it back up, maybe stick a hot screwdriver against the split end to hold it together.

I find in general it’s better to fill at a slightly lower temp than higher, generally the gearboxes can take a bit of extra fluid before the fluid level reaching the rotating assembly and you get any issues with cavitation and foaming.

Should get the job done this weekend and I’ll report back, maybe give some tips to people stumbling onto this thread in the future.

It probably took longer to go from 40-45 than 20-40 because you were adding cold fluid to the system.
littlepolo
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Joined: Thu Jul 21, 2011 9:47 pm

Re: ATF auto transmission fluid change

Post by littlepolo »

A quick update. 1200 miles later decided to drop ATF from the main drain plug and measured it out at approx. 2.1l. The fluid is 'reddish brown' (more brown than red) and has an odour (nowhere near as bad as the first drop). I reckon this is contamination from the residual ATF that was in the torque converter (It must be a sump for all that is nasty). I have some more Febi ATF at hand and will refresh with this and drop again after a few hundred miles to check it again.

Edit: I found that the ATF fill plug (at least the new one I put in) holds firmly and it takes a bit of effort to remove it. I've not reused the locking cap, yet.
Last edited by littlepolo on Sat Nov 26, 2022 6:55 pm, edited 1 time in total.
4aceman
New
Posts: 8
Joined: Mon Oct 03, 2022 7:23 pm
Drives: Polo 9n 1.4 auto BKY
Location: London

Re: ATF auto transmission fluid change

Post by 4aceman »

The polo started slamming gears, pretty much exhibiting the same symptoms you had. The leak from the pan didn't look too bad, but apparently it let enough fluid out over time.

Got the job done today, got 3.3 ish L out, just like you and put back in 4.2L. I didn't set the level with the procedure since I couldn't be bothered but I used your guidelines and put in just over 4L.

Shifts are back to normal now, there wasn't any excessive wear in the gearbox but the fluid was dark and didn't smell great. Pan magnet had a typical amount of fine metal particles around it, nothing out of the ordinary for 100k miles of wear.

Unfortunately, me being stupid, forgot the whole "wait 24hrs for sealant to dry" thing and filled it up after probably 20-30 minutes. I degreased the mating surfaces very well and the sealant dries quite quick so hopefully it holds and I won't be doing this job again soon.

Filling the gearbox up was very easy. I had to loosen and put aside a wiring bracket attached to the gearbox, then stuffed my funnel in a hose which fit perfectly into the fill port. Reused the sealing clip and the fill plug. In hindsight a jubilee clip clamped around the sealing clip would hold more securely, but mine still latched in place.


Thanks for the help and information
littlepolo
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Joined: Thu Jul 21, 2011 9:47 pm

Re: ATF auto transmission fluid change

Post by littlepolo »

Ah, that is good to hear. I'll post updates when I next drop and refill after several hundred miles. Will also drop and inspect sometime next year as a gauge for condition of the transmission. It's very easy to do via the main drain plug and easy to fill with the right funnel.
littlepolo
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Posts: 778
Joined: Thu Jul 21, 2011 9:47 pm

Re: ATF auto transmission fluid change

Post by littlepolo »

Just a quick update. A few weeks ago I dropped about 1.5l of ATF from the lower drain plug. I was more brownish red than reddish brown and with a bit of an odour. I'm wondering if the residual old fluid in the torque converter might have flushed through in the 1700-ish miles covered since my previous post. The vehicle drives well and I'm achieving better than over mpg - 47.5mpg on a recent (mainly highway) run of 375 miles.
littlepolo
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Joined: Thu Jul 21, 2011 9:47 pm

Re: ATF auto transmission fluid change

Post by littlepolo »

Just a quick update on mpg. 48.25 highway.
littlepolo
Gold Member
Posts: 778
Joined: Thu Jul 21, 2011 9:47 pm

Re: ATF auto transmission fluid change

Post by littlepolo »

latest mpg 49.49 over 341 miles on supermarket dishwater and an ethanol countermeasure. not bad for an old one.
littlepolo
Gold Member
Posts: 778
Joined: Thu Jul 21, 2011 9:47 pm

Re: ATF auto transmission fluid change

Post by littlepolo »

39 mpg during recent v cold weather with local driving only
44 mpg mixed driving 70/30 motorway/local just recorded
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