Recently my car has been reluctant to shift into 4th gear for the first shift of the day. It will get up to 40 mph where it would normally shift, but won't. So I have to either drop down in speed and continue driving a bit or just maintain 40 and then it will shift and it's fine for the rest of the day.

I thought this was just a freak thing when it did it for the first time when it got cold a few weeks ago but now that we've had 60 degree temps, it still does it.

1991 300d, 235k

I had this once on my W124, upon which I proceeded to do a fluid change (it was due anyway) and I dose the ATF with lubegard anyway, after that it never did it.

However upon investigating, there was a small screen in the secondary part of the valve body that could stall/gum up and prevent this - its been quite a while and I lost the MB service literature for hydraulische automatikgetriebe in the flood which claimed the car.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

According to a transmission shop, he says the lip seals are probably starting to shrink. He says to just let it warm up for 3 minutes before driving it in cold weather and “cold” even means now (February) where it’s 44 degrees out and not shifting into 4th gear on the 1st shift of the day. So just let it warm up and then drive it. He says if it starts doing it even in warm temps then you have some more serious seal problems and you might have to rebuild the transmission at that time because they have to take the whole transmission out to get to all the seals.

The transmission in my 85 has been doing this for at least the last 100K miles. Its only in cold weather, and if you drop it into neutral and allow the transmission to disengage, as soon as you move it back to D it drops into 4th.
If you let it warm up for 5 minutes or so before driving, it has no issues.

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1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

X2 on service it (drop pan install new filter, drain converter) and add Lubegard.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer