was speaking to a guy who runs a auto gearbox repair garage today and was asking him about flushing machines. he said a gearbox flush over a simple drain and fill is pointless as the oil in the torque convertor still does not come out and that is usually 50% of the oil

anyone care to comment ? surely that cant be right

The oil in the TC gets pumped round like the rest of it... it doesn't just take root there..... Pete

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2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
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thanks for your reply , he was positive that 40% of the oil will stay trapped in the TC due to the small holes in the TC. He was rebuilding one while I was there, he said the flush would push oil through the transmission but so much is trapped in the TC the flush just passes over the holes and inlets , it made sense to me anyway.



he said the only way is to seperate the tc from the box or just perform several flushes with 100 miles inbetween, ive googled this and im seeing the same story on some other sites.

do you work on gearboxes, do you know this for sure?

You said in your first post that it doesn't come out.... well that's not true it will come out... he maybe correct on how long it takes, he may not be, I've never taken a FF one apart, god knows why they don't put a drain on it... be simple then...

You will still get more oil changed with a proper flush than just dropping the oil a few times though.... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

thanks haylands, I guess he was half right and trying to justify why they don't have a flushing machine. as you said more comes out with a flush so maybe that's some from the TC, in truth I bet some stays in the TC

when I have my flush im going to catch the old oil and as it turns good I will swap containers, the amount of old oil v total capacity is whats trapped

No sure its the same for a ZF box as my GM 5L40E. But I have just rebuilt my auto. First I drained the oil out. Got about 6 litres . Them I just let it sit for a few days with the drain plug out. Eventually got most of the oil out. Took awhile but then I had lots of time.