7g Gearboxes

[John042]

I've yet to start the oil change on my 7g gearbox but have had past experience of a R129 gearbox torque converter that had no drain plug. Apparently some did or didn't in my case. My present car is a 2004 500SL fitted with a 7 speed box (7g) Am I possible going to find the same problem, no torque converter drain plug? If so is it a case of draining filling from the gearbox sump pan and repeating the process as the next best option to replace as much of the oil as possible? Thanks for any replies. J C.

 

[whitenemesis]

I think you'll also need a special device to fill the 'box as it's filled from below using the drain plug..

 

[zipdip]

Well John I have always used a Indy to change the 7G gearbox oil,if your box is anything like my S320 you will need new sump bolts as well as filter and gaskets,for what the Indys charge it is not worth doing it yourself,and yes you need to fill it via the sump plug .

 

[John042]

Thanks Whitenemesis/Zipdip. Yes I realise I need the fill adaptor for the drain plug and the level tube which sits inside the sump pan. My indie although is good is not that conversant with 7g gearboxes. In fact stated that if it was working alright to leave it alone. Hence the plan to carryout the oil change myself. I guess if I'm confronted with the lack of a converter drain plug a couple of flushes through the sump pan is better than leaving it. J C.

 

[ashenfie]

I have done my old Jag S-type. The process looks to be more or less then same, but you need the exact process for your variant of the box and the correct oil for that variant.

Key points;

1) Car must be 100% level on axel stands.
2) Measure the amount that came out and use that the the basis for calculating how much to put in.
3) The oil temp must be correct (with a degree)when topping up, it's amazing how much it expands. Laser measurement tools are not ideal for this, i see a star computer is recommend. I used a meter with probe and tested the oil with the box and this worked fine.

I would change the pan/filter but not flush. The biggest risk is disturbing dirt or introducing some grit.