So today's mission was to check the fluid level in my ZF 6HP26...
As far as I know, it still has the factory fluid in there. The transmission has been performing pretty well for the (nearly) five years I've had the car and although I've been wanting to do a full fluid replacement on it, the war-stories I read from people performing fluid changes on high-mileage transmissions have me holding off. Mine is now at 235,000km.
Anywho, lately the transmission has been feeling a bit off when cold. Ok on the flat but if you load it on a hill when cold, it feeels like it might be slipping a bit and it vibrates a little. Sounds like low fluid pressure or level. It's fine once it's warmed up , so I figured it was worth the time and cost to do a quick level check. I intend to complete the full fluid/filter/pan gasket/jump seals/bridge seal/mechatronic sleeve service soon but I don't have the time for this right now - or the funds! I just
know that the seals will be old, hard and not sealing propery....
There's aren't any real fluid leaks but there is a thin film of fluid residue around the pan gasket and around the mechatronic sleeve - not enought to be a worry on a 15 year old vehicle - yet.
Once the car was up on ramps and level, my process was: -
1. Removed transmission shield (the 3.0d has a large plastic shield over the transmission) - 10x 8mm screws.
2. Cracked open fluid fill port on the pan - this is a BIG plug with a 17mm hex and it was TIGHT! I had to use a short breaker bar to get this sucker open. It let go with a loud crack!. Either it has NEVER been opened or the dealer over-tightened it when I asked them to check the fluid level four years ago. Which ever is the case, I'm not impressed....
I nipped it back up before any fluid escaped.
3. Hooked up INPA and started car. Used INPA to monitor trans fluid temp.
4. Waited until fluid temp was up to 25Deg.C. and removed fill port plug. No fluid came out (as expected).
5. Pumped about 500ml of fresh ZF Lifeguard 6 fluid into the port, and at about this point, fluid started to run from port.
6. As the fluid temp came up, the fluid flow rate from the fill port was a fine steady stream. At a fluid temp of 35Deg.C the fluid stream slowed to a drip.
7. As the fluid temp increased beyond 35Deg.C the fluid drip from the port did not increase in rate, so at this point I closed it up and called it good. I was tempted to let it run up to 40Deg.C as per the ZF process but the drip rate was slowing so I figure the level was pretty good now.
8. Stopped the engine. Torqued the fill port to the correct 80Nm (~60ft.lbs) and put the trans shield back on.
9. Compared fluid volume added with fluid volume recovered during level check. 500ml - 300ml = 200ml added in total. Old fluid was quite dark and but it was not "gritty" or contained any visible particles when held up to the light (or dripped onto white paper).
10. Test drive. Went for a 35km drive and wasn't expecting any difference. Maybe it was a plecebo effect or maybe I'm dreaming but wow - was the tansmission now smoother when cold. It shifts beautifully...
How can 200ml make such a difference...? The obvious answer is.. it can't. No way. But whatever the reason, my ZF 6HP26 is currently pretty happy.
So am I...
(For comparrison, my wifes's Mazda trans fluid check is one-step - pull the dip stick and look!
).