DCT top off procedure?

[Wally1552]

hey there
Searched and mostly found instructions related to flushing DCT oil. I just want to top off. I found these instructions in another thread. Can someone verify these are correct? Why can't I just unscrew fill hole and top off until oil comes out?

Connect diagnosis system and
start service functions (drive).
- Start engine (drive position N or
P)
- Record transmission temperature
using Tester
- (Drive position P)
- Permissible starting temperature
≤ 32 °C
- Idle speed: maintain at approx.
2000 rpm for 1 minute.
- Open fluid adjusting screw (1)
- Fill until fluid emerges
Max. transmission fluid
temperature 40 °C
- Insert screw

[roastbeef]

because overfill can cause foaming or incorrect fluid distribution/throw. there shouldn't be any need to "top off" anyways, and if there is, that should be addressed.

[M43S7RO]

Looks correct, keep the car level and fill while the car is running.

The procedure is in this thread, linked four posts down:

https://www.m3post.com/forums/showthread.php?t=457178

The GTS adds an extra liter with no mechanical difference so you have wiggle room on the upside.

[Wally1552]

Originally Posted by roastbeef

because overfill can cause foaming or incorrect fluid distribution/throw. there shouldn't be any need to "top off" anyways, and if there is, that should be addressed.

Previous owner had dct leak at 66K miles. Replaced bottom.and.side pan including gaskets. At 81K miles, its leaking again. Enough to coat the DCT felt cover. I was hoping to just top it off if running low vs replacing with OEM again and getting another leak 14K miles later. Also wanted to avoid upgrading to aluminum pan/steel screws and viton gaskets .

Never tracked in my ownership and DCT is smooth as butter for now.

Actually now that I'm thinking about it, I should probably check.to see if any of the pan screws and the accessible side pan screws are torque properly.

[roastbeef]

it might not be as urgent as needing to top it off. a very slow oil leak can appear to be large and fresh. i'm not saying to ignore it, but if its not leaving a drop in the driveway, skip the bandaid of trying to fill it incorrectly and just pay to maintain it and have it done right. being slightly down on fluid is less damaging than overfilling.

[GORDON.M3]

if it's slowly weeping its not an immediate problem. the mechatronics gasket can leak even after a repair after a couple thousand miles. It's a horrible design.

keep an eye on the level every few months. when the fluids get too low you'll get a transmission error light.

Like what roastbeef said, overfilling is more of a problem. Get the dct fluids serviced.

[Wally1552]

Thanks guys! I'll keep an eye on it.

[wyatth]

Hmmm... I don't think you can overfill the DCT (if done properly) since the instructions are to "fill until it comes out." Mine is weeping, so I topped it off with the GTS method until I tackle the pans.

[Theodore]

Originally Posted by Wally1552

Previous owner had dct leak at 66K miles. Replaced bottom.and.side pan including gaskets. At 81K miles, its leaking again. Enough to coat the DCT felt cover. I was hoping to just top it off if running low vs replacing with OEM again and getting another leak 14K miles later. Also wanted to avoid upgrading to aluminum pan/steel screws and viton gaskets .

Never tracked in my ownership and DCT is smooth as butter for now.

Actually now that I'm thinking about it, I should probably check.to see if any of the pan screws and the accessible side pan screws are torque properly.

The previous owner may have misdiagnosed the leak, take a close look at the Mechatronics Harness O-Ring. Pictures can be found in this DIY Thread.

[M43S7RO]

Agreed. I've filled twice from empty, adding an extra liter after it started pouring out each time. No issue.

Trying to fix the leak with oem parts is a waste of time and money, its bound to leak again. Until I'm ready to replace pans with better, proven solutions, topping off every couple years it is. So far only the slon pans fit the bill.

Originally Posted by wyatth

Hmmm... I don't think you can overfill the DCT (if done properly) since the instructions are to "fill until it comes out." Mine is weeping, so I topped it off with the GTS method until I tackle the pans.

[roastbeef]

Originally Posted by wyatth

Hmmm... I don't think you can overfill the DCT (if done properly) since the instructions are to "fill until it comes out." Mine is weeping, so I topped it off with the GTS method until I tackle the pans.

not quite that simple.

https://www.newtis.info/tisv2/a/en/f...dkg/1VnXljlF6b

[Wally1552]

Originally Posted by roastbeef

not quite that simple.

https://www.newtis.info/tisv2/a/en/f...dkg/1VnXljlF6b

Roastbeef
In step one of this procedure, it states if no fluid comes out, refill and close fill hole. I may be reading this wrong but it sounds like when doing an actual full refill is when you need to follow the temp rules and run the car. Am I wrong?

Open fluid adjusting screw (1). If fluid emerges, close screw again immediately
If no fluid emerges, top up until fluid emerges and close fluid adjusting screw (1) again

[roastbeef]

Originally Posted by Wally1552

Roastbeef
In step one of this procedure, it states if no fluid comes out, refill and close fill hole. I may be reading this wrong but it sounds like when doing an actual full refill is when you need to follow the temp rules and run the car. Am I wrong?

Open fluid adjusting screw (1). If fluid emerges, close screw again immediately
If no fluid emerges, top up until fluid emerges and close fluid adjusting screw (1) again

Topping up transmission oil after a repair:

Stand vehicle on a level surface and secure against rolling off.

1. Open fluid adjusting screw (1). If fluid emerges, close screw again immediately

If no fluid emerges, top up until fluid emerges and close fluid adjusting screw (1) again

Note: If fluid has been replenished here, a further refill must be carried out during the actual fluid adjustment

2. Connect diagnosis system and start service functions (drive).
3. Start engine (drive position N or P)
4. Record transmission temperature using the diagnosis system
5. (Drive position P)
6. Permissible starting temperature ≤ 32 °C
7. Idle speed: maintain at approx. 2000 rpm for 1 minute.
8. Open fluid adjusting screw (1)
9. Fill until oil emerges

Max. transmission oil temperature 40 °C

10. Insert screw

how is steps 1-7 unclear? you're skipping to step 8 and 9. topping off after step 1 doesn't mean you're done.

[Pig Farmer]

This is not rocket science, but BMW does a great job making it sound difficult. Let me try to simplify,,, if you crack open the fill bolt and fluid begins to drain, The transmission is within the safe zone. However, it may not be topped off. The fluid has to be added while the engine is running and the transmission is spinning (in neutral). While the transmission is spinning, the fluid level drops because it is picked up by the spinning components.

The whole warm up procedure is also a bit confusing. The temperature range for the refill is between 90 and 104 degrees Fahrenheit. The instructions tell you to warm up the transmission by running the engine at 2000 RPMs. The transmission will continue to rise in temperature when the engine is returned to idle speed. Depending on the ambient temperature, you don’t have much time (<3 minutes) to perform the refill so plan accordingly. I like to use a large funnel connected to a 1/2” hose with in-line ball valve at the end of the hose. I hang the funnel about 6’ off the ground, fill it with fluid before the warm up procedure, and use the ball valve to control the fill when ready. The fluid is not like differential fluid. It’s very thin and flows quickly. With the transmission warm and engine running, open the fill bolt, and fill until is starts to overflow. Once it starts to overflow, quickly reinstall the fill bolt and you are done.

If you want to overfill (i.e. GTS fill), perform the procedure above with the passenger side of the car raised to the point the unsprung wheels are 6-8” off the ground. This will allow you to add ~1 additional liter of fluid before it starts to spill out.

One last thing. Let the car cool overnight and don’t drive it before you perform the refill procedure. In normal driving conditions, the transmission temp is well above the refill range and takes forever to return to the ambient temperature.

[Scrippy]

IMO this topic is over thought by so many. DCT trans isn't voodoo like folks think. Get it up to the proper temp and pump fluid in until it can hold no more and close the fill plug. The only error made is not adding fluid at the proper temp or not using the proper Pentosin unicorn blood. The DCT is not an unknown technology so relax folks! Folks act like it's a flex capacitor or something.

[Wally1552]

Originally Posted by wyatth

Hmmm... I don't think you can overfill the DCT (if done properly) since the instructions are to "fill until it comes out." Mine is weeping, so I topped it off with the GTS method until I tackle the pans.

Can you or someone explain this GTS method and what's the relation to others warning overfilling is a problem? Sounds like by tilting the car you can add more fluid but seems others saying it's a risk?

Is there proven advantages to the GTS method? Does it bring down temps? I'm curious because I recently got a gts tune and I'm concerned gts tune + leaking dct =no bueno