rivera2j

I have an SL500 (R230) with major transmission issues. Last year, the car went into limp mode for 5 minutes. The problem went away on its own but came back over a month ago. Here are my sequence of events:

Took out the TCU (Conductor Plate) and sent it Bulgaria for repairs. The TCU came back, installed it and limp mode went away. But a new issue came after replacing the TCU. The car started slipping only in sport mode but not in Confort mode. So I thought the oil tube was damaged or missing. I dropped valve body and installed new oil tube and put it back together. This time the problem went from bad to worse. The transmission started slipping no matter was setting the car was on, Sport or Comfort. I contacted a local shop (not the dealer) and they advised to rebuilt the trani since it was slipping so much. They are charging me $2700 (HI. price) to redbuilt the trany, (that's me taking the old one out and putting the new one in). So I am ordering a used transmission from a salvage yard for $900. I am going to use my (rebuilt) conductor plate in this transmission but not sure on the process to change the oil on the torque convert. Has anyone out there replaced the transmission with one from a junk yard? If so, would you mind sharing your ideas, experience and recommendations on how to proceed? Do I really need to remove the exhaust system to drop transmission down?

At this point, this is the most cost effective way. Otherwise, I would have definitely gone with a remanufactured one.

Thanks in advance.

Welwynnick

Changing the transmission is a lot of work but straightforward. You need a way to support and lift the tranny up and down, and then get it in and out of your car.

What facilities do you have? Will you have any help? Have you done anything like this before?

You probably don't have to remove the exhaust system, but it will make access easier.

You fill the torque converter by alternately starting the engine and filling the transmission a bit at a time.

Nick

rivera2j

Hi Nick,

I am doing this at home in my garage. So the car is not lifted high enough like a lift but it is on jack stands. (Enough to get in/out and remove transmission). I've taken a transmission down 3 series BMWs over 20 years ago. Based on your comments, the TC should have a drain plug. If it makes it easier to work exhaust system out, I most likely we'll do that. At least one side. I have adequate tools, air compresor, oil filler and even an SDS C4. (waiting on Solid State Drive (SSD) to come back from China). The SSD stopped working and I had to sent it for replacement/repair.

Thanks again. Will post pictures and comments when done.

mbwolf

Hi rivera2j
Your post does not tell how many miles you got on the refurbished conductor plate but I am concerned that you do not have full diagnosed the root cause of your problem. If the tranny only slipped in sport mode and not in comfort mode does this mean it slipped only in the first gear and than later it slipped in second and third later?. Can it be that you are dealing with leaking or damaged valves in the conductor plate? Maybe there is somebody out there with detailed knowledge to make sure that you do not change the tranny and just transfered your problem with this refurbished conductor plate.
In regards to the draining of the TC I hope your new tranny has a drainplug in the TC!! In case there is no drain plug I would like to suggest to do a flush/refill after you have installed the new tranny . I made up a little elbow which connects to the return line and allows to drain the oil in a milk jug. A little 12 volt gear pump (ebay) is pumping fresh oil into the pan. After flushing and reconnecting the return line a reverse switch on my pump allows me to adjust the oil level @ 45 degrees C by sucking excess oil out of the pan.

rivera2j

The car currently has 65K miles. When I changed the Conductor Plate (CP), the tranny only slipped in sport mode. I only put roughly 200 miles on the tranny after the rebuilt CP. When I took the VB down, the 2nd time, to replace the Oil Tube, the oil and the filter looked like it had never been replaced. When I in fact, I had just replaced the oil (6 lts) and filter 200 miles/3 weeks before. That's when I started having problem slipping in the lower gears, more like what you mentioned, 1st, 2nd and 3rd; at hwy speed the car ran fine.

mbwolf

If you only changed 6 liters the first time you left about 1/3 of the old fluid in the system which might have contributed to the color change.
I can not explain slipping but it seems that your first symptoms started with contaminated old fluid. If all your other symptoms started with rebuilding the conductor plate the conductor plate might be contributing to the issues. Slipping can also be caused by low fluid level or low flow. I assume that you adjusted the level according to WIS.
I just do not believe ( just a gut feeling ) that the 722.9 is slipping without major mechanical damage and symptoms in higher gears. 1st and 2nd are transmitting the highest torque. If there are flow resrictions (dirt) in the little screen of the conductor plate valves there might be not enough oil flow during hight torque situations. If you did not do a proper flush the first time there is the chance that you got a lot of old fluid and maybe particles into the valves screen again. Since you are planning to move the Conductor plate anyway maybe you want to inspect the screens before you buy a replacement tranny.
Just food for thought.
Wolf

rivera2j

I welcome all your comments and recommendations. I did add the oil according to WIS. I also inspected the solenoids filters and they looked fine (clear) both times, I alos checked the ohms and they were within range. Like you mentioned. Adding only 6 liters, that's only one 2/3 of the oil. I do have one question about the oil. What color should the oil be? The initial oil I used was RED. Pentosin ATF 1. I also bought a quart from O'Reilly's but this one was more like the color of a synthetic engine oil. Even though it was ATV1 LV. Since I already purchased the used tranny, (still in transit to Hawaii), and I haven't taken the tranny off the car yet. I may have to wait for the SSD to arrive and connect the SDS and do a full test.

Welwynnick

Simplest question last - do you have a dipstick?

You know what I'm going to say next.

Nick

rivera2j

Nope! Not sure what you are going to say next. LOL

Welwynnick

Sorry, I keep forgetting these transmissions don't have a dipstick - I think you fill them from underneath until they overflow. Nonetheless, its really important to get the fluid level right, and its an exacting procedure. The transmission must be at the right temperature, car level, engine running, etc. I read the procedure somewhere, but its not to hand. Try to find the procedure first, and get the fluid level right before doing anything else.

Nick

rivera2j

That's correct. They temp has to be somewhere around 40 C. (Don't quote me on that). I have the specs at home.