Hey guys, I have an odd tranny leak. Dont have a pic at the moment but it looks like its leaking from the bottom of the seam where the bellhousing part of the case bolts to the second part of the tranny. Only other thing I can think of is the input shaft seal but I would think the fluid would run down and out where the holes are where the trans bolts to the engine. Has anyone had a tranny leak similar to this?
Weird trans fluid leak
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nightkrawler
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does the cap have a hole in it or something to let pressure out?
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Just going by other vents but the cap could be there to protect a small filter of some sort. Not all vents have filters though, they are usually porous foam. The cap will be bigger than the tube and where it inserts into the tube be fins likely so that air can pass freely. Once you get the cap out you might want to check and see if there is something else hidden in the tube. Welcome back to E39 world.
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I knew I should have taken a picture of that thing when I pulled mine out for inspection at one point. Anyway, if I remember correctly, it’s nothing more than a plastic piece that’s a little smaller in diameter than the transmission hole. It has a bell type of cap as depicted in Sailor’s picture that protects anything from going in the transmission. As far as your leak goes, I don’t think this is causing your problem. If your leak happens while the car is just sitting in the garage and not on, I can’t see how anything would leak upwards then out of this vent cap? I’ve thought the very same thing at one point. I still think your problem is related to the casing.
John
I agree. From the way I understand it, the vent is used to relieve pressure on the seals while the transmission is moving. So, if it's clogged, it could potentially force a leak. In my case, I saw no obstruction and I actually put a screwdriver down the hole just to make sure. I'm going to try and poke around my car this weekend and I will try and pull that cap and take a picture just so you all can see that there is not much to it. I also have one of those video scopes and will try and shoot some video of the area.
John
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im outside right now installing a set of rogue tranny mounts. i lowered the tranny and was able to get my hand up there and check the cap. the cap just spins around idk what secures it in place. i tried to pop it off but it didn't want to move and i did not want to break it.
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update, i have finally been able to pinpoint where the leak is coming from but all my attempts to fix it to date have failed. its leaking from the hole where the dowel pin is on the drivers side of the tranny. i tried jb weld, indian head schellac, i even heated it up and filled the hole with pulmber's solder. it doesn't make any sense as there is really is no pressure in the gearbox so any of these fixes should have held. im done messing around, this weekend im taking it up to my friends shop to have him tig weld the hole closed!
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nightkrawler,
Did you manage to fix your leak? I had to disassemble the transmission in order to fix jammed cruise control pin that got my tranny stuck on 3rd gear. I installed everything back last night and found the same leak this morning. I haven't started the car,so there is no pressure in tranny. I'm considering loosing the bolts and torquing them back in a crossed pattern, just being more precise in the right torque wich by TIS I found it to be 22Nm
I'm curious to know what did you endup doing.
Thank you!
Ves
Did you manage to fix your leak? I had to disassemble the transmission in order to fix jammed cruise control pin that got my tranny stuck on 3rd gear. I installed everything back last night and found the same leak this morning. I haven't started the car,so there is no pressure in tranny. I'm considering loosing the bolts and torquing them back in a crossed pattern, just being more precise in the right torque wich by TIS I found it to be 22Nm
I'm curious to know what did you endup doing.
Thank you!
Ves
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no not yet, im going to have my friend weld tig weld the hole. it doesn't make any sense as there isn't really much if any pressure inside the gearbox, idk why that spot wont stop leaking. if i had the trans apart i would have knocked out that dowel pin and put a nut and bolt through the hole with a crush washer on both sides. you had the trans apart, is there any way the pin could possibly be knocked through with the trans already bolted together?
You need to punch out the dowels in order not to stress the housing while taking it apart. So yes, you can punch them out with the trans in the car. There is one more on the top part.
My guessing so far is that getrag didn't use any gasket in order to escape gasket failure since tranny is designed to be not serviceable. To manage that the surfaces needs to be extremely smooth and when assembling it in the factory would be used specific sequence and applied torque.
I'm curious why yours, if it haven't been dissembled, developed a leak.
In my case I may have scratched it or just haven't manage to torqued it properly which I will check tomorrow
My guessing so far is that getrag didn't use any gasket in order to escape gasket failure since tranny is designed to be not serviceable. To manage that the surfaces needs to be extremely smooth and when assembling it in the factory would be used specific sequence and applied torque.
I'm curious why yours, if it haven't been dissembled, developed a leak.
In my case I may have scratched it or just haven't manage to torqued it properly which I will check tomorrow
Ves, thats the detent for the main selector shaft, right? I hear they fail under hard use - is that why yours failed? What mileage on the tranny?
Did you have to take the tranny apart because pieces had fallen inside?
Yes it is on the main selector shaft, BMW calls it locking pin, #8 on the diagram bellow:
RealOEM.com  BMW E39 M5 S6S420G INNER GEAR SHIFTING PARTS
I attached a picture of my old broken pin next to the new one
And here is some more pictures of it
Home Page > ES#43749 LOCKING PIN - 23317501584
I had a problem with the cruise control and had changed the spring that goes inside that locking pin and presses it against the selector shaft. I was unable to pull out the locking pin then and didn't want to mess with it anymore. That fixed the cruise control problem but after about 2 months I started having difficult time taking it out of gear occasionally. Last week it just got stuck in 3rd gear. The top part that of the locking pin that touches the selector shaft had broken into 4 pieces(attached picture below) and the roller that is on top of the locking pin got jammed between the selector shaft and trans housing. Two of the pieces had fallen into the transmission and had been collected by the big round magnet that sits at the bottom which apparently works well, and two other pieces, the roller and a small pin had jammed in the housing.
I have 156000 miles on the car, so can not tell if its due to driving style or mileage. I do drive spirited but do not abuse the car. I drive manual transmission since 17 years old and I am 34 now.
Anyway I would definitely recommend changing that pin as a preventive maintenance since it is inexpensive and not difficult to do and saves you from taking the transmission apart if it fails!
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Good advice. Thanks.
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great! so you did this with the tranny in the car. was the pin hard to knock out? i was worried that if this is indeed possible the pin might be in there really tight and worried about cracking that flange area knocking it out. which way does the pin have to be knocked out, toward the front or the back? ie can it only come out one way?
Yes, did it with the tranny in the car. It is not difficult if you get it right. Make sure you keep the punch or whatever you use straight in the hole,so you don't get it to dig into the housings two parts. I used an exhaust bolt instead of a dedicated punch, it fitted with some play into the hole. I was keeping a rag between the bolt/punch and tranny so I don't damage the housing while hitting on it and worked my way with a short 4-5lb hammer. The pins can go either way but you will be limited by space and angle to keep the punch straight. I did the front housing pin towards the rear of the car and the rear pin towards the front of the car. For the rear pin I had to disassemble the metal bar that holds the exhaust to the tranny. Make sure you use WD40
P.S. I'm happy to contribute to this great forum!
Ves
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knocked out the pins last night. fyi if you take a propane/map gas torch and heat the area up a bit they tap out quite easily. now my next question, what did you do about the front pin hole as the forward side of hole is not flat so a nut or bolt head doesn't sit flush against the case. i ground down the bolt head at an angle to try and get it to sit right.
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