Shifting = impossible when tranny is hot. What gives?

[Itsablurr]

Changed fluid with Royal Purple last year, 20k miles on the changed fluid.

Went away and parked the car for a month at my folks place for safekeeping. Car shifted fairly smoothly before the trip (1st would hang up only once in a very great while). Upon my return, gears 1, 2, and 3 require significant force to jam into gear when the tranny gets hot. Reverse is even more difficult. The car was not driven, except for being backed out of the garage once while I was gone... so no abuse there.

When the gear selection is difficult, it usually helps to press the clutch back in again, then move the selector into position.


What could be causing these issues to suddenly crop up like this?


**Edit- problem solved, post #29

[thejlevie]

When the transmission is hot and difficult to shift, is it also difficult to shift into those gears with the engine off? If it isn't hard to shift with the engine off it might be that the clutch isn't fully disengaging.

[Itsablurr]

When the transmission is hot and difficult to shift, is it also difficult to shift into those gears with the engine off? If it isn't hard to shift with the engine off it might be that the clutch isn't fully disengaging.

I didn't think to try that.... will certainly do when I get back from the current 3wk bsns trip abroad.


Fwiw..... car has 90k miles, stock everything on the tranny/drivetrain.

[sbblowz]

my guess is to try bleeding the clutch.

[savage217]

my guess is to try bleeding the clutch.

+1

[Hova]

bleed the clutch +2

[Ron97M3]

Where does clutch disengage at? It shouldn't take a full press to near the floor.
The clutch shouldn't require bleeding for no reason, If clutch does only disengages near floor it might be the clutch slave or even the clutch master is leaking. Bleeding is perhaps worth a try but it's likely a symptom of a system leak due to a bad clutch slave?

If the clutch disengages at the proper point then I would try changing the transmission fluid, that's easy and cheap. I have used valvoline synthetic ATF for 32,000 and 5 years now without any troubles. I have 112,000 on my M3.

Make sure and let us know with a final post on this thread as to what the problem actually turns out to be.

[NeilM]

it might be the clutch slave or even the clutch master is leaking.

I'm with Ron. The OP reports that a second pump on the clutch pedal helps, so to me that says either a failing slave or master cylinder, or else air in the clutch hydraulic circuit. I'd try bleeding the clutch line first simply because that's free, but be prepared to replace one or the other cylinder.

Oh, and do make sure that the brake fluid level is fine, since the clutch circuit shares that.

Neil

[Ron97M3]

Neil -- what do you think of the ONLY when HOT part?
What would heat have to do with causing a hard to shift trans? Air in hydraulics shouldn't get worse with heat should it?

The heat factor is part of why I am thinking maybe it's the transmission fluid.
The fact he didn't mention needing to pump the clutch or press to the floor to disengage makes me also suspect something else besides hydraulics too.

[M3do]

I had the same problem.

I tried bleeding first and it didn't help.
Second I changed slave clutch and no difference.
Finally, changed master clutch and it worked like charm.

[Ron97M3]

I had the same problem.
I tried bleeding first and it didn't help.
Second I changed slave clutch and no difference.
Finally, changed master clutch and it worked like charm.

Good you posted here!

Heat was required for it to act up?

How did you bleed the master clutch cylinder?
I have read that can be difficult.

[m0digital]

Could check your clutch line as well. Over time the rubber line could bubble and crack. When hot the line would just expand with pressure instead of releasing the clutch.

[M3do]

Yes, when it got really hot it was very difficult to do reverse, 1st and 2nd gear. At cooler temp it was easier to shift but still a problem.

It was somewhat frustrating taking the old master off due to lack of space, but if you are good with ur hands it shouldn't be hard

[Balthazarr]

Any air is going to expand when hot much faster than the fluid.
So pedal travel is going to be greater to achieve the same displacement of the clutch and possibly the clutch won't disengage fully at the point you're used to, so you have to press further.

My theory, thank you.

Also, without use, seals have a tendency to shrink and that COULD be the reason fluid might leak around them requiring extra effort to shift.

[m0digital]

I noticed that you are using RP. I tried RP for a year and it was great initially but quickly deteriorated. Mine definitely didn't last till 20k. Was smooth at first then ridiculously notchy and hard to get in gear. I've since switched to Redline MTL and feels much better now. Not saying this is the cause but may be a small factor.

[Balthazarr]

I noticed that you are using RP. I tried RP for a year and it was great initially but quickly deteriorated. Mine definitely didn't last till 20k. Was smooth at first then ridiculously notchy and hard to get in gear. I've since switched to Redline MTL and feels much better now. Not saying this is the cause but may be a small factor.

How many miles on RL?
I ran D4ATF for a while and had notchiness, which is why I switched to RP SMax.
Lasted longer than RL, but is a little notchy, now.

[SmellyGreek]

I noticed that you are using RP. I tried RP for a year and it was great initially but quickly deteriorated. Mine definitely didn't last till 20k. Was smooth at first then ridiculously notchy and hard to get in gear. I've since switched to Redline MTL and feels much better now. Not saying this is the cause but may be a small factor.

I was in the same boat and now my MTL is notchy.

OP -- I have the exact same problem.

[Ron97M3]

How many miles on RL?
I ran D4ATF for a while and had notchiness, which is why I switched to RP SMax. Lasted longer than RL, but is a little notchy, now.

I have had valvoline from 80,000 to 112,000 (32,000) for 5 years and no issues.

If he does change the ATF and the transmission then gets better we will know it's the trans and/or the fluid. If he uses Valvoline like me he should have the same good results with no additives needed.

[TH3 Shifty]

question....


is it that you cant get the shifter into the gear? .. if so.. i would suspect a syncro issue..

if its that you CAN shift but the clutch is not engaging/disengaging.. then i suspect clutch or clutch line issue...

[jonb94118]

I am having the same problem - when hot, it is VERY hard to get into gear from a stop and is notchy - I first changed the tranny fluid - RP was like water by the way when I changed it and it was only in there for a few track days and limited street miles. I went back to MTL and seems a little better, but I think there still may be air in the hydraulics which I am currently trying to bleed. The clutch does not slip and when speaking with a BMW shop, they indicated that it is likely hydraulics and recommended pressure bleeding from the slave - pushing fluid up. It seems there are many methods and opinions for best way to accomplish...

[Itsablurr]

Thank you for the tips and opinions, guys.

First order of business when I return from my trip will be to do a fluid check/change/bleed, then eyeballing the clutch master cylinder.

Will update thread.

[Ron97M3]

If it was hydralics the problem would be reduced or go away by pumping the clutch at least for a little while. Problem would likely be there worst when the car was cold and not hot. If it's air in the hydralics that means something is leaking/failed ... so the game won't be over with just bleeding.

If you change the fluid and the problem totally goes away then you will know either the fluid was not good. Bad fluid would be VERY bad press for RP, hard to believe? If the problem gets better then one would think transmission has an internal wear problem. If there is no change either the transmission is really sick or it isn't the transmission at all .... off to look else where ... bleed the system? Possibly a clutch issue somehow?

[Itsablurr]

When the transmission is hot and difficult to shift, is it also difficult to shift into those gears with the engine off? If it isn't hard to shift with the engine off it might be that the clutch isn't fully disengaging.

Ok....



Just got back from the business trip this morning, took the car out, got it hot, gears were jamming up like crazy, and tested if it makes a difference when the engine is not running. The verdict is that the problem with engaging gears is completely gone when car is not running.

[bennyfizzle]

Slave, brah. Remove, inspect, bench bleed, inspect, reinstall or replace.

[Itsablurr]

Slave, brah. Remove, inspect, bench bleed, inspect, reinstall or replace.

I'll take a look at it this evening... whats the best way to access the slave?


I also observed that, with e-brake off, foot off brake, clutch fully pressed in, and engine running.... the car would start to creep forward/backwards a bit as I moved the shifter into 1st gear/reverse... definitely sealing the deal that clutch disengagement is the root of the issue.

[bennyfizzle]

From under the car, it's on the drivers side of the tranny. two bolts and the hydraulic line, I pressure bled it on the car and it was fine, but there's a tool you can get to make bench bleeding really easy. do not under any circumstance press the clutch pedal when the slave is not full installed, the piston will shoot right out of it in dramatic fashion.

[LuxoM3]

Ahem... what shifter is in your car?

By any chance is it a B&M shifter? Or an aftermarket China deal?
Why do I ask?

http://3werks.com/bmw/images/BnM%20shifter%20for%20BMW.jpg

The B&M has a HORRIBLE reputation for seizing up with it gets hot. I'm not sure what it is BUT... since the CATS are so near the tranny tunnel, my guess is the shifter ball collar soaks up the heat and expands. And thus expanding... it seizes up around the ball so you can't shift.

Easy to check... undo the leather shifter cover... if it's a funky blue or red aluminum collar there's your answer.

How do I know this? Ask me why I have a UUC SSK with DSSR. :)

[Itsablurr]

^ nope, everything in my clutch/trans is as it was from when it rolled off the assembly line, with exception to a fluid change.




Anyway, got under the car and under the dash last night....

No outward signs of leaking/shaft play/anything on either the master or the slave. Time to just throw $ at parts and hope for a result? :dunno



Q: If the slave fails, can it be leaking fluid into the inside of the bellhousing?

[Itsablurr]

Okay.....


Issue is finally solved. It was a 2-part problem, difficult to diagnose visually, but in the end makes sense if you think about it.

-Slave cylinder was replaced since there was a film of fluid on the underside area of the transmission, around the bellhousing are. Problem still persisted.

-Upon further inspection while a friend was pressing the clutch, it was observed that the soft clutch hose section had tiny pinhole leak that was only apparent under pressure. A teeny bubble of fluid appeared to seep out. Definitely not the ultimate root cause of the problems, but it certainly wasn't helping anything.

-This left the master cylinder as the remaining culprit. Under pressure, it seems the internal seals were failing and allowing fluid to escape back up into the reservoir, depressurizing the system with no apparent significant loss of fluid onto the ground over time.

Replaced the master cyl, and the soft line with Turner braided stainless, and it feels better than new.

[savage217]

:redspot

[lanxevolution]

Im actually having the same issue. I just recently replaced the slave cylinder and nothing. I recently attempted to change the clutch, but when the a bolt stripped I decided to put everything back together and take it to a shop. After putting everything back together my gears started going in smoothly. Which was very weird to me. Maybe I should just try replacing the master as well as the lines.

[Hova]

:redspot