Haven't had a chance to fully check things but I figured it was worth checking with people that have more experience than me. So, when I got my 128i 2 years ago the clutch was slipping. Had just rolled 60,000 miles, seemed like it could have worn out by then. So, a year ago, I did a full clutch replacement. The old clutch looked suspiciously okay but I swapped it all. And sure enough, the clutch still slipped. The oil pan gasket was leaking so I thought the oil getting in the bellhousing was contaminating the clutch. So, this month I did the clutch again, along with the oil pan gasket. A real pain. And... it still slips. I haven't been able to get it back on a lift yet but I'm looking for thoughts on the culprit. Did I install something incorrectly on both clutch jobs? Can improper torque specs cause a clutch to slip? Torquing the pressure plate and flywheel with the dual mass flywheel is a pain but I think they are close to spec. Bad slave cylinder? I'm hoping I can just bleed the slave and its solved but bleeding it shouldn't cause it to have less pressure on the throwout bearing, right? Any thoughts are appreciated.
And for a more interesting whodunit, when I dropped the oil pan I found this in the bottom.
I have my suspicions. There are some bolts in the head that are known to be overtorqued on the N52 and its possible thats the source. The pieces appear to have gone through something to get deformed like that. Anyone got a guess where it came from? Could it have caused more damage? Should I be concerned. I drove the car 20,000 miles before I found it and have driven it since without any obvious problems. Should I be pulling the valve cover, etc and trying to find the source?
Anyway, without a lift available for a day or two, trying to get it off my mind for a bit.
That looks suspiciously like the head/flange from these:
"N52 Aluminum Cylider Head Bolt Set"
On the clutch still slipping:
"When the clutch is released the piston in the master cylinder should move back far enough to uncover the port to the reservoir so that no pressure would build up, the fluid would just go back into the reservoir. If pressure is getting locked in the line the piston is not retracting far enough because the master cylinder/pedal is not adjusted properly.
Have you still got the clutch delay valve fitted? Be worth getting rid of."
Did you replace your flywheel when you replaced your previous clutch? Do you still have a clutch delay valve in place or has it been removed?
Did you change the dual mass flywheel when you did any of the clutch changes?
Is there any rattling noise coming from the bellhousing area at idle?
I am just wondering if the dual mass flywheel is the cause of your slipping. There is not much you can mess up when installing the clutch other than having the flywheel oily, etc.
Also, is this like the e46/e92 M3 clutches where you have to release a spring loaded part out of the flywheel?
In reply to Olemiss540 :
Those are the bolts I mentioned. The one thats visible below the intake manifold it still there but I have to remove the valve cover to check the others. That's what I expect it is.
Hm, I'll have to look into the master cylinder. I was under the impression that there wasn't a way to adjust the clutch pedal. I haven't removed the clutch delay valve. Could try that too.
In reply to Slippery :
I did replace the flywheel the first time. I do have a rattle that seemed to start after I replaced it... I have the original flywheel. I really don't want to replace that again...
It does have the "throwing star" or "ninja star" that you remove after torquing the pressure plate.
In reply to white_averson :
The only thing I can think of is the fork being bent, I really doubt it but I usually swap them out when I change the clutch as it is cheap. Did you by any chance inspect the input shaft guide tube for ridges not letting the fork retract all the way?
If you swapped the flywheel, even if you have a slight noise now, I would think one of them could be bad but not a new one ... I have been wrong before though.
The upside to all this is that you will get really good at removing that transmission lol.
I replaced the fork both times. And the guide tube seemed fine. I inspected and cleaned it both times. I do want to check if the fork has at least a little play when I can get the car on a lift.
It is a new, or now a year old, Luk flywheel which should be OE? I hope its fine but I've had a vibration at idle that new engine mounts didn't fix.
I don't know if anyone can get good at removing that transmission lol. I'm leaning towards something in the hydraulic or clutch release system but I guess the only real next step is closely inspecting all those parts. And that might just be wishful thinking lol
I am not convinced on the hydraulic system having anything to do with this as all it does is release the clamping force of the pressure plate when applied. If you cut the hose from the master to the slave and jump start the car in second, it would hold all day long.
Now if you told me you could not change gears, that would lead me to the hydraulic system.
I guess there is no harm in bleeding and looking it over making sure the slave is properly installed and not pushing onto the fork, but my attn would be elsewhere.
In reply to Slippery :
I guess I'm thinking the slave somehow overextended and is slightly releasing the clutch. It took significant effort to push the slave cylinder in far enough to get the nuts on to install. Its wishful thinking but I want to believe thats what it is.
I would 100% remove the E36 M3ty CDV and re-bleed the system before dropping the tranny.....
The debris in the oil pan does look like the bolt head from the aluminum cylinder head bolts. The good news is the rest of the bolt normally backs out with very little effort. The bad news is the vanos cam gears need to be removed to access all of them. This will give you a chance to check the bolts on back of the vanos gears as they can break the bolt heads as well, the non tamperproof bolts are the updated design.
The clutch disc can be installed backwards & prevent the clutch from fully seating. Most discs will say getriebe on the side that faces the transmission.
In reply to Caperix :
Yeah, thats how I understood it. Its ready for the valve cover gasket too. Just not excited to do it.
I'm pretty certain I installed the clutch the right direction. It stresses me out enough everytime that I double checked.
white_averson said:
In reply to Caperix :
Yeah, thats how I understood it. Its ready for the valve cover gasket too. Just not excited to do it.
I'm pretty certain I installed the clutch the right direction. It stresses me out enough everytime that I double checked.
Valve cover gaskets easy cheese. The top of the motor is a fun little project, bottom side or tranny, not so much :-)
I would put money on the hydraulic system not letting it fully engage.
Well, I fiddled with it the last two nights. Pulled the slave out and confirmed the fork has a half inch of free movement so there's no mechanical pressure on the pressure plate. Tried crack the bleeder to release potential residual pressure. That did nothing. Deleted the CDV and bled the clutch. The feel is better but it still slips. Losing confidence that the issue is hydraulic. Try a new slave? Its frustrating because I can't think of a way to confidently diagnose the culprit. The next would be the flywheel? The one half rotated quite a bit torquing the pressure plate but thats normal? Not excited to drop the trans again
white_averson said:
Well, I fiddled with it the last two nights. Pulled the slave out and confirmed the fork has a half inch of free movement so there's no mechanical pressure on the pressure plate. Tried crack the bleeder to release potential residual pressure. That did nothing. Deleted the CDV and bled the clutch. The feel is better but it still slips. Losing confidence that the issue is hydraulic. Try a new slave? Its frustrating because I can't think of a way to confidently diagnose the culprit. The next would be the flywheel? The one half rotated quite a bit torquing the pressure plate but thats normal? Not excited to drop the trans again
Dont drop the tranny without posting threads on other BMW specific forums/boards. Narrow the thread to only the clutch related problem. I sure wouldnt drop the tranny again until ruling out the master/slave as a culprit completely.
Any info on when/how it slips would be helpful and how quickly after your last 2 replacements it started slipping.
It slipped immediately after both replacements. And was slipping before I replaced it the first time, though I wasn't paying attention to how it slipped at that time.
It slips when I'm in "too high" a gear and step on it. Think passing on the highway. If I drive it like I'm trying to get in trouble, it won't slip and if I baby it, it doesn't slip.
I'll make a thread on 1addicts and see what they say.
Also add bimmerforums, e90post, etc. Just copy/paste it to 3 or 4 sites.
I hate to say this, but I see you dropping that transmission again. Its not a hydraulic issue.
What clutch flywheel/disc/pressure plate did you buy? OEM?
What throws me off is that I cant see three different pp/disc/flywheel being bad.
In reply to Slippery :
OE I guess. All Luk branded. But the flywheel was only replaced the first time
Slippery said:
I hate to say this, but I see you dropping that transmission again. Its not hydraulic.
What clutch flywheel/disc/pressure plate did you buy? OEM?
What throws me off is that I cant see three different pp/disc/flywheel being bad.
This^
Back in the 90's I had an 1986 Toyota pickup, SR5 4x4. Clutch finally wore out at about 120K. Put in a parts store replacement that lasted all of 2K miles. Took it back and got a replacement, 1500 - 2K miles later, same result, shredded clutch disk and burnt pressure plate surface. Took the last one to a local clutch rebuilder. Turns out the parts store replacements were actually Corolla SR5 clutch and pressure plate assemblies labeled as Truck parts and packaged in the Truck box. Outwardly the parts appeared identical, but the pressure plate springs and clamping surface were much beefier and the clutch disk was thicker for the trucks. The rebuilder identified the problem right away, as he had seen quite a few come through his shop. This could be something similiar. Not "bad" parts, just incorrectly spec'd for the application.
In reply to white_averson :
Also the feeling is a shuddering, like its rapidly catching and slipping, that almost maintains revs when it does slip
