Gearshift problem

[ollie]

After an extended period of not using my 250SL,  I have trouble getting gears to engage.  This is a four speed manual,  and I can easily shift gears with the motor not running.  The clutch engages smoothly with normal resistance.  As soon as I start up the motor,  I am unable to get the gear to engage.  There is resistance and a scraping noise when I do try to select a gear.  Interestingly I can engage and use the reverse gear?!
I regularly started the engine while the vehicle was in storage,  and let it run to warm up.

Any ideas,  before I load it up to take to my local stealership?

Thanks
Ollie[]

[Naj ✝︎]

Hello, Ollie,

Welcome to the site  

The gear shifter bushes may be worn giving too much play when you try to engage gear.

Have a look at the bushes on the front of the shifter shaft under the tunnel.

There is an inspection cover on the front of the tunnel under the carpet in the cabin.

Also have a look in the wiki:

http://www.sl113.org/wiki/pmwiki.php?n=ManualGear.Start

Shifter Maintenance is way down under the gearbox title. Its not been indexed yet as it is still work in progress.

Hope this helps.

naj

[david patten]

I had this problem on my 230sl and cured it by slightly adjusting the length of the piston on the slave cylinder.Be careful not to adjust too much as you don't want the bearing to be in constant contact with the clutch. You must have some clearance between the piston and the clutch lever.
david patten.

[jeffc280sl]

Sounds like your okay linkage wise if you can fully engage the gears while the engine is off.  You problem seams to occur when things start spinning. You may want to have a look at the fluid level and/or change the transmission fluid.  Could be a lubrication problem with the synchros.  They can get a little sticky on the gear and may not want to spin into place.  

Here is a picture of a synchro.  The synchro helps gears mate. They are cone shaped and supposed to spin freely until you shift the cone shaped gear into place.

Download Attachment: sticky synchro.jpg
77.92 KB

[graphic66]

Sounds like clutch trouble to me. Try starting it in gear with the clutch in. You may just need to bleed the clutch. The best way is a power bleeder. Easy to build http://www.bmw-m.net/TechProc/bleeder.htm  I use mine all the time, it makes changing your brake fluid a very easy one person job. Or just run a hose from the front brake caliper bleeder to the clutch slave cylinder bleeder and use the brake as a pressure bleeder. An earlier posting on this someone said you could also bleed it by pushing the slave cylinder manually in to push the fluid back up to the master. If someone finds that method please repost it. That sounded very easy. I have never had luck just bleeding one without pressure from a power bleeder. You may also have a bad clutch master cylinder or a bad slave cylinder. First of course top off you master cylinder with brake fluid and try it. Also, I believe if you change your transmission oil, these cars use ATF, not gear oil in the tranny. Don't go by my guess though

[jeffc280sl]

Now that I read your email more closely I agree with graphic66.  If the car is not moving and the clutch pedal is depressed the transmission gears will not be spinning.  It appears the gears are spinning because os a clutch issue.

[pagoden]

Ollie - I wonder if your clutch disc became stuck to either the flywheel or clutch friction faces.  This can happen with extended storage --usually in humidity, freezing humidity especially-- and your maintenance regime in storage wouldn't affect the clutch assembly.  This scenario seems to me to explain your situation ---UNTIL I get to the reverse gear quirk; that one baffles me completely.

And even if I am right, you'll still need to rely on wiser heads to tell you how to unstick it (short of dropping the tranny for access to the clutch assembly --for its dis-assembly).

My experience with such things is with other marques.  I am still building familiarity with the way our lovelies work and so am cautious about improvising, especially on someone else's significant other.  However, the direction in which my thinking goes has me wondering what would happen if you set all the brakes firmly, put the tranny in gear (4th is probably safest as well as stoutest), RELEASED the clutch by fully depressing the clutch pedal, then "bumped" the starter a time or two by turning the ignition key to start position: quickly on/off.  This would never pop loose a clutch disc firmly squeezed between flywheel and pressure plate, but freed from that constraint it might very well.
 
This sort of thing gets into the "...please don't try this at home." area, so I ask that you let this idea season in the light of day for a bit and see what the Wiser Heads may have to say before you let me get you into trouble, yes?

I do wish you well with your circumstance and will be watching with interest.  Let us all know how it goes.

Denny

[ollie]

Denny,  you are THE MAN!!
worked like a charm,  in fact,  I was waiting for a awful crunch/crack/grind,  but all that happened was a slight shudder,  lasted about 1 second.  All seems well.  Took the car for a nice 50km run,  and all seems as nomal.

THANKS, THANKS

Ollie

[HJ]

Worked like a charm.
Thank You