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#1
12-01-2004, 03:43 PM
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1982 300sd transmission
I have scheduled a trip to the mechanic tomorrow, but need to know what to ask him to look for.
First - I have a clunking sound when car is in park and engine running. Have looked at many posts on this site. Possibilities in similar situations - flex discs, center driveshaft bearing, transmission mount, or exhaust system banging due to broken exhaust mount. What are flex discs? They are discussed in many of the posts but no technical information is given. Second - clunking with each downshift. Possibilities have been said to be the T fitting to the modulator gets a clogged orifice and needs cleaning - i.e. it is a vacuum problem - not enough vacuum during downshift. Thank you very much for your feedback. I want to ask educated questions. 
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#2
12-01-2004, 04:21 PM
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Quote:
One flex disc on either side of the drive shaft connects it to transmission in front and differential at rear. They are made of rubber and cushion the torque for a smoother acceleration/shift. Exactly when in the shifting process does the clunking occur? Shifting out of park to reverse also? On hard shifts only?...
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-Marty 1986 300E 220,000 miles+ transmission impossible (Now waiting under a bridge in order to become one) Reading your M103 duty cycle: http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13 http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14 Last edited by A264172; 12-01-2004 at 04:40 PM.
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#3
12-01-2004, 05:07 PM
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I presume you are going to pay to have this checked out. If so your problem is in finding someone with experience on that model and MB in particular. Find an indendent that has been in business for more than ten years with more than half the cars in the parking lot Mercedes. Describe the problem, get them to drive with you if they don't see it.
Adjusting that transmission is not for beginners, especially if you are paying.
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Steve Brotherton Continental Imports Gainesville FL Bosch Master, ASE Master, L1 33 years MB technician
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#4
12-03-2004, 07:55 AM
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when clunking occurs
The clunking specifically occurs at downshift. It occurs in each downshift.
There is also a clunking when I put the car in park and it has a gradual shake from side to side or a rocking. When this is going on I hear a clunk, clunk, clunk, coming from the rear of the car until I turn the engine off. It does not do this at a stoplight with the car in drive - only when car is running and in park.
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#5
12-04-2004, 09:22 AM
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Quote:
It does not seem as though this should happen in park, which I think is just neutral (i.e. transmission not engaged) with the parking tooth engaged. It may be possible that shifter bushings are shot allowing it to slip into reverse a little, but that does not cover your downshifting problem as far as I know. I am definitely no pro. Best to do what stevebfl says and let someone specifically familiar with MB's diagnose this as it would be worth the fee to prevent $$ being thrown in the wrong direction. In the mean time, avoid downshifting. Good luck
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-Marty 1986 300E 220,000 miles+ transmission impossible (Now waiting under a bridge in order to become one) Reading your M103 duty cycle: http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13 http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14
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#6
12-04-2004, 10:12 AM
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Umm, with a rock 'n roll engine and a clunking while in Park, I'd like to suggest that you check the motor mounts, particularly the rear mount at the transmission. The engine/transmission might be moving around enough for hard surfaces to contact.
At idle in gear, torque reaction could move transmission away from contact, so no noise. The torque reaction of downshift might the move the trans enough to produce the noise. By all means check the flex disks too, but you mentioned the noise occurs in Park. I wouldn't think that the flex disk would make noise unless the car is moving and the driveshaft is rotating. This is all based on what you've said. Please update us on what you found out. Best Regards, Jim Last edited by Jim H; 12-04-2004 at 10:18 AM.
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