My Spousal-Component(wife) drove the Benz today (rare occurrence)and noticed a nasty, metalic grinding when shifted into Reverse and the same when shifted into Drive and then back to Park. I couldn't duplicate when I got home this evening, of course. I checked the fluid and it was low by about a pint. Could this have been the cause of the noise?

The transmission shifted normally for me before and after topping off the fluid.

Any thoughts?

Thanks ahead of time!

Greetings Panzer,

Did your spousal-component mention if the sound seemed to be coming from under her backside or the tranny, or more so from the rear differential? Grinding would be coming from the rear differential if something is amiss, low 80-90 weight lube perhaps. The low tranny fluid situation should either cause the shift in most cases from first to second gear to somewhat flare before shifting, hence not enough fluid for the high start off load of the tranny. An overfill condition will cause the same problems as well. A longer hesatation when putting it into gear from park also indicates a low fluid situation. I'd check for leaks if the tranny fluid was low, and correct that problem as well.

Charles

Was the car fully stopped when it was shifted into park ?
William Rogers......

Can-do:
I'll check the diff level and look for leaks this weekend. Haven't been able to duplicate the problem. Also, she didn't indicate where the noise originated.

William:
The car was stopped when it happened.

Thanks for the input!

OK, It did it for me this afternoon! It isn't the diff. It is definetly coming from the transmission area. I started the car and it was whining when in park. When shifted to either R from P or N or from R to either P or N it made a metallic clunk, not quite grinding. When in either P or N it made a whinning sound. When I shut it down the whining sound dropped off like something free-wheeling(the torque converter?) to a stop.

Anyone have any suggestions? Thanks ahead of time!

Greetings Panzer,

Let's take another approach to your problem. Jack up the front end at set some jack stands under each side for safety of course. Besides, you're gonna need to get access to the bell housing underneath. At the bell housing there's a 8" inch or better slot cut into the bottom of the housing for access to the torque converter for draining the fluid. I'd start by inspecting this area for maybe a tree limb, twig or anything else that might have gotten run over and caught up in the housing and making contact with the torque converter while it was running. If it's whining it is also possible that you lost fuid flow to the torque converter, or the finned internally have broken loose. You can check the fluid in the torque converter for contamination first. There is a metric allen plug on the torque converter. Need two people for this job because the plug is small and you want someone topside manually using a socket or wrench to line the plug up to the bottom access area so you can remove it. I used a wrench on the power steering pulley bolt to turn the engine in most cases, easier to reach than the crank bolt. I think I'd drain the fluid from the converter and look for broken metal chips that may give you a better indication and confirm that it's the torque converter gone bad. I've seen some American cars loose their welds in the converter and it sounded like a turbine winding down when they shut off the engine. Check the fluid first and we'll go from there.

Charles

Checked the Torque converter. No twigs or such in there. Drained the fluid and no metal chunks. I did find that the Drain plug/filler/dipstick connection was leaking quite a bit. Replaced the washers and filled everything back up. I'll have to see if that takes care of it or not. I'll be checking the trans fluid level more often and just keep an eye on things.

Thanks for the help, I'll keep you posted on how things go!

Ok, it's been awhile since I last broached this subject! The trans made the noise again for my wife. I'm wondering if it could be pump failure or what. Also, can anyone tell me what if any harm is being done? There are no noises after it engages in gear other than a slight whine.

Thanks,
Rich

Sounds like a rev clutch problem.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks Steve. I looked at the first post again and i forgot to mention that it grinds going into Drive also. This is hard to figure out since it only happens every couple of months and then after it's shut done it goes away.

Thanks again
Rich

Unfortunately there is no way for an automatic to grind engaging gears (at least in theory). The reason for this is that the gears are not engaged and disengaged as are standard trannies. They are always engaged.

The point to reverse clutches is that they engage the case with large spline/dogs. I forget the actual mechanism but when the clutches wear out somehow there is enough play for the dogs to disengage the slots in the case. They jump a few slots and then re-engage. This sounds like gears grinding. It can take place even when you aren't in reverse (although it usually only happens in reverse).

Hope I'm wrong!

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Hope your wrong too! :-)

Well the saga continues! While my daughter was driving (with me along,learners permit) the trans was slipping a little. This was pulling from a stop or at slow speed (10-15mph). I got behind the wheel and everything seemed fine, of course. The car had the modulator and linkage adjusted about a year ago from a shop that specializes in MB. I have the receipt from the previous owner but haven't called the shop yet about the problem.

There was no noise associated with this occurance. The Shifting noise is accompanied by a whine which sounds like it is associated with the torque converter. The whine winds down when the engine is shut off.

What would a transmission overhaul cost, or do I want to know?

Thanks,
Rich

If I were to be right the pan would be full of rev clutch material. It will clog the filter and cause a whining of the front pump.

You should have the pan pulled for observation. Hard to say how much a rebuild would cost. I think MB rebuilds are about $1800 plus installation etc. We do them for about 1500 total.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks Steve. I'll take a look at it after i get back and have the chance. What am I hurting if I continue to use the car? Also, should I see clutch material in the fluid if I drain it?

Thanks again for the help!

Rich