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  #1  
Old 08-28-2003, 11:00 PM
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Join Date: Nov 2000
Location: St. Petersburg, FL
Posts: 200
87 300SDL Tranny Woes

To all,

I had this going on another thread, but I had it suggested to me by a sage forum member to start a new thread. Bottom line is that, last week I was driving to Costco and everything was fine. Coming back, the transmission refused to shift into 3rd or 4th gear. I was driving along I-270 at 40mph at 4000 RPM. Not good. Pulled over and checked the fluid. It was a little low and I topped it off, but no joy.
I spent a fair amount of time chasing down vacuum leaks and adjusting the bowden cable, to no avail. Based on advice in the other thread, I capped off the offending vacuum lines (to the EGR and air recirc valve), disconnected the kickdown switch to see if that was causing the problem, and finally put some Trans-X in it since it seemed I was heading to rebuild time. Minimal effect.
My questions -

1) Vacuum - When I hook the Mity-Vac up in the lines, the vacuum will go up to 15, but it goes up pretty slowly. Quite a bit slower than if I stick the 'T' right at the vacuum pump. Should the vacuum increase go fast up to 15 and the slowness indicate something else going on?
2) Do I need to unplug the kickback solenoid on the transmission to completely disengage the kickback circuit? I unplugged the switch under the foot pedal, but don't know if that's sufficient.

Any other ideas welcome since I haven't found the detailed tuning information on this transmission like we have for the 82 model. Thanks for any help!

- Ted

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1987 300SDL 265,000 mi.
1982 300SD 325,000 mi. (and holding)
1956 Packard Clipper 150,000 mi.
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  #2  
Old 09-08-2003, 09:43 PM
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Join Date: Nov 2000
Location: St. Petersburg, FL
Posts: 200
I thought I'd give an update here on the transmission. I put the Trans-X in the transmission and thought that things were marginally better. I ended up letting the car sit for 5-6 days, and the car seemed to shift much better for the first few miles, then back to what it was before.

I decided to pull the pan off and replace fluid/filter before doing anything else. The PO had told me he had kept things up to snuff, so I hadn't changed this as soon as I bought. The cold winter temps helped me to decide that, too.

Anyway, the fluid was ugly and there was a lot of dust in there. I'm not sure if it was something the Trans-X helped with or not, but it was there on the bottom of the pan. Cleaned the pan, put new fluid in and the car shifted fine. I couldn't get the torque converter done since I was by myself and got tired of trying to turn the engine over to get the bolt in place.

I'm going to do another fluid/filter change, along with the torque converter, this weekend. I hope this will keep me from putting in a rebuild. (He says, with fingers and toes crossed...)

- Ted
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1987 300SDL 265,000 mi.
1982 300SD 325,000 mi. (and holding)
1956 Packard Clipper 150,000 mi.
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  #3  
Old 09-10-2003, 12:34 AM
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Join Date: Jan 2003
Location: USA
Posts: 699
Dear tstarr:

Your PO must be a good liar. He told you he had kept things up to snuff so that you bought his car, and that serves his purpose well I believe.

Well try to drain the torque converter and the AT pan again and put in new Dexron III in it.

Good Luck,

Eric
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  #4  
Old 09-10-2003, 09:15 AM
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Join Date: Nov 2000
Location: St. Petersburg, FL
Posts: 200
Eric,

The good news on the car is that if this is the worst that happens, I still got a great deal. The car was actually priced assuming a transmission rebuild, since it was shifting really hard (a problem fixed with a few inches of vacuum hose). The ironic thing is that I would normally just do this right away, along with changing hoses, etc., but I bought the car in January, it was about 20 degrees outside, and I did not have access to the garage for the work.

The torque converter drain and new filter/fluid is on this weekend's agenda. So far, so good...

- Ted
__________________
1987 300SDL 265,000 mi.
1982 300SD 325,000 mi. (and holding)
1956 Packard Clipper 150,000 mi.
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  #5  
Old 09-10-2003, 09:35 AM
Registered Diesel Burner
 
Join Date: Aug 2001
Location: Northern Virginia
Posts: 2,911
You may want to consider using a synthetic ATF this time around. It did wonders for my 1982 300D that was experiencing a 3-4 shifting problem when cold. Since changing to synthetic the problem cleared immediately. I think the synth has better cleaning properties and is probably a little slicker and flows better, especially at cold temperatures.

The only thing I could find locally was Quaker State 4x4 Synthetic, which seems to be good. I understand Mobile has a synthetic ATF but I have not found it around here yet.

To me, not shifting properly could easily be a dirt / varnish / crud buildup in the valve body that a good fluid can help clean out.

Transmission fluid change maintenance seems to be very critical for the vintage MBs.

Also, what I do for the torque convertor drain is turn the engine (clockwise only viewed from the front) enough to get close, and then use a large screwdriver to gently coax the drain into position. Almost impossible to get it into position by just turning over the engine.

Ken300D
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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles
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  #6  
Old 09-10-2003, 09:39 AM
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Join Date: Nov 2000
Location: St. Petersburg, FL
Posts: 200
I'm actually using Amsoil ATF right now, although I should have thought it through more, since it's pretty expensive for running in the transmission for just a few weeks. Mobil-1 ATF is available here lots of places, so I'll probably switch to that in all my cars. I'm a bit surprised, but in a good way, that the problem could be resolved with a simple fluid/filter change. But that's OK by me!

And I have a new appreciation for all of my cars with maintaining more regular transmission service. The last time my wife took the minivan in, they did a transmission "flush". I'm going to be dropping the pan on that one and replacing the filter/fluid as well.

- Ted

__________________
1987 300SDL 265,000 mi.
1982 300SD 325,000 mi. (and holding)
1956 Packard Clipper 150,000 mi.
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