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Old 12-27-2006, 12:51 AM
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Transmission Oddity (In Gear, While Sitting Stationary)

I'll give you all the basics. Tonight, I decided to go visit some family members and take the 300D since it had not been driven since the 23rd. It was a little chilly out, in the 40's, if not already down in the 30's. I had just driven about 12 miles on the freeway cruising around 65mph and I was sitting at a red light. While sitting, I felt it "hunker down" like it does when you shift into drive. I found that odd because I was not touching the shift knob. So, I shifted into neutral, and back into drive to make sure everything was operating properly, and it shifted back with like half a second of hesistation from the usual amount of time it takes. I drove back home without incident, and the shifts came in properly, but I found tonight's incident odd. I always make sure the transmission fluid level is at the proper level, checking it after a 20 mile drive and on level ground. It had a filter change and refill with Mobil 1 ATF in March, about 10K mi ago. What would be the cause of it jumping like that?

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.
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Old 12-27-2006, 09:38 AM
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We can only guess.

It sounds like you had a delayed downshift of some sort while sitting still. And when shifting to neutral and back into drive.

This is possibly a slow valve body piston action, and this can happen with a varnish/gunk buildup in the transmission. The cold weather may have had some impact too, but not too likely after 12 miles of driving. But I have definitely had "cold weather" issues with regular ATF after 5 miles of driving.

I strongly recommend Mobile 1 ATF in these era transmissions. It is great for cleaning out the transmission as well as maintaining the same viscosity over a wide temperature range. Sure it is expensive, but how about that expense compared to a transmission overhaul or replacement?

Ken300D
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Old 12-27-2006, 10:59 PM
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Quote:
Originally Posted by Ken300D View Post
We can only guess.

It sounds like you had a delayed downshift of some sort while sitting still. And when shifting to neutral and back into drive.

This is possibly a slow valve body piston action, and this can happen with a varnish/gunk buildup in the transmission. The cold weather may have had some impact too, but not too likely after 12 miles of driving. But I have definitely had "cold weather" issues with regular ATF after 5 miles of driving.

I strongly recommend Mobile 1 ATF in these era transmissions. It is great for cleaning out the transmission as well as maintaining the same viscosity over a wide temperature range. Sure it is expensive, but how about that expense compared to a transmission overhaul or replacement?

Ken300D
I already use Mobil 1 ATF, had it put in with a new filter 10K mi ago. It happened again today. I was driving to work and I was sitting still in a turn lane so I could make my turn. I took my foot off the brake and then, "thump!" It did the little movement associated with a shift. So I drive the half block to the parking lot, and decide to shift into neutral and back into drive. I counted how long it took me to get back into drive from neutral, one second... two... three..., so I decide to give it a little acceleration. I press the pedal, it engages and jumps forward so I hit the brakes. I got out and removed the dipstick and smelled the fluid. There was no burnt smell and it was just as red as the day it flowed out of the bottle. The rest of the day, the transmission operated seamlessly.
Funny thing is that it happened after about 12 miles of freeway driving, just like last night's situation. The only difference was the ambient temperature was higher, it was in the 50's. I'll see if it happens tommorow. If it does, I plan to siphon out a quart of ATF and replace it with a can of Trans-X and drive on that for 1K mi, hoping that'll help. After that, I'll have a fluid and filter change done.
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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.
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  #4  
Old 12-27-2006, 11:29 PM
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You're feeling the delay in dropping down from second to first.

The '86 does this every so often. Usually, when I just crack the throttle, it drops down into 1st.

Cannot tell you why it does this "occassionally". You might wish to put a touch more slack in the Bowden cable and see if it has any effect.
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Old 12-27-2006, 11:46 PM
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Trouble is, the bowden cable adjustment nut is broken. It won't adjust it at all, it's snapped off from the shaft. I have a new cable on the way in, but it's funny it would do that now when I've never adjusted it since I've had the car.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.
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