Hard 1-2 shift on 94 E420 and more

[AtlBenz]

Well first off, I always thought that these cars started off in 2nd. I guess not because I count 3 shifts (1-2, 2-3, 3-4) which lead me to believe its starting in 1st.

Anyway, it’s weird; the 1-2 shifts are unnaturally hard. The rest are nice and smooth. I guess I don’t really know how to explain it. It’s not a “knock” like a bad flex disk or something, just a strong, uncomfortable jolt forward, surely this isn’t normal. Any ideas on what I can do?

While I have you, what’s up with tranny flushes? What are they supposed to do? Do they "fix" anything by washing everything out? Like are detergents used or something? Is this something that’s good to have done and if so can any reputable shop do it (ie. its not a Dealer-Only procedure)?

Last tranny question I promise. Sometimes the 2-3 shifts are very fast. By that I mean, the car is in 2nd for only…well… a second! I don’t know if this behavior is okay or not, but its something I noticed that seems kinda weird to me.

[Gary Ganaway]

on my 95 E420 the first couple of shifts are like you describe but generally when car is "cold". After it warms up shifts are smoother. I believe this is normal from what I have read on past posts.

[skiier3_9]

Atlbenz: how many miles on the car? In any case i'd replace the tranmission fluid/filter (i don't like the flush, just change like your motor oil) and see if it changes the situation.

[AtlBenz]

about 150k-ish. is it easy to change the tranny filter? how many quarts of oil will I need to replace as I assume the entire tranny will be drained? So flushing the system isnt generally a usefull procedure. ....just an oil and filter change. okay-dokay

[zeronero]

Originally Posted by AtlBenz

Anyway, it’s weird; the 1-2 shifts are unnaturally hard. The rest are nice and smooth.

My 400E used to do the exact same as your car, and since they have the same drivetrain it's probably due to the same reason.

The quality of the shifts are controled by a vaccum modulator on the transmission. There is an adjustment on it that can improve the quality of the shifts and make it shift much softer. When I adjusted mine it solved the problem and it now shifts like butter.

Do a search on a transmission shift modulator, or of something like that and you will find several posts on it.

[skiier3_9]

I would check out the vacuum lines ^^ as stated above, but also drain the torque converter and transmission pan. The filter/gasket kit shouldn't be more than about $30 from Fastlane and includes the gasket, filter, and any other seals necessary. When I did my 94 e320 trans fluid/filter (trans 722.369) it took about 6.5 - 7 quarts (I used Mobile 1 synthetic)

[zeronero]

Originally Posted by skiier3_9

drain the torque converter

Unfortunately on the V8 models the exhaust pipe goes right underneath the access point to get to the torque converter making removal of that section required.

[skiier3_9]

seriously?? wow...that kinda sucks...

I've heard of people using a topsider to remove tranny fluid, if you could get 6-7 quarts out (or 90+% of the overall capacity) I suppose that would be an option. Then you wouldn't need to remove that section of exhaust (big PIA i'm sure)

[zeronero]

I have a topsider, but only change my engine oil with it. I was going to try the transmission but I've heard it doesn't work as smoothly.

I changed my transmission fluid recently, and though I only did the pan, the fluid was like new. Since it was in such good condition after 30k miles I don't think it's worth the effort to get to the torque converter drain plug. But if the fluid looked horrible then I might try it.

[AtlBenz]

I wouldnt even know where to start when it comes to changing the filter and gaskets in the tranny. I bet its not too hard, but since i've never done it before, I suppose I'm in for a treat. So is there a drain plug for the tranny like there is for the oil pan? what exactly do I remove to get to the filters?

[skiier3_9]

there is a drain plug in the transmission pan and then you have to take the pan off to get to the filter. There are about 6 or 8 bolts that you'll need to remove to get the pan off. This is the messiest part because theres usually some leftover fluid in the pan (even if you've drained it). The filter is then visible and just pulls out of place. Replace the filter and pan gasket, then bolt the pan up (to the correct torque so that you don't bend the pan causing a leak). If the fluid hasn't been changed in awhile (or ever) its probably a good idea to do the torque converter since thats where most of the fluid is. You'll get 2-3 quarts out of the transmission pan and 4-5 out of the TC.

[deanyel]

Forget all this talk about changing the fluid and adjust the vacuum modulator as someone suggested about five posts ago - takes about five minutes and will eliminate the problem.

[JMaxwell]

I agree with deanyel, sounds just like the symptoms I had when I needed a vacuum modulator change/adjustment.

Also, I have used a topsider to drain the transmission fluid after I stripped the allen head drain on the pan and couldnt get the drain out. Figured I would try the topsider route cause i didn't want to bathe in tranny fluid. It works really well, and if I remember correctly I got 5 or 6 quarts out that way (I still drained the TC too). But in your situation, using the topsider might be the most reasonable option.

John

[AtlBenz]

BTW my other 94 E420 has got a leaky gasket/seal at the B2 piston (I think thats what its called), is changing that straight forward and doesnt require removing any pans?

[skiier3_9]

Originally Posted by deanyel

Forget all this talk about changing the fluid and adjust the vacuum modulator as someone suggested about five posts ago - takes about five minutes and will eliminate the problem.

While I agree that adjusting the cauum modulator will likely fix his issue, it is a good idea to change the transmission fluid if you want your transmission to last. You don't have to do it, I'm just suggesting it.