Very odd transmission issues - PeachParts Mercedes-Benz Forum

Johnhef · #1 06-20-2005, 11:22 PM

Some of you have been following the thread on the 83 300SD I recently got off of ebay.

I'm reposting a few questions here from that thread. I bought it with pulling the trans in mind upon arrival, but if it can be avoided, I'd like to fix it while its still in the car.

1) When I got the car last saturday, the trans was way overfilled. 2 inches or so over the high mark when hot
2) The car wont move forward untill about 1500 rpm, and then its jerky
3) reverse is almost non existant, it will move only about 40% of the time and again, it jerks
4) in park, it will sometimes still attempt to move forward
5) in reverse (with lights on) it will sometimes attempt to move forwad as well.

Anyways, if anyone has any thoughts, or ideas to try out, let me know, I need to get this car driveable as soon as possible.

thanks!

blueranger · #2 06-20-2005, 11:33 PM

here is a little test for you...

disconnect the vacuum hose going to the trans... its at the top
of the fuel pump.... leave the one dangling from the tranny and put
a plug in the other one... (no vac to the tranny is the goal.) start it up
and drive it around the block and see what happens....

if the thing drives and shifts right away then the problem is in the vac system...

usually when you have a reverse problem it means you need to rebuild the trans...

Johnhef · #3 06-20-2005, 11:57 PM

Well, its strange, its the only one I have that I cant tell when its goes in gear- theres no clunk, so I kinda have to guess. I will have to try thought though, I hadnt thought of that being the problem.

The vacuum system is all screwed up. I dont think the white 3 way valves are even there under the cover on top of the valve cover. Huge vacuum leak inside the car too from the acc, it hisses loudly.

rs899 · #4 06-21-2005, 06:55 AM

My guess is that its either in the front pump/torque converter or in the valving. You might try taking off a transmission radiator hose and seeing what's going on with the fluid when the car is trying to move. If you have an extra good valve body lying around you might be able to swap that in and see what happens.

Just as a pont of reference my W116 wouldn't even make any attempt to move in any gear. Turned out to be a ruined front pump

Johnhef · #5 06-21-2005, 07:10 AM

I've got a trans that slipped out of an 85 TD. That should work for the VB, right?

rs899 · #6 06-21-2005, 11:36 AM

You are getting out of my league. I know the 85s have some very different characteristics than the earlier ones. I don't know how different the valve bodies are. If you've got the time, it may work. I don't THINK you can hurt anything. Just compare the two valve bodies before you slap them in there and make sure they look similar as far as bolting and input/outputs.

Isn't there anybody else out there who has at least an opinion?

C32AMG · #7 06-21-2005, 08:20 PM

[

Quote:

QUOTE]The car wont move forward untill about 1500 rpm, and then its jerky
3) reverse is almost non existant, it will move only about 40% of the time and again, it jerks
4) in park, it will sometimes still attempt to move forward
5) in reverse (with lights on) it will sometimes attempt to move forwad

You have an internal mechanical problem, broken planetary gears or a set of clutches fuse together. Can you push the car with the engine off and in any gear?

blueranger · #8 06-21-2005, 08:51 PM

this guy is probably right you probably have internal problems but
go at this in a systematic way....

1. eliminate vacuum becasue 90% if problems are vacuum..

you probably have a combination of problems...

rs899 · #9 06-21-2005, 10:10 PM

The problem, whatever it is , will be obvious once you pull the tranny and get it on the bench.

I say it's not vacuum. You can try the valve body if you feel like wasting an hour. Beyond that , the fix is pretty academic because it will be out of there.

Johnhef · #10 06-21-2005, 10:15 PM

I'm going to try a few things out on it tomorrow, at least plug off the climate vac leak and straighten out the mess the previous owner left me with the engine vacuum system.

In park with the car facing downward on a hill it doesnt always want to catch in park and will "pop" as the car rolls forward a little after each pop. Of course that could just be missing shifter bushings, but I just need to get some time to go out there and start trying things. time is very limited around here. I am aiming to have this thing driveable by the end of next month.

I'm just not to motivated to have to pull the trans here, I have yet to do just a trans alone (usually pull engine with trans) here at home, as I do not have a lift here. I'll be paying harbor freight a visit to pick up a tranny jack soon as well since I'll most likely be doing this in the driveway since I've got two other projects disabled in my garage

blueranger · #11 06-21-2005, 10:20 PM

an electrician when troubleshooting a circut always checks the breaker first then the switch then the blub before he starts tearing out the wall...

you should do the same thing....

1. change the fluid and fliter...you would be surprised what symptoms a 20 year old cloged filter will cause...

2. disconnect the vac from the trans... (the vac reduces to cause shift quality) so with no vac it should shift...

3. pull the tranny and have it rebuilt..

kiwi_bloke · #12 06-21-2005, 10:24 PM

i agree, filter and fluid first.

I had a 230e 1989 that was flaring between gears. That service fixed it right up

rs899 · #13 06-21-2005, 10:28 PM

Hmmm. Check that linkage carefully. I am wondering if the selector shaft in the valve body isn't going where it should.

You might consider forgetting Harbor Freight. The tranny jack is way too high. You will have to dump the tranny off the jack and then somehow lift it on there to get it back in- if you have enough clearance. Gravity will help you remove it. I've heard its good to drop it on a set of nested cardboard boxes and then just collapse them (sounds good to me). After you tud that thing out of there and consider the height of the jack, I don't think you will want one. I plan on putting mine back in with 2 trolley jacks

blueranger · #14 06-21-2005, 10:34 PM

exactly, i have a 87 300e that does not go into reverse or drive for a long
period and i found that if i wiggled the shifter it worked... so i thought my problem was internal but it turned out to be the shifter... so amend my list to
examine shifter as #3 then remove tranny as #4

83 300sd
87 300e
94 300te

rs899 · #15 06-21-2005, 10:41 PM

could also possibly be the INTERNAL mechanical linkage is somehow messed up. You can see this with the pan off.

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