300SD Shifting and Climate Control Issues - PeachParts Mercedes-Benz Forum

Rocketrider · #1 10-07-2008, 11:12 AM

I'm having an issue with my 82 300SD and now it's time to consult with the Grand Poobas! I bought the car with 152K miles and a bad tranny for $450. I just happened to have a parts car of same model with a bad engine and good tranny. The car had been sitting for almost two years, with very little history before that. I replaced the tranny and now that I'm driving the car, I have discovered several issues.

I am experiencing hard shifts from 1st to 2nd and flares into the other gears. I think it is due to vacuum issues. Other possible vacuum issues include door/trunk locks inoperable, no air coming out of dash vents, air only coming out of defroster vents, hot air only coming out when defrost selected (regardless of temperature dial setting), cool air only coming out on other vent selection modes (regardless of temperature dial setting). Is it possible that it's all related?

IVIuzzy · #2 10-07-2008, 11:18 AM

i am having the same problem be sure you read the post on this forum on how to tune tranny vaccum. also http://www.continentalimports.com/ser_ic20242.html this article helped me understand the importance of being sure i have a good vaccum going to the tranny. i will be staying in tune to this thread and let me know how you make out. Good luck

Rocketrider · #3 10-07-2008, 11:21 AM

Thanks! I'll take a look and keep you posted on my progress.

kerry · #4 10-07-2008, 11:24 AM

Trunk and doors are on a separate vacuum system so those are not related to the shifting issues.
Climate control and tranny vacuum modulator are on the same system so those are related. If you fix your vacuum leaks in the climate control the harsh 1-2 shift should smooth out. It probably wont have an effect on the flaring because (I believe) that is caused by too high a vacuum as opposted to too low.

mobetta · #5 10-07-2008, 11:24 AM

I'll take a stab at a few issues.

I am experiencing hard shifts from 1st to 2nd and flares into the other gears. I think it is due to vacuum issues.

Other possible vacuum issues include door/trunk locks inoperable,

no air coming out of dash vents,

Center vents only work when AC is on.

air only coming out of defroster vents,

?

hot air only coming out when defrost selected (regardless of temperature dial setting),

Normal. if AC functions, both the AC and heat is on. warm, dry air defrosts the best

cool air only coming out on other vent selection modes (regardless of temperature dial setting).

Is it possible that it's all related?

[/QUOTE]

I think you should start by tracing vac leaks, or disabling the entire lock system for now, and blocking the lines to it (yellow w/ green and yellow w/ red stripes under brake booster.)

Maybe the bad tranny wasnt even bad??

Phil · #6 10-07-2008, 12:18 PM

Your car has two seperate vac systems. There is a vac/pressure pump in the trunk next to the spare tire that is for the door locks. At no point is the door lock system connected to the transmission and HVAC vac system. I would suggest finding the point where a vac line comes off and goes to the HVAC system and plug the main system at that point and then see how it shifts. If this helps then you have vacuum issues in your HVAC system. This probably will not completely clear up your shifting issues but it might help. How are the brakes? The brakes are on the same vac system as the HVAC and tranny.
After you get all the vacuum issues corrected then do a search for adjusting the tranny, there is a good write up on it that you will find. The 1-2 shift is handled by the vac modulator on the side of the tranny. the 2--3 shift is handled by the K-1 valve and may need a new spring kit.
On my car I cleared up all the vacuum leaks and then was able to adjust the tranny so it shifts the way I want but when I first got it it flaired between shifts.

Rocketrider · #7 10-07-2008, 12:54 PM

Brakes work well. I didn't know that 1-2 and 2-3 were controlled by different apparatus. That definitely explains why it bangs on one shift and flares on another. Thanks! I'll try to take a look at it this weekend.

Phil · #8 10-07-2008, 01:34 PM

Quote:

Originally Posted by Rocketrider

Brakes work well. I didn't know that 1-2 and 2-3 were controlled by different apparatus. That definitely explains why it bangs on one shift and flares on another. Thanks! I'll try to take a look at it this weekend.

Also the 3-4 is controlled buy yet another valve although I will have to check my notes to remember which one. After you get everything sorted out then if you are still getting flare on the 2-3 shift changing the K-1 spring is not hard. I would definitely pull the line going to the HVAC system and plug the fitting before you get into the tranny adjustments so you can tell how much that part is causing your problems.

Read this post
http://www.peachparts.com/shopforum/showthread.php?t=158216
Just by the size of the post it looks intimidating but take your time and you will do fine.