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  #1  
Old 01-25-2007, 07:50 PM
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Location: Woodstock, GA
Posts: 89
Question '83 300SD 126 - Hard Upshift!?

OK heres the story....

I bought a 1983 300SD Turbo, about a month ago. Has 295k+, seems pretty well maintained, have partial service records etc...

Had no real problems, other than a slow oil leak (looks like Valve Cover gasket). Havn't had to refill yet (still measuring on the high side)

Today I decided to check/topoff the fluids. All of the fluids looked fine except the ATF was just under the low mark on the stick when idling in P. So I added a little more than half a quart and after letting it settle it looked like a little under the top mark on the stick.

Well right after that a took her for a spin and it started shifting hard on acceleration but was fine on decel and on down shifting.

I cant understand what i did to screw up the previouslty perfectly shifting tranny.

Could I have overfilled? have adverse affects on Upshifting?

Any insight would be great.

One side note: When looking around under the hood i noticed the vacum lines that connect to the double prong on the passenger side of the Valve Cover had fallen out, the rubber connector lines are dryrotted but i duct taped them pretty tight back in place and the shifting seemed to slightly improve, but still shifts hard UP from 1-2 2-3 etc.. I dont know if i knoked these lines loose when i was checking fluids or if they have been off the whole time, or if that even has anything to do with it.


Last edited by vito; 01-25-2007 at 07:58 PM. Reason: spelling
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  #2  
Old 01-26-2007, 09:49 AM
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Questions.........

OK, I took a picture of what I believe to be the Thermo Vac Valve and the EGR Valve(looking at a diagram posted on this forum), where I duct taped the dry rotted connections. I plan on getting some tubing and doing this corecctly, but I am trying to get a better understanding of this vacuum system before i go any further.

Qeustion 1: What does EGR stand for, and can I bypass?(seems that I read this on here)

Question 2: Could these leaky connections at the ThermoVac Valve be causing my hard shift problem?

Thanks

I know I am just one more newbie without a clue, but I have a great interest in learning about this car from front to back.
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'83 300SD 126 - Hard Upshift!?-83300sd.jpg  
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  #3  
Old 01-26-2007, 09:52 AM
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Exhaust Gas Recirculation. Yes, vacuum leaks can cause shifting problems.
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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #4  
Old 01-26-2007, 10:11 AM
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I attached a picture of the connection on top of the valve cover. All the vacumn leaks will cause how things including shifting will work and duct tape will not hold the vacumn. Get some hose and fittings and start replacing everything thats not in good shape. Only after you take care of the leaks will you know what the transmission is doing. After all the leaks are taken care of then you can start making adjustments to fine tune stuff.
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'83 300SD 126 - Hard Upshift!?-egr-valves1.jpg  
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  #5  
Old 01-26-2007, 12:08 PM
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Ditto: vacuum leaks

If you have some dry-rotted vacuum connections, save yourself a lot of headaches and replace them all. I believe all of the flex fittings cost me all of $10 and all but the 3-way connections are available locally at most parts stores. It's hardly worth picking through them one-at-a-time. You will also eliminate a lot of intermittent problems.
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84 300SD 350K+ miles ( Blue Belle )
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  #6  
Old 01-26-2007, 02:51 PM
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Still shifting hard

I just replaced the duct taped connections in the picture with good rubber connectors and new lines, and I even replaced the rubber connector at the modulator on the tranny. Alas, to no avail same issue. Shifts hard and abrupt.
I just cant understand why, just yesturday it was smooth as silk, and all i did was add a half quart of fluid, and repaired the vacuum lines. !?!?!?!

Just a little agrivated that I screwed up a perfect tranny...

I realize i should pressure check the whole vacuum system which is fine, but being that it was perfect yesturday then shifting hard today after adding some fluid, I cant figure out what could have happend to the vac system.

Any other thoughts?

Thanks in advance

PS I did notice today when checking ATF level (perfect level now) that there were small bubbles in it like spit, this doesn't seem normal....
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  #7  
Old 01-27-2007, 01:57 PM
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Update and SUCESS

I preformed the patented Brian Carlton "EGR black box thingy bypass manuever" and man shes shifting smooth as silk!

Thanks Brian if you read this.

Here are the before and after pics
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'83 300SD 126 - Hard Upshift!?-300sdoldway.jpg   '83 300SD 126 - Hard Upshift!?-300sdnewway.jpg  
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  #8  
Old 06-02-2007, 09:55 AM
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can you explain?

"EGR black box thingy bypass manuever"

Im having the same problem (hard shifts), can you tell me what you did, I cant tell from the pictures.
Thanks
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  #9  
Old 06-02-2007, 11:05 AM
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Location: Arlington, Texas
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Mine shifts firmly but not hard. I presumed that as normal. While diagnosing the a/c problem, I left the red/green vacuum tube from the booster line to the a/c junction off and if shifted softly and even flared & slipped a little into 3rd. I plugged that vacuum line while working on the a/c and it went back to the firm shifts.

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