First and foremost check your fluid level. How long since your last filter change?

Secondly, its time to check out your vacuum system. Maybe you have a leak thats slowly getting worse.

Do you have a MityVac?

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I check tranny fluid periodically - the level's good, and the fluid color is what it's supposed to be. I haven't done the fluid or filter change since I acquired the car, but I am planning to have that done soon.

I do keep an eye on my vacuum hoses and fittings, but no - I don't have a MityVac. I assume by MityVac everyone means the hand-held vacuum pump?

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84 300SD - bought in April '06 with 237,000 mi

Yep.......you'll need it to further diagnose the system.

The modulator is the least of your concerns at this point.

BTW, do you still have all the connections to the black box on the top of the valve cover.........all EGR related?

No, I don't see any black box on top of the valve cover - only linkage-related stuff and the rubber breather tube. The previous owner also plugged the EGR valve connections.

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84 300SD - bought in April '06 with 237,000 mi

Well, it was probably removed before your ownership.

Pick up a Mityvac and we'll sort it out.

If the AC makes the tranny symptom worse, I would guess you have a leaking AC vent vacuum pods.

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'85 300D Turbo - CA Version

I am suspecting the same thing as well. Where can I find the vacuum line that supplies vacuum to the ACC?

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84 300SD - bought in April '06 with 237,000 mi

Alright, I finally got Mityvac and a little bit of time... So now I'd like to sort out why my drivetrain is so clunky.

Where do I begin?

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84 300SD - bought in April '06 with 237,000 mi

I have somewhat the same problem, however mine shifts the best when A/C is on. If it is turned off it can be very rough. I am going to spend time on it this long weekend. Any ideas.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

First thing to check is the supply vacuum to the VCV. You'll see a T above the VCV. One leg comes from the vacuum pump and the opposite leg goes to the transmission. The bull is connected to the VCV via the green vacuum damper.

Disconnect the supply line that goes into the T and measure the vacuum from the source (the vacuum pump) at idle.

Then, reconnect the line that goes into the T and disconnect the line to the transmission (from the T). Connect the Mityvac to the open T and read the vacuum at idle.

Report back.

I am thrilled you started this thread--I have the EXACT same issues. Low load clunking.

Which MityVac did you get?

Question for others--What mode of MityVac is suited to do this job? Would this one do it or do you have to have the 0400 model? Is there a recommended place to get one? Thanks in advance!

http://www.amazon.com/Mityvac-7000-Automotive-Tune-Up-Bleeding/dp/B000BPFB3A/ref=pd_bbs_sr_1/104-9001271-1222314?ie=UTF8&s=automotive&qid=1188520535&sr=1-1

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1998 E300D, 287k, barely broken in.