Got 92 300D back from indie after gas-in-tank fiasco. Somehow the vacuum system got disturbed, but I don't notice any disconnected lines. The symptoms are a mild transmission bump under certain circumstances and the rear headrests won't go down.

Does anyone know which vacuum line goes to the rear headrests? I figure that if I can identify it I should be able to figure it out.

Thanks.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

if you look behind the brake booster you will see a few vacuum lines, the white one is for the headrests and leads to the vacuum valve under the rear seat that directs vacuum to the pods that pull the headrest locks which makes them fall.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

D'oh! After inspecting and replacing hoses on the DRIVER side, I noticed a disconnected hose over on the PASSENGER side. Further proof that passenger side vacuum is evil and must be eliminated!

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

That is one hose I don't have on my 300TD, no headrest dropper on a wagon...

I did the evil right side hose delete on mine.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech