All right guys, please don’t beat me up too bad. I have searched the forum and have not found an answer.

1981 300SD 97,700 miles (New to me)—The vacuum pump in the trunk is not working. Would this affect the tranny?. Or does the pump in the trunk only provide vacuum for the doors? My transmission flairs between 2nd and 3rd and I am trying to figure out if the problems are related.

Once I figure that part out I can start with the vacuum system under the hood and then move on to the B-2 if need be.

Thanks!

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Anders

1995 E300
2015 VW TDI Sportwagen 15K
1977 240D (197K)
2002 Subaru Legacy L Wagon (115k) (Wife's)
Gone but not forgotten:
2005 Buick LeSabre
1998 C230
1984 300D
1983 240D
1981 300SD
1974 240D
1974 Fiat 124 Spider
1968 Triumph TR250

Sounds like me!

Anyway... everything is vac related on these cars. For the trans... I bet it has something to do with the underhood business.

The lil diaphragm (sp? it's late) on the trunk could be leaking/torn or the hose loose.

IMO - I'd start under hood and work the opposite way. As I understand stuff works in that direction on these vehicles.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

The pump on my 84 SD is only to perform locking and unlocking. It locks the doors, the gas door and the trunk.

If you are having a problem with the tranny, sounds like the tubes up under the hood would be the best place to start.

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1998 W202 C230 - The money pit of late.
1984 W126 300SD (356,800 miles) Gone to the wrenchapart
1984 W123 300D Gone to the wrenchapart
1972 W108 280SE 3.5 (sold but not forgotten)
1986 Buick Grand National 3.8l Turbo (86k miles)
1966 Glassic Model 'A' Replica http://www.glassicannex.org

http://banners.wunderground.com/weat...Round_Rock.gif

Fuzzball's right - the door locks on the SD are controlled by the trunk-mounted pump and it has nothing to do with the transmission.

Do a search for flaring, transmissions, etc and you should find lots of info.

Seems most SD's flare on the 2-3 shift. If you have a nice firm 1-2 and 3-4, there's probably not much you can do without hardening up the whole thing, which will make your 1-2 pretty hard.

If the flare is bad, some people have been known to disconnect the vacuum from the trans in order to get firm (really firm) shifts that they feel prolong the life of the trans.

That's really low mileage for an '81!

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1984 300Sd 210k

Former cars:
1984 300D 445k (!!) (Strider) Original (and not rebuilt) engine and transmission. Currently running on V80 ( 80% vegetable oil, 20% petroleum products). Actually not, taking a WVO break.
1993 300d 2.5 275k. Current 120/day commuter
1981 300SD 188k (Hans) Killed by a deer

My 83 SD use to do this a lot, but after following Marshall Booth's advice, I put synthetic in the Tranny. After about 10-15K it reduced dramatically. My son doesn't even notice it as the car is now assigned to him. This probably is not a vacuum problem.

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D. Blake
86 300SDL 340K (for sale)
83 300SD 205K (gone)
06 Chevy K3500 LBZ CCLB 50K
94 Chevy K2500 6.5L TD 250K (gone)

[QUOTE=tenknots]...some people have been known to disconnect the vacuum from the trans in order to get firm (really firm) shifts that they feel prolong the life of the trans.[QUOTE]

Yes, it WILL prolong the life of the tranny. But it WILL kill your flexdiscs in short order (Mine self-distructed less than a year after I disconnected vacuum.)

Yeah it runs full line pressure at low throttle... not what you want. That gives you bumps/excessively firm shifts at low throttle.

You want line pressure to increase as throttle does (vac drops) to prevent slippage of the clutches under load.

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]