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Old 11-14-2006, 05:03 PM
Registered User
Join Date: Jun 2005
Posts: 17
vacuum problem...

Own a 81 300d,160000 miles.This is what happens
-doors lock ok
-problems with shutting the engine
-no power brakes
is it the pump or a leak ...
please advise
regards z

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Old 11-14-2006, 05:13 PM
rrgrassi's Avatar
mmmmmm Diesel...
Join Date: Jun 2006
Location: Royse City Tx
Posts: 4,885
Sounds like a pretty good leak. Do a search for vacuum leaks, and you will find lots of info on the subject.

70's SPM #5608 Fairmont A-4 MOW car

06 VW Jetta TDI 280K miles

03 VW Golf TDI 5 speed 400K Miles Engine died

RIP--Lost in fire...82 300D 322K was My Daily Driver-Looking at a w124 now...

90 Dodge D250 5.9 Cummins/5 speed. 400K
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Old 11-14-2006, 07:12 PM
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Join Date: Jan 2006
Posts: 28
There is a checkvalve in the line going to the brake booster. It's one of the yellow ones and has 4 lines going into it. I knocked the center line loose once durin an oil change and had no power brakes and it wouldn.t shut off. I'd say the valve is either bad or one of the lines are loose.

Hey, Flanagan has a picture posted here mystery vac line
That shows the valve. You can see it best in the second picture just in front of the filter he's holding.
1980 300d on veggie

Last edited by cconbalsam; 11-14-2006 at 07:17 PM.
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Old 11-14-2006, 09:31 PM
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Join Date: Jun 2005
Posts: 17
thanks for the input,I will play with it during the weekend
problems come in 87 560 sl developed a loud noise when started could be timing chain
thanks guys
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Old 11-15-2006, 11:06 AM
Biodiesel300TD's Avatar
Join Date: Dec 2004
Location: Albany, OR
Posts: 4,845
To directly check to see if its the vac pump or the break booster try this:
Hook up your mitvac to the main line that goes from the pump to the booster. Then plug any other lines. Start the car and see if it holds steady or not. It should be reading 20"-25" If yes then both the pump and booster are fine. If no then use a wrenchc to remove the main line from the booster. Then plug the end of the main line. I usually lick my thumb and put it on the hole tightly. If the vac is 20-25 then the pump if fine, and the booster is your leak. If the vac is jumpy or much below 20 than the pump needs rebuild or possibly a replacement.

'04 Jetta TDI Wagon
'82 300TD ~ Winnie ~ Sold
'77 300D ~ Sold
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