I just put in a new shutoff valve. I installed it correctly with the hook 'hooking', etc. However, I can sometimes shut the engine off and sometimes it just keeps going.

Can anyone suggest where i might start looking for the problem? If it is a vac leak, shouldn't the problem be more consistent? help!

rodsob

__________________
$500 1982 240d owner "Gunter"
125k miles,4 speed manual
crank windows, MB Tex, all original
no a/c, daily driver
Scorecard so far....
$230 Maaco paint job
$27 dimmer switch, $40 shutoff valve, $45 brake MC, $260 calipers, $40 brake hoses, $40 side fender trim, $20 balancing, $109 lifetime alignment, $10 fuel return lines, $115 oil&fuel filters for next 30k miles

I had same problem.
I checked out other components - there is quite a bit on this forum about checking key switchetc. Also tersted vacuum at mai line - it ws low so I bit the bullet and put in new vacuum pump - result - it works perfectly!
If you can test vacuum at the main line (from pump to brake booster) it should tell you if it is low - if so - replace pump. Pump can be rebult but there are risks with doing that.

If you want the cheap way to check your vacuum system for leaks get yourself a little rubber connector and some golf tees.
Start plugging things off until you find that the car shuts off normally every time. Then focus on reconnecting lines until it starts it's poor performance agin. It is pretty simple to take for instance your door locks out of the circuit.

It may be also that the one way valves on some of your lines are performing incorrectly so if you have a leaky door lock it is allowing vacuum to draw off the main feed system.

If your original shutoff valve had oil in it then it is a good bet that the tubing where the two vacuum lines connect to the key shutoff are leaking. The oil from the shutoff valve will make it's way up to the key shutoff valve and really plug up the lines and ruin the rubber tubing there.

That would be the one other item that I would check is for a partially blocked vacuum line.
Good luck.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

The prior post is where my bet is.

Tons of this kind of varying problems are due to which doors are locked, unlocked with engine on or off. Also, oil changes affect the vacuum cuz of all the interference above the filter area.

Go for the small cheap stuff. Its almost always there.

A simple search will net some well defined steps towards discovery.

Don

__________________
DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

i noticed that when the car does shut off the right way (quickly), the door locks work perfectly. however, if the engine does not shut off the normal way, some of the doors do not lock.

does this scenario give me any clues as to where to look?

__________________
$500 1982 240d owner "Gunter"
125k miles,4 speed manual
crank windows, MB Tex, all original
no a/c, daily driver
Scorecard so far....
$230 Maaco paint job
$27 dimmer switch, $40 shutoff valve, $45 brake MC, $260 calipers, $40 brake hoses, $40 side fender trim, $20 balancing, $109 lifetime alignment, $10 fuel return lines, $115 oil&fuel filters for next 30k miles

Only so far as vacuum, vacuum, vacuum. You've got a leak somewhere...
Start pluggin those lines and testing. You may find it is a small rubber Y or piece of hose that has a crack in it.
About 2 bucks should fix it all.

If you've got access to someone with a mityvac it can speed up the testing process for sure. remember too that it could be in the door locks or the other side of the circuit being door unlocks.

is this a CD (2 door)? It could be in teh seat back locks if it is.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

On my TD, if the heater is on, it shuts off slower and the downshifts are harder--there's vacuum leak in the foot well vents. Lesson: Try shutting yours off with the heater on/off. It might tell you if the vacuum problem is in the heating system or not.

__________________
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