Hard shut down
 

When I shut down my 1977 240D it shakes the whole car. Is this normal? Or is there some why to fix this?

Thanks.

It sounds like a weak/faulty Fuel Shut-Off Valve. It is vacuum operated and pulls the fuel injector rack out of position so that fuel is not delivered to cylinders. Hence: shutdown.

When the diaphram within the Shut-Off Valve breaks down, the valve no longers holds full vacuum and the rack is only partially moved. Eventually the diaphram totally fails and no vacuum is held and shut-off has to done manually, under the hood (major PIA in the wintertime). Partial fuel flow results in rough idle (shaking car) as motor is slowly denied fuel and eventually dies.

The Fuel Shut-Off Valve is about $100 at the dealer. It is very easy to replace. Just do a search of this forum's archives for directions.

Also, you will want to fully inspect the rest of the vacuum system as oil will have been pulled into the lines through the bad Shut-Off Valve diaphram. The oil can eventually foul any plastic (lines) and rubber (connections and diaphrams) with which it remains in contact.

how are your door locks working? If they also arent working(which i suspect) you could have a leak elsewhere. Your best bet is to buy a mitivac guage(about 30 bucks) and test each individual system of the car. E.G. Test the shutoff valve to see if it holds vacuum, if it does, then that isn't your problem. Test all diaphrams's/lines that you can find, you will eventually find your problem. It could even be a faulty trunk locking mechanism causing your engine to not shut off, these vacuum lines are a major PIA to fix, but are normally very inexpensive, just time consuming....
Ryan

Thanks for the information. I will look into it. My car doesn't have the vacuum door locks. My car has the do it by hand style. One more question it seems that the spring in the door handle has gone out so that door handle doesn't return so I have to push down the catch so that I can close the door. How does one fix this? Does it cost allot?

hmm, thats a good one there. Not owning a W123 chassis car, i cant tell you how to get the door pannel off to check out whats aray in there. Search the archives, i know someone posted how to remove that door pannel recently. I'd do a visual inspection first, and then see what you can do yourself. I'd take it to someone as a last resort personally....
Ryan

I do not see the relationship between "hard shut down" and a leaking shutoff valve. Can someone educate me a little more? I am thinking that If the valve is leaking air, the engine will not shut down or take longer to shut down, not a hard shut down.

David

I am not an expert but had the hard shutdown and repaired it with a new fuel shut-off valve. The shut-off valve pulls the Injection Pump Rack out off "Run" position so that the fuel is denied to the system. If the shut-off valve is in the process of failing, the rack gets moved partially out of position and some fuel is allowed to pass. The result is a a degeneration from Idle to Rough Idle to Very Rough Idle to eventual Shutdown as the IP Rack is slowly drawn into the Shut-Off position. Before long the Fuel Shut-Off Valve will probably fail completely and the engine will continue to run unimpeded with the key in the "Off" position.

BTW, there is no exchange of air from the vacuum system to the Injection Pump. The vacuum pressure is used to draw the mechanism which pulls the Rack out of position.

motor mounts??
 

I'm not sure what you mean by "hard shutdown", but since you say it shakes the whole car, I understand that you mean that the engine rocks and shakes the car.....I assume you dont mean that the engine does not shut off quickly.

Based on that, I would look at motor mounts....if the whole car shakes when the engine rocks a little at shutdown, engine vibration is not properly isolated from chassis.

most like motor mounts!

Start with a test on the Fuel Shut-Off. VERY simple. COSTS NOTHING (always start with the option which gives you the most information with the least investment of time, energy and money).

Motor Mounts may well need to be replaced, but they are not the most likely culprit in the shutdown/shaking scenario.

Trace the brown vac. line coming off of the unit (Fueal Shut-Off Valve) at the firewall end of the Injection Pump. Pull this line from the junction at the other end (bunch of vac. lines meet next to brake booster).
Is there oil in this line (a sure sign of Fuel Shut-Off Valve failure as oil is being vacuumed from the Injection Pump Rack through the Shut-Off Valve diaphram and into the vac. line)
Apply vac. pressure to the line while the car is running. How is the shutdown?
Apply vac. presure while car is not running. Does the unit hold presure or does the pressure leak out? If there is pressure leaking out then diaphram is leaking and unit has to be replaced.

Once you've tested this Shut-Off Valve you will have spent a very few minutes and no money and you will know whether to replace the part or move on to further diagnosis.

Hippie....

Your door handle replacement job is very easy. Procrastinated on mine and didn't need to. I think it was a bit over $9 for the part and took less than 20 minutes.
Be careful when popping off the cover to the inside of the door and everything else goes smooth.

Don

Ok, Do you know the part number that needs to replaced on the door?

Come to think about it, the spring in the door is actually what returns the handle to normal position. However, I've had two separate handles snap in such a way that they opened the door but did not return normal. I only discovered this upon taking off the door skin and examining it. You might have the same situation. It is a very quick move to examine it.

I don't have the part number off hand, but its an easy order on fastlane.

Don

How much and how long does the car shake? I would think given the process of shutdown, basically starving the motor for fuel,a little tremor or shake might be expected.

It is a very hard jolt and it lasts about 2 or 3 seconds after you turn the engine off. I don't hear any sounds when I shut it down. I'm going to have a repair shop work over the car to see if there is any other problems. I will let let them check out this problem.

On the door handle problem, so what happens when you pull on the inside door handle?