1980 240D won't turn off!!!

I recently bought this car and yetsreday couldn't get the engine to shut down. Iturned it off manually. I have been told this is a vacuum supply problem. The brakes are fine so I don't think it's the pump but both the door locks and turn signals are on the fritz. The car was just in for a diagnostic 2 weeks ago & the mechanic didn't mention anything about the vacuums. How big of a problem is this to fix and how much should I expect to pay. I live in Berkeley CA where everything seems to be more expensive

[stevebfl]

To make your car usefull untill you can get it repaired you can by-pass the door lock leak. Follow the large supply line to the booster, follow the small line teed before the vacuum check valve. The lines will turn into a number of tees and check valves feeding as many as four systems (depending on the year model); door locks (yellow), A/C (green), shut-off (brown) and cruise control (black). Take the yellow line from the source and pull the hole. If the leak was in your doors that will eliminate the leak. The car should shut-off.

If that doesn't work try the blocking off the green, then the black till all you have is the brown. If it still doesn't stop then the vacuum diaphram in the injection pump is probably the problem (sometimes its the vacuum switch on the steering lock/ignition).

I would block each leg till the system works then replace them one at a time while seeing if it still works. We often see leaks in both the A/C and door locks. The 240D can actually work alright without the vac systems if you don't mind manual locks.

------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

thanks Steve! I'm taking it in tomorrow to my mercedes mechanic. I just want to have a good idea of what the problem is first so I will know if he is making unnecessary repairs. He had said it might be the vacuum pump. I have heard this is very expensive, would you know approximately much? It's a 1980 240D

nicoleh,

Don't worry it's almost sure to be a vacuam leak just like Steve said. Just follow his explanation and trace the leak.

If you were unlucky enough to ever lose a vacuam pump, they are about $200 plus an hour or so labor.

Good luck,

------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

thanks Larry! it seems like this is a common problem with the diesels.

nicoleh,

The vacuam pump is very long lived. I just replaced the original on my 240D a few weeks ago. It had over a half million miles.

The other vacuam components are the same on the gas cars.

You probably just have one of the locking diaphragms that needs replacing, they are readily available and inexpensive.

Have you checked all the vacuam line connections and rubber fittings near the oil filter area? It is not totally uncommon for a line to knocked loose here when the oil filter is changed.

Good luck,

------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Larry
I am planning on taking a good look this weekend at all of the vacuum lines. Am also planning on buying a handheld pump and vauum gauge to find the leak. My mechanic just made me nervous since he immediately assumed it must be the pump. The car has 223,000 miles on it.

nicoleh,

A Haynes manual has a diagram of the vacuam lines as they distribute through the vehicle. If you take the color code information given by the pro, you can start by plugging testing them with your pump to find which leg the leak is in, trace down from there.

If it's the locking circuit, which it probably will be, you can start at the passenger door and determine if it is source or destination at that point. If it's supply go to the drivers door, if it's destination go from there to the rear passenger door and on to the fuel tank door.

By splitting it in half and seeing which way to go, you will statistically decrease the number of door panels to take apart.

Of course, if your luck is like mine, it doesn't matter where you start, because it will be the last possibility that will contain the problem <g>.

Good luck,

------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

thanks again larry. Hopefully I can get it back together!!

[Larry Delor]

nicoleh,

My pump went of the fritz around 145k miles. I bought a rebuild kit from the dealer ($106.50) (waaay cheaper anywhere else!...like around $55-$65) It took me some time to get to the darn thing, but the rest was pretty easy, and has since worked fine. Well, at least it did for another 42k miles, since then a few interesting things have happened, and I am going to rebuild the motor, with the exception of the pump.

-Larry

------------------
03/83 300D 184k
07/73 280 160k