Anyone have any ideas, sometimes I'll have vacuum right off the pump. Ten minutes later nothing. There is no oil in the lines. It's a 83 240D. Thanks.

Josh

My pump did that right before it died.You might want to order a rebuild kit and be ready.

__________________
85 300sd SOLD ,85 745i,95 740i,1972 Suburban,1938 International

The intermittent nature of the problem is very consistent with a failed check valve. The check valve is located inside the nipple where the vacuum line attaches to the pump. It can be removed and inspected with the pump in place.

Well I thought I could do that, when I disconnected the line I couldnt see anything in the pump but metal. Should there be some kind of rubber valve or something?

Josh

The check valve is kind of like a nut that screws on between the hard vacuum line and the vacuum pump. When working properly you should be able to blow through one side but not the other side. The air goes toward the side that faces the vac pump as the pump sucks air.

I'm assuming the check valve on your car would be exactly the same as on mine. I had an intermittent problem a few months ago, tangofox suggested the check valve, and he was right. In my case it was just a bit gummed up and some carb cleaner took care of the problem. I didn't experience the total failure you're describing, though.

I believe a 22 mm socket will allow you to remove the check valve. Best to do it when the car is cool.

__________________
Ralph

1985 300D Turbo, CA model
248,650 miles and counting...

I had the same problem but it wasn't the check valve that screws onto the vacuum pump. It was one of the 3 internal check valves inside the pump.
Some people say you can spray a little WD40 in there and it will may work again for a little while.
I would just as soon rebuild it and inspect the internal parts.

http://diymbrepair.com/easley/Rebuild_vac_pump.htm

danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1TH129NWZ1VO10NMFA&year=1983&make=MB&model=240-D-002&category=D&part=Vacuum+Pump+Check+Valve&appEngines=_any
The part that typically breaks is the metal disk the is shown inside the fitting in the picture in the lower right. You need to remove the check valve from the pump to see that end of the valve. It will likely be very obvious if it is broken. If it is okay, a pump overhaul will likely be needed.

There are 3 check valves inside the pump. The cheaper re-build kit includes those valves, the piston (ring) seal, and the cover seal. It is an easy job to do. I'll be doing it on Thursday on a friends vehicle and will do a photo DIY.

__________________
Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

I already posted a DIY link. See post #6.
If you have never done this before do yourself a favor and make the board. You will be very happy you did.
Also, don't forget to buy a new gasket.

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination

Thanks for the info, I ordered the rebuild kit from Diesel Giant. Hopefullly it will shoe up today!


Josh