Re: [MBZ] Vacuum pump check valves
The vacuum pump has 3 check valves (poppet valves), one to the engine (exhaust) and 2 from the vacuum system (intake). If the exhaust poppet fails, your piston or diaphragm will be full of crud and there will be little vacuum which will take a long time to build up. Pulling vacuum on the pump from the in line check with a Mityvac will be impossible. If one of the intake poppets fail, nothing other will result than no vacuum. If two poppets, one on each side, fail, there is a chance of oil entering the lines due to blow-by pressuring up the crankcase. Unlikely to happen. On 11/1/05, Marshall Booth [EMAIL PROTECTED] wrote: Bob Rentfro wrote: So...if these check valves fail, how do I know? If I'm getting oil in the vacuum lines is this indicitive of check valve failure? How can oil get into the vacuum system unless there is a rip in the diaphram? Every other time the diaphram has ripped I've gotten oil in the air cleaner housing and none in the vacuum lines. I'm stumped. Oil in the vacuum lines USUALLY comes from a rip in the shutoff valve diaphragm (on the injection pump) or from the transmission (if your car has a vacuum modulator that leaks), but when the pump diaphragm is damaged, oil CAN migrate from the pump thru the lines each time the engine is shut down. For it to fill the lines takes some time (usually many months) since when the engine is running there is some force drawing the oil back toward the pump until the pump completely fails. As to diagnosing the pump - PUT a vacuum gauge on it, read the vacuum produced and how fast the vacuum drops when the pump is shut down. Covered in 43-660 of the chassis manual (attached). Marshall -- Marshall Booth Ph.D. Ass't Prof. (ret.) Univ of Pittsburgh School of Medicine Department of Pharmacology 1300 BST Pittsburgh PA 15261 USA [EMAIL PROTECTED] -- next part -- A non-text attachment was scrubbed... Name: 43-660.pdf Type: application/pdf Size: 158525 bytes Desc: not available Url : http://striplin.net/pipermail/mercedes_striplin.net/attachments/20051101/40d1247b/43-660.pdf ___ For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net -- Hans Neureiter, Houston, TX '82 300SD, '95 E300D
Re: [MBZ] Vacuum pump check valves
If you have oil in the vaccum lines either the diaphram in the fuel shutoff valve is leaking or the diaphram in the vacuum pump is. Bob Rentfro wrote: So...if these check valves fail, how do I know? If I'm getting oil in the vacuum lines is this indicitive of check valve failure? How can oil get into the vacuum system unless there is a rip in the diaphram? Every other time the diaphram has ripped I've gotten oil in the air cleaner housing and none in the vacuum lines. I'm stumped. Bob Rentfro '77 300D 142K Litchfield Park, AZ ___ For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net -- Kaleb C. Striplin/Claremore, OK 89 560SEL, 87 300SDL, 85 380SE, 85 300D, 84 250 LWB, 83 300TD, 81 300TD, 81 240D, 81 240D, 76 450SEL, 76 240D, 76 300D, 74 240D, 69 250 Okie Benz Auto parts-email for used parts
Re: [MBZ] Vacuum pump check valves
Bob Rentfro wrote: So...if these check valves fail, how do I know? If I'm getting oil in the= vacuum lines is this indicitive of check valve failure? How can oil get in= to the vacuum system unless there is a rip in the diaphram? Every other tim= e the diaphram has ripped I've gotten oil in the air cleaner housing and no= ne in the vacuum lines. I'm stumped. = Oil in the vacuum lines USUALLY comes from a rip in the shutoff valve = diaphragm (on the injection pump) or from the transmission (if your car = has a vacuum modulator that leaks), but when the pump diaphragm is = damaged, oil CAN migrate from the pump thru the lines each time the = engine is shut down. For it to fill the lines takes some time (usually = many months) since when the engine is running there is some force = drawing the oil back toward the pump until the pump completely fails. As to diagnosing the pump - PUT a vacuum gauge on it, read the vacuum = produced and how fast the vacuum drops when the pump is shut down. = Covered in 43-660 of the chassis manual (attached). Marshall -- = Marshall Booth Ph.D. Ass't Prof. (ret.) Univ of Pittsburgh School of Medicine Department of Pharmacology 1300 BST Pittsburgh PA 15261 USA [EMAIL PROTECTED] -- next part -- A non-text attachment was scrubbed... Name: 43-660.pdf Type: application/pdf Size: 158525 bytes Desc: not available Url : http://striplin.net/pipermail/mercedes_striplin.net/attachments/20051= 101/40d1247b/43-660.pdf
