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#1
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New 300SD!!!! Oil Pressure gauge reads ZERO at idle and 2 at WOT. Where to start?
I just picked up my first W126 for $250. It was purchased "as is" because it wouldn't shift past 1st gear. Unplugged the kickdown switch and that was fixed. then a few other issues (no alternator, etc).
But now that that's all working I finally got it home (1 hour plus drive). Anyways, I noticed the dash gauge says ZERO on the oil pressure at idle and only 2 at 3-4k cruising speeds. So... that's not good. The car was run on SVO (stock fuel system). Anyways, where do I start. My guess is to second opinion the oil pressure (i.e. make sure the gauge is telling me the truth). But not too sure how to go about that. thanks for any ideas.
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-E300d '99 350k -Suburban '93 220k -TDI Jetta '03 350k Sold -F250 '96 7.3 -Dodge Ram 12V -E320 '95 200k -E320 Wagon 1994 155k -300d Turbo '87 187k miles -E320 1994 200k -300d Turbo '84 245k (sold to Dan62) -300d Turbo '84 180k -300sd '80 300k -7.3 Powerstroke Diesel 15P Van 500k+ miles -190d '89 Non Turbo 2.5 5cyl 240k (my first MB) Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's. |
#2
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I'm sure you've already checked the oil level...
If the pressure really were that low, wouldn't the engine have self-destructed or overheated by now??
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Current cars: 2000 ML55 AMG, 174k miles 2003 C240 T-Modell, 202k miles 1995 S320, 207k Miles |
#3
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As long as the oil level is normal then you probably have a bad oil pressure sender.
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-diesel is not just a fuel, its a way of life- '15 GLK250 Bluetec 118k - mine - (OC-123,800) '17 Metris(VITO!) - 37k - wifes (OC-41k) '09 Sprinter 3500 Winnebago View - 62k (OC - 67k) '13 ML350 Bluetec - 95k - dad's (OC-98k) '01 SL500 - 103k(km) - dad's (OC-110,000km) '16 E400 4matic Sedan - 148k - Brothers (OC-155k) |
#4
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As far as the alternator, if your car still HAS one on and isn't functioning, check the voltage regulator held on by 2 screws in back of the unit--9/10 times that is what goes. If you do have to buy a new alternator, I would recommend upgrading to the bosch AL129X for more amps (search "AL129X" on here for more info on this) and it costs roughly the same.
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TC Current stable: - 2004 Mazda RALLYWANKEL - 2007 Saturn sky redline - 2004 Explorer...under surgery. Past: 135i, GTI, 300E, 300SD, 300SD, Stealth |
#5
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Answer
Quote:
If that is correct, your starting point is the two small O-rings on the oil filter cover dip tube. This is a common issue overlooked during oil changes... When the two small O-rings become rock hard and/or break/crumble = the oil pressure reading drops/reads low. Seal ring, x2 MB# 015 997 94 48 Fastlane: Oil Filter O-Ring http://catalog.peachparts.com/item.wws?sku=W0133-1644350 Have a great day.
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ASE Master Mechanic asemastermechanic@juno.com Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 1984 190D 2003 Volvo V70 2002 Honda Civic https://www.boldegoist.com/ Last edited by whunter; 06-06-2011 at 05:02 PM. |
#6
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Quote:
Well it's not ZERO while driving but it is while idling. It's around 2 at cruising speeds (most of the way home). So it hasn't had zero oil pressure. Idling has only been a second or two. Quote:
__________________
-E300d '99 350k -Suburban '93 220k -TDI Jetta '03 350k Sold -F250 '96 7.3 -Dodge Ram 12V -E320 '95 200k -E320 Wagon 1994 155k -300d Turbo '87 187k miles -E320 1994 200k -300d Turbo '84 245k (sold to Dan62) -300d Turbo '84 180k -300sd '80 300k -7.3 Powerstroke Diesel 15P Van 500k+ miles -190d '89 Non Turbo 2.5 5cyl 240k (my first MB) Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's. Last edited by 777funk; 08-03-2010 at 07:17 AM. |
#7
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I have to say, I have never seen the little canister o-rings affect the oil pressure by more than .1 bar between being old and brittle and fresh.
__________________
-diesel is not just a fuel, its a way of life- '15 GLK250 Bluetec 118k - mine - (OC-123,800) '17 Metris(VITO!) - 37k - wifes (OC-41k) '09 Sprinter 3500 Winnebago View - 62k (OC - 67k) '13 ML350 Bluetec - 95k - dad's (OC-98k) '01 SL500 - 103k(km) - dad's (OC-110,000km) '16 E400 4matic Sedan - 148k - Brothers (OC-155k) |
#8
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When I had the same problem a new pressure sender fixed it.
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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 |
#9
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If it were me, I'd attach my mechanical gauge and see what the actual pressure range is and go from there. Pretty easy to do on these cars.
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____________ 1998 E300 +310,000K1996 E300 +460,000K |
#10
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That's what I was thinking. Where do I tap into the pressure at? I've got gauges for various things so I'd think one of them will have a range that will work.
__________________
-E300d '99 350k -Suburban '93 220k -TDI Jetta '03 350k Sold -F250 '96 7.3 -Dodge Ram 12V -E320 '95 200k -E320 Wagon 1994 155k -300d Turbo '87 187k miles -E320 1994 200k -300d Turbo '84 245k (sold to Dan62) -300d Turbo '84 180k -300sd '80 300k -7.3 Powerstroke Diesel 15P Van 500k+ miles -190d '89 Non Turbo 2.5 5cyl 240k (my first MB) Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's. |
#11
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maybe you can just remove the electronic sensor & connect there.
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Grumpy Old Diesel Owners Club group I no longer question authority, I annoy authority. More effect, less effort.... 1967 230-6 auto parts car. rust bucket. 1980 300D now parts car 800k miles 1984 300D 500k miles 1987 250td 160k miles English import 2001 jeep turbo diesel 130k miles 1998 jeep tdi ~ followed me home. Needs a turbo. 1968 Ford F750 truck. 6-354 diesel conversion. Other toys ~J.D.,Cat & GM ~ mainly earth moving |
#12
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Quote:
I've had oil leaking at the cluster in past MB Diesels. As far as fittings what am I looking for to connect to a gauge?
__________________
-E300d '99 350k -Suburban '93 220k -TDI Jetta '03 350k Sold -F250 '96 7.3 -Dodge Ram 12V -E320 '95 200k -E320 Wagon 1994 155k -300d Turbo '87 187k miles -E320 1994 200k -300d Turbo '84 245k (sold to Dan62) -300d Turbo '84 180k -300sd '80 300k -7.3 Powerstroke Diesel 15P Van 500k+ miles -190d '89 Non Turbo 2.5 5cyl 240k (my first MB) Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's. |
#13
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The SD set up has an electrical connection, no oil line to the cluster. On the lower back of the oil filter canister is where you'll find the sending unit.
Don't know of the connections necessary.
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83 SD 84 CD |
#14
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Yep -- pull the 'lectric sender at the oil canister and attach yer gauge there.
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____________ 1998 E300 +310,000K1996 E300 +460,000K |
#15
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Lux, any idea what kind of fitting I'll need to check the pressure? Not the standard 1/8" pipe thread fitting most US made cars use I'd guess?
__________________
-E300d '99 350k -Suburban '93 220k -TDI Jetta '03 350k Sold -F250 '96 7.3 -Dodge Ram 12V -E320 '95 200k -E320 Wagon 1994 155k -300d Turbo '87 187k miles -E320 1994 200k -300d Turbo '84 245k (sold to Dan62) -300d Turbo '84 180k -300sd '80 300k -7.3 Powerstroke Diesel 15P Van 500k+ miles -190d '89 Non Turbo 2.5 5cyl 240k (my first MB) Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's. |
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