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#1
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oil pressure drop after oil change
Panic here,
I have a 240 D with 275000 miles. Oil pressure between 2.1 and 2.4 warm at idle. Today I changed filter and oil and the pressure when warm is now 1.5 to 1.9 What has happened ??? Old filter purolator and oil Rotella 15W 40 New filter Mahle and oil Rotella 15W 40 Any thoughts? Thanks because this is very concerning.
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85 MB 300TD with om616 4 spd 83 MB 300TD 83 MB 240D scrapped 82 MB 240D scrapped 97 Ford E350 diesel 4x4, WVO 94 Ford E350 4x4 diesel blown head..parts car 85 cherokee diesel 2.1, 300.000, WVO 85 cherokee diesel 2.1 85 lebaron convertible, to be electric 85 lada niva 4x4 with 1.9 peugeot diesel, 72 citroen DS 5spd, LPG 77 Jaguar XJS, LPG 73 corvette 350 auto 88 MB Gelande 240 GD military 98 Ford E350 mini bus to be new 4x4 camper |
#2
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Not enough oil put in?
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2009 ML320 Bluetec 1985 300CD 1981 300TD Past Mercedes 1979 300TD 1982 300TD 2000 E320 4Matic Wagon 1998 E430 1984 300SD 1980 300SD |
#3
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I'm pretty sure your still in specs....
according to my manual it states .5 bar at idle and 3 bar at 3000 rpm. When you increase RPM you should have an increase in pressure. Does it (pressure) fluctuate at idle or on speed. If at 30mph it jumps all over I'd be more concerned. Overall all I think your ok. After a little more thought "O" Rings in the oil filter canister getting worn? I think I've read something in the forums about that and oil pressure. Bob
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92 300D 2.5L OM602 OBK #59 |
#4
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1.5 - 1.9 is what it *should* be when warm and at idle.
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http://superturbodiesel.com/images/sig.04.10.jpg 1995 E420 Schwarz 1995 E300 Weiss #1987 300D Sturmmachine #1991 300D Nearly Perfect #1994 E320 Cabriolet #1995 E320 Touring #1985 300D Sedan OBK #42 |
#5
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Yes , there is enough oil, I always let it run for a couple of minutes and then wait a couple and check the level.
The oil pressure goes up right away above idle but definetely slower the it was before the oil change. The 2 O-rings on the bottom were there but kind of flat I did not replace them. With the old puralator the pressure was always repeatable. I do not get that directly after this oil change with a "better brand " filter the pressure dropped so much , an dthat is not even driving highway. I will try to find the situation on these O-rings and exchange this Mahle filter for a purlator to see the difference. Thanks for the help.
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85 MB 300TD with om616 4 spd 83 MB 300TD 83 MB 240D scrapped 82 MB 240D scrapped 97 Ford E350 diesel 4x4, WVO 94 Ford E350 4x4 diesel blown head..parts car 85 cherokee diesel 2.1, 300.000, WVO 85 cherokee diesel 2.1 85 lebaron convertible, to be electric 85 lada niva 4x4 with 1.9 peugeot diesel, 72 citroen DS 5spd, LPG 77 Jaguar XJS, LPG 73 corvette 350 auto 88 MB Gelande 240 GD military 98 Ford E350 mini bus to be new 4x4 camper |
#6
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You have this completely backwards. The oil pressure you had before at idle was ok per FSM but abnormal. The oil pressure you have now is normal.
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http://superturbodiesel.com/images/sig.04.10.jpg 1995 E420 Schwarz 1995 E300 Weiss #1987 300D Sturmmachine #1991 300D Nearly Perfect #1994 E320 Cabriolet #1995 E320 Touring #1985 300D Sedan OBK #42 |
#7
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If your old filter had flow resistance, it can cause a higher pressure reading, but a flow resistance also means oil is not reaching the moving parts very well. Purolator is not the best name in oil filters.
Your oil pressure is fine.
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RRGrassi 70's Southern Pacific #5608 Fairmont A-4 MOW car 13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete. 91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K 90 Dodge D250 5.9 Cummins/5 speed. 400K |
#8
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Could you have that backwards? Its been a while, but whether the oil pressure reading was pre or post filter was one of the things I explicitly looked up when I first got my car. As I recall, it was post filter, which means a plugged (or more efficient) filter would restrict flow and produce a lower oil pressure. Or is my memory playing tricks on me again?
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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png Broadband: more lies faster. |
#9
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Ok, I am back from the car,
Thanks for all the response and piece of mind about the "remaining oil pressure" May the pressure was to high original according to the specification? I assume that the oil pressure is taken somewhere in the oil gallery so that should be after the filter. Please correct if I am wrong. In the mean time I have left the Mahle filter in and replaced the completely hardened O-rings with new ones. It did not make a difference. In the oil stem pipe ( the one through the filter ) are a hole in top and bottom. This should be to allow the air out. I can only blow through it in one direction and that is towards the bottom of the filter. That would make sense, it would allow the air out and not allow the air back in and drain the filter out. So I assume this is good. I bought another purolator filter and changed it with the Mahle. No difference. So it only can be the viscosity of the old oil versus the new oil. I have the car for about 14000 miles and the pressure has always been 2.1 to 2.4 at idle depending on wheather and driving situation. I regret not bringing up one more variable: WVO Since the last oil change the car has driven 3500 miles on veggie oil, centrifuge filtered soybean. Two tank system. Heated to 160-170 before the ip and up to 220 through injector line heaters electronic induction style. Can veggie oil pollution have increased the viscosity of the old motor oil? How does that relate to my oil pressure before the conversion. Thanks again for al your inputs. .
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85 MB 300TD with om616 4 spd 83 MB 300TD 83 MB 240D scrapped 82 MB 240D scrapped 97 Ford E350 diesel 4x4, WVO 94 Ford E350 4x4 diesel blown head..parts car 85 cherokee diesel 2.1, 300.000, WVO 85 cherokee diesel 2.1 85 lebaron convertible, to be electric 85 lada niva 4x4 with 1.9 peugeot diesel, 72 citroen DS 5spd, LPG 77 Jaguar XJS, LPG 73 corvette 350 auto 88 MB Gelande 240 GD military 98 Ford E350 mini bus to be new 4x4 camper |
#10
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patbob and qwerty,
Thanks I learned something here , as an engineer I would have designed it the other way around , interesting to realize that the mercedes engineer were more interested in pressure of the pump then the pressure at the bearings???? Thanks again
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85 MB 300TD with om616 4 spd 83 MB 300TD 83 MB 240D scrapped 82 MB 240D scrapped 97 Ford E350 diesel 4x4, WVO 94 Ford E350 4x4 diesel blown head..parts car 85 cherokee diesel 2.1, 300.000, WVO 85 cherokee diesel 2.1 85 lebaron convertible, to be electric 85 lada niva 4x4 with 1.9 peugeot diesel, 72 citroen DS 5spd, LPG 77 Jaguar XJS, LPG 73 corvette 350 auto 88 MB Gelande 240 GD military 98 Ford E350 mini bus to be new 4x4 camper |
#11
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Quote:
The smaller lower part of the Oil Filter is the Full Flow part of the oil system and that Oil goes into the Oil Gallery.
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84 300D, 82 Volvo 244Gl Diesel Last edited by Diesel911; 10-09-2008 at 10:20 PM. |
#12
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That is a nice sketch,
Yeah I was wondering about the max pressure, Thought about taking the peg of the meter and see where it would go. It would be nice to talk with one of the old desiners of the car and read in their notebooks why they decided to pick the oil pressure at the pump and not at the bearing. So may roads to Rome.
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85 MB 300TD with om616 4 spd 83 MB 300TD 83 MB 240D scrapped 82 MB 240D scrapped 97 Ford E350 diesel 4x4, WVO 94 Ford E350 4x4 diesel blown head..parts car 85 cherokee diesel 2.1, 300.000, WVO 85 cherokee diesel 2.1 85 lebaron convertible, to be electric 85 lada niva 4x4 with 1.9 peugeot diesel, 72 citroen DS 5spd, LPG 77 Jaguar XJS, LPG 73 corvette 350 auto 88 MB Gelande 240 GD military 98 Ford E350 mini bus to be new 4x4 camper |
#13
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oil pressure reads post-filter
Quote:
It shows that the unfiltered oil (a) goes through the oil filter and then to the turbo bearings (e), oil pressure gauge (e) and bearings (b). The pressure is measured from the filter housing, but there will be only a small pressure drop between where the gauge taps off and where oil is dispensed at the bearings. Sooo.. the designers were not stupid. They plumbed the oil pressure to read the pressure of filtered oil being sent to the bearings, which is the single most important measurement of the system to have. A restricted oil flow through the filter, would cause a drop in indicated pressure. That drop in flow can be from a plugged filter, one designed to restrict flow more (fewer pores in the filter media), or even thicker oil. Veg oils have been known to polymerize, thicking the crankcase oil (there's a small amount of fuel oil in the blowby gasses).. but I'd think that would be more likely to cause a rise in oil pressure by raising its viscosity. Sounds to me like you don't want to wait quite so long before the next oil change if you're still running veg oil.
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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png Broadband: more lies faster. |
#14
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This is my oil pressure at idle with the engine cold. When I rev the engine cold or hot it goes up to 98 psi. Notice that I tapped into the bypass part of the oil filter at thetop of the tubular stem. The oil pressure on the out side of the filter element was the same.
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84 300D, 82 Volvo 244Gl Diesel |
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