Ah ha... ok, good to know. I am used to the actual line on the 300D models I've owned. I wasn't aware that the SD's used electric gauges for the oil pressure. Thanks!

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.

Don't remember the size. It wasn't in my kit. Think I found it up the street at NAPA. Just take your sender and your gauge connector to a real parts house so they can match up what you need.

__________________
1998 E300 +310,000K
1996 E300 +460,000K

I just took a look under the oil fill cap and watched the cam oil squirters and it's getting plenty of flow. That's at idle where the pressure gauge reads zero or close to it.

So I take it that the gauge reading is off or I wouldn't be seeing that.

But it'd be a good thing to fix that anyways. I noticed the tach isn't working either so I may have gauge electrical issues.

__________________
-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.

Those (85's) have an OVP relay, I believe it's with the rest of 'em under the fuse cover. Check the one with a red top, there is a fuse that may have blown. You might get your tach back.

__________________
83 SD

84 CD

The tach inop is most likely due to the tach amp issue. The fix involves unscrewing the amp cap (located on drivers side inner fender)-pull the plug out of the cap and place a shim between the cap and the plug. Then reinstall.

__________________
81 300D Turbo 190K sold
83 300sd 319K best $500 I ever spent-daily driverw/ 2 tank WVO set up

^ MB changed that system in 1984, no more amp.

__________________
83 SD

84 CD

The 85 also has a KLIMA relay in the mix, but I do not know it's location.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

1985 300SD
In the rear of the fuse box.

Also chasing zero oil pressure at idle issue with OM617 in W123. Mechanical gauge with oil feed line to gauge. Oil pressure hits full off idle above 1000rpms.

I believe I replaced the o-rings in question at last oil service a few months ago. I can replace them again just for kicks.

Any other suggestions? oil pump? drive chain? (I cant see how the chain would cause this.)

__________________
85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

Could still be sub standard gauge in dash. Remember the normal pressure above mid rpms is always pinned. That is caused by pressure higher than the gauge can read.

Just because your gauge is touching the third mark at higher speed does not mean that it is not still reading low.

As mentioned before by Hunter you have already changed the old oil rings on the filter stem. Or at hot idle have a quick look to see if oil is still being supplied at pressure through the oil filler cap hole. I went back and see you have done this.

The electrical oil pressure sensor is highly suspect from your description as already mentioned I believe.

To the OP with 300SD, if indeed you have an electronic sender, replace that. When they age, they read lower and lower.

Renntag, you'll want to "second opinion" the oil pressure gauge as well, feed comes from the oil filter housing. If the pressure is at 0.5 bar at idle (is your idle speed too low?) and reaches 3 bar by 2000 RPM, you're OK.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

what size o-rings are on your filter?
should be 6mmid, 2mm wall, and 7mm id, 2mm wall.
EVERYBODY keeps saying 6mm is right for both. I disagree. the 6mm is stretched really thin on the upper groove.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I have only used the o-rings that come with my filter. Where can I source just the two you mention?

__________________
85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

397 Piece Metric O-Ring Assortment
http://www.harborfreight.com/397-piece-metric-o-ring-assortment-67580.html

Listen to VsTech first... be sure those are correct AND that the tiny hole down the center of that tube is clean and open.... critical to oil everything in these engines...
Then if there is still a problem one thing the FSM says is that the screw in oil pressure valve on the back side of some of our engines can fail or even fall off... this might allow the symptoms you mention.. 2 at high rpm.. but 0 at idle....
When you do replace it be sure you have the latest recommendation.. there are at least 3 designs or pressure changes over the years... all shown in the FSM of course..

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html