Oil Pressure Problems 87 190D

Oil Pressure problems, on my 87 190D I just started to experience a drop in oil pressure at highway speeds while underway for at least 10 minutes. The gage on suddenly starts to creep from the normal 3 reading through the two's and to zero, and subsequent to zero the oil warning light also illuminates. The first time this occurred I stopped, and checked the oil, which was reading full. When I re-started the car the oil pressure went back to the normal 3 range. However, on the highway on the way back the same thing occurred. Is this indicative of the sending unit in the sump going bad, the sending unit on the side of the oil filter housing, or pump failure. The oil and filter are changed religiously at 3000 mile interval. Owned car for last 100K miles and never seen a oil pressure problem.

87 190D 203,000
87 300SDL 119,400
99 F350 Super Duty

[chowpit]

I would start by connecting a manual test gauge where the sending unit is located and proceed to drive the car the necessary distance it takes for the problem to occur. This will eliminate the gauge in the cluster and the sending unit as well as determining if you in fact have a problem.

Chowpit, thanks for the reply I will pick up a aux guage at supply house and give it a try this weekend. This problem is making me nuts, never see it driving around town, just when on the expressway. Since the W201 is my daily driver I am very concerned about a possible oil pump failure. I am hoping for the 500K club for this fine automobile.

[MBenzNL]

I would go for the sending unit. I had replaced the sending unit on my former 190D once and this renewed little rascal gave a reading of 0 every time I got of the autobahn after driving at 140+km/h speeds.
The first time it scared the hell out of me. I opened the windows to listen to the engine, but it definitely sounded like it was still enjoying a good oil pressure.

greetingz,

MBenz, I am hoping the issue is a sending unit issue also! The one in the sump is a easy swap out, just replaced the O-Ring last oil change. However the sending unit on the back of the oil filter canister looks impossible to get a wrench in place to remove. I just happen to have a complete spare motor in the garage (long story), I think I will borrow the sending unit from the oil pan and see what happens.

I am with you when I saw this happen it freaked me out as well and went through the window exercise also. Seemed to be no change in the music.

I have a thing for getting the little car to triple digits as part of my after work purge ritual, it feels great!

[MBenzNL]

Originally posted by petef
However the sending unit on the back of the oil filter canister looks impossible to get a wrench in place to remove.

It is not impossible, maybe a bit difficult...I know what you mean! It is nearly impossible (but still possible though) to get a wrench on that nicely hidden sending unit.

greetingz,

MBenz, Done! I swapped out both sending units Sunday morning with an oil change. The one on the back of the oil filter canister was truely a pain. Easy to get off since it was loose and 1/8th of a turn at a time to put back. I only wish that I would have replaced it with a new sending unit. I borrowed from a spare engine that has 120,000 miles. Well I will get replacement and swap out with new one on my next oil service. This seems to have resolved my pressure problem, I will post after I can put 20 - 30 miles at consistent highway speeds.

I have a new issue that I believe I caused myself somehow. Since I completed my wrenching Sunday. The motor does not shut itself off when the key is removed. Any clue as to what I have done. I was foolish and did not remove the battery cable when I started and subsequently hit the positive side of the solinoid whith the 17mm when re-installing the oil sending unit. Well the stop lever on the fuel injection assembly does what it is supposed to, however I am baffeled as to what needs to be done to get to a more expedient method of shutting off the engine.

[P.E.Haiges]

Check the vacuum lines to the injection pump. The shutoff line is probably brown.

P E H

[MBenzNL]

Right,
I go with P.E.Haiges. You probably disconnected one of the vacuum hoses to the engine shut-off valve...
It is possible that the vacuum pod itself went bad, but that would be a real coincedence.

I presume that you didn't do anything under the dash (near the ignition lock or so)?

BTW: If this sending unit functions well, I wouldn't bother to exchange it for a new one. This used sending unit may last for a long time.

greetingz,

I will check on the vacum lines this evening. My hands and arms seem to be too big for this type of work. I find wrenching more rewarding than my gig in the software industry.

Did not go into the dash, however any advice on how to replace dash lights, the one that illuminates all of the fuel/water/oil gauges has failed. Is there a tech trick for easy replacement.

BTY it looks like you have a twin to my 87 diamond blue SDL in the background of one of your photos.

[jgauto]

Hello fellow 87 190D owner. I absolutely love this car. This is actually my second. The first was totaled after owning it for 3 months and I have had the current for about 4 months.

My question is: What are you getting in fuel mileage? I'm getting about 24/29.

Yep, great car had mine for 9 years and almost 100,000 miles. Car is great on fuel! I currently get 470 - 490 miles betwen fill ups. Have not done the math in some time, but I expect a little over 30 mpg. And I drive it hard with little or no expressway time. May want to check that air/fuel filters have been changed within last 15,000 miles. I change all filters once a year including transmission.

I thought so much of the car, and wanted more space for trips weekends, I bought a 87 300SDL for a weekend driver 5 years ago. The S class gets 24-25 mpg.

[MBenzNL]

pete,

The car on the background is a 1993 silver 190D with class interior (you have a trained W201 eye).

The best way to get the dash cluster bulbs replaced is to start with removing the lower dash panel (5 screws and one (plastic) nut in total). Remove the plastic outer vent hose and additive piece at the side of the heater house, unscrew the speedo cable and push the dash cluster to the front (from the back). Personally I prefer this method to pulling the dash cluster with hooks.
When the dash cluster is pushed to the front, you can take off the plugs and connectors and replace the bulbs with new ones.

greetingz,

Well, I found the culprit on the top of the vacum block as you suggested. Problem resolved. I will try your dash technique this weekend.