Question 1:
Does anyone know what might cause an oil pressure gauge on my '95 E420 to drop momentarily to 0 while driving during cold outside temp then goes back up to 3. I checked the oil level and was fine and was changed recently. I am suspecting the oil pressure sending unit. any ideas? This only happened once while it was cold outside. No malfunction light came on.

Question2:
Is it easy to replace the oil pressure sending unit?

Question 3:
If anyone has specific instructions on how to change the oil pressure sending unit on a 95 w 124.034 (E420) would appreciate an e-mail or something.

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Joe95E420

I would say your definitely on the right track thinking it is a faulty oil press. sending unit. Do a search in the archives, or if my memory serves me correct, look at the bottom of your oil filter housing, you should see a single wire sending unit there.

Dale

flushing your engine with an over the counter engine flush and then change your oil. Sometimes sludge will build up in the engine and since the oil sender unit comes in contact with your oil... Please note that MB does not recommend engine flush but, it worked for me. However, my symptoms were different. Low oil level light on when turning (specially to the left) and oil pressure gauge would fluctuate. Obviously, before you do this, check ALL your connections.

By the way, were you driving in a straigh line when you noticed this? ANy warning lights on in the instrument cluster?

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J.H.
'86 300E

Yes, I was on the highway. Here are my conditions when this happens:
Cruising at 80MPH, outside temp was 40 degrees F and engine temp was 90 degrees C. This happened after about 25 minutes drive after the car sat outside for about 8 hours. The oil gauge dropped to 0 for about 10 seconds then it backed up to 3. No warning light whatsoever. I haven't seen it do that before nor did it do it again. I am keeping an eye on it and will check the connections to the sending unit whenever I get a chance (have to remove lower cover and crawl underneath car to do that).

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Joe95E420

hello to all
i had the same problem i change the oil pressure sending unit
problem fix

It seems that everyone i talk to about this incident tells me it is the sending unit that is staring to act up. I should get it in few days and will install it myself since it seems to be a DIY type of thing. Does anyone know if I will need a special tool to remove and install it? The thing has a weird shape ... see picture.

Attached Thumbnails

 

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Joe95E420

It's an easy task. The hex head on the picture is easily visible and accessable from underneath (17 mm., I think). Have the new one ready (with the aluminum crush washer for sealing) so you can slap it right in and not get much "moter erl" on yourself. Don't over torque.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

I hope the part comes with the washer you mentioned.

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Joe95E420

Joseph, this is really more in the realm of maintenance than repair. If you have an easy access to it (I had to remove the air filter housing in my 190), it will take you 5-10 minutes. No sweat.

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1985 190D 2.2l Sold-to Brother-in-law
1996 Mustang 3.8l -"thinks it's a sports car"
1988 Grand Wagoneer - Sold (good home)
1995 Grand Cherokee Ltd -"What was I thinking??!!"