OK so I just installed a new oil pressure sensor because it was the source if a new oil leak. Oil leak appears gone. Previously it was bad and pegged to 3 with key in POS 2. A new oil sender and working pressure gauge are new to me.

At first it operated normally, it went up from 2 to 3 when I rev'd or accelerate. Short test drive all good, longer errands run and after restart it started to act up.

First the gauge would not go higher than 2 and dropped to 1 at idle, which is not normal, but didn't seem out of odds.

Next, this morning added oil BC it was low, 1qt, due to previous oil leak. Now the gauge goes down when revving/driving and returns to 2.5 at idle.

I've read this is a failing pump, but the only change I've made is the sender and oil change the week before. Bad sender or what?

Here's a vid of what I see.

https://youtu.be/VwDc1gL5zXY

Dude, need to add context. We don't even know what year & model car you are talking about.

Sounds like an electronic sender. If so, sounds like perhaps a grounding or sensor problem. My 84 & 85 have a mechanical gage w/ nylon tube straight to the dash cluster.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Good point which I thought my siganture, which is not showing, would indicate. 87 300 TDT with electronic sender and gauge.

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Treetops
06 E320 CDI 127K Miles
87 300TD 231K Miles

99 E300 269K Miles-Sold

Check pressure with an external oil pressure gauge, then you'll be 100% as to what your problem is. At 212k miles, unless that engine was run without oil, or had sand in the oil, those oil pump gears will not be worn out. These oil pumps are ridiculously robust.

To me, it's just a bad sender. Not sure what you bought, if it's a cheapo I've had a few that were hit or miss and crapped out within 20 seconds.

Regardless, external pressure gauge and go from there. No sense in messing around swapping senders, etc just check with a gauge set and you're done.

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Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....

My guess is a defective new sender. What is the condition of the wire and connector to the sender? A mechanical gauge test is the best way to go but it may be easier to just replace the sender again particularly if you do not have access to a mechanical gauge.

Please complete the post when the problem is solved.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Change the O-rings on the tube of the Oil Filter. Tht also can cause oil pressure fluctuations.

0159979448 Oil Filter Housing O-Ring; For Tube at Oil Filter Canister Lid; 6x10x2mm

That is the same size as the 617.952 Engines.
Autozone has an O-ring assortment for about $8. Oil Filter O-ring/Gasket; For Tube at Oil Filter Canister Lid; 6x10x2mm; 0159979448
Dorman 172 piece O-ring Value Pack #799-450

In it are 24 of the 6mmIDx10mmODx2mmW O-rings that you need for the bottom of the Oil Filter Stem: enough for 12 O-ring changes if you use the same sized O-rings each time you change it.

You need 2 O-rings when you change them.

Also a loose electrical connector or wire can cause oil pressure fluctuaiton on ones with an electric sending unit.

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84 300D, 82 Volvo 244Gl Diesel

Those orings do NOT come with the Filter kit from the dealer if I recall correctly. I do have the harbor freight version of viton orings, but they seem to be US sizes not metric. Looking for a replacement as I don't have gauges.

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Treetops
06 E320 CDI 127K Miles
87 300TD 231K Miles

99 E300 269K Miles-Sold

These oil pressure senders sometimes are bad out of the box. I had one promptly fail recently. I'm actually back to running the original factory sender:

http://www.peachparts.com/shopforum/diesel-discussion/369025-photos-inside-oil-pressure-sender.html

None of the Oil Filter I have used on My Engine have the little O-rings in the kit; not just the the Oil Filters from the Dealer.

Lots of People don't know those O-rings are even there. If the leak the oil just leaks back into the oil pan.

Also inside of the Tube attacked to the Oil Filter Cap is a spring loaded Valve. I have never had mine apart so I cannot give details but obviously if that valve is being held open it is going to effect the Oil Pressure.

In the pic the green circle shows where the valve is and the orange circle shows where the 2 O-rings are.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

Got a new sender, Meyle, installed it and seems all good. No more gauge reading backwards. The 1st sender was a FAE. I did notice that with key in POS2 it did twitch up to .1...i.e. just hair off zero, then proceeded to act up.

The 2nd does not budge with the key in POS2 and seems to work just right. Ive read many times if the oil pres needle is jumpy or twitches with the key in POS2, its bad. I had no idea how bad it could be and given the cars age made me assume the worst.

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Treetops
06 E320 CDI 127K Miles
87 300TD 231K Miles

99 E300 269K Miles-Sold