W123 Oil Pressure Drop
 

Just nursed my 83 240D home. I was driving from gainesville,fl to starke to see Blackfoot in concert!! 10 minutes outside of town i notice my oil pressure gauge dipping. I've never seen it below 2 while at speed. I was going about 45 mph. Terrified, i pull over to turn around and head home. It continues to drop to a little below 1. I pull into a parking lot and as it's idling , the pressure goes back up!!! It stays up as long as I don't go above 35mph. at idle, it's pegged. At about 30-35mph it's around 2, Above 35mph it drops off quickly. I had just topped the oil off right before starting out on the trip. 2 weeks ago a compression test came back 300,300,400, 300. I have about 190k miles on her. I've NEVER had this car give me oil pressure problems. Also my understanding was that as a pump started to go bad, it was at low rpm when you would notice it first. Any clues, comments or suggestions gentlemen?(and ladies if there are any out there!)

Dale

How many miles are on her? Any leaks? Any unusual noises like a rod?

81 240d 140k rusty but runs great
85 300d 319k " its alive!"
85 300td 149k
83 300d 187k
84 300d 287 parting out

Sounds to me like the pick up screen may be getting clogged. The more suction the pump produces, the tighter it is clogging the screen? You could drop the lower sump and get a look at it.

First of all, stop driving it with this problem.

If you have no external leaks, I'd bet on the oil pump, pump pressure regulator, or clogged pickup screen/oil filter.

no leaks and no noises, 190,000 miles. clogged screen sounds like a nice problem to have. i'll drop the pan tomorrow and take a looksy and post back. thanks guys.

Dale

Alright. Got up this morning and figured I'd drive around and see if my problem was still there. Started up, pressure went straight up to 3 barr and stayed there. drove around for about 20 minutes, went to the auto zone to get oil for the change since i was going to drop the pan. NEVER dropped below 2 barr.
I dropped the pan and it is IMMACULATE. i mean i'd eat off of it. no gunk or sludge or metal bits. so i'll just clean it up a little bit and put her back together. This leaves me wondering what happened last night? can an oil gauge act screwy? it's a pretty simple device with no electrics involved. was my pump maybe sucking something up and eventually just digested it adequately so that flow resumed? did something maybe oclude where the sensor is? where is the sensor by the way? maybe i should pull that and look at it.
Thanks for opinions.
Dale

Oil pressure drop
 

You could always tee off the filter output with an additional line to a temporary real oil pressure gauge mounted in the cabin to confirm this is not just instrument error or malfunction but a real drop....the little holes in the linkage and the brass pivots can wear to cause erratic readings in these old gauges...never hurts to have a little more information...

[QUOTE=Dale240D;1321514] I've never seen it below 2 while at speed.

Does this mean your oil pressure gauge is NOT "pegged" all the time when you are driving?

Scretch that, I mis-read your post doh:o