oil pressure dropping on 16v...
 

in the 8-9 years i've owned my 16v, i've never seen my oil pressure drop below 3 bar. a couple of years ago, i needed a rebuild and opted for the 2.6 stroker kit with sport cams (276). so, i've posted questions on its tuneability, rough idle, and performance on this forum. so now, my mechanic got a new head tech who fixed my hard starting and rough idle - car runs like a dream (or the way it should have after the stroker to begin with).

however, i immediately noticed my oil pressure dropping after the engine is warmed up. on highway cruising speeds, it drops to about 2 bar. in traffic and idling, i see it closer to 1 bar. my mechanic said it needed an oil change (i use mobil 1), so i changed it > no major difference. a week later, he changed it to non-sysnthetic and charged me a pretty penny. no big deal, atleast the pressure is back up.

so, a month later: it's dropping again! is it really the oil viscosity? some people tell me problems with the oil pump or even the sump... at this point, HELPPPPPPPPp!

From what I’ve read and seen, oil pressure on the gauge anywhere between 1-3 bar is fine when you are at idle, but when you are driving (rpm over 1000) you should get 3 bar reading. Not sure if your car has an oil pressure sending unit, but this will be first thing that can cause funny readings. I changed mine once and it fixed my problems. It’s relatively cheap (~$40) and easy to replace. Hope this helps. Good Luck.

In normal conditions, I as well, have not seen my 16v oil pressure go down from the 3 position. Day or night, hot or cold, cruising in the highway, or in stop-and-go traffic the pointer remains up there. The only time it goes down is when I turn the engine off.

So for your 16v to behave this way in definitely peculiar. The previous comment on the sender could be considered but personally I think it could be an oil cooler or the oil cooler thermostat problem since the symptom occurs only when the engine warms up. In other words, it presents itself like a normal regular 190E with no oil cooler.

I would check the oil cooler and oil cooler lines for any kind of obstruction. I think your local Radiator shop can service it for you if needed. I would also check the oil cooler thermostat and the filter by-pass valve in the oil filter housing for any problem. The oil filter housing is a real pain-in-the-......... to remove so might as well do everything needed. Be carefull not to strip the oil cooler threads when you take the lines out. You can very easily damage this aluminum part which would cost a lot of $$$ to replace. The by-pass valve and the thermostat are very inexpensive.

Good Luck

Bernie
1986 190E 2.3-16

thanks all for the reply. i changed the sender with no success. my oil cooler and lines look fine... only other "weird" sympton is that my oil is thin - lost it's viscosity! after only a month! my mechanic said he could change the oil again, but that i'd be back or change the oil again next month. so, anybody??? i am carless and my mechanic is stumped too...

I wouldn`t worry about it. I believe the owners manual states anything between 1- 3 bars with a warm motor is normal. 1 bar at idle is fine, won`t cause any damage, as long as (as Joesph stated) it jumps to 3 bar above idle. Mine stays close to 3 bar at idle and if I get it really hot will range between 2 -3 bar.

Possible cause for a low pressure at idle??? Could range from something as simple as a leaky seal at the oil pickup tube in the pan, bad ground at the instrument cluster to worn main bearings.

Tinker

What viscosity oil are you using?

How did you or your mechanic know the viscosity had dropped???

This seems like a significant clue. Is the oil getting diluted somehow (by coolant or gas)?