No Oil Pressure? 1.6 AEA Engine Help

Hello diesel mechanics,

I'm having a problem with a Volkswagen Golf 3 (Mk3) with the engine code AEA, a 1.6L engine producing 75 horsepower.

"As soon as the engine oil reaches its operating temperature, the oil pressure warning light (including the audible alarm) turns on. However, it goes off again when the engine speed increases."
Repair attempts already made:
- Oil pan removed and cleaned: No contamination was found.
- Ölpumpe hatte riefen auf den Zahnrädern => Ölpumpe wurde daraufhin gegen neue orign. Pumpe replaced.
- All bearings (main and connecting rod) inspected => no findings.
- Changed oil and filter myself.
All of this brought no improvement; the oil pressure at the cylinder head is up to 4 bar when cold, but drops to only about 0.3 bar when the warning light comes on. So, the oil pressure definitely decreases. I can therefore rule out a faulty sensor. If the sender line is shorted to ground (31), the warm-up indicator immediately goes off, which also eliminates a problem with the combination instrument and wiring.

Does anyone have any other ideas about this, or has anyone encountered a similar situation before?

I seem to recall that we've discussed something similar in the forum before. Back then, someone added oil that was too thin, if I remember correctly.

Therefore, my question is: What kind of oil is being used? Did you perhaps mean to do something special with it?

Greetings.
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It refers to a sudden and strong gust of wind.

Quote:

Therefore, the question is: What kind of oil is being used? Did you perhaps mean to do that in a particularly good way?

. This type of complaint is not uncommon with 5W30 oil. Additionally, there have been changes to the oil pressure switches that respond slightly later.

I would start by replacing the oil pressure switch and then change the oil to a good quality 5W40 or 10W40.

Of course, a mechanically sound engine is a prerequisite.

I had similar problems with a nearly identical 1.8-liter engine with an unknown repair history. In my case, the problem was caused by debris in the fuel line, possibly originating from a poorly cleaned and rebuilt cylinder head.