Audi 8E Old Oil Pressure Problem

Hello!

My neighbor brought his Audi to me today because he suspects there's a problem with the oil pressure.

Car is:
Audi A4 Avant, model 8E, manufactured in 04/2002.
Engine: OLD, 1984cc³, 96 kW.
Mileage: 130,000 km.

He's had the car for about 10 years. He only drives very short distances, about 1 km twice a day, and occasionally for shopping, etc.
The car is an oil guzzler; it constantly needs oil added, and therefore, he believes that regular oil changes are not necessary.

He told me that he drove to work early this morning, and before starting the engine, the clock display on the instrument panel had stopped working.
After driving for a few meters, the instrument indicated that the oil pressure was too low.
It then normalized on its own.

I looked at it myself just a moment ago.
First, I read the error codes.
The engine control unit indicated, in essence, "Please read the diagnostic data from the instrument cluster."
I then did that, and it reported a short circuit in the coolant temperature sensor (G 62). This error appears frequently in the car, often without any visible issues or problems. Anything else?
The car has always had a certain quirky electronic behavior.

Okay, so I started the engine, and everything seemed fine at idle. But when I slightly increased the RPM, the oil pressure warning light came on again in the instrument cluster.
The oil level is okay, and the engine isn't making any unusual noises.

I somehow need to get to the bottom of this.
I have already acquired a case containing a pressure gauge and adapters for measuring oil pressure.

Perhaps someone has a tip about the common problems associated with this engine. And where I should start.
The conditions under which the car is being used are far from ideal.

Furthermore, I'm not sure if it's related, but years ago, the drain on the water reservoir of the car was blocked, probably for a long time, until in the winter the brake booster was completely full of water and frozen.

Hello.

Is it a known issue with the engine when it's frequently used for short trips?
The entire oil pan is clogged with sludge, and the oil pump's strainer is blocked.
When the pump is idling, it may still receive enough oil. However, if the speed is increased, not enough oil will pass through the strainer, and the required flow rate will no longer be achieved.

Lower the front crossmember and remove the oil pan; you might be surprised.

Also, I'm also going to remove the oil pump and check the pressure relief valve, as it can sometimes get stuck due to such contamination. Even a look under the valve cover and into the crankcase can provide information about the level of contamination.
Continuing to drive like that for a long time usually results in bearing damage.


Have fun cleaning!

Regards, Mpire.

Hi!

The vehicle owner suspected a problem with the instrument cluster, as there were other unusual issues associated with it. He probably read it somewhere.

Today, I measured the oil pressure with a pressure gauge, and it's showing a nice 4 bar, which it's maintaining very consistently.

I installed a new oil pressure switch (according to , the engine only has one), but that didn't change anything.
The cabling appears neat and undamaged.

Are you aware of any problems related to the instrument cluster?

I told him about the oil sludge issue. He said that when the next oil change is done, he'll bring an endoscope from work and try to take a look.

Hello everyone!

Do you have the original VAG oil pressure test adapter, the one where the oil pressure sensor can also be reattached and connected for function testing?

Checking the oil pressure briefly and finding it to be within the acceptable range (as mentioned here) doesn't really provide conclusive information.

If you suspect a problem with the AI system, at the very least, the relevant data, including the status of the oil pressure switch, should be read out and evaluated.
That means: Even if you take a quick measurement with a pressure gauge, you still can't be sure whether there might be an oil pressure problem occurring intermittently during operation!

Do you have basic knowledge of (pseudo-)dynamic oil pressure control? Otherwise, I will send you some reading material.

Best regards from Munich!

Hello Diesel Bear,
Thank you for your willingness to help!

DieselBär30x wrote:

Do you have basic knowledge of (pseudo-)dynamic oil pressure control? Otherwise, I will send you some reading material.

We could do a quick knowledge check.
In my opinion,
Is there a...? Oil pressure control 2: Oil pressure switch.
Once, a low-pressure switch was expected to trigger at approximately 1000 RPM, corresponding to about 0.6 bar.
and then a pressure switch that, for example, wants to have a value of 1.5 at around 2000 RPM.
If these conditions are not met, a warning is displayed to the driver.
If there's something fundamentally new here, please let me read it!

Since, according to my search and the statement of the (experienced and reliable) parts service employee, this Audi only has a single oil pressure sensor (1.2 - 1.6 bar), and the engine maintains a stable oil pressure of 4 bar, I do not believe there is a problem with the engine or the oil pressure sensor, based on my understanding. I just installed a new switch.


My oil pressure gauge is a simple, universal part, unlike the VAG part you described.

I only briefly checked something on the laptop.
I reviewed the list in the AI system.
Regarding the oil pressure, there was something that indicated it, but it only showed me that the oil pressure was above 2 bar. So, it just indicated whether it was greater than 2 bar, yes or no, nothing more. Although the oil pressure warning light was illuminated at the same time.

I think I'm going to have to get a complete scan done on the car; something else seems to be wrong.
The battery is very weak. When the vehicle is turned off and the ignition key is in the ignition, the ventilation flaps may be operating continuously. Probably that's why the battery was dead this morning.

Hi.

It's important to measure the oil pressure when the engine and engine oil are properly hot, meaning the oil is extremely thin, as this will reveal the actual condition.

Best regards, Rüdi.

What actually came out of that car?

Hi!

After installing a new oil pressure switch, spontaneous self-healing occurred 2-3 days later.

Everything seems to be normal. Also, the other malfunctions in the instrument cluster have disappeared. Without doing anything to it.

Unfortunately, I haven't electrically tested the switch, but I suspect the issue was due to a malfunction in the control unit.

That was quite a few weeks ago now.
If anything changes or happens, I'll be the first to know.