zu viel Öldruck keine Kompression AFN | Posts 16+

From the VW repair manual:

- Screw the test device into the cylinder head instead of the oil pressure switch.
...
- Increase the speed further. At 2000 revolutions per minute and an oil temperature of 80 °C, the oil pressure should be at least 2.0 bar.
- At higher speeds, the oil pressure must not exceed 7.0 bar. If necessary, adjust accordingly. Replace the oil pump cover with a pressure relief valve.

The values are specified as being based on an oil temperature of approximately 80°C; therefore, they may be somewhat higher when the oil is cold.
So, the measured 6 bar at cold temperature is fine.

"We had the exact same problem with the 1.8T engine in my sister's A4 B5. The engine would start normally and run smoothly at idle, but it would stall when the RPMs were raised above 2500. It was impossible to restart the engine; it would just spin freely without any compression." After a waiting period of approximately 20 minutes, the engine could be started again.

After replacing the oil pump, the problem was resolved. The pressure relief valve on the old pump would get stuck around halfway through its travel, which meant it couldn't release enough pressure in cold conditions, when the oil viscosity is higher.




Regards, Mpire.

Assuming the oil and oil filter are in good condition (what kind of oil are you using?), I would replace the oil pump with the pressure relief valve. Measuring won't really help you much. It is, of course, still possible that the hydraulic lifters are too tight when the engine is cold.
hg
Herbert.

Quote:

From the VW repair manual: - Screw the test device into the cylinder head instead of the oil pressure switch. ... - Increase the speed further. At 2000 revolutions per minute and an oil temperature of 80 °C, the oil pressure should be at least 2.0 bar. - At higher speeds, the oil pressure must not exceed 7.0 bar. If necessary, adjust accordingly. Replace the oil pump cover with the pressure relief valve. The values are specified as being based on a fundamental oil temperature of 80°C; therefore, they may be somewhat higher when the engine is cold.

The pressure relief valve opens at a pressure: 5.7...6.7 bar overpressure at the valve. Interesting - it's supposed to measure approximately 7 bar (which is 100% of the total pressure) at the ZK (presumably a specific location or device), and certainly not at 80°C.
It seems there's probably a bug in the documentation...

Autoservice wrote:

The pressure relief valve opens at a pressure: 5.7...6.7 bar of overpressure at the valve.

Okay, that's also stated a few lines below the quote I provided.

Quote:

Interesting - it's supposed to measure approximately 7 bar (which is 100% of the total pressure) at the ZK (presumably a specific location or component), and certainly not at 80°C. It seems there's probably a bug in the documentation....

No...
The pressure regulator's wear limit is 7.5 - 8 bar. However, it cannot be determined without expanding it, therefore the measurement must be taken at the central unit.
It's quite good.


I consider it absolutely possible for a control valve to become stuck.
I've only experienced this issue with the 827 models on engines that don't have hydraulic lifters, and in those cases, the seal on the oil filter blows out.

Quote:

I consider a stuck control valve to be absolutely conceivable.

But what would contradict your statement is if the measured pressure at the ZK is 6 bar.

No... Why?


At the time of the measurement, it was functioning perfectly.
The valves sometimes tend to get stuck.
That's the fatal thing about the error. You can actually only detect it if you constantly use an oil pressure gauge. Then you suddenly see a significant fluctuation in the oil pressure.

Okay, I'll go ahead and replace the oil pump; it probably won't hurt.

"I still hadn't had time to change it, but since then I've been careful about how much I accelerate, and so far I haven't had any problems..." But on Saturday, I'm going for it...

Is there anything I should be aware of when changing [something]?

Quote:

Is there anything I need to be aware of when changing it?

Yes - Cleanliness. You might need to adjust it slightly until the motor engages with the vacuum pump.
And you should prime the pump with oil beforehand.

Hi, was it the oil pump?