Jetta TD Oil Pressure: Troubleshooting & Solutions

Hello everyone,

'I'm having a problem with my 1987 Jetta TD. When the engine is cold, everything is fine. However, when it's fully warmed up, the fuel pressure warning light illuminates at idle. This issue seems to disappear if I slightly depress the accelerator pedal, and the car then runs better.'
In addition, at higher speeds and at an engine speed of 2200 RPM or less, the lamp also illuminates, and a warning buzzer sounds.

So far, I have:
Oil change with filter replacement.
Both oil pressure sensors (0.3 and 0.9 bar) have been replaced.
I replaced the combination instrument (because I wanted one with a tachometer anyway).

The problem persists.

As soon as I press the accelerator and reach over 2200 RPM, everything is fine again.

I read that there's a relay for the dynamic oil pressure control, but I haven't been able to locate it yet.

Note: The car runs like a dream and doesn't make any unusual noises either!

Regards,

Hendrik.

How about checking the oil pressure sometime ? It might be possible that the light flickers when the oil is very hot (or perhaps just too thin), but the alarm at 2000 RPM shouldn't necessarily be ignored...

Dirk.

Hello,

The engines are quite inadequately equipped in terms of oil pressure . Even a new engine only develops just enough pressure to barely avoid triggering any warning contacts }}. The JR design has remained practically unchanged compared to the naturally aspirated diesel, meaning that the oil pump must now, with the same flow rate, also supply the oil nozzles for piston cooling and the pressure lines for the hydraulic lifters. VW apparently didn't see a problem with this. It is sufficient if the oil reaches the lubrication points in sufficient quantity; the load-bearing pressure of several hundred bar is then generated on the sliding surfaces through relative movement.
Initially, I replaced the connecting rod bearings and the oil pump on my car because I felt that the oil pressure was too low after installing an auxiliary gauge. Now it's slightly higher, but still quite low; it just barely reaches 2 bar at 2000 rpm and 80°C oil temperature.
You might consider installing an oil temperature gauge. I had cracks in the cylinder head between the intake valves and swirl chambers on my old CY-Passat (a common issue with TD engines without an external oil cooler), which were already more like craters. Somehow, the combustion gases were leaking into the oil, and I was getting an oil temperature of 130°C after a few minutes at a constant speed of 120 km/h, making the oil very thin. With the other cylinder head, it's now around 110°C at 120 km/h. If you have less than 1 bar of oil pressure at 80°C and 2000 rpm, I would recommend installing new connecting rod bearings (around €30). Otherwise, I suggest looking for a different cylinder head/engine/car... (depending on your mechanical skills/time/budget).


Best regards, Uli.

Here's a picture of the typical cracks we were talking about.


Warning: This file is 500 KB in size.

http://www.luxus-wg.de/~martin/auto_bilder/0242.jpg

Hello,

Before you disassemble the engine, try using 10W-60 oil, preferably Castrol RS (but the old version, not the new 0W-40). It should usually improve things and stop the knocking sound. Also, always keep the oil level at the maximum mark; a little more is also okay.

What experiences do you have with oil filters from different manufacturers? I currently have a Bosch filter installed, along with 5W-40 full synthetic oil.
I'm going to change the oil again and use the Castrol oil mentioned, but I'm not sure which filter I should get.

Regards,

Hendrik.

The filter manufacturer doesn't really matter; the important thing is that it's a reputable brand (like Mann, Fram, Bosch, Purolator, etc.).