Morning all

 

I am looking for some advice on possible causes of the fault in the header, my 2002 1.9 tdi fabia has occasional low oil pressure warnings it only happens when I have been sat stationary for some time in traffic, so appears to be when then engine is getting warmer then normal. During normal driving conditions I never have the alarm and when I get underway again the alarm goes. I have tested the sensor on the filter housing and that is working correctly so this appears a genuine alarm.

 

I did a major service back in October last year (belts, coolant, etc) and have been changing the oil every two years as I only do 4-5k miles a year in it these days due to work vehicle being my primary mode. Car has done 148k total.

 

Can anyone offer any potential advice on cause? Has anyone had a similar issue before?

 

Thanks

 

David

 How did you test the sensor - was this by applying a pressure at a controlled value  - what pressures did you use as a basis for reviewing the result. This switch will probably be a very basic open/closed circuit with the change-over at a set pressure and not a pressure transmitter giving variable resistance dependant on pressure.

Test the radiator fans to ensure that the low speed function is operable.

Do this by linking pins of the radiator thermoswitch connector.

Pinout details can be provided if non-obvious. Does the car have A/C or not?

Edited 2 April, 20233 yr by Breezy_Pete

39 minutes ago, Locknuts83 said:

Morning all

 

I am looking for some advice on possible causes of the fault in the header, my 2002 1.9 tdi fabia has occasional low oil pressure warnings it only happens when I have been sat stationary for some time in traffic, so appears to be when then engine is getting warmer then normal. During normal driving conditions I never have the alarm and when I get underway again the alarm goes. I have tested the sensor on the filter housing and that is working correctly so this appears a genuine alarm.

 

I did a major service back in October last year (belts, coolant, etc) and have been changing the oil every two years as I only do 4-5k miles a year in it these days due to work vehicle being my primary mode. Car has done 148k total.

 

Can anyone offer any potential advice on cause? Has anyone had a similar issue before?

 

Thanks

 

David

 

The problem is your two year oil change schedule. Turbodiesels such as yours with a few miles on the clock tend to blow fuel past the piston rings, gradually this dilutes the oil in the sump to the point that it becomes too thin to adequately float the crank bearings and it leaks out around the bearing causing a drop in oil pressure, particularly noticeable when the engine is warmer than normal.

Change the oil and the problem should go, BUT you may already have damaged the bearings so it might not work.

1 hour ago, KeithCheetham said:

 How did you test the sensor - was this by applying a pressure at a controlled value  - what pressures did you use as a basis for reviewing the result. This switch will probably be a very basic open/closed circuit with the change-over at a set pressure and not a pressure transmitter giving variable resistance dependant on pressure.

Hi Keith

i used a mutimeter to test the voltage at the sensor to ground. From what I understand this is an on/off switch and not a potentiometer but hapy to be corrected.  
 

David

32 minutes ago, sepulchrave said:

 

The problem is your two year oil change schedule. Turbodiesels such as yours with a few miles on the clock tend to blow fuel past the piston rings, gradually this dilutes the oil in the sump to the point that it becomes too thin to adequately float the crank bearings and it leaks out around the bearing causing a drop in oil pressure, particularly noticeable when the engine is warmer than normal.

Change the oil and the problem should go, BUT you may already have damaged the bearings so it might not work.

Thanks for the advice I did think that a more frequent oil change might make sense i was going to try that over the next 12 months and see if that helps, might even do a 6 month change. 
 

David

54 minutes ago, Breezy_Pete said:

Test the radiator fans to ensure that the low speed function is operable.

Do this by linking pins of the radiator thermoswitch connector.

Pinout details can be provided if non-obvious. Does the car have A/C or not?

Yes the car has a/c i will give that a try. I have also discovered that there is a oil cooler below the filter housing that is recommended to be replaced so could be that?

 

David

Try the radiator fan test first, very common fault on VW group cars of this age, and will lead to higher temps in the conditions you describe.

 

Any old bit of wire will do for linking, the currents through these connections only power relay coils on A/C equipped cars, not the fans themselves.

 

Note that ignition needs to be on to test full speed function.

 

 

1 hour ago, Locknuts83 said:

I have tested the sensor on the filter housing and that is working correctly so this appears a genuine alarm

If the oil pressure switch is working correctly it's possible that the pickup is partly fouled. Sadly, the only way to (dis)prove that requires dropping the oil sump.

1 hour ago, Locknuts83 said:

Hi Keith

i used a mutimeter to test the voltage at the sensor to ground. From what I understand this is an on/off switch and not a potentiometer but hapy to be corrected.  
 

David

 

That still doesn't prove the switch is working correctly, it could still be flase alarm.

 

Getting a test gauge is probably the best way of checking the oil pressure before you go ahead and do anything drastic like take the sump off.

 

I would be quick about it though, I wouldn't want to drive my car about knowing that it has potential oil pressure issues.

Morning all

 

Thanks to everyone who provided advice on this topic. For reference to help anyone else who might come across this problem replacing my oil cooler solved the issue.

 

David

On 03/06/2023 at 09:00, Locknuts83 said:

Morning all

 

Thanks to everyone who provided advice on this topic. For reference to help anyone else who might come across this problem replacing my oil cooler solved the issue.

 

David

 

What was the issue with the old one?

On 06/06/2023 at 22:24, SuperbTWM said:

 

What was the issue with the old one?

 

Not 100% sure tbh I think that my increased oil change interval hadn't helped the cooler so I performed a flush of the engine with mineral oil before changing the cooler. All been working fine for 6 weeks now