Hello All Great site. Can Anyone give a possible diagnosis as on my 98 300tdi the oil light has started to come on at idle now and again when at operating temp? If I increase the Revs it goes out. I am about to change the Oil pressure sender switch if it still continues what would you recommend investigating next? Any Help or Experiences welcomed I'm worried about Knackering the engine drying to diagnose the problem. so would like to find the cause ASAP. Many thanks

TDi have an oil pressure spring that can be adjusted to increase pressure. . Bit of googling should help you find it.

 

I would start by purchasing a new oil pressure warning light sender.
Make sure the crankcase is full.
If there is no change, the next step is to install an oil pressure gauge and check the real pressure.
I did a short thread on this about a year ago.

 

How old and thin is your oil ? Does the oil on your dipstick smell like diesel ?

Since you are in Hertfordshire I'd throw a new sender on and see if that remedies the problem. They are cheap as chips, aren't a very good design and are prone to failure.

 

Sorry to side hijack here. Have you witnessed slow senders? My oil light comes on at startup then turns off after about a second, then stays off. I have a new sender to install, just haven't felt like getting messy. Oil is nearly fresh 5W40 synthetic Rotella. Oil level is full.

 

I've actually just developed / noticed the same problem. I have a 12J engine (1984) and the oil pressure warning light flicks on at idle but goes off as soon as I tap the gas. The light does not come on while driving, only when idling / stationary.

The oil and filters have been in for ~3 months or about 2k miles.
I changed out the oil pressure sender so I doubt that's it.

The idle seems fine (not rough, etc) but is it possible my idle is just a tad slow and should be tuned up a couple RPM? I have no dash tach so I cannot report the idle rate.

Any suggestions/ideas welcome. Thanks!

 

Beware the cheapo senders, they really are crap... I had one that leaked oil out of the top where the electrical connection is!

 

You should also drop the oil pan and check for blocks in the oil pump intake screen.