low oil pressure light related to fuel pressure?

right this has been getting on my tits...........

couple of weeks ago i changed my vacum pump becuse ive been chasing this tapping sound. anyway tapping was still there, drove it 5 miles and the oil light came on at idle for the first time....

so i checked oil, fine. i replaced pressure switch, this made the oil light come on earlier than the old so proberly more sensitive.

got oil change, stayed the same.

the tapping noise is not excesive and do not believe to be anything major ie bearings....

i know i shouldnt but i have still been driving it as i do not have a choice, recently i have noticed when cold it takes a little bit of cranking to start and i ve been getting white smoke and takes a little while to clear then all is clear.

ive also noticed possible pulsing on the injector pipes...

i know i could but have not -

had the pressure checked by gauge
compression check.
dropped sump to check strainer, screen etc etc....

know can a fuel lift pump on the way out create low pressure to bring oil light on?

change the injector sealing washers - bet that stops the tapping

ok that can be looked into- thanks

also check the idle speed - it might just be a little low

Sean said:

also check the idle speed - it might just be a little low

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i have played with this, and below 1g the oil light appears, 1g or more it does not.....but it should not appear at all in my eyes....

The correct idle speed is 750 rpm and you shouldn't the oil warning light on at that speed. Does the engine being hot or cold make any difference as to when the light comes on?

James_300tdi said:

i have played with this, and below 1g the oil light appears, 1g or more it does not.....but it should not appear at all in my eyes....

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1g ?

how many miles has it done ? - it may well just be getting tired

Richard Martin said:

The correct idle speed is 750 rpm and you shouldn't the oil warning light on at that speed. Does the engine being hot or cold make any difference as to when the light comes on?

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yes, after a few miles after warming up it will appear and not flicker. basically hust as the needle hits the first line on gauge

Did this start happening after an oil change, or have you tried changing the oil and filter since it started?

yes have changed oil & filter but after this was happening and made no change

was it an original pressure switch or a cheap n cheerful one ?

Sean said:

was it an original pressure switch or a cheap n cheerful one ?

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dont know,

Rich I bought this of you?

I can't remember Jamess. What did it say on the bag? I know I got it from a reputable supplier...but anyhow the problem was there before and after the switch change, just a bit more after, so there's more to it than that.

ok,

well unsure then dont remeber there being a landy logo or anything....

can you not replace the oil light switch for an oil pressure gauge to see what your oil pump is performing like? could it not have a faulty oil pressure relief valve as i once had a bmw that did the same and it turned out to be a weak spring in the pressure relief valve?

Do oil pumps on 300TDI's wear out? Could it be that the light is telling the truth?

how about buy an oil pressure guage and test it

fanatic said:

how about buy an oil pressure guage and test it

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how about you read the original post, that was one thing I have not got round to doing

anyway semi good news!
I cleaned up the old sensor and it had a little bit of muck in it, stuck it on and wulla so new sensor was proberly duff and old was clogged! least I know I have not been knackering the motor at a alarming rate.....

know just left with this ticking and know convinced its noisey injectors.......so was going to try first-

injector cleaner/or ? a bit of petrol in me diesel?
then finnally new injector rail!

thanks for your time fokes

:dohh and the funny bit was-

i read a old thread and someone said take out sensor run engine and if oil comes out pump is not completly shot, anyway it was coming out on my flats carpark like a super soaker lol about half me oil :doh: