Help needed!!!! - Oil warning light

[Stinky-Disco]

hey all, happy new year! Nicest day we have had all year dont you think?

I have a 300TDI Discovery Series 1. The old girl is an early 98 model and has an auto transmission.

That little red warning light came on a few days ago with the red oil light (pic of the oil dropper) was coming on intermittently. Topped the oil up to full (on 3/4 level when) level and thought she'd be okay.

I used 15w50 penrite to top it up but i cant remember what was in it from the service... (yes i know thats bad, although i know it was a penrite oil)

any ideas what the problem is?... there doesnt seem to be any new leaks...
the light was only really coming on when idling or breaking not while it was reving.

I checked levels and had a physical level in the engine oil cap replaced that. I then took her for a drive and the light didnt come back on. drove 3 hrs with not a problem the whole way.

does that red light mean just engine oil or alll oil levels? anyway i'm very unsure, im going to change oil, oild and fuel filters tomorrow.

any advice for me? or the problem?

Cheers Stink

[andylandy]

Hey Stink,

i had this problem on my 98 300tdi, near the oil filter , it's part of the housing, there is the low oil level sensor, take the connector off and clean it this should should fix the problem in the short term, the spade connector that runs through the sensors become loose and oil seeps out around it and at low rpm this breaks the electrical circuit, when the revs build more amps connects the circuit!

you may need to fit a new sensor at some point, about $50 if i remember correctly, though i just cleaned mine every few weeks and it lasted about 1year before i replaced it!

hope that helps

Andy

[dmdigital]

What he said. My Tdi Defender's switch actually started weeping. Clean around the switch and also check the state of the wire going to it. I had to replace both the connector and the switch.

[Leo109]

What them blokes said, but...

In the housing, just above the oil filter, is the switch they're talking about. It's actually an oil pressure switch, not a level switch. That's why it takes a few seconds to go off if the engine hasn't been started for many days or after replacing the oil filter - takes a few seconds to pump the oil around and pressurise the system.

As mentioned, you could try pulling the 1/4" spade wiring connector off the switch and cleaning the connector and the terminal on the switch. BUT, if this doesn't solve the problem, get the car to someone good with LRs because, if it really is low oil pressure, you may wreck your engine if it's not sorted out quick-smart.

By the way, I couldn't follow "I checked levels and had a physical level in the engine oil cap replaced that." Please explain???

Ian

[Blknight.aus]

yeah all the leaking pressure switch and failed pressure switch is good if its the case...


take it to a mechanics and have them fit a decent pressure gauge in place of the low oil sender and then check the actual pressure when its low...

in an old worn engine with an old worn pump with new oil you can have the pump out put so low that it cant maintain oil pressure, thicker oil will help in the short term, as will raising the idle speed, in the medium term overhauling the pump will help a little but at the end of the day the donk will need a rebearing.

if the pressure switch is on the way out and has started leaking in some instances the oil behind the bit of the switch that makes the light go out can raise the pressure required to get the light to go out.

generally with the exception of the engine not being started or an electrical failure of the switch, if the low oil pressure light is on your doing damage to the engine

[Stinky-Disco]

hey, thanks for your replys!

I checked levels and had a physical level in the engine oil cap replaced that is meant to mean "I checked the levels and had a physical look inside the engine block through the fuller cap opening and then replaced that after i wipped it clean when i replaced it" must have had a big space out when i wrote that.

yeh, ill keep you all posted on how it goes.
Stink

[PhilipA]

I checked levels and had a physical level in the engine oil cap replaced that is meant to mean "I checked the levels and had a physical look inside the engine block through the fuller cap opening and then replaced that after i wipped it clean when i replaced it" must have had a big space out when i wrote that.
Is it me?
I still do not understand.
There is a thing on the side of the engine called a "DIP STICK". Did you remove it and check the level of oil on it?
Was it low when the oil light came on?
How much oil did you add?

Regards Philip A

[87County]

fascinating thread....

in the 300tdi and for most engines of that era:

the oil indicator on the dash will light with the ignition ON if there is insufficient OIL PRESSURE....(not necessarily anything to do with oil quantity)

the engine sump dipstick will indicate if there is sufficent OIL QUANTITY...

TWO entirely different measures .....

... & I'm certainly not clear on whether it was pressure or quantity that caused the initial problem (or a poor electrical contact for that matter ... but the light did go off apparently)

[Stinky-Disco]

my appologies to all on not replying,... Everything turned out okay after i checked the sensor and it didnt bother me again. BUT...

It started again just yesterday and again today at no throttle in drive or neutral. The oil was changed about 200klms ago. Oil level is full and theres a new oil filter.

Now i looked at the spade connection and its pretty grubby, so im going to clean that as a first step and see if it goes away again, what im worried about is that theres more of an underlying problem to it all.

In reply to a previous post: I went from pressure to quantity because the book / manual says check the oil level when this light comes on and it makes sense.

Cost wise the switch doesnt seem to expensive... unless i have underestimated the labour involved.

Is this something i should have looked at by a profesional?

Can i confirm that the next option is the pump? And after that would be a rebearing... what are we looking at the costs?

[Stinky-Disco]

Is it me?
I still do not understand.
There is a thing on the side of the engine called a "DIP STICK". Did you remove it and check the level of oil on it?
Was it low when the oil light came on?
How much oil did you add?

Regards Philip A

It was 3/4 full when i checked it the very first time, i added 250ml to bring her to full and the light gave me no more problems. I was under the impression this fixed it but i asked on the thread anyway, i also checked the spade connection and it was fine - or so i thought.

[slug_burner]

stinky,

oil light comes on when oil switch/sender cannot detect enough oil pressure in engine. reasons for not developing enough pressure:

insufficient oil in sump causing pump to pick up air, pump is not able to pressurise air;

Pump is worn and not able to pressurise oil, or; (like trying to blow up a ballon when your lips don't seal properly, difficult to build up pressure)

engine bearings on crankshaft are too worn therefore not offering enough restriction to oil and pump can't keep up with the volume of oil required to build up pressure (i.e., oil is leaking out the bearings without much resistance due to the sloppy fit due to ware) (like blowing up a ballon with a hole in it, difficult to build up pressure)

Spinning the engine faster (off idle) spins the pump faster therfore increasing the volume pumped, if the volume pumped excedes how much is leaking out the bearings then the pump might have a chance of building up pressure.

Dave suggestted that instead of replacing the switch or as well as replacing the switch you install an oil pressure sensor to connect to a pressure gauge. That way you will be able to establish how much pressure your pump is developing under different engine speeds (quantitative mesurement instead of light on or off). This will hopefully indicate if you need to service your pump or if you need to overhaul your engine.

The need to overhaul your engine will be termined by a few other messurements as well like cylinder pressures (compression) and leak down tests, etc. Other tests to determine if overhaul is required will involve pulling down your engine to measure some components for wear.

How many kms your engine has done and how good a service history the engine has has will be pretty good indicators of the need for an engine overhaul.

Hope this clears up the questions you still have.

(Mechanics please correct as required)

[Stinky-Disco]

hmmm..

rightio, well the sensor is clean and fixed solidly. ... one thing i noticed when i start the car with the sensor disconected the red light doesnt show at all, even when ignition is on.... this is the same for when the car is running and its disconnected. When the sensor is connected it acts as normal,

i havnt taken it for a drive since cleaning it though. but im curious how i get a pressure sensor to test it? can i do it myself?

(sorry im a bit of a newb when it comes to this kind of stuff)

[slug_burner]

As I am not a mechanic I can't tell you for sure, but I expect that mechs might have a gauge they can hook up temporarily. The gauges I know about are the type that you place on the dash with a sender that taps into the oil circuit/pipes/internal galleries. Old gauges use a capillary tube to physically sample/feed the pressure to the gauge. New gauges use a sender that sends an electrical signal to a gauge that then displays a pressure value on the gauge/dial.

[Blknight.aus]

that oil pressure switch is on or off.

when the ignition is on and the engine is stopped there will be no oil pressure (well less than say 8psi which is an average turn off point for them) so the light will come on as the switch is closed.

when you start the engine the light will go off because the oil pressure has risen and turned the switch off.

if you have an intermittant contact or remove the wire the light will generally stay off.

IF you have a failed switch that has allowed oil to bypass internally it will not turn off or will require more pressure to turn off so it may indicate that you have no oil pressure when really you do.

changing the oil sensor is easy, usually you can get it with a shifter, correct ring spanner or socket. head down to supercheap, repco, landy dealer or anywhere else that sells auto stuff and tell them the year model and type of vehicle and they can generally look up your vehicle and sell you the appropriate sender.

I still think it is worth your while to head down to a mechanics (almost any will do so long as its not your average K mart type place) and get them to hook up (at least temporarily) an actual guage and see what the oil pressure is while the engine is hot and at idle.

[Stinky-Disco]

hey, Ive cleaned the sensor spade, used wd40... there was alot of oil and dirt in it, im going to get thr pressure in the engine tested next week, although since cleaning the sensor it hasnt happened again.

to be on the safe side im also thinking of replacing the switch with a brand newy...

another thought i had could be running 20w oil rather than 15w that im using now.

I normally use Penrite 15w40 but at the moment ive got in it gulf western 15w40. i personally think it looks a bit mear as an oil.. i can see the dipstick through it, while the penrite is as black as black can be!

anything else?