M30 oil pressure light odd goings on

[jimbom30cab]

Strange goings on !

When I turn the ignition on the battery and low oil pressure light come on, as they should.

Then, when I crank the engine to start it the oil light goes out immediately whilst its being cranked.

Then, when the engine starts, the oil pressure light slowly comes back on, over the course of a second or two.

It's like it's the wrong way round!

There is plenty of oil being pushed around so I'm sure it's indication fault

My m20 works exactly the opposite, the oil light is on when cranking and goes off when the engine starts.

I'm pretty sure it's not the sensor as it worked fine in the donor car,

Could be a wiring issue.

When I disconnect the pressure sensor terminal with the ignition on the light remains on which the Bentley manual says is a wire being earthed.

I'm still using m40 clocks so need to change them first as it could be this.?

[jimbom30cab]

Update, I have changed the clocks to 6 pot clocks and also have fitted a replacement oil sensor

The oil light still goes out when cranking, then slowly comes on over about 3 seconds as the engine fires

Looking through the oil filler cap,shows plenty of oil splashing about from the end spray bar and center holes, well not gallons of oil but kind of a bit more than piss rate.

Odd

[mcbonio]

Must be a wiring issue, Unplug the oil sender and bridge the 2 wires on the harness, see what it does then.

[jimbom30cab]

Thanks mate

I might have another idea

The oil canister apparently has a plastic check valve. If let's say for arguments sake I got this power coated without taking the plastic check valve out it could lead to problems.

I got the idea from here

http://www.bmwe34.net/E34main/Trouble/OilCanister.htm

Obviously I wouldn't be so stupid to do this

[mcbonio]

LOL

You had the inside of it powder coated?

[Rav335uk]

You didn't have it powdercoated inside

[jimbom30cab]

No but the heat may have destroyed the valve as it is plastic, I'm just guessing though.

I'll open the canister in a tic as if its empty then the check valve is bust.

[Rav335uk]

Powdercoating oven is at about 230-240 degrees

[jimbom30cab]

Yer, I can't see anything plastic surviving in that especially something moving with tolerance like a valve.

Anyone have a spare I could purchase?

I just opened the canister, it's full of oil, I'll have another look in the morning

I've still not ruled out an electrical issue as its very odd that the light behaves EXACTLY the opposite than it should.

[Rav335uk]

I don't think it'll be an electrical issue, if it was a short somewhere, the light would be on constant.

It's defo a pressure reading issue.
And it's not listed as a seperate piece on RealOEM.

[TPS]

Sounds like a similar problem to mine, but mines an M42.

[jimbom30cab]

I think that sound right Rav

I read this on the Internet

OP... The canister will drain if you pull the center bolt out, that is normal. The little o-ring on the bottom of the bolt seals it up. It shouldn't drain back once closed up though.

Is this true, as when I open my canister the oil stays level, I'm thinking it could be the oil I poured in on initial fill and that the powder coating has blocked the oil ways?

What's do you think?

[jimbom30cab]

Tomorrow I will drain the oil and see if the level drops in the canister.

Need to get a new or replacement canister ASAP

Just a hunch but I bet the pressure sender is directly downstream of the canister. If the canister is blocked then the sender will get no pressure.

My money is on a blocked canister.

Bugger

[jimbom30cab]

QUOTE : "Must be a wiring issue, Unplug the oil sender and bridge the 2 wires on the harness, see what it does then."


Chris, my pressure sensor has only one single wire

[Rav335uk]

You can put an oile pressure switch onto the canister from the RealOEM pics.

[jimbom30cab]

Oh yer, nice spot mate, I might put a switch in there, jumper the connector to the loom connection and see if that turns the light out

I guess looking at its location, it's just before the filter and valves so it should receive full oil pump pressure

i'm defo going to change the canister if I can find a replacement one also

[Rav335uk]

Lee still has his, i'm sure the last buyer pulled out.

[jimbom30cab]

Cool, could you PM me a number I could drop Lee a text on please?

[Rav335uk]

He's replied to your post JIm.

[jimbom30cab]

got it thanks mate, have sent Lee a PM.

I'll get my canister off first think in the morning and have a look at it.

cheers guys

[jimbom30cab]

ok guys , I've got the oil drained, cam cover and oil filter housing off

all in the head looks just fine





oil in here



when I took the cap off this there was still loads of oil in so the check valve should be ok (unless its blocked) , i'll test it soon

[jimbom30cab]

I drained the oil through this filter to check there was no debris in the oil

happy days, all looks ok, just some fluff there from where I wiped the drain pan before hand



i'm going to get another filter housing anyway to rule that out, Lee has one which has connections for a cooler, if they are easily blanked off that will be just perfect.

plan is to replace the housing, fill her up with oil, add a pressure guage to where the pressure sensor goes and see what oil pressure it's making.

If it makes good pressure then it must be an indication fault. If the pressure is weak then....well I've got real problems then.

can't think of much else to do really ????

[jimbom30cab]

ok here's my theory

I found this pic on the net of the inside of another oil filter housing

the yellow arrow if is the check valve (ignor the red circle) sorry its a crap picture



now here is a pic of mine




yellow arrow again - no check valve it appears (defo something missing)

and the blue arrows point to 4 recesses which are not being used so I must be missing a bit

I also read on the net you can push it down with a screwdriver to allow oil to flow down and prime the pump - I can't move mine at all

maybe this missing bit came off when the powercoating was done?

new filter housing needed me thinks !!

Lee, would you be able to have a look at your one for sale and see which picture it resembles? well appreciate that mate

[Rav335uk]

If the check valve is stuck, wouldn't you get a build up od pressure???
The only other thing I can think off is to do a pressure check, or did you fiddle around with the oil pump????
I.E. take it apart to clean it up?

[jimbom30cab]

fiddle around with the oil pump

nope, all I did was take it off, look at it and think "sod that" and put it back on again. The pump should be ok as there is loads of oil coming out the spray bar (I hope) mate

[Rav335uk]

Oil pressure test then with a good guage

[jimbom30cab]

will do, Phil (TPS) is coming round on sunday for the show and is bringing his guage.

[jimbom30cab]

quick update

I re-fitted the filter canister but with no filter in it

topped up the oil - all of it through the cam cover fill cap - the oil filter housing was bone dry

flashed her up

all sounded fine, oil pressure light still on though

only ran for about 5 seconds

opened the filter housing and it was full of oil

so I guess the pump is working ok

I need to pressure test the sensor connection next

now I might be imagining this but the oil pressure light was definitely brighter where as before it was kinda half brightness when running. With no filter fitted it was full brightness like when the engine is off

i'm really thinking I have an Australian oil sensor, it seems to do exactly the opposite that it should be doing.

if the pressure guage indicates good pressure, it's good bye OEM pressure switch (and bulb in the dash) and hello new oil pressure gauge in the cabin.

I'll change the oil filter housing anyway to rule that out and pick up a brand new OEM oil pressure switch whilst out and about tomorrow.

[jimbom30cab]

I know you're all probably getting really bored with this now....but..

the Oil pressure sensor (OPS) should have continuity with ground when the car is off

mine doesn't

the OPS should then go open circuit when oil pressure is satisfactory

mine is always open circuit even when not running

the OPS should be supplied with 12v when the car is running (so it can work)

mine is supplied with F all.

so all in all i'm feeling a bit let down by this OPS circuit the F'ing piece of Sh1t. !!!!!!!!!!!!!

me thinks there is something odd going on with my electrickery and if I can somehow convince the system to supply a nice 12v when the car is running I might actually be less blinded with warning lights when driving.

internet research to find a M30 DME1.3 wiring diagram next...

[jimbom30cab]

by the way, I thought i'd write everything down here as one day it might help someone, but i think its clear that here is nobody in the whole world as thick me

[mcbonio]

Sounds like your OPS is faulty Jim. You sure you didn't powdercoat it?

Swap it out and try that.

[jimbom30cab]

Chris, I think you could be right

I've got the circuit diagram here

It is dead simple

The wire from the OPS goes to c101 pin 5

From there is goes to the blue plug on the back of the instrument cluster, pin 18

The blue plug is also supplied with 12v from fuse 10 into pin 23 of the same blue plug

The only thing between pin 18 and 23 is the red low oil pressure light LED

So, I need to

1. check fuse 10 is not blown
2. Check for continuity between pin 23and 18 of the blue (noted as c1 on the drawing below) plug with the ignition on
3. Check for 12v at pin 23
4. Check for continuity between the c101 plug pin 5 and the blue instrument plug pin 18
5. Check for continuity between the OPS plug and pin 5 of the c101

There is nothing else according to this diagram it could be then apart from a duff OPS

I've had 3 cans of Stella so on a mission

Bugger, also run out of smokes

[jimbom30cab]

[Rav335uk]

I can't help tonight, I've just walked in from the pub

[jimbom30cab]

Pub and new tools , all in one day, check you out !!!