Should i worry?

[JohnHA]

I am concerned that the oil pressure & level gauge on my BX GTI appears to be sluggish. From cold, switch on, the dash lights up like Concorde & the needle of the oil pressure/oil level gauge rises to between no's 6/7.
Crank the engine & the needle falls back to zero, engine starts, all lights out except oil gauge, 15 to 20 secs later needle rises to about 6+ & the light goes out. Everything A O.K. Nothing lights up whilst driving and when starting the engine whilst hot, lights go out & needles rise quickly.

What do you think Guys, should i worry or am i fussing over nothing?

[Philip Chidlow]

Hi

It is my understanding that when the oil pressure guage lights up initially it is indicating oil level and when the light goes out, that's oil pressure. Nothing to worry about so long as the needle's over the right hand side of the dial!

[Philip Chidlow]

I should add that when at idle the needle does sit lower on the dial. But if your is anything like mine, one day it'll be up between 6 and 7 and later on in the day it'll be around 5 and (at idle) rest at 2, before suddenly deciding to be more optimistic towards the top end of the dial again..! French electronics, and it's age, I guess. I do check oil levels regularily, just in case!

[Way2go]

Phil, your last post relates to oil pressure. When the white backliight is on the guage should be reading oil level.

Sounds like John may have a sticky relay as the light and meter changeover from level to pressure should occur at the same time.

[jeremy]

Glass's technical service data for 1989 states that the oil pressure for the 8 valve GTi should be 3.5 bar (51 psi) at 4000 RPM. This would of course be with the engine fully hot.

The presssure for the 16valve is 2.0 bar (29 psi) at 850 rpm and 4.8 (70 psi) at 3000 rpm. This figure is NOT comparable to the 8 valve as the 16 valve has a much bigger oil pump (same as the TD)

jeremy

[Stewart (oily!)]

The guage reads oil level with ignition on engine not started, then upon startup after a delay? it reads oil pressure.
Stewart

[Geoffrey Gould]

Worried about low oil pressure, turn on the head lights and gain 15 psi. French electrics pah.
Cheers.
Geoff.

[JohnHA]

Thanks everybody for your expert help.
Phil, my gauge acts a bit like yours,it pleases itself!
Way2go,i will get the relay changed but i am still not clear how the bl--dy gauge indicates pressure and level. If i have the engine ticking over & have to wait 15/20 secs before the light goes out & the needle moves, surely that dosn't mean for that period of time i have no oil pressure and Stewart, how long a delay?
I know i seem thick but bare? with me.
Regards, John.

[jeremy]

The oil gauge itself has no influence on oil pressure - disconnect it and the pressure will remain unaltered - as the oil pressure is a measure of the pressure in the engine's lubrication system. The pressure measured is the pressure as the oil pump tries to force oil out through the bearings and as I'm sure you will appreciate this is purely a mechanical/hydraulic process - with no electrical components at all.

Your car is also protected by the oil pressure warning light, which is also used to power a check system for some of the other warning lights to provide a test function when the ignition is turned on - extinguishing shortly after it starts - with the oil pressure warning light. This means that the 'STOP' light is operated by the oil pressure light as well as the hydraulics, possibly the temperature warning light and possibly the coolant level.

The pressure at start (generally high as the oil is thick and cold) and the idle pressure (often low) is of no concern - its the running temperature that matters and Citroen have been thoughtful enough to provide you with an oil temperature gauge to help you wait until the oil has reached running temperature before extracting full performance from your engine.

jeremy

[Way2go]

Hi John, don't worry this part of the circuit is a compound one so is not easy to follow on the schematics.
Firstly, the switching "relay" is an electronic module inside the instrument cluster so will not be the easiest thing to change but is may to be at the root cause of the problem. This same circuit analyses the output from the pressure sensor to give the output to the meter when in "pressure mode". If the pressure sensor on the engine is sticking when cold this will also give the same problem you describe and is probably an easier first course of action to clean or replace.

There are four things to observe on this compound meter:
1) A red light at the zero end of the range.

This will be on when you turn the ignition on & will go off when the engine is started indicating oil pressure is "safe".

2) The white backlight "in the groove"

This is ON when reading Level, OFF when reading pressure

3) Meter Oil level indication mode with backlight ON

Should give reading when ignition is turned on then change to pressure mode after a couple of seconds or so of the engine starting.

4) Meter Oil pressure indication mode with backlight OFF

Should read the oil pressure as soon as the white backlight goes out.
Reading is usually high at cold then will give varying indications at warm depending upon engine revs.


Good luck John but doesn't sound if you have anything to worry about with actual oil pressure so long as the light going out 15-20 seconds later is the white one.
If its the red one you do need to check out the actual mechanical oil situation urgently!

[mat_fenwick]

Glass's technical service data for 1989 states that the oil pressure for the 8 valve GTi should be 3.5 bar (51 psi) at 4000 RPM. This would of course be with the engine fully hot.

The presssure for the 16valve is 2.0 bar (29 psi) at 850 rpm and 4.8 (70 psi) at 3000 rpm. This figure is NOT comparable to the 8 valve as the 16 valve has a much bigger oil pump (same as the TD)

jeremy

Are these figures minimum pressures? My TD (when hot) reads 4 bar at idle and 6-7 when revved (add up to 1 bar depending on electrical load!)

I think what might be happening, correct me if I've missed something but before the engine starts, oil level is OK - then after the engine is started but before the pressure gauge starts reading (i.e. backlight still on) the effective oil level drops as it is circulating round the engine.

[jeremy]

Oil pressure a bit in excess of a stated figure is nothing to worry about - and in fact can be regarded as normal. The high speed figures may in fact be the opening point of the pressure relief valve.

Very high pressures can be an ndication of serious problems - like a blockage.

[JohnHA]

Hi Guys,
Thank you all for your interest in my "worry", with all your replies, you have put my mind at rest. I have copied everything so i can "read, note, and inwardly digest". Regards to all!
John.