Oil warning light - Page 9

Crossle · 05-08-16, 08:49 AM

It does follow the pressure, 100%. The pressure pretty much goes up and down inline with the rev counter when at a standstill. When on the move its constantly between 4-5 bar and doesnt dip below that even at low revs. It literally only when drive is disengaged that the pressure then follows the throttle movement.

Where is the pressure ball then?

The history that I know of the car is that the head gasket went and it very recently (maybe 2-3k miles ago) has had the head rebuilt, new valves, gasket etc.

esseff · 05-08-16, 10:59 AM

The pressure relief valve is a spring-loaded ball that seats against a mating face. Oil pressure pushes against the ball which will only move a certain amount against the calibrated compression spring, allowing the oil to pass. Sometimes the ball seat is worn by chattering or there may be a particle of something holding it off, allowing oil to return to the sump all the time. That's why the oil pressure indication will follow the revs.
Here's a generic diagram:

Maybe when the engine was rebuilt some debris got left behind and ended up in the lubrication system.

Something to think about.

sinbin5t · 05-08-16, 12:53 PM

Quote:

Originally Posted by Duffy3074

The basic mechanism is easy enough, there's wear or a fault that's allowing the oil to go where it shouldn't hence the drop in pressure.
The oil relief ball wouldn't cause smoke, just a drop in pressure. Bore,valve guide, crank bearing wear are the worst case scenarios.
A compression test would be next on my list of things to do.

I agree with Duffy i am afraid, i really hope one of the above is not the problem but my mate had already mentioned these, i just didn't want to put anything after making a cobblers of things earlier

Fingers crossed for you Scot

Duffy3074 · 05-08-16, 01:41 PM

Has it occured to you that there was hee-haw wrong with the sensors and that they were just reporting, accurately, the real situation?

You can overthink these things quite easily (unfortunately)

Crossle · 05-08-16, 05:15 PM

I am thinking there is nothing wrong with the sensors now yes. Probably the point where I started to believe the sensors is when I saw oil smoke coming out the exhaust as the oil pressure dropped away! The fact that I've now got two signs of oil problems does kind of point to the fact that there might be a problem!

Dont really know what to do to be honest, I'm not in the financial position to start pulling around with engines and I dont have the mechanical ability myself to start tinkering around. As it stands the car runs quite well as long as I keep the revs up when hot which isnt difficult on my daily run to work and back. I'm thinking if I can stop the oil light coming on when hot which probably requires about an extra 0.2 bar out of it to just bring it safetly above 1 bar then I might just use it for the rest of the summer and flog it on. I didnt go out to buy a project and while I appreciate old cars need maintenance I'm more thinking along the lines of Suspension joints and wheel bearings as oppose to cranks and sumps lol. I dont think its unrealistic to go out with £1500 to spend on a coupe and expect one with a reliable motor, certainly my last two Coupes of the same sort of value didnt cause me these sorts of worrying issues. Interestingly the first week I ran the car it didnt cause any problems at all, it was the second week of ownership it started playing up. Either I was just very unlucky or the previous owner some how did some temporary bodge to make sure the car ran smoothly while he was selling it.

Duffy3074 · 05-08-16, 06:19 PM

You are wasting money trying to fix it until you know what's actually wrong.
Your mechanic should have known enough to plumb in a mechanical oil pressure guage to work out whether the dash guage was right.
A compression test should be next. Is there a rumble from the bottom end at low RPM or any other symptoms?

sinbin5t · 10-08-16, 05:21 PM

Have you got any further with this Scot ?

Got my fingers crossed for you big time

Crossle · 10-08-16, 08:37 PM

Quote:

Originally Posted by sinbin5t

Have you got any further with this Scot ?

Got my fingers crossed for you big time

Thanks Bruce. I've backed off a bit on it as I was just getting out of my financial depth. It's started running a bit better on this oil and I've also put a repair oil additive through it. The tickover for me was always too low and not helping things so I've increased that as well. Oil pressure is sitting higher for longer now and lowest it's gone to is 1.5 bar a few times but no oil smoke anymore and doesn't smell oily like it was. Got someone compression testing it for me but they are just going on holiday so can't do it for a few weeks. Will run it as is for a few weeks, drop the oil out and see what it's used and compression test it. Depending on the out come of that as to where I go with the car. Feeling a bit more positive about it now although I am sure I've not seen the last of the problems

Crossle · 18-08-16, 09:31 AM

Just a quick update on this for all the very helpful people that advised. Its early days at the moment so I am not jumping round the room with excitement as yet but the car seems to be running alot better now touch a hell of alot of wood!!

The pressure is dropping to 2 bar rather than 1 bar, the oil light is not coming on and there is no oil smoke. Hard to say exactly what has improved it but certainly the correct oil has made a difference! Also the tickover on the car was too low, from hot it would almost cut out when I pulled up and at that point the oil pressure would dive away with the revs. I have set it at 900rpm when hot now. Seems to be a little bit too high when its cold but overall I think not too far out. As yet it doesnt appear to be using any oil either but I think I will drop the oil out in a week or so time to measure exactly and to be sure. The only real thing that currently puts doubt in my mind that there might be something wrong with the motor is that it does seem very sluggish and slow at anything below 4000rpm which is when it kicks into life. I dont want to rev it above 4000rpm which means I am always driving below the power band which can be a bit frustrating. This might just be what that engine is like anyway, I dont honestly know as I dont have any experience with the 2.3 but I should imagine a car with 170k on the clock is not going to me running at its peak anymore anyway. The head was fully rebuilt not long before I got the car so maybe someone hasnt set the cam timing up correctly?

Only other thing is it does seem to be running slightly too hot still but its depending a bit on the journey. If I get stuck in traffic on the way to work it tends to be about right but if I get traffic it settles a bit high on the gauge for my liking. I have had the coolant flushed which made no difference at all.

Ben · 18-08-16, 11:57 AM

Air leaks on the inlet can make it feel like it's holding back, plus it leans out the fuel mixture which makes the engine run a bit hotter. Is yours a quattro? if so, check the thin purple pipe where it goes under the battery tray, mine had a hole worn in it.

Anyway, not going over 4k

that's where the fun is

05-08-16, 08:49 AM	#81
Crossle Grown up member Classic Audi Club Member Join Date: Jul 2015 Location: northampton Posts: 266	It does follow the pressure, 100%. The pressure pretty much goes up and down inline with the rev counter when at a standstill. When on the move its constantly between 4-5 bar and doesnt dip below that even at low revs. It literally only when drive is disengaged that the pressure then follows the throttle movement. Where is the pressure ball then? The history that I know of the car is that the head gasket went and it very recently (maybe 2-3k miles ago) has had the head rebuilt, new valves, gasket etc. Last edited by Crossle; 05-08-16 at 08:51 AM.

05-08-16, 05:15 PM	#85
Crossle Grown up member Classic Audi Club Member Join Date: Jul 2015 Location: northampton Posts: 266	I am thinking there is nothing wrong with the sensors now yes. Probably the point where I started to believe the sensors is when I saw oil smoke coming out the exhaust as the oil pressure dropped away! The fact that I've now got two signs of oil problems does kind of point to the fact that there might be a problem! Dont really know what to do to be honest, I'm not in the financial position to start pulling around with engines and I dont have the mechanical ability myself to start tinkering around. As it stands the car runs quite well as long as I keep the revs up when hot which isnt difficult on my daily run to work and back. I'm thinking if I can stop the oil light coming on when hot which probably requires about an extra 0.2 bar out of it to just bring it safetly above 1 bar then I might just use it for the rest of the summer and flog it on. I didnt go out to buy a project and while I appreciate old cars need maintenance I'm more thinking along the lines of Suspension joints and wheel bearings as oppose to cranks and sumps lol. I dont think its unrealistic to go out with £1500 to spend on a coupe and expect one with a reliable motor, certainly my last two Coupes of the same sort of value didnt cause me these sorts of worrying issues. Interestingly the first week I ran the car it didnt cause any problems at all, it was the second week of ownership it started playing up. Either I was just very unlucky or the previous owner some how did some temporary bodge to make sure the car ran smoothly while he was selling it. Last edited by Crossle; 05-08-16 at 05:18 PM.

18-08-16, 09:31 AM	#89
Crossle Grown up member Classic Audi Club Member Join Date: Jul 2015 Location: northampton Posts: 266	Just a quick update on this for all the very helpful people that advised. Its early days at the moment so I am not jumping round the room with excitement as yet but the car seems to be running alot better now touch a hell of alot of wood!! The pressure is dropping to 2 bar rather than 1 bar, the oil light is not coming on and there is no oil smoke. Hard to say exactly what has improved it but certainly the correct oil has made a difference! Also the tickover on the car was too low, from hot it would almost cut out when I pulled up and at that point the oil pressure would dive away with the revs. I have set it at 900rpm when hot now. Seems to be a little bit too high when its cold but overall I think not too far out. As yet it doesnt appear to be using any oil either but I think I will drop the oil out in a week or so time to measure exactly and to be sure. The only real thing that currently puts doubt in my mind that there might be something wrong with the motor is that it does seem very sluggish and slow at anything below 4000rpm which is when it kicks into life. I dont want to rev it above 4000rpm which means I am always driving below the power band which can be a bit frustrating. This might just be what that engine is like anyway, I dont honestly know as I dont have any experience with the 2.3 but I should imagine a car with 170k on the clock is not going to me running at its peak anymore anyway. The head was fully rebuilt not long before I got the car so maybe someone hasnt set the cam timing up correctly? Only other thing is it does seem to be running slightly too hot still but its depending a bit on the journey. If I get stuck in traffic on the way to work it tends to be about right but if I get traffic it settles a bit high on the gauge for my liking. I have had the coolant flushed which made no difference at all. Last edited by Crossle; 18-08-16 at 09:35 AM.

18-08-16, 11:57 AM	#90
Ben 4 ring whore! Classic Audi Club Member Join Date: Mar 2008 Location: Stockport Posts: 2,348	Air leaks on the inlet can make it feel like it's holding back, plus it leans out the fuel mixture which makes the engine run a bit hotter. Is yours a quattro? if so, check the thin purple pipe where it goes under the battery tray, mine had a hole worn in it. Anyway, not going over 4k that's where the fun is __________________ 1992 80 quattro 20vt

05-08-16, 10:59 AM	#82
esseff Grown up member Classic Audi Club Member Join Date: Jul 2010 Location: Castle Donington Posts: 57	The pressure relief valve is a spring-loaded ball that seats against a mating face. Oil pressure pushes against the ball which will only move a certain amount against the calibrated compression spring, allowing the oil to pass. Sometimes the ball seat is worn by chattering or there may be a particle of something holding it off, allowing oil to return to the sump all the time. That's why the oil pressure indication will follow the revs. Here's a generic diagram: Maybe when the engine was rebuilt some debris got left behind and ended up in the lubrication system. Something to think about.

05-08-16, 01:41 PM	#84
Duffy3074 4 ring whore! Classic Audi Club Member Join Date: Aug 2015 Location: Dalgety Bay, Fife Posts: 2,151	Has it occured to you that there was hee-haw wrong with the sensors and that they were just reporting, accurately, the real situation? You can overthink these things quite easily (unfortunately)

05-08-16, 06:19 PM	#86
Duffy3074 4 ring whore! Classic Audi Club Member Join Date: Aug 2015 Location: Dalgety Bay, Fife Posts: 2,151	You are wasting money trying to fix it until you know what's actually wrong. Your mechanic should have known enough to plumb in a mechanical oil pressure guage to work out whether the dash guage was right. A compression test should be next. Is there a rumble from the bottom end at low RPM or any other symptoms?

10-08-16, 05:21 PM	#87
sinbin5t 4 ring whore! Classic Audi Club Member Join Date: Jan 2010 Location: Where a spike points skywards Posts: 12,960	Have you got any further with this Scot ? Got my fingers crossed for you big time