RS2 - Oil Warning Light at Idle - 1.0 bar

[K Simmonds]

You can do the bottom one from underneath, if your on a ramp and can work completely blind and don't mind skinned knuckles, which I'm very used to doing, though thinking about it I don't know if I'd be able to hook the line up to the mechanical pressure gauge. With all the plastics etc in place that side of the motor is a sod to get at however you go about it, that's why I binned half of them on my 3B S2, also is your car LHD? I've never done extensive work on a LHD RS2 or S2 so there could be some difference's I'm unware of.

1.1 bar at hot idle is a little on low side but it's still well within the acceptable zone and as it picks up so quickly with rev's I wouldn't be too worried about it. Unless you find once you replace the F22 (which is almost certainly the cause of your current problem) that it continues to get lower with more miles covered, then I'd be concerned.

What did the oil you dropped out look like, was it nice clean with no signs of shinny stuff?

As Dave says this does confirm that the garage stuff was a bit thin.

Please keep us updated on the situation.

[Tractor Dave]

F22 is the 0.3 bar switch so you need to change that one. F1 is the 2,000 rpm switch.
The gauge in the car (auxiliary dial) is taken from a separate linear feed from F22.
However, changing your oil has also proved the stuff the garage put in was too thin!

All the info you need is here

https://forums.quattroworld.com/s4s6/msgs/96161.phtml

[Bowie69]

Well the good news is that it is likely just the small cheap switch that is dead.

So swap it out and be happy

Buy a quality one, they like to fail randomly leaving an oil slick down the road.

[Bimmerod]

Just wanted to provide an update on the Oil Pressure situation. I got a chance to work on the RS2 today.

Why didn't you guys tell what a pain in the *** it is to access either of those sensors!!!!
There is no way to access from the bottom and I didn't want to start taking off coolant lines from the top if I was going to be able to test things after getting the gauge hooked up. I was finally able to remove the electric fan but that lower bolt was a pain to get to. In addition, the ABS lines are in the way and prevent the fan from coming out of the car. I just had to push it back a little and try to squeeze my hand down there to try and get access. Pretty disappointed with the way that was designed.

Now on to the testing.......
First up was just hooking up the OP gauge to see what is was really doing is comparison to the factory gauge. Cold idle was at 4.5 bar and the after the engine got warmed up it dropped to 0.9 bar. Steady 2k RPM and it's at 3.2 bar
Next I changed the oil with the 10W-40 I spoke about above. Did the same test, engine had cooled but was not cold. Idle again was above 4.0 bar with hot idle dropping to 1.1 bar so not a huge difference with the new oil. Steady 2k RPM and it's at 3.5 bar.
OP is VERY responsive with throttle application and there doesn't seem to be any lag in OP rise while revving. I even checked the relief valve but everything was spotless in there as well.

I did not get the (2) replacement sensors yet but I guess I will just swap them out to see if the warning message still comes on. There is no way at any time the oil pressure was at or below 0.3 bar so I'm not sure which sensor it actually bad or why the warning is coming on in the first place? In reality, the factory gauge reads about 0.2 bar higher than the mechanical gauge we used.

Thoughts / Suggestions ???

Thanks in advance

[K Simmonds]

At idle(800-850 RPM)... Straight from cold the oil pressure should be 4-5 bar, at 90C 1.8 - 2 bar on a freshly built engine would be in the right ball park.

Yes, you can get to the bottom sender from underneath, it's still a bit of a pain though.

I've always ran the stock size OE filter from Audi, to be honest I wasn't aware of a larger unit as I've been kinda out of action for while, I certainly don't see any harm in using a higher capacity filter, will look into that option myself when I drop the oil out of mine next.

That 10w-40 looks perfect, the only reason I'm running such thick oil in mine is I had a fresh 5L left over from my 3B which used to regularly see oil temps well in excess of 100C, think 130C was the highest I ever (briefly) saw. Will probably go with 10w-40 myself when I do my next change as I drive my RS2 with more respect than my my old S2.

[Rikki Kitto]

Have you looked into the larger oil filter gives you .5 of a litre more oil I use fuchs titan 10/50 seems to work fine so much choice with oil good luck

[Bimmerod]

Thanks for all the feedback guys. I will be getting my hands on a gauge set and head over to the garage this weekend to test the mechanical pressures.

What values should I be looking for at cold idle, hot idle. etc...?

I should be able to remove the lower splash pan and access the smaller (F1) OP unit from the bottom, correct? Trying to access anything from the top does not look possible without removing a bunch of things.

I also grabbed a new oil filter and have this 5 gal pail of 10w-40 I can put in to get rid of the 5w-40 that's currently in there.

https://torcoracefuel.net/products/sr-1r-racing-oils?variant=15929519767663

Are you guys running the larger revised Oil Filter - 068 115 561 B

Or the original - 06A 115 561 B

Thanks again

[K Simmonds]

I agree that the problem probably lies elsewhere and im watching for the next episode! I

I sincerely hope that a freshly built engine isnt struggling to produce hot oil pressure but it wouldn't be the first time

A mechanical pressure gauge will soon spill the beans

Yep, I recon it's probably a problem with one of the oil pressure senders or even possibly the wiring to said senders being muddled up as Mike's mentioned. However without confirming what's actually happening with a reliable mechanical gauge we're all just taking an educated guess.

I to have seen freshly built engines struggle with hot oil pressure, though never an Audi I5, that would be going back to my MK2 Golf days. I also sincerely hope that's not the case here!

Sent from my SM-A115F using Tapatalk

[newsh]

I think you’ll find that the 1Bar switch has failed, they can leak internally and oil gets into the switch mechanism.

[steve briance]

I should have perhaps gone into more depth, I was merely advising on what oil I thought would be best use given his cold start condition's (hence me asking about them) as well as trying help diagnose a problem I don't actually think is related to the oil grade currently in use.

I agree that the problem probably lies elsewhere and im watching for the next episode! I

I sincerely hope that a freshly built engine isnt struggling to produce hot oil pressure but it wouldn't be the first time

A mechanical pressure gauge will soon spill the beans

[Bimmerod]

It's almost like the wires are on the wrong senders or you have the wrong sender. 1 bar at idle does not trigger the warning so you've either got the wrong sender in there or the wires are reversed.

That's always a possibility but that doesn't explain why it's been working for a couple thousand km's. The only thing that has happened is the car was sitting in storage for the past year or so but was started every couple months to keep things in working order......or so I thought....LOL

[Mikes2]

It's almost like the wires are on the wrong senders or you have the wrong sender. 1 bar at idle does not trigger the warning so you've either got the wrong sender in there or the wires are reversed.

[K Simmonds]

I should have perhaps gone into more depth, I was merely advising on what oil I thought would be best use given his cold start condition's (hence me asking about them) as well as trying help diagnose a problem I don't actually think is related to the oil grade currently in use.

[steve briance]

Im going to throw a grenade into the thread and run away...

There is discussion and advice here about 5w40 being a bit too thin and 10w40 or 15w40 being better to maintain pressure in an engine displaying oil light when hot.

Im not sure there is any difference between them...



The figure before the W is the oil viscosity when cold so yes, 5w is thinner than 10w which is thinner than 15w.

The second figure though is viscosity when hot and as both mentioned oils are 40 grade hot, there is no difference and as the concern only occurs hot, it is this figure that is most relevant.

10w50 would be a thicker oil once hot (or anyone remember 10w60 castrol oil??!) and should be the sort of grade to try though i can't help think that if it does make a difference it would only be masking the symptoms of whatever is causing the problem.

[K Simmonds]

If your in California then a good quality 10w-40 should be absolutely fine all year round and under all but the most extream driving condition's as should 15w-40 for that matter but if I was you I'd go with 10w-40, especially as you mention the engine is freshly built.

90C is normal operating temp for the oil and to be honest a decent 5w-40 should be still be fine under the conditions you describe which make me think the problem is elsewhere.

As I'm a hoarder of old OE parts I really can't comment on what aftermarket senders to go for as I've never had to purchase one, perhaps some other members would be better advising you on that one...

I would offer you one however I only have a single good spare and that's for my car.