donromani

Just rebuilt the motor with some forged connecting rods and other swag and had my trusted mechanic put on the finishing touches. The motor runs fine, but the oil warning light comes on as soon as you touch the accelerator.

The shop tested the oil pressure at idle near the oil cooler - 44psi, just like it should be. Everything seems to be getting lubricated. Best part is, VAGCOM lists no codes but I'm going to have to verify this myself.

Just wanted to toss this out there and see if anyone has any ideas. I have to deal with the (most likely) unrelated issue of replacing the accessory tensioner. Damn thing fell apart while driving...

jamesdmanley

bad level sensor or the wiring to?

Chris's S4

The instument can display up to three different configurations of oil situations.

Engine oil pressure, is the standard oil can with a drop.

Check engine oil level, oil can with "min" down to the right of it.

Engine oil sensor defective, oil can with "sensor" down to the right of it.

Also in which section is the light on? Yellow or red section?

If it's in the "Red" section, it's only one thing, Engine oil pressure.

If it's in the "Yellow" section, it's engine oil level or engine oil sensor defective.

Hope this helps.

Chris

So which is it?

EuroXS4

Couldnt agree more with Chris.Right on the money.Is the pickup tube installed in the engine??and the baffle pan??I believe the s4 has a baffle pan but I could be mistaken.

Peter Badore

When I replaced my broken 2001 S4 upper and lower oil pans they were the same as a regular 2.8l 30 V except for the return in the upper oil pan for oil from the turbochargers. On that S4 there were no extra baffles. As the lower oil pan is easy to remove it can be taken off to check for correct installation of the oil tubes and o-rings to and and from the oil pump.

donromani

Thanks for the help guys,

It's the red engine oil pressure warning. It comes on while idling if you rev the motor a bit and then goes away again. Once you get moving it comes on and stays on.

Pressure tested correctly near the oil-cooler and filter with some home-made device the shop built for that purpose - this was with the motor idling. The concern is that the upper portion of the motor may not be getting any oil, but so far there has been no indication that that is happening. No knocking, no abnormally noisy clicking from the valve-train, no signs of turbo distress/whine from overheating.

I replaced the various o-rings throughout the lubrication system and in the course of the rebuild I had to take out the oil-pump and remove the oil-pump chain and sprocket. Those would be relatively easy to double-check. Would it be possible for the oil-pump sprocket to be loose, allowing it to slip under higher revs? But that would cause the oil pressure to drop throughout the motor, in which case, things should get noisy very quickly...

I'm stumped but I haven't had time to do much diagnosis on my own and am relying mostly on what the shop told me.

Chris's S4

Well they got oil pressure with 44 psi. So maybe they do have to pickup tube... right? I've never seen a motor pickup oil without one. but could be wrong.

I wonder a couple of things. I'm not real sure but just throwing it out there. Does S4 have a oil pressure "switch" or "sensor"? I know we have an idiot oil light in the cluster.

But is there a pressure sensor that the ecu reads? My thinking is this, if you touch the throttle and the "some" oil light comes on, maybe... just maybe it's getting too much pressure somewhere and there's a pressure relief plug clogged/stuck. The thing is, there isn't a "high" pressure idiot light. So really there's no way of knowing. Unfortunately without ripping into the motor.

My mind is brewing, Ill let it sit with this for now.

Hope this helps
Chris

Chris's S4

A lack of pressure just before the pressure switch/sensor, which ever it has. Being when the car starts moving, it knows "bad things are going to happen if this driver doesn't stop driving right now" kinda thing, so the light stays on, continuously warning the driver.

I now seriously think it has to do with low pressure somewhere before the oil pressure switch/sensor.

Gonna take a look into the manuals i got and see if I can post a picture of the oil gallery for ya to inspect the relief plugs and pressure switch/sensor. Again I dont remember if it has a switch or sensor for oil pressure. Hence my mentioning of both.

Chris

donromani

I've got this: http://ardisus.com/Audi_S4_engine_english.pdf

Looks like it's a switch.

Honestly, every B5 S4 owner should get a copy of that manual.

Chris's S4

I was working to attach a pdf file of the oil gallery of which you can use to help you diagnos what could be wrong. As mentioned earlier about the pressure switch/sensor. It only has a oil temp sensor and pressure "switch". No pressure sensor. Rats!... Anyways take a look at the diagram and check the check valves, relief valves, and whatnot. But you posted it before me. hahahah oh well. Hope it'll help with know what and where to check for the componants.

Did you read the next two pages of that file? 15 and 16.. they explain what the componants do. Good for checking if they're working correctly.