New S2 Avant Nothelle N300 owner

[steve briance]

Is the shim the dark grey washer between spring and brass part? Live and learn! I still don't think the shim will have any effect on the oil pressure but if it is meant to be there it should stay.

The spring in Alex's picture looks like a constant rate spring with evenly spaced coils and they need the same amount of force to compress 10% as they do 100%.

This is an interesting website re springs.

https://www.yostsuperior.com/variable-rate-springs-progressive-vs-linear/

[twoqu]

Going back to the multimeter. You could test something convenient such as an injector. Remove the connector and touch the terminals. We know it should be in the high teens Ohms. I have measured one I had laying around so we can use that to illustrate the different scale readings:

16.5 @ 200 Ohms scale
0.016 @ 2K Ohms scale
0.01 @ 20K Ohms scale

As you can see you lose the fine detail from the measurement higher up the scale. For most automotive measurements we are only concerned with the lower end of the scale. So for the sender either the 200 or 2K would give us the answer. From the specs of your multimeter it still use those scales for resistance it just does it automatically !
The reading with the engine off is probably not as important as with it running. If you could find something with a resistance of @100 ohms you could feed that to the guage and see if it read mid scale.

[twoqu]

It's unclear whether there is a direct connection between a fuse and the aux guages but no harm in checking. It looks as those its S14 a 5A fuse. Might just be for the illumination.

[Error404]

Is the shim the dark grey washer between spring and brass part? Live and learn! I still don't think the shim will have any effect on the oil pressure but if it is meant to be there it should stay.

The spring in Alex's picture looks like a constant rate spring with evenly spaced coils and they need the same amount of force to compress 10% as they do 100%.

This is an interesting website re springs.

https://www.yostsuperior.com/variabl...ive-vs-linear/

All springs compress proportional to force - otherwise they wouldn't be springs they would be more like dampers - lean on them and they sag to the bottom of their travel under a constant load.
Linear spring rates compress at a rate linear to the force increase, hence the name. "Progressive" or non-linear springs follow a rate curve.
Normally in this century, the unit used is commonly n/mm. For example a 10n/mm linear rate spring, the spring will compress 1mm for each 10n of force applied. I.e. 20n = 2mm compression, 100n = 10mm and so on. Compression=Instant rate / force.
If you pre-load the spring, (by compressing it), you are increasing the force needed to compress it further, as your required force is always 0+preload. Thats why shimming the relief valve increases PEAK pressure as it increases the force needed to be applied to the piston (and spring) before the valve starts to open.

In the context of the oil pump though the relief valve is only open when the oil is cold and more viscous. I have an accurate & calibrated analog 0-5v oil pressure gauge on my car and cold start PEAK oil pressue is around 800kPa = 7 bar gauge pressure. During normal running, more like 500-600kPa = 4-5bar gauge pressure. I will say also that my OEM VDO oil pressure gauge misreads by at least 1 bar under all conditions! They are an indicator, nothing more so don't get too hung up on what they read as long as it's somewhere about right.

Dave you need to verify that the gauge is tell the truth - easiest way is to put a mechanical oil pressure gauge on the car and see what its actually doing

HTH
Alex

[Tractor Dave]

Cheers Alex. I'm glad you explained the spring/shim stuff as I'm not qualified or sufficiently knowledgeable to comment

I didn't get time today but will hopefully have a play tomorrow. I haven't bought an oil pressure gauge yet as they were too many to choose from and I didn't want to buy the wrong one. Would you take a reading from where that sensor sits?

[Error404]

Just buy a branded 10bar mechanical gauge, it will be fine and accurate enough for general testing purposes
You’ll need a short hose too, to connect it. The OEM sensor positions are really the only option you’ve got -they are supplied from the main oil gallery so ideal
Smaller upper thread is M10x1.0. Larger lower thread is M16x1.5, OEM adapter takes it down to M10x1 also
HTH
Alex

[Tractor Dave]

I needed to take some pics for the agreed value with the insurance co.
So, gave her a quick wash.









Just a few things to sort now. The rear wheel bearing, the centre interior light, the oil pressure gauge and of course the paint.

Has anyone got a spare S2 Avant rear hub? I don’t want to waste another bearing until I know what the issue is. It’s either the hub or the hub carrier.


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[M2ki]

What is the problem with the hub and/or hub carrier?

[Tractor Dave]

What is the problem with the hub and/or hub carrier?

I don’t really know for sure. The first bearing had play so I ordered another new one thinking it was faulty. The second one, another SKF, also has play.
They were pressed in correctly with support. Maybe they are not seating in the hub carrier properly or the hub has wear. It looked good with no sign of corrosion or wear.


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[Tractor Dave]

Then this afternoon I went for a spin and did some altitude testing.




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[Vorsprung durch Technik]

Then this afternoon I went for a spin and did some altitude testing.




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Lovely, looking great and in it's best environment out on the road in interesting scenery enjoy!

[Error404]

I don’t really know for sure. The first bearing had play so I ordered another new one thinking it was faulty. The second one, another SKF, also has play.
They were pressed in correctly with support. Maybe they are not seating in the hub carrier properly or the hub has wear. It looked good with no sign of corrosion or wear.


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How much force does it take to press the bearing into the carrier and the hub into the bearing?
I have had issues a couple times recently where the carrier/upright had corroded and the bearing bore was oversize meaning the bearing fit was not tight enough in the carrier resulting in slight play in the wheel.
It should take around 5T of force to install the bearing in the carrier and around 2T to press the hub into the bearing. If you can install either with much less, that will cause problems as the bearing is designed to be installed with a tight interference fit.

[Tractor Dave]

How much force does it take to press the bearing into the carrier and the hub into the bearing?
I have had issues a couple times recently where the carrier/upright had corroded and the bearing bore was oversize meaning the bearing fit was not tight enough in the carrier resulting in slight play in the wheel.
It should take around 5T of force to install the bearing in the carrier and around 2T to press the hub into the bearing. If you can install either with much less, that will cause problems as the bearing is designed to be installed with a tight interference fit.

To be honest I wasn't watching the gauge. We used a 30t press. I think I'm going to have to take it all apart again and examine the carrier carefully to see if there is something preventing it going all the way. Thanks for your advice.

[Tractor Dave]

The only specs I have seen are from the AAN/3B for the pressure sensor. Doubt whether its different for the ABY.

5-10 Ohms - Engine off
70-120 Ohms - Idle
170-200 Ohms @3000 RPM

That is measuring from the G terminal to ground. So you can verify that the sensor is producing a signal that makes sense. You could also measure pre and after the connector to see if it varies. If it does then the issue might be the connector itself. If it passes through the connector ok then that leaves the wiring back to the guage.
It looks as though the higher the resistance the higher the reading!

Should say thats with engine oil at 80C!

More useless info. Found some VW1301 measurements that equate to oil pressure from the sender. You have to divide by 2 and add 10 to convert to resistance.

350 = 5.0 bar
150 = 2.0 bar
10 = 0 bar

So converted:

185 Ohms = 5.0 bar
85 Ohms = 2.0 bar
15 ohms = 0 bar.

Not as accurate as a guage but hopefully that should allow you to determine whether there is an issue.

Tested when the oil was warm.
Engine off - 10 Ohms
Engine running - drops to 0
Makes no difference if you rev the engine.
I think I need a new sensor.

[Bowie69]

There's a switch on the sender as well, you sure you didn't measure that?