Dumb question time

[ClarkyBoy]

E92 M3's and some other similar cars (new M5,135M, rs4, rs6, S5) have electronic dipsticks, and physically don't have a dipstick - its a bloomin nightmare, the car has to be up to FULL WORKING TEMP! before they read, I.E the engine could be fecked before you know its not got oil!!

[mwmackenzie]

E92 M3's and some other similar cars (new M5,135M, rs4, rs6, S5) have electronic dipsticks, and physically don't have a dipstick - its a bloomin nightmare, the car has to be up to FULL WORKING TEMP! before they read, I.E the engine could be fecked before you know its not got oil!!

I recall the 997 GT3 being just the same, Freaking Germans... My passat and A4 have an oile level monitoring system which throw us a warning if it drops low, also has dipstick though which is handy as on the A4 the sensor is goosed although it is the second one I've fitted grrrr, I just go by the dipstick anyhow.

[Al.]

I have an old smiths mechanical one in the shed it replaces the dipstick with a tube ,

How many miles do you get between oil changes in the shed? What is oil consumption like?

Sadly not so funny, I bought that + a load of other Smiths gauges in about 1978 to fit to a Capri 1300 or something equally wild and never got round to ANY of them. All came under the heading of too difficult at the time. I binned them all about 5 years ago on a garage clear out still in tatty boxes. (before I became Forums savy and now realise somebody would buy them somewhere )

[scottishselise]

E92 M3's and some other similar cars (new M5,135M, rs4, rs6, S5) have electronic dipsticks, and physically don't have a dipstick - its a bloomin nightmare, the car has to be up to FULL WORKING TEMP! before they read, I.E the engine could be fecked before you know its not got oil!!

Jimbo, good qu

Clark, that is a pain guess you just top it up every time it shows half then...

[pete]

Dipsticks don't fail. That's why pilots dip fuel tabnks.

Everything can fail When flying a Navajo to Tenerife we stopped at Jersey for fuel. The proud owner (who was learning to fly) wanted to dip the oil in the engines so I let him do it. Anyway, on the climb out, I noticed the left engine oil pressure drop, followed by one of the passengers shouting that he could see oil coming from the engine cowling. So with an emergency declared we started our turn back and I contemplated prospect of shutting down the engine and an asymmetric landing . Well, when double checking the readings, I got confused - was it the left, or the right engine? Wait a minute! They're both dropping!! At least that made the decision easier So it became a very tight circuit, but a successful landing with a full emergency response by the emergency services

What had happen was that, when the owner had dipped the oil, he had done it like a car and failed to latch the dipsticks back in. On take off, at full boost, the dipsticks were blown straight out followed by a steady stream of oil. It took us a while to get the aircraft sorted and cleaned, but with Lycoming engines being what they are, there was no serious damage and our journey continued the next day.

OK almost infallible. (qv Gimli Glider).

My mate once closed the runway at Glasgow when he left his trainers on the floats and they fell off when he was lining up. (Flying barefoot a la Tut so he could get out at the other end).

[ClarkyBoy]

E92 M3's and some other similar cars (new M5,135M, rs4, rs6, S5) have electronic dipsticks, and physically don't have a dipstick - its a bloomin nightmare, the car has to be up to FULL WORKING TEMP! before they read, I.E the engine could be fecked before you know its not got oil!!

Jimbo, good qu

Clark, that is a pain guess you just top it up every time it shows half then...

yup - exactly what i used to do, 1l between min and max, so used to wait till it got to half and topped it up,

had a load of problems with it to start with from BMW - apparently it was wrongly calibrated - left the showroom, got to the centre of town, temp came up and told me it was empty

[DJ]

By the way, Keep the dumb questions coming - it's interesting to see the answers to questions that some of us are too ashamed to ask

OK, I'll go next.

How do you guys know when it is time to change your brake discs? I am not talking about obvious warping, cracks etc. but just through general wear. Tyres and pads I can see, exhaust I can hear and fluids & services are time or mileage related. But brake discs??
I'm asking as after it's service the dealer is telling the Mrs her Merc needs new front discs. It has only done 20k miles and whilst I can feel a small lip around the edge, it doesn't feel significant to me. A secondary question might be it's the first auto we have had and does the driving style of autos mean disks (and pads) wear out quicker?

I'll add this ==> just now in case its something obvious I am missing however, guessing most of us don't have micrometers. How do you check or know?!

cheers

[woody]

Measure the disc thickness. You'll need a set of callipers or verniers to get a good idea of where they really are. The manufacturer should be able to provide a minimum thickness.

[robin]

If the dealer is saying they need replaced then ask them for the disk thickness measurements that they must have taken. Also ask them for the service limits and thickness of new disks. Then you can work out for yourself whether you need new ones AND how trustworthy the dealer is

Vernier calipers are cheap so easy to measure yourself. Be sure to measure the actual thickness and not the lip.

Cheers, robin.

[BiggestNizzy]

If you have a lip calipers might struggle to clear it.

A micrometer is cheap as chips. And won't be effected.

[j2 lot]

Your second and less technical question: yes I assume autos are harder on brakes as you have little or no engine braking unless you manually go down through the gears so you must be using the brakes more.

[DJ]

If you have a lip calipers might struggle to clear it.

A micrometer is cheap as chips. And won't be effected.

Thanks all. Re the above, looking at these on line, the slide rule types calipers I don't think would be any good as you say as the lip on the disc would foul the reading on the straight edges and and the 'prongs' wouldn't contact the disc. Do you get curvy ones? (not very technical terms being used here!). Micrometers seem to be 0-25mm or 25-50mm and typically I want to measure something about 25mm . Suggested (cheap n cheerful) product??

I dug out the service sheet and see disc thickness are mentioned (26.9mm nsf , 26.1mm osf), but looking on line, the discs all seem to come in different thickness depending on manufacturer. There are 28mm with minimums of 25mm, 25mm ones with minimums of 22.5mm and others in between. Average wear allowance seems to be about 3mm but looks like I need to find out what make of discs the OEM are to determine if mine are OK.

[robin]

Which is why you should ask the dealer - they must know the answer to the new disk thickness/service limit in order to be able to make the call on whether to recommend replacement, and how they react to your question will tell you all you need to know about whether you want to carry on dealing with them.

You can use shims to measure with normal vernier type calipers - e.g. measure two pound coins back to back, then measure coin+disk+coin using the same two coins. Actual thickness = measured thickness - two coin thickness.

You wouldn't want to do this where you want very high accuracy, but you only need +/- 0.2mm ... you can repeat the measurement several times at various points on the disk and use the lowest one.

Cheers,
Robin

[BiggestNizzy]

Aldi are known for doing Digital Calipers for £8 now and again.

[sendmyusername]

Re: brakes and oil.
My mates almost valid question - what is the point in having a low level oil alarm if the engine is already fckd by the time the light comes on. I say almost valid, as he killed two engines and was on his third by then, and still doesn't check the dipstick. (two different cars)
There is another post about the brakes discs on here, guy advised to replace them at 15,000, again at 30,000 (next service) and eventually when getting an mot at 40,000 at a different garage was told he had about 2-4000 miles left on them.
So that was more than double the initial garage.
Think the phrase is - they were at it !
Get a cheap set of micrometers (they get around the lip, and measure it yourself)
I'd be surprised if they really needed done.
After you do it, if they are ok, contact the garage and ask for an explanation - it will probably be a "misunderstanding"