meriva

Mileage clocking? How shiny is the steering wheel? What are the pedal rubbers like?

Tim

If it has one, timing belt and water pump.

It does sound rather low.

At least the OP will be able to look up old MOT mileages. If it has been clocked it would have been a while ago.

no, it's not been clocked, know the original owners nearby. It's not been used much which is what bothers me. What is likely to be a problem ? It passed its mot on March 1st 2018 after bits and pieces were repaired ie boot, tyre, the usual things.

My sister had one (but 2005), and that had a timing chain that was always noisy.

so after a complete failure of the engine start up procedure, the engine decided not to start. I had looked at the fault codes on the "what ever its called" and it was a crankshaft sensor failure.

very common fault on any vauxhall

On some makes, pretty easy to change.

Never quite understood why so many makers use hall effect sensors for this. They are *far' less reliable than VR. But VR do require screened cable and slightly more complex electronics in the ECU.

had it changed at local garage, job done.

Hall effect sensors do have their advantages.

Any simplification to increase the reliability of the ECU gets my vote too. I'm not sure if VR sensors aren't also subject to similar failure rate?

Yes.

Hall effect are electronic, and most electronics like solid state devices and caps don't like heat. Or rather heat will shorten their life.

A VR sensor is just a simple coil.

The extra electronics needed for VR is just a simple zero crossing detector. Not rocket science.

Especially after cooking an engine. Most automotive sensors have a higher temperature qualification, but yes, temperature and temperature cycling (thermal stress) have a deleterious effect on semiconductors.

Coils that are subject to engine vibration also have a limited life.

For a VR sensor any wheel runout and missing tooth upset the response, making timing dependent on wheel position and rpm. An ECU for a VR sensor will be an analogue input and inherently more sensitive to damage.

The way a Hall sensor works means the output is far more stable. It potentially has a response down to 'DC'. VR sensors don't, hence the 'upset' around a missing tooth.

No matter what the temperature spread quoted, heat still shortens the life.

No need for that. Easy enough to pot to prevent movement.

You are looking for the zero crossing point, so the amplitude of the signal isn't critical. Except that at low rpm, it tends to be less than a hall which gives a constant voltage pulse. But provided the cable is decent and screened, not a problem.

But the ECU should be positioned well away from engine etc heat.

There is truth in that for things like ABS where you might need to measure a very low speed. But on an engine, a VR sensor reads perfectly even when cranking.

It's not just my view. The old EDIS system used a VR sensor on a 36-1 wheel. And was about as reliable as ignition systems come. I've had a couple of (hall) CPS sensors fail on my cars, and know plenty others who have too.

worth buying one as a spare to keep in the car perhaps.

Watch for the rear exhaust mounting. Mot failure but simple welding job

will do, thanks John