Please excuse the car question, but no resps in uk.recs.car.maintenance

[newshound]

A mate of mine has had the solenoid (perhaps the wiring) fail on an R plate Polo, does anyone know where it is located? Under the wheel arch? or do you go in from the inside?

TIA

[Clive George]

Which solenoid?

[TMC]

I am not sure what other bits of the car would need a solenoid to function apart from the door locks as most indirect swithcing is done by relays

[TMC]

Ah just found your post in uk car maintenance

the clue is in the subject there

'Filler cap'

Quote from a 2005 post in google 'it seems to fit into some slotted holes on a panel behind the plastic trim'

[Graham.]

panel behind the plastic trim'

Oh, the *filler cap* solenoid? I guess we all knew he meant that ;-)

[Dave Plowman (News)]

Central locking more commonly uses motors. They're more efficient than a solenoid - and probably cheaper to make. Only solenoid I can think of is in a pre-engage starter motor.

[newshound]

[newshound]

Well spotted, I feel a right prat now!

[Colin Stamp]

There's various solenoid valves dotted around as well. Idle speed control, EGR, carbon cannister purge, that kind of thing but, as you say, the only one people seem to just refer to as a "solenoid" is the one on the starter. I always thought it annoying that people referred to the starter relay in cars with inertia starters as "the solenoid" too.

Cheers,

Colin.

[Dave Plowman (News)]

New at all this? ;-)

[The Natural Philosopher]

starter motor contactor often referred to as a solenoid

[Piers Finlayson]

So we know now that there's a problem with the filler cap. I had a problem with the filler cap on my V reg Golf, which is presumably very similar. The motor (don't believe it's a solenoid) controlling the filler cap release had got stuck, and I needed to remove, dismantle, and then rebuild then mechanism to get it to work again.

It's located to the rear of the filler cap. On the gold you get in (from memory) by:

- removing the trip from the inside of the boot (below the opening, the trim "facing" the front of the car

- removing the trim on the RHS wall of the boot (where the filler cap is), all the way to the roof

- the mechanism is screwed in place in a rather hard to get place within the bodywork.

You'll probably find some photos if you google hard - here's a useful thread (but without photos):

that this link suggests bying a new mechanism.

[Dave Plowman (News)]

It might well wrongly be, but only pre-engage starters have a solenoid. To engage the pinion before the power is applied. That solenoid is usually switched by a relay. I've never heard a car relay referred to as a contractor. That term is usually applied to high power AC devices.

[Dave Plowman (News)]

Ah - forgot those. Although idle control is often a stepper motor these days.

[Roger Chapman]

Of the three terms solenoid, contactor and relay solenoid seems the only one that has anything close to a precise meaning. Collins dictionary for instance defines contactor as: "a type of switch for repeatedly opening and and closing an electric circuit. Its operation can be mechanical, electromagnetic or pneumatic." Air blast circuit breaker?

So a contactor could contain a solenoid as could a relay according to its entry in Collins.

Part of the entry for solenoid states: "such a device used as a relay, as in a motor vehicle for connecting the battery directly to the starter motor when activated the ignition switch.

[Dave Plowman (News)]

Dictionaries are rarely much use for technical terms.

[Roger Chapman]

They might be a bit vague on occasion but in my experience rarely completely wrong.

To me a contactor was a heavy duty switch for industrial sized workshop machinery. I would never of thought of National Grid switchgear as contactors although the definition I quoted surely covers them as well as a multitude of other stuff and a relay is a combination of solenoid and contacts which did fit the definition pretty exactly.

[The Natural Philosopher]

No, it's a contactor.

High power any device in my experience.

[The Natural Philosopher]

Top me a contactor is a heavy duty relay or switch where the contacts are not generally self wiping slide, but heavy lots of pressure and THUMP.

[newshound]

I hadn't thought of that, but on reflection it is perhaps more likely.

Thanks very much for the helpful advice!

Steve