La meccanica dice che il volante è duro e che i tergicristalli vanno cambiati.

In this sentence, la meccanica is most naturally understood as the female mechanic.

Italian often uses:

• il meccanico = the male mechanic
• la meccanica = the female mechanic

So La meccanica dice... means The mechanic says..., specifically a woman.

You are right that meccanica can also mean mechanics in other contexts, for example:

• la meccanica quantistica = quantum mechanics

So the exact meaning depends on context.

Here il volante means the steering wheel.

The word volante can have different meanings depending on context, but in car-related language it usually means steering wheel.

Examples:

• girare il volante = to turn the steering wheel
• tenere il volante = to hold the steering wheel

So in this sentence, it is not something like flying or flyer; it is clearly the car part.

È duro literally means is hard, but in this context it means something like:

• is stiff
• is hard to turn
• is tight

When talking about a steering wheel, duro usually means it takes too much effort to move.

So:

• Il volante è duro = The steering wheel is stiff / hard to turn

Because duro agrees with il volante, which is masculine singular.

Agreement in Italian:

• masculine singular: duro
• feminine singular: dura
• masculine plural: duri
• feminine plural: dure

Since volante is masculine singular:

• il volante è duro

If the noun were feminine, you would use dura.

I tergicristalli means the windshield wipers or windscreen wipers.

It is a masculine plural noun:

• singular: il tergicristallo
• plural: i tergicristalli

The word is made up of parts that suggest the idea of wiping the glass:

• tergere = to wipe
• cristallo = glass

In everyday usage, you just learn it as the normal word for wipers.

Both forms are possible, but they are slightly different in style.

Vanno cambiati is a very common Italian structure meaning:

• need changing
• should be changed
• need to be replaced

It uses:

• andare
  • past participle

So:

• I tergicristalli vanno cambiati = The wipers need to be changed

A more explicit alternative is:

• I tergicristalli devono essere cambiati

That also means The wipers must/need to be changed, but vanno cambiati often sounds more natural and idiomatic in this kind of practical statement.

Because the subject is i tergicristalli, which is plural.

So both parts agree with a plural masculine noun:

• vanno = plural form of andare
• cambiati = masculine plural past participle

Compare:

• Il tergicristallo va cambiato = The wiper needs to be changed
• I tergicristalli vanno cambiati = The wipers need to be changed

This agreement is very important in Italian.

Italian often repeats che before each new subordinate clause for clarity and smoothness.

So:

• dice che il volante è duro e che i tergicristalli vanno cambiati

means:

• says that the steering wheel is stiff and that the wipers need to be changed

In English, the second that is often optional:

• The mechanic says that the steering wheel is stiff and the wipers need to be changed

In Italian, repeating che is very common and often sounds better.

Sometimes yes, but in this sentence repeating it is the most natural choice.

So:

• dice che il volante è duro e che i tergicristalli vanno cambiati = very natural

Without the second che:

• dice che il volante è duro e i tergicristalli vanno cambiati

This can sound less clear, because after è duro the listener may need a moment to recognize that a second full clause is starting.

So for learners, repeating che is a good habit in sentences like this.

Italian uses definite articles more often than English does.

Here they are all normal and expected:

• la meccanica = the mechanic
• il volante = the steering wheel
• i tergicristalli = the windshield wipers

Italian usually wants the article with nouns like professions or concrete objects when speaking about a specific person or thing in context.

English sometimes drops articles where Italian keeps them, but in this sentence the articles are straightforward and necessary.

Yes, in a way. In vanno cambiati, the past participle cambiati agrees with the noun and behaves much like an adjective.

It matches i tergicristalli:

• masculine plural noun
• masculine plural participle: cambiati

This is why you get:

• il volante va cambiato
• la batteria va cambiata
• i tergicristalli vanno cambiati
• le gomme vanno cambiate

So although it is part of a verbal expression, it still shows adjective-like agreement.

You would say:

• Il meccanico dice che il volante è duro e che i tergicristalli vanno cambiati.

Only the first part changes:

• la meccanica → il meccanico

The rest of the sentence stays the same.

Yes. The main verb dice is present tense:

• dice = says

The sentence reports what the mechanic is saying now.

Inside the clause:

• è duro = is stiff
• vanno cambiati = need to be changed / should be changed

So everything is presented as a current assessment of the car’s condition. Italian often uses present forms for this kind of diagnosis or recommendation.