My Nissan Avenir Salut had a clutch replacement now the speedometer doesn't work. I assumed the mechanics didn't connect a cable or broke something. They say they have no idea way it happened and weeks later haven't got a solution for me. What do you think has happened.

This says belt

https://www.google.com/search?q=1998+Nissan+Avenir%2C+timing+belt+or+chain

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If it was working before you got the clutch replaced, it is most probably the mechanics fault. They may have broken a wire or cable or the speedo sensor as a result of not disconnecting it before trying to remove the transmission. You need to bring it to another mechanic to find the problem to see if it was a result of the clutch removal. Then you may be able to seek retribution from your original mechanic.

There could be an electronic speedo sensor which is faulty.
I am sure if there was a cable at the gear box they would have found it in that period of one month!

No that doesn't sound like the problem, the fan clutch locks up to cool the engine off due to the increased load of the AC system on the cooling system, so it locks up and gets much louder. If it didn't lock up the engine would overheat.

check the connection that is on the transmission if you have a real cable then check the end to make sure the cable connections are not broke. look at the speedometer then spin the cable with your fingers the speedometer should bounce if not then cable is broke also check the ends usuall the end by the trans gets stripped out. a speed sensor will also make the meter not work if you have that kind of vehical.

there is a cable that connects from i beleive the transmission to the speedometer (isdtrument cluster) this cable is devised of two parts an inner cable and an outer cable, the inner cable has a square end that connects to the speedometer and could be broke or loose, check both connections on each end of cable. replacement of cable is very cheap but getting to it is somewhat difficult, you have to take out the instrument cluster . if cable looks fine on both ends,not worn,rounded or broke then I would say replace the cluster

will cost you near 50 dollars an hour for a good mechanic and please do not try it yourself,, I use to own a harley repair shop,, think you are looking at about 150 to get it fixed

Check the clutch lever free play. It should have about 3/4 inch of movement before any resistance is felt. The speedometer problem may be a bad inner flexible shaft within the speedometer cable. Unscrew the meter end of the cable and pull out the flex shaft--it may be frayed (replace) or just need lubrication.

check your speed sensor

lady never trust a husband who said there nothing wrong with a car he just repair lol stay married take the car for and oil change and ask the mechanic to check if every was put properly mariage is safe our kid are safe everybody happy as long as or husband dont know about it and for the speedometer maybe he forgot to hook it up or broke the sensor hope it help fixya our post good luck ronnie77