Noise from engine

Hi, to all fiatians I hope you all are doing fine with your punto’s n linea’s.It’s been a long time since I posted for the last time.This time the issue is with the engine and the temperature guage.While starting in the morning when the engine is cold it makes a hissing noise or noise of pressure release at once,and recently the needle of temperature guage has dropped hughly below the C level and doesn’t come up over a quarter after the engine is warmed.Looking for help if anyone can suggest me what to do.



The first pic is taken when the engine is cold and second one is while it get warm.

 

The dangling temperature needle appears to be a faulty instrument cluster. Hope you are keeping an eye on coolant temperature and levels. Would recommend get diagnosis done at asc.
How many kms has your drive done?

 

My car has done 54364kms and is 5year and 7 months old.The car is timely serviced and taken good care.Also coolant is up to its level and recently changed.My worry is that hissing noise coming from engine while starting in the mornings.Specifically in cold mornings.this problem has started just 4 month ago.

 

Would recommend taking your car to ASC to diagnose the issue. Over a search I found a link which points to potential turbo charger failure.
https://www.dowleys.co.uk/blog/turbo-failure-what-can-i-do/#

Earlier diagnosis could prevent further damage.
What is the routine you use to switch off the engine? What I mean to ask is when the car has run for over 2500 rpm for a long duration do you switch off the engine immediately or after few minutes?

 

I’m very cautious of starting and switching off the engine so as to let turbo get settle down.Whenever the engine runs beyond 1700 rpm i habitually switch off the engine after 2-3 mins.even in the morning I adopt the same.Also I conveyed this problem while routine service to FASS but at that time the car was fine while starting as the problem appears only during cold starts in the morning usually.

 

Might be worth checking the alternator bearings.

 

I used to follow a pause before shutting engine but that too for 15-20 seconds. I have clocked 1,50,000 Kms till date and my car is 9.5 yr old now.

It's still give mileage of 20-23kmpl at 60-80kmph speed.

 

I had a very strange grinding noise during my recent visit to Kolli hills. It was during a cold start. Tried to replicate the problem once back at Bangalore but not been successful. The weather at Kolli hills is not quite different to Bangalore so ruling out that to be a reason. My suspicion is the Alternator either pulley or the alternator itself. But I can see the charging voltage of 14.8 V on the battery when engine is running. Does that points to a weak alternator? Hate these intermittent noise most difficult to reproduce.