Just got home from school, and i opened the hood on my 91 740 turbo, and i heard an almost boiling sound coming from the coolant overflow tank. my coolant is full and the car was not running hot. Is this any cause for concern?

 

It could be air in the system. Has it been drained and refilled recently?

To remove any air gently squeeze the large hoses several times.

 

I have had the car over a year, and it has not been drained etc. I will try the hose squeezing. Thank you.

 

Thermostat might be bad making it run a little hotter but not show up on the guage.

 

Ahhhh thats a good tip tech. I cant remember when it was changed last so this weekend....ill put a new one in before i get stuck somewhere.