Engine question...
 

i had a question to find out some tell signs that my coolant seals are going bad or already need replacing. went to start up my car a couple days ago and noticed a funny sound like it was struggling to start. then right away i noticed a smell of coolant in the air so i then went to the back of the car to look at the exhaust and noticed a bit of smoke with a faint smell of coolant. as soon as the car warmed up the smell and smoke both went away. so my question is how do i know if my coolant seals need replacing or is it something else...? thanks in advance for any help...:scratch::scratch:

1) Mysterious disappearing coolant
2) Bubbles while the engine is running
3) Overheating / boiling coolant