Oldsmobile/Buick Repair: 91 Buick Regal 3.1L Belt Tensioner, coolant levels, coolant recovery

Question
I have a 91 Buick Regal. A few weeks ago I noticed the Low Coolant Light flashing, it now stays lit. The car gets hot after a while and will die when idle. Checked coolant levels and all seems fine. I've also noticed at night that the lights will dim right before the car dies, car is easy to restart. I've checked everything I could think of and think I found the problem in the accesory drive belt. I can push it down several inches, and since this belt runs the alternator and water pump I think if I tighten it that it will fix my problem. Right? But the problem is I can't figure out how to tighten the belt!! Any suggestions? Do I maybe need a new tensioner? How do I find out? Is that something I could fix myself? If you could help me I would be ever grateful. Thanks much for your time. -CRF


Answer
Hello Cassie,
The only way to know if the coolant is really low, is to remove the radiator cap, and look inside the system.
This should only be done when the car is cool. Then fill the radiator as full as possible. Add some to the coolant recovery tank if needed, but if the radiator is low, and the recovery tank is full, there may be a leak in the hose between them.
If that car has a tensioner, that is possibly what you need, and yes, it is something you can replace.
However, it is also possible that the alternator is the adjustment system for that car, and may need to be moved to tighten it. A new belt may also be needed.
Another possibility is it may have the wrong belt.
But the heating up, and the lights dimming can both be caused by a loose belt.
A belt tensioner is a spring loaded gizmo that holds tension on the belt, and they do occasionally stick.

Van