1991 Park Ave.
While checking under the hood after the engine had been run, I saw a bubble of green coolant appear from a hairline crack on the top/right side of the radiator.
To rate how much leak it is...I see a small spot on the driveway below the general area...about 4 inches in diameter...while parked overnight.
I think the radiator is plastic. I wonder if "stop leak" additive would help and how long? I new radiator online sells around $150. Not sure if I could replace that myself....seems too involved.
Some people would give up and stop fixing this 20 year old to buy a newer vehicle, but I haven't gotten to that point. This problem added to the list...and has gotten longer...(tranny slip..possible shift solenoid and the climate control DOA...(can live with til June in Florida).

 

Does the crack look very big? Or it is just a small hole? Stop leak should work, just keep an eye on it to make sure it don't leak anymore. For a step by step how-to on replacing the radiator, message the user Buickbag, he has a lot of great write-ups that he posts on the forum. He should have one for that. Good luck!

 

If you like and enjoy doing some of the repairs on your car that 91 is a gift.
The radiator isn't a big deal to remove and replace. If you had a newer year I could see why you might consider having someone else do the job. The newer they get the more stuff you have to remove to get the job done. Lately a lot more guys are holding on to the older models because they are so much easier to repair than the newer models. AND,, the mileage of some of the newer models isn't much better than what you are getting with the one you now have. I haven't heard of anyone being successful with temporary repairs to the plastic radiator ends.
If the radiator is still in decent shape a radiator shop may be able to just replace the cracked tank portion. Worth checking into.