UIM/LIM Problems

I have a 1999 buick regal ls. these cars are piles. i started the car and ran great later went out to get in and the car was burning coolant. first thought was a blown head gasket or intake manifold gasket. lower intake manifold gasket was blown on every port but went ahead and changed the head gaskets also. also had to replace head bolts. but anyway put the engine back together and ran fine until the thermostat opened up then continued burning coolant although not as bad. just today found out that the upper plenum at the coolant passages are notorious for cracking or burning holes through them. the big hole in the plenum had a hole about the size of a straw in it. so hopefully thats the problem. but should definitely be recalled.

Welcome to AF.

Sorry to hear that but don't feel alone. How many miles did you have before repairs? You're the first person in a long time with a '99 or higher model that has reported a EGR stovepipe meltdown problem on the UIM. Most of the time it is just the UIM gasket or LIM gaskets. The UIM plenum issue was more prevalent on GM cars from '95'-98 with the NA Series II 3800 engine. So EGR stovepipe issues are rare for '99 and up models but possible.

After repairs did you flush out the engine just to make sure all the residual coolant was removed from the engine? Just continue monitoring coolant level and hopefully you should be OK.

BTW- Your post title was renamed from "Piles" to UIM/LIM Problems.