11th May 2016, 16:22
GM has had intake manifold coolant leak problems on several models. The 3800s (from the 1990s) are known for it, and so does the 3100. Although they are completely different engines. They both have occasional issues where the intake manifold meets the heads. The later 3800s sometimes develop an internal coolant leak that very slowly feeds coolant to all cylinders. I have worked on all of them.
30th Oct 2012, 16:13
This problem with the intake manifold is mainly isolated to the 3.8 Series II produced from around 1994-2005 and the 3.1. These engines were used on a lot of models. I personally have had a Chevy Lumina with the 3.1 and 2 Buick Park Avenues with the Series II 3.8, and never had any issues with the engines. However I have known several people who have experienced it with both engines, including my parents with a Bonneville that had the 3.8.