Originally Posted by tnwalker01
Here are some better pics of the open port in question. Anyone know what goes here? The car is a 1999 Grand Prix, 3.8l non-turbo but I believe it has a 1997 3.8l from an Olds 88. Thanks in advance for any info.
I second the UIM/LIM Gasket needing to be replaced.
I also recommend not driving the car anymore until this is fixed, if enough coolant gets into the cylinders it could cost you a motor, liquid does not compress like air, it can possibly cause catastrophic engine failure.
I'll look at my motor tomorrow and see if I have that same hole, if I had to guess I'd say it was used for holding the engine block while it was being made in the factory, but it does have threads, so I am probably wrong.
The oil that is leaking is most likely coming from the LIM Gaskets like Justin said, I had the same leak from them until I replaced mine.
While you are doing the UIM/LIM, if possible try to change that serpentine belt, it is pretty cracked, and will most likely not hold up too much longer.
Back when I did my UIM/LIM I had never done one before, so I started a thread, it is not a how to like Justin'* thread, so stick to that when doing the repairs.
Reading it may help you with any possible questions that could come up with, I am pretty sure I asked them all, and I got some great answers, I will warn you it is quite long, about 26 pages, but there are some good tips throughout the thread.
Replacing UIM, UIM Gasket, and LIM Gasket. - 3800Pro.com Forum