Chevrolet Repair: Intake manifold, 1999 chevy lumina, chevy lumina

Question
my 1999 chevy lumina has been leaking anti freeze, i have in the past year brought it in to the shop for this problem. i paid to replace the thermistat and serpentine belt. now my car is leaking antifreeze again and they said it is the intake manifold.what is an intake manifold and how much is a repair for a leak?
Could this have been the problem the first time?  

Answer
Hello M,
Yes, it is possible that it could have been the problem all along, however, the thermostat housing is in the intake manifold on most vehicles, and sometimes the exact source of a leak is hard to see, with all the accessories bolted on limiting visibility, and coolant dripping off from several different points.
Possibly closer scrutiny may have found it, or it is also possible that the thermostat gasket was leaking also when it went in. If you see something like that leaking, it would be reasonable to expect replacement of that gasket to fix the problem, which may well have been the case.
Replacement of the intake manifold will be a much more complex task, thus costing quite a bit more.
The intake manifold is the large aluminum assortment of tunnels that all the air passes through to get into the engine.
The belt was probably in shape for replacing, and was done so with your best interests in mind, not to fix the leak. Having it off, though, would allow better checking of the water pump, which is another potential leak area, so I would say they didn't try to get to you, but rather, they did reasonable, and expected repairs.
Van