intake on 97 Lumina - advice needed

Hello - I happened to find this site by accident yesterday and found some wonderful advice here.

I have a used 97 Lumina (132,000) 3.1 V6 that started making loud tap-tap-tapping noise a few days ago. Yesterday it got louder and then the temp gauge went crazy ---> high then low then back to high. I was half-afraid to drive it but was about 80 miles from home. I stopped at a local garage and the mechanic took a quick look and said the coolant was low....and took the cap off the oil filler and showed me gunk on the cap. Said that was not good at all and that the intake gasket could be shot. Does this sound right? Is this an expensive repair? Any ideas, suggestions are greatly appreciated.
I don't want to sink a ton of $$ into something that may end up costing me more in the long run but I really love my Lumina and wouldn't want to park it if I don't have to....

Thanks to all who respond. :)

If the oil looks like pudding, you already blew the gasket. I'm inclined to think that anyhow due to the sounds you describe;that would be the crank bearings knocking or lifters collapsing. Usually once the problem is in this stage its going to need a good bit of work to get everything back to how it should be. Call around and ask shops how much they want for the lower intake gasket replacement.

More or less every single 3100 will have to have its lower intake manifold gasket replaced; reportedly GM 'fixed' the problem in their 2002+ engines but only time will tell.

thanks!

I contacted my local Chevrolet dealer and they quoted me a rough estimate of $578.00 + tax.

I'm waiting to hear from a few other local mechanics before proceeding.

Apparently, I've been told this is a common occurrence... :(

Yup, like I said, almost every 2nd generation (3100 labeled) 3.1 V6 from GM has this problem.

That's not bad, at the dealer I work at we bash the customer for $698, plus tax, for the same repair.