I've been battling intermittent coolant loss and puddles for about 9 months so decided to dig into my '00 II to replace the lower intake manifold gasket, assuming it's leaking. I did discover (ain't that why they call it a Discovery) evidence of coolant under the manifold, which was expected, but I also found the valley gasket to be more a mountain gasket. The center of it looks like it was pushed or blown up from underneath. Strangest thing. Also, the coating on the top surface of the gasket is coming off in flakes. I must admit that my son did drive the truck home from school many months ago with the red overheated light on so maybe it got so hot the gasket warped/expanded. But the truck starts, idles, runs and drives excellent -- both before and after the overheat incident. I have perspiration but not steam in the exhaust, the oil cap does not show foam and the exhaust has no coolant smell. I know folks will say I'm guaranteed to have a trashed motor by now or at least warped heads but I'll save that for another dissasemble.
My question remains - why would the lower intake gasket be raised in the middle? I would like reassurance before installing the new one and reassembling everything else. Many thanks for your suggestions.

 

Overheating will do weird things to materials like de-laminate the composite coating on your valley gasket. Fix your truck before you kill it.

 

It needs fixed, indeed. Rest-assured it's in the O.R. My concern is was there some pressure build-up that caused the gasket to puff up or is the deformation simply the result of overheating. Im looking for anyone who's encountered this and what they attributed it to. Did the gasket issue cause my leakage or did the gasket get weird because of the heat. BTW, the lower manifold gasket bolts required almost no force at all to remove. The vehicle has ~110k miles. I'm just assessing the extent that i take on more work on it if I have no other symptoms.

 

i have owned these trucks for ten years now...most times its hard to explain what they do...some time its easy but very rarely...if you are down to the heads...why not just do the heads......it seemed to me the most work was getting down to the heads....Also a valley gasket and intake gasket is about in price what you will pay for the whole upper gaasket kit...and at 100k ...you might as well make sure you dont....kil it....with the next overheat....i was at the heads and then relalized 1...i was another 20 bolts and a couple of hours away from pulling the entire block...2....i really dont want to work or tinker with anymore engine problems for a long while so i am rebuilding it...and i also discovered where my PAS is leaking from now that i pulled the raditor out...