Broken/Warped Plenum's all over the place

[happydog500]

I went to my mechanics today to get some work done. Another car just like mine was in the shop. It had a warped "Plenum."
That's the black, half moon shaped plastic intake manifold on the top of the 3.8 motor. There is water (antifreeze) that goes in part of it. If it warps, cracks or leaks, it pores liquid into the motor. On this particular motor, it warped, having liquid into the intake did damage (water doesn't compress like air does) The motor was full of antifreeze when it was running. Wrecked the catalytic converter, O2, and needs the barrings checked.

They have another car that has a warped part also. While i was in talking to him, another guy came in with trans problem and asked about fixing his leak in the same place. His cracked.

We went and looked at mine. What do you know? Mine has a leak also. First you get a leak externally, then internally. This is 4 in one day. Has anyone had a problem with the plastic intake leaking?

I thought maybe I might need just a new gasket but the mechanic said they almost always warp and I need to get a new one. The total price to replace one is $500-$600.

Why does GM make a plastic manifold and have fluid inside like this?

Anyone know of a aftermarket replacement part that's made a little better?
Thank you,
Chris.

[HotZ28]

Do a search in this forum for "intake plenum". Below is one of many!

http://www.automotiveforums.com/vbul...d.php?t=483407