What you have pictured is the upper intake manifold. There is a lower manifold....also made out of plastic. To my knowledge there isnt any issues with the manifolds besides the bolts can strip out if overtorqued and to make sure your gasket/orings are in decent shape if you are reusing them. The newer engines (PUG or Pentastar upgrade) have better designed ports on the lower manifolds and can be swapped for a few extra HP (supposedly).

 

I had to take my upper manifold off this summer to change my plugs. At 110k miles it was still in perfect condition

 

Mine was in good shape too, until I stripped one of the bolts while putting it back on. Any one know if there is any was to fix them? Also, will those newer manifolds fit?

 

Many if not most of todays manifolds are a plastic composite, in everything from our Jeep to the Corvette. They reduce weight and don't heat soak as bad as aluminum.

 

As stated above, plastics are used extensively in modern cars. My only concern is 'creep' of the plastic after multiple heating/cooling cycles, and the resulting loss of the clamping force generated by the fasteners.

Background:
I recently replaced my (plastic) Oil Cooler Assembly, meaning I had to R&R the Upper and Lower plastic intake manifolds. At disassembly, I noticed evidence of slight leaking at almost all of the Upper and Lower intake manifold seals. I also noticed that the fasteners didn't seem very tight.

During re-assembly I followed the factory manual for torque value and sequence and/or steps.

Now, I always go back and check my final torques. I found that the plastic Oil Cooler took 3 passes at final torque before the bolts didn't move. The Lower Intake took about 6 passes! The Upper Intake checked good after the first pass, but it is a lower torque than the rest.

After this experience, I did a little digging and found many reports on loose plastic manifold bolts on other FCA products as well as other manufacturers.

 

Good to know , Thanks
I went over mine just twice today.
I better check again in the morning

 

I just noticed today that my upper is starting to split and warp at the seam.

Go figure with hot plastic eh