Wildman4x4nut. I am having the same issue with my 1999 dodge ram 1500 5.2 with 50,000miles on it. My plenum gasket was blown so i replaced it now my truck is overheating. It ran at about 210 before i replaced the gaskets. So far i have replaced both the intake manifold gaskets, plenum gasket, water pump, thermostat, radiator, and clutch fan. I have also backflushed the heater core and block. Still overheating. Did you ever figure out a solution?

 

What mix did you use 50/50 or you running strait 100% Antifreeze? Remember the engine needs that water mix to cool properly..

From the way it sounds.. to begin with you were already running a little warm.. when you say your running 210.. is that sitting in traffic with the AC on or running down the road.. sitting in traffic with AC on.. that's kinda normal.. esp if you dont have electric fan as well.. (AUX Fan) with the Fan Clutch.

Are you sure your fan clutch is working? ( you will feel the drag when it engages- and hear the big roar when you accelerate from a stop with it engaged) then i would be leaning to following conditions.

A. Some debris dropped down in the coolant ports when you were doing the plenum and is partially if not all the way clogged.
(Most likely if your truck is now running hotter than it was before the repair. )

B. Radiator is clogged and or has so much build up on the side walls that it's not transferring heat properly.
(You can check this out by checking the temp of the core in different spots.. and see if you get any spots that are cooler than others.. that might be indication of a clogg.

C. Head gasket blown/weak between the cycl and the coolant passage.. this is will cause excessive heat.. can also lead to other issues if the coolant or oil seeps into each other..

 

Sounds like a blocked coolant port from debris since it started after the plenum fix. Get a radiator pressure tester and check for a leak in the coolant system first thing. If you can eliminate or confirm a blown head gasket or cracked head, you will have a better chance at narrowing it down. This actually is a pretty good tutorial from Autozone:
http://www.autozone.com/autozone/rep...btitle=inspect

 

yeah that's what i was kinda thinking being he just got done with the plenum.