Overheating Problem

[jdsixtos]

I wanted to see if someone may be able to point me in the right direction. I have a 2008 Dodge RAM 1500 3.7L V6. Just recently, I started noticing the temperature rise as if it was overheating. I just recently had the transmission rebuilt (the mechanic said that he wasn't able to get all of the metal shavings out of the trans-cooler and to bring it in if I start having problems because it's under warranty). Also, just recently, I got another strange issue where the tops of both catalytic converters (where it connects to the pipes going into the exhaust manifold) broke, literally (of which I have no idea how they both just "broke"). I will be getting my exhaust system fully replaced (cats, muffler, and pipes) this week.

All in the mix, now I have an overheating problem (and no noticeable water leaks, fan clutch seems to be good, and coolant level is good)...

Things I've done so far: I've replaced the upper and lower hoses, the thermostat, coolant temp sensor, and radiator cap. Checked the fan clutch, thinking maybe it wasn't spinning fast enough, there is still resistance and it doesn't spin freely by hand. Squeezed the upper hose while it's running to make sure water is traveling through the radiator (there is water, and it's very hot). I also noticed while driving, at higher speeds the temperature would drop (but because air is passing over). I also noticed when temp got pretty high I popped the hood to see if I hear any boiling/bubbling/gurgling/hissing noises, and there is nothing, no steam either.

(I really hope the block isn't cracked, but I can't see it being cracked)

I'm out of ideas and can't think of anything else if the overheating problem doesn't go away after fixing my exhaust, and possibly taking it back to the transmission shop to service the trans-cooler. The next step will be to replace the water pump. I'm thinking the exhaust is what is causing the problem (I think the cats areally both clogged which is why the both broke, and I think it's still not breathing too well as there isn't much of a gap). Any ideas?

 

[RonJon '06]

You could try running a 180° thermostat instead of the factory 195°. Also make sure there's no air in the system by parking the truck on an incline with the engine highest, remove the radiator cap and start the engine. Once it comes up to temp shut the engine off and see if the level changes.

 

[Maximumrisk]

If i understood it correctly, you have an exhaust leak just before the cats?
if so, you oxygen sensors could be reading lean, telling the computer to enrich the air/fuel ratio which, if rich enough, can cause it to overheat.
Your cats could also be plugged, but you would het noticeable poor performance.
Long shot, but since you mentioned the problem decreases at highway speeds, check your fan shroud and make sure it is in one piece. A cracked or broken fan shroud will cause overheating at low speeds.

 

[SilverStreak88]

Ok - I just went through this myself except I (was) losing water "somewhere". I couldn't figure out for the life of me where it was going, I put some of that Bars leak stop in there and it stopped the leak. I had no leaks anywhere, water pump, radiator, hoses, I went ahead a replaced my thermostat, upper and lower hoses and flushed all of the leak stop out. The water started disappearing again... long story short I get my truck back from the trans shop and I can smell Antifreeze in the cab and my temp is good so I make it home and look around and my passenger floor is wet! A few day later I get to work, shut it down and I hear psssssssssssss, boiling water under the passer dash, shine my light and coolant/water is ******* everywhere. My heater core had a small leak that went unnoticed because it would leak out the evap. drain tube and it got bigger. I bypassed my heater core, did a complete flush of everything to get the leak stop out filled it with water and haven't had a leak since. Hopefully you don't have to endure what I'm about to and you just have a sticky thermostat, btw my thermostat was in 2 pieces when pulled the housing off.