08 hemi temp problems.

[KyrpticKyler]

I have a 08 megacab with the 5.7 that ive owned about a month. And now I’m battling water temp problems, at first the temp was varying between 208-221 then the fan would kick on and it would cool back down, so I replaced the thermostat, and that fixed it ( or so I thought), temp would stay between 208-210 but I just got back from a camping trip, and if I give it any excessive throttle it climbs up to 221 rapidly. Or just cruising at freeway speeds, it will hover between 213-218. I just replaced the fan clutch and that didn’t help, if anything it made it worse because the new fan clutch won’t disengage so it’s always on. I’m lost with this, thermostat again? Water pump? Radiator? All of the above? Thanks for any help

 

[fastf]

You profile says 4.7 and your post is 5.7 what size engine do you have and how many miles do you have on it?

 

[KyrpticKyler]

Sorry, in the process of updating my profile, it’s a 2008 5.7 hemi. With 88000 miles

 

[fastf]

When you did the thermostat did you flush out the coolant and replace it with new?There have been a mumber of forum members replace the water pump and such and the heater doesn't get warm and the heater core is stopped up.Take in mind the radiator and the heater core is aluminum not made out of the old stuff like brass you cannot rod them out.I had a old Ford truck that would do that while pulling a ski boat and the radiator needed rodding out but it had the old stuff.This just stuff running through my mind also have you checked the cap for pressure and check pressure on your whole cooling system and see if it holds pressure.I hope this stuff will help you get things going right.

 

[KyrpticKyler]

Thanks for the info, and no I didn’t flush it out and replace with new, I just barely a few mins ago tried putting a new cap on it, no change, think I’m going to move forward and do a flush and replace the water pump this week

 

[fastf]

Do a pressure check on the whole cooling system.Now as far as the water pump if it ain't broke don't mess with it you shouldn't have to worry about it unless the seal is leaking .You put a pressure check and and see if it loses pressure .Now I take it back the water pumps now days the impellers are made out of plastic not metal and when they get older they fly apart.I had one on a VW in downtown Atlanta traffic when I got off the interstate it looked like the front end was on fire.Had to put it in the shop everywhere there was a union for a hose it was pieces of pump and broke union.

 

[KyrpticKyler]

Just put 16psi into it, held it just fine,is there a possibility it could be the temp sensor?? And will swapping from a 203 thermostat to a 180 help at all?

 

[fastf]

Could be on engines now days nothing suprises me.Take care may God Bless you real good.