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3rd Gen Ram Tech2002-2008 Rams: This section is for TECHNICAL discussions only, that involve the 2002 through 2008 Rams Rams. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
Finally got time to do this today after setbacks with the brake lines blowing, front calipers seizing, and some other stuff prevented me from installing the new rad until now.
Starting out with the chemical flush with the old rad still in so the system is clean before the new rad install and I've hit an issue right away - Ran the vehicle to circulate the flush chemicals and topped off distilled water and after 20 minutes the lower rad hose is still cool, top is hot, and overflow did not drop in level as expected when the thermostat was supposed to open. Upper hose was hot and heater blew hot air after only a few minutes so heat works (had it on hottest setting and full fan speed). Coolant temp gauge stayed at the halfway mark.
So seems like the thermostat is stuck that's why the lower rad hose is remaining cool and level of coolant didn't drop?
Possible. You can remove the thermostat
That will allow you to run the flush through unobstructed AND while its out you can test it in boiling water to see if it opens.
Do not drive without the thermostat. Keep an eye on the temperature gauge to make sure it doesn't overheat on you.
Note: the temperature rating of the thermostat is the temp at which it begins to open. So a 195*F begins to open at approximately 195*F and doesn't fully open until around 215*F +/- a few degrees
Possible. You can remove the thermostat
That will allow you to run the flush through unobstructed AND while its out you can test it in boiling water to see if it opens.
Do not drive without the thermostat. Keep an eye on the temperature gauge to make sure it doesn't overheat on you.
You can drive without the thermostat. Unless the radiator is clogged, it will run cold. Personally, I'd just replace the thermostat, then run the flush thru it.
Tried without the thermostat but since gasket is on it, water leaked out when housing was bolted back up.
Ended up just running water thru the top hose with bottom disconnected, then hooked the shop vac up to top hose and blew all water out of engine block. Next flushed the heater core by disconnecting hoses going to it.
Will put in the new rad, hoses, thermostat, and rad cap tomorrow.
I did check the old thermostat and although it is a 195 degree like the new one I bought, it seemed to stick a bit as it opened around 205-210 instead (spring worn out maybe?). New one opens up at 195.
New thermostat has no notch in the gasket/seal like the old one though - is it just to make sure the position is right for the "jiggle pin" and/or will the jiggle pin position move without the notch in the seal?
Last edited by RedRam2002; 11-12-2020 at 03:23 AM.
New thermostat has no notch in the gasket/seal like the old one though - is it just to make sure the position is right for the "jiggle pin" and/or will the jiggle pin position move without the notch in the seal?
Don't overthink it. Just install the thermostat and make sure it's facing the right way.
Everything is back together, put the thermostat's jiggle pin/brass valve at the 1 o'clock position just like the stock one was and how it should be for the 4.7L. Read it needs to be around that position as it helps bleed off air/air pockets which is very important for these V8's so they don't overheat and possibly drop a valve seat.
Ran the engine for 30 minutes but thermostat didn't seem to open as lower hose was cold and level of coolant in tank never dropped (heat was blowing hot after first few minutes) but its near freezing here so maybe that is the reason. Temp gauge read just under halfway.
I will have to take it for a drive tomorrow and see if level drops then. Put in about 3 gallons of coolant only so it should need more when thermostat opens.
Last edited by RedRam2002; 11-17-2020 at 01:06 AM.
Can I ask a ? Chris Fix's video says heat temp and fan both on full, and Eric The Car Guy says too run only the heat without
the fan. To get flow through heater core. And mentioned something about a valve.
Poster of this thread mentioned he ran with both heat and fan ?
So which is the right way for our 3rd gens 5.7s ?
Just the heat no fan or both at same time.
Poster of this thread mentioned he ran with both heat and fan ?
So which is the right way for our 3rd gens 5.7s ?
Just the heat no fan or both at same time.
Makes no diff. Just keep it set to hot. The only thing the fan does is push air off the core. If the temp is set to hot, coolant flows thru core regardless of whether its being blown or not. In my Dak, there isn't even a heater valve. Its all controlled by the vent doors, so coolant is flowing thru core at all times. Not sure about the Rams.
Everything seems fine now with cooling system, changed the Stant thermostat seal out for a Felpro one as the stant seal was thicker and not allowing the plastic housing to be fully flush when mating to the engine surface.
Here’s a pic of blue Felpro seal installed and old rad, not sure why but rad it is bowed at top and bottom for some strange reason :
Stant thermostat with Felpro gasket Old rad bowed
Last edited by RedRam2002; 11-16-2020 at 11:36 AM.
Possible, old owner was driving with low coolant much of the time the last winter from what I saw. Wondered where the coolant was going but when I got it found out it was leaking from the seams of the rad on one side once it was heated up. Was already bowed when I got it.
Last edited by RedRam2002; 11-18-2020 at 03:21 AM.
11-09-2020, 01:32 AM
