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5.7 Hemi Overheating After Thermostat Replacement

44K views 5 replies 4 participants last post by  Intense RT 
#1 ·
Hey Guys,

I've been reading this forum for a while, and haven't had a problem finding solutions to my problems until now.

The Basics: 2005 Magnum RT, 138K Miles, bone stock, recently replaced throttle body and thermostat, still need to replace crank sensor and fix front suspension problems. Owned since 2006 with 13K miles.

I had problems with the thermostat sticking a while ago and the engine not heating up. Seemed to clear itself, so I didn't worry about it until I was going in to replace the throttle body. After completing those installs (stock mopar parts), the engine now overheats(temp gauge will max out if I don't shut it down, even idling). I've bled the system multiple times, and checked to make sure that the wiggle valve on the thermostat was up. Still overheats, but more slowly. The fans do turn on. I did notice the rubber membrane on the new t-stat, so I just checked the old one. The membrane is completely gone on the side that faces out, and half gone on the inside.

Where do the pieces of membrane end up going, and it is possible that a piece is partially blocking coolant flow? Or have I just not gotten all of the air out of the system? When I bled it this evening, the coolant came right out of the bleed plug with no bubbles.

This has been going on since last Sunday, I can't keep driving my wife's car forever.

Any thoughts?
 
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#3 ·
Just swapped my tstat yesterday. Was no membrane on the outside fwiw. Just on the inside/ spring side. Mines in good shape. You could drill a 1/8" hole in it (flat area close to the ridge and keep it away from the braces on the stat that hold the center). That will ensure the air escapes. Mine functions well like this. It's something I picked up years ago. Radiator fins blocked/plugged? Try a cooling system flush? Overflow tank look clean inside?

Just some areas to look at.
 
#4 ·
The 5.7 motors don't come with a bleeder valve, have you installed one???

Remove the plug in the water pump housing and install a bleeder valve, I got my parts from Advance Auto Parts.

Here is what they look like.

Bob

PLUG:


Adaptor:


Bleeder Valve:


Installed:


Old plug removed:
 
#5 · (Edited)
Thanks for the responses.

Bob, I did mean that I had opened the plug, I hadn't thought of a bleeder valve as shown above. I may need to consider that.

IntenseRT, I don't really want to pull the tstat back out to drill it, don't want to damage the gasket and deal with that.

Hemi31, thanks for the advice about the valve seat. Definately don't want that to happen. The temp gauge only got above 3/4 a total of 3 times. Once on the way home, and twice while trying to bleed the system. Hopefully no damage done.

I decided that I'm going to take it in to the mechanic. I can't get to the crankshaft sensor without having it on a lift and/or dropping the starter. I wrench on my cars for fun, these few things are not fun for me, so I'll just have someone else do them. I'll have the cooling system flushed while it's there, the coolant is original, so it's time to change it anyway. I'll let the mechanic deal with bleeding the system.
 
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