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Black Beauty 2.0 (06’ 300c 5.7)
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Discussion Starter · #21 · (Edited)
it sounds like you have a air bubble in the system . if you look on the water pump you will see a hex screw on there . Back out and remove it. Once it’s out , fill system and when it starts coming out with pure coolant you should be good. Install the hex screw and should have all the air out. I’ve build several hemi and have had problems with overheating if I don’t bleed this way. Good luck.
I knew that it existed but on some past vehicles I’ve owned the bleeder screw/bolt never did me any good but this is my first mopar and first hemi so I appreciate the help! Definitely gonna need to go pick up some extra ZEREX G05 coolant
 

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Black Beauty 2.0 (06’ 300c 5.7)
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Discussion Starter · #22 ·
Hi mate;

I concur with the guys above, likely a burping problem, as long as temp has not damaged anything.

Whenever something happens on a car and someone brings it to me, first thing I say is "what has changed??" Because "Car running fine, do something = have problem" - SOMETHING is where the likely start of it is.

I have had people say "They did xxx, but couldn't be that, because they fixed it..." But car was fine until then???

Firstly, I am old and I don't trust anything. The thermostat. Your car ran fine before, now it doesn't AFTER new thermostat. I always test "new" things. ONCE (ONCE!!!!!) I didn't test a radiator cap on an old car, meant to be 13 lb. It blew the hose off. When tested, it was 19 lb. These items are cheap, and remarkably reliable, but every now and then get a dud.....................So - I would test the thermostat. MAKE SURE it opens when it should. Just boil it on the stove with a thermometer in the water, watch when opens, make sure it opens all the way. Make sure temp isn't reading direct gas from stove etc etc (you know the drill).

Secondly, temp gauge. Good to read the EVIC temp, that should be ok. I would double check. IR temp checker is 8 dollars, or $20 if you "get a good one". Be careful as different surfaces give different readings sometimes, but take a heap of readings, can work out what is spurious.

The temp gauge in new cars often isn't linear. Otherwise people would panic. As these engines run hot; the "operating range" they are meant to run within is compressed in the middle of the gauge, and is a component of the engine monitoring "showing what people want/need to see". That is why the needle goes to about the middle, then hardly moves as temp wanders up. When the computer gets to a "warning temp"; it will then elevate the gauge, but often by then warnings (lights, even codes) will start to take over.

The point is, the gauge will sit "at normal" for a bit of a range that it deems "normal"; so if you want to see any movement, use the EVIC, (which you are, great) once you confirm that THAT is correct.

Remember that EVIC can only read correct temp if correct circulation, otherwise it will be a "hot spot". Fan belt tension, water pump (incorrect clearance, but yours new????), thermostat not opening/not opening far enough can all cause that. Again, IR will show if temp even throughout or not. Is radiator red hot when it is doing this? The average old blokes hand can tell the difference between "Hot" (normal) and "HOT hot" (overheat)..............

I would remove thermostat and test. Test the old one. See if any difference. THEN I would burp again, go from there.
I appreciate the info sir as well this is my first mopar and first hemi so lots of researching with this car and learning. I will admit the top radiator hose did get very bloated and extremely hot, hotter than the reservoir cap. Leaning towards faulty tstat maybe finally gave out, especially seeing it’s been leaking. No glowing red radiatior here.
 

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I currently drive a 2006 Magnum SRT8, 190 degree thermostat, cold case aluminum radiator, Dorman XD fan module, Diablo tuned with cooling fans set to 205 degrees, have zero issues here in Houston area, sit idling in traffic on San Jacinto bridge some days for half hour, and temp stays at 199. Also, you don't need to have rtv smeared all around that t-stat housing as the t-stat has it's own seal, no clue why your tech said they had leaking issues at the housing, that's a false statement.
 

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Black Beauty 2.0 (06’ 300c 5.7)
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Discussion Starter · #24 ·
I currently drive a 2006 Magnum SRT8, 190 degree thermostat, cold case aluminum radiator, Dorman XD fan module, Diablo tuned with cooling fans set to 205 degrees, have zero issues here in Houston area, sit idling in traffic on San Jacinto bridge some days for half hour, and temp stays at 199. Also, you don't need to have rtv smeared all around that t-stat housing as the t-stat has it's own seal, no clue why your tech said they had leaking issues at the housing, that's a false statement.
So many 300c members are leaning me towards getting the 180/190 degree thermostat, however what brand is best? I don’t need the tstat failing on me so fast like the one I currently have in the car did, I got the water pump, tstat, and radiator hoses all replaced 8-9 months ago and already the tstat went bad on me but the lower tstat seems like such a great benefit for our hemis. I think I’ll stick to a more pricey/higher end stock 203 degree thermostat until I can get my hands on a Diablo tune device so I can adjust the fan settings once I switch to a lower tstat.
 

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fwiw... putting in a lower temp t-stat now won't hurt anything. You can adjust the fan setting when ever you get access to software or a tuner.... Why go thru changing the t-stat now, and getting the air out... only to go thru it again?... unless you're having so much fun ;) (my 2 cents)
 

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Discussion Starter · #26 ·
fwiw... putting in a lower temp t-stat now won't hurt anything. You can adjust the fan setting when ever you get access to software or a tuner.... Why go thru changing the t-stat now, and getting the air out... only to go thru it again?... unless you're having so much fun ;) (my 2 cents)
I’ve tried searching on the forum but maybe I’m not typing the correct wording as I tried to figure out if i can just put a lower temp tstat in already without the fan setting change, how long can I go with a lower than oem tstat but no changed fan settings? Thank you for the help! Also what brand is best for the lower tstat? Don’t need my tstat failing on me so quickly again lol figured if someone knows from experience better to know before I make a purchase shrug
 

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So many 300c members are leaning me towards getting the 180/190 degree thermostat, however what brand is best? I don’t need the tstat failing on me so fast like the one I currently have in the car did, I got the water pump, tstat, and radiator hoses all replaced 8-9 months ago and already the tstat went bad on me but the lower tstat seems like such a great benefit for our hemis. I think I’ll stick to a more pricey/higher end stock 203 degree thermostat until I can get my hands on a Diablo tune device so I can adjust the fan settings once I switch to a lower tstat.
I’d look for the Motorad with the fail safe design, if something ever happens in future will fail in open position and save your motor. I believe the 5.7 Hemis are ok with the 180 degree t-stats, my 6.1 didn’t like it so I stepped it up 10 degrees and zero issues
 

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Discussion Starter · #28 ·
I’d look for the Motorad with the fail safe design, if something ever happens in future will fail in open position and save your motor. I believe the 5.7 Hemis are ok with the 180 degree t-stats, my 6.1 didn’t like it so I stepped it up 10 degrees and zero issues
Didn’t know they even made those tstat designs! Cheers mate! I’ll look around on here more and see what temp tstats work best for most people on the 5.7’s
 

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Discussion Starter · #29 ·
I’d look for the Motorad with the fail safe design, if something ever happens in future will fail in open position and save your motor. I believe the 5.7 Hemis are ok with the 180 degree t-stats, my 6.1 didn’t like it so I stepped it up 10 degrees and zero issues
Also when you say your 6.1 didn’t like the 180 so you went up to 190… what issues was it causing?
 

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"...tried to figure out if i can just put a lower temp tstat in already without the fan setting change, how long can I go..."

Yes, you can just put in the lower temp stat and go so long as you would with a stock stat.

If you don't change the fan settings, then the fans will still keep the engine at stock temps... at least around town and in warm weather.

If you're running on the highway, then the temps might stay a bit cooler with the lower temp stat... variables: ambient temp, a/c on... that's about it.

So far as brands... Generally, what the guy at my local shop sells is what I install.
 

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Do Not do a failsafe design. Especially if you won't be changing the fan settings right away. One hard run could be enough to lock it open. Then you'll have to remove it to reset it. Terrible design, imo.
Ikrc, mine is a motorad, but normal design. Ran the same in my 300.

Sent from my SM-G988U using Tapatalk
 

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Discussion Starter · #32 ·
Hello all, thought I would give an update for all you fellow 300 members who chimed in with advice/help… replaced the thermostat with a 192 degree tstat since I won’t be changing the fan settings anytime soon, and also replaced the thermostat housing since the one that was on there was aged (no more coolant build up in that area AKA a leak), then replaced my radiator/coolant reservoir cap since the old one wasnt holding correct pressure. Only had the old cap on there since I replaced the water pump and it already went bad on me! I know it’s not OEM so that could be why so I went ahead and got a safety lever cap instead, everything is all good again and I’m liking the lower temps when I’m on the move! I ended up just putting the car on a nice incline and burping it with the rad cap off and letting it run with the heat on… and it had many bubbles! Then topped it back off with Zerex G05! Cheers everyone!
 
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