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Re: Hemi 5.7 overheating after new thermostat and air purge. [Re: KcCrown] #2855877
12/05/20 11:32 PM
12/05/20 11:32 PM
Joined: Aug 2003
Posts: 954
garnett kansas
rhad Offline
super stock
rhad  Offline
super stock

Joined: Aug 2003
Posts: 954
garnett kansas
pull the spark plugs and see if one looks a lot different than the others!!=head gasket


my ladder of success is missing some rungs
Re: Hemi 5.7 overheating after new thermostat and air purge. [Re: rhad] #2855883
12/06/20 12:03 AM
12/06/20 12:03 AM
Joined: Jan 2007
Posts: 10,115
A Red State
SNK-EYZ Offline
I Live Here
SNK-EYZ  Offline
I Live Here

Joined: Jan 2007
Posts: 10,115
A Red State
Originally Posted by rhad
pull the spark plugs and see if one looks a lot different than the others!!=head gasket


iagree

Pull one plug from each cylinder and look for signs of coolant.

Bad head gasket symptoms

Quote
White smoke coming from the tailpipe.
BUBBLING IN THE RADIATOR AND COOLANT RESERVOIR.
unexplained coolant loss with no leaks.
Milky white coloration in the oil.
Engine overheating.


Just because it doesn't seem to run bad for now doesn't mean there isn't a head gasket problem.


Kayse can't keep up at all now. lol
Re: Hemi 5.7 overheating after new thermostat and air purge. [Re: SNK-EYZ] #2855886
12/06/20 12:13 AM
12/06/20 12:13 AM
Joined: Jan 2003
Posts: 32,882
Grand Prairie,Texas
stumpy Offline
I Win
stumpy  Offline
I Win

Joined: Jan 2003
Posts: 32,882
Grand Prairie,Texas
You can have a blown headgasket and not have water in the oil.

Re: Hemi 5.7 overheating after new thermostat and air purge. [Re: stumpy] #2855892
12/06/20 01:25 AM
12/06/20 01:25 AM
Joined: Jan 2003
Posts: 4,131
Canada -- Posts: 4034 -Registe...
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5thAve Offline
Doesn't care what this says anyway
5thAve  Offline
Doesn't care what this says anyway
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Posts: 4,131
Canada -- Posts: 4034 -Registe...
You said you drove for a few weeks before the problem started. Air would purge out on it's own long before then.
Did you fix whatever the leak was at the reservoir? If not that can be causing the problem. The reservoir with the rad cap is part of the pressurized system and if it has a leak on that part and not pressurizing properly it can cause problems.
It sounds like you still didn't bother pressure testing the system yet? Without doing that you're wasting a lot of time guessing. Same with checking for other problems people mentioned. Just because parts are new doesn't mean it doesn't have a problem.

Last edited by 5thAve; 12/06/20 01:25 AM.
Re: Hemi 5.7 overheating after new thermostat and air purge. [Re: 5thAve] #2855991
12/06/20 12:51 PM
12/06/20 12:51 PM
Joined: Dec 2012
Posts: 257
Alberta
4
440_Offroader Offline
enthusiast
440_Offroader  Offline
enthusiast
4

Joined: Dec 2012
Posts: 257
Alberta
iagree

There is air entering the system somewhere. I would pressurize the system with the spark plugs out. With pressure on the system, use a borescope to look into the cylinders. You may see the leak in there. A coolant leak in a cylinder will knock the carbon off and make it look clean/newer than the rest. So note that as well while doing a borescope. It may be external as well. Use some windex or something on the top of the tank where there's no coolant. The windex will bubble where there's air leak. You might not find any leaks either. With the engine cold, it might be fine. When it's hot, it changes the growth of the metal/gaskets, and will leak then. I've pressure tested cylinder heads and are fine when cold. Wen they get to 180°, then they opened a crack. This is what I would do. Take it or leave it.
Like mentioned, new parts aren't always good parts, so don't rely on that to fix a problem. Maybe something wasn't installed correctly? Maybe something has been damaged during all the overheating the engine has encountered lately?

Re: Hemi 5.7 overheating after new thermostat and air purge. [Re: 440_Offroader] #2856001
12/06/20 12:59 PM
12/06/20 12:59 PM
Joined: Aug 2005
Posts: 371
Kings Beach, CA
T
tahoechallenge Offline
enthusiast
tahoechallenge  Offline
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Joined: Aug 2005
Posts: 371
Kings Beach, CA
I worked on a diesel engine that had a small crack in one of the cylinders. The crack would not allow coolant into the cylinder, but would allow hot gases into the coolant passage. The engine could idle for hours without a problem. When the engine was under load (full boost) it would boil the coolant in minutes.

Re: Hemi 5.7 overheating after new thermostat and air purge. [Re: tahoechallenge] #2856225
12/06/20 07:56 PM
12/06/20 07:56 PM
Joined: Jun 2006
Posts: 472
Central NY
G
GarageDodge Offline
mopar
GarageDodge  Offline
mopar
G

Joined: Jun 2006
Posts: 472
Central NY
You need to test for combustion gasses in the coolant,also does the fan work?

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