2010 ACR Blowing Coolant out overflow

Emosgarage

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I had my ACR at the track last weekend for the first time, and I had two spins on track, which I now believe was the result of coolant spraying out the overflow tube into the front wheel well, then spraying down the side of my car, and then soaking my rear passenger tire. One spin happened early in the day, which I had attributed to cold tires, but then after the second spin, I figured out it was the coolant. I pressure tested the cap, and it is holding pressure right at 21 psi. I’m not sure what else could cause it to spray so much fluid out the overflow. the engine temperature was fine the entire day, including the 2 hour drive to and from the track. There was not too much coolant (it wasn’t overfilled). Any ideas what would cause this? something must be causing excessive pressure to build in the expansion tank?
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MoparMap

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Kind of sounds like a bad head gasket. That will pressurize the cooling system even at low temp. I remember back in college with our formula SAE car that it would blow liquid coolant out of the radiators non-stop, even when it wasn't that hot. Turned out the head gasket was bad so it didn't need to heat up to see pressure. You might be right on the edge where it doesn't leak coolant into the cylinder, but it will let combustion pressure out. Might check your oil and even send it off for analysis as well to see if they see any trace coolant in it.
 
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Emosgarage

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Kind of sounds like a bad head gasket. That will pressurize the cooling system even at low temp. I remember back in college with our formula SAE car that it would blow liquid coolant out of the radiators non-stop, even when it wasn't that hot. Turned out the head gasket was bad so it didn't need to heat up to see pressure. You might be right on the edge where it doesn't leak coolant into the cylinder, but it will let combustion pressure out. Might check your oil and even send it off for analysis as well to see if they see any trace coolant in it.
Thank you for that. That makes a lot of sense. It seemed to be worse after long straights with wide-open throttle, so perhaps that's why it is intermittent and didn't happen under normal driving conditions. I just recently changed the oil, and there was no visual coolant in the oil (and the coolant level has been consistent for past 2 years), so I don't think it was consuming coolant before this event. Thank you for that response! Sounds like a fun winter project is now in my future...
 

Goggles Pizano

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If you think the above, just run a coolant combustion check. Easy test to do kit available at local auto store and they might even loan it to you but you will need to buy the fluid that is a consumable.
 

99RT10GTS

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I assume you have checked your oil? Milky brown? Are you losing coolant? Want to sell?
 
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Emosgarage

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I assume you have checked your oil? Milky brown? Are you losing coolant? Want to sell?
Oil was fine shortly before the event. haven't checked it since. I’m losing coolant out the overflow, but not otherwise. not for sale .

I did a test today for exhaust gas is in the coolant. the color didn’t change which means no leak. so, maybe not the head gasket…..
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Steve M

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I don’t get the impression that head gasket failure is common with the Gen 4s…I’d be more worried about the pistons durability-wise.

There are aftermarket pressure cap options. Relevant info:

Stock (21 psi): Mopar 5183710AA, superseded by 5278767AB (still 21 psi)
Stock Replacement: Stant 10235
24 psi Moroso: 63324
28 psi Moroso: 63328

I run the 63324 on mine.
 

Goggles Pizano

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thanks for the questions. temps were cool entire day when on track and during the 2 hour drive home afterwards. no fluctuation. I went back and checked the in-car video. It’s so weird.
More interested the delta between now and before. Could be a pump/flow issue if the temps are higher now then before.
 

MoparMap

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This one is a weird one for sure. Only other thing I could think of would be some kind of a blockage in the system that is causing the pump to overpressurize from flow, not necessarily heat. Some rubber hoses have been known to break down on the inside and block flow once enough pressure is put on them, but that seems like a stretch here. The vast majority of the cooling system is solid components and I'd kind of expect a blockage to cause high temps as well if it's stalling flow. Maybe not super high as flow is still happening, but hard to keep your eyes on a gauge while also driving at speed on a track.
 
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