Strange coolant issue
10-09-2019, 08:13 PM
#1
JK Enthusiast
Thread Starter
Strange coolant issue
This one has me pulling my hair out.
Temp gauge going from normal (in the middle) to the 3/4 and back... and forth... and back...
You get it. Sounds like air in the system right? It is. Now here's where it gets weird. I pressure tested the coolant system. No leaks. The coolant is filling up the reservoir and not cycling back into the system thus creating air in the main system. I keep taking coolant out of the reservoir and putting it back into the system.
But it keeps happening?! What's going here?? Once the reservoir gets filled up enough it just starts spewing out the overflow. Wash, rinse, repeat. Now I just keep an eye on the temp gauge and when it starts to creep past midline I know it's time to check the coolant reservoir bottle and repeat the process.
???
Temp gauge going from normal (in the middle) to the 3/4 and back... and forth... and back...
You get it. Sounds like air in the system right? It is. Now here's where it gets weird. I pressure tested the coolant system. No leaks. The coolant is filling up the reservoir and not cycling back into the system thus creating air in the main system. I keep taking coolant out of the reservoir and putting it back into the system.
But it keeps happening?! What's going here?? Once the reservoir gets filled up enough it just starts spewing out the overflow. Wash, rinse, repeat. Now I just keep an eye on the temp gauge and when it starts to creep past midline I know it's time to check the coolant reservoir bottle and repeat the process.
???
10-10-2019, 03:38 AM
#3
Super Moderator
What year of JK do you have?
This sounds like one of the following to me.
- Thermostat/thermostat housing
- Oil cooler housing
- Lower Intake Manifold gasket
Any of those would be difficult to see as a problem with a pressure test.
This sounds like one of the following to me.
- Thermostat/thermostat housing
- Oil cooler housing
- Lower Intake Manifold gasket
Any of those would be difficult to see as a problem with a pressure test.
10-10-2019, 03:54 AM
#4
Super Moderator
He's got a 2013 10A so the 3.6l
10-10-2019, 10:13 AM
#5
Super Moderator
10-10-2019, 05:00 PM
#6
JK Enthusiast
Thread Starter
2015 10a. 3.6l
Just performed an oil change and nothing irregular with the oil. No foam, discoloration etc. I don't think it's the manifold gasket.
Just performed an oil change and nothing irregular with the oil. No foam, discoloration etc. I don't think it's the manifold gasket.
10-20-2019, 03:39 AM
#7
JK Freak
Sounds like you are sure no water is in the oil and there is no oil in the water so at least not a head gasket. Normally you would think that when it cools down the water would go back out of the overflow. The next easy thing I would replace is the thermostat and the radiator cap.
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04-08-2020, 01:00 PM
#8
JK Newbie
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No water and no oil in my head gasket leak.
With my head gasket leak there was no oil and no water in the coolant and no coolant in the oil but the radiator was consistently low and under pressure when I opened the radiator cap even when cool. It was a small head gasket leak on the pressure side of one of the pistons.
Last edited by Seldom Seen; 04-08-2020 at 01:33 PM.
04-09-2020, 05:51 PM
#9
JK Newbie
A cracked head can cause similar issues, compression gasses entering the cooling system when up to temp and the crack closes up as the engine cools. Noticing any white smoke out the tail pipe? Even pull the spark plugs and check for discoloration from coolant burning off.