04’ JMT’s Twin Teenagers Build

JMT said:
That was the first thing we thought of since intermittent. Not sure what to do about it though. Get another thermostat? It was cold. Can that cause it to stick? It was a Stant and I put the hole at the top. It happens once every 5-8 months. 🤷‍♂️
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Stant use to be the number one quality but not anymore.
Unfortunately, the only way to test it is to pull it and heat it up in a pot of boiling water. But then you can watch it to see if it opens each time.
 
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BlueC said:
I'm another vote for bad thermostat. Not that I think it's your issue, but if your radiator cap is old, it's a good idea to replace it.
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bobthetj03 said:
Get a Mopar stat and a new radiator cap.
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He just told me he saw liquid coming out of the radiator cap (small amount) while it was boiling in the overflow. Is that normal?
 
JMT said:
He just told me he saw bubbles coming out of the radiator cap. Is that normal?
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Bubbles coming out of the overflow tank or with the cap off bubbles coming out of the radiator? Or bubbles coming out from under the radiator cap?

1) Bubbles coming out of the overflow tank- Could be boiling the anti-freeze

2) Bubbles in the radiator- Again could be boiling which isn't good. Need to test the anti-freeze to see if it's protected to cold enough.

3) Bubbles coming from under the cap- This would mean you need a new radiator cap. Whish was why you needed to test the cooling system and cap like I recommended before.
 
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Wildman said:
Bubbles coming out of the overflow tank or with the cap off bubbles coming out of the radiator? Or bubbles coming out from under the radiator cap?

1) Bubbles coming out of the overflow tank- Could be boiling the anti-freeze

2) Bubbles in the radiator- Again could be boiling which isn't good. Need to test the anti-freeze to see if it's protected to cold enough.

3) Bubbles coming from under the cap- This would mean you need a new radiator cap. Whish was why you needed to test the cooling system and cap like I recommended before.
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I’m just bad bro! I’m sorry. I think I did rent it, but my rush to figure it out led me to flush it and move on, assuming fixed.

The liquid was a small amount coming out the radiator cap while it was sealed on the radiator and at the same time boiling in the overflow tank.

Thank you for help.

I’m dealing with another cooling system issue in my wife’s Yukon and looks like I’ll need a new radiator, heater T’s and hoses.

On my rig I’m dealing with a slow leak on one tire after replacing the valve stem coming from between the rim and tire. I probably didn’t clean it good enough.

Just trying to balance life with 5 kids and a wife. Yes, I’m asking for some grace.
 
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JMT said:
I’m just bad bro! I’m sorry. I think I did rent it, but my rush to figure it out led me to flush it and move on, assuming fixed.

The liquid was a small amount coming out the radiator cap while it was sealed on the radiator and at the same time boiling in the overflow tank.
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If its coming out of the cap, its not holding pressure (obviously). When the system can't pressurize like normal, the boiling point will be lower (which you're seeing). I'd replace the cap and thermostat, and see where you go from there. If that don't work, take it to a shop and get a pressure check done.
 
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Mike_H said:
If its coming out of the cap, its not holding pressure (obviously).
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Yes, that seemed obvious to me. If water can get through obviously air can. Just didn’t know if there was some kind of fail safe built in. Thanks. We’ve got some parts on order. I love that thermostat you linked to. Makes me want one on Big Red even though I have no sign of trouble!
 
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Likely a stuck t-stat, if the cap is venting before it gets to temp it could be bad or it could be a head gasket,get a test kit to rule that out. Make sure you burp the air all out cause that will cause overheating too, was the heater working?
The kit below is about $40.00


1670215026021.jpeg
 
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DrDmoney said:
Likely a stuck t-stat, if the cap is venting before it gets to temp it could be bad or it could be a head gasket,get a test kit to rule that out. Make sure you burp the air all out cause that will cause overheating too, was the heater working?
The kit below is about $40.00


View attachment 381907
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No, the heater was not working. I failed to mention that earlier. Thanks for help.
 
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Did you trill a hole in the top of the new thermostat (1/16"-1/8")? If it's not the thermostat itself it could be an issue burping the system where air bubbles are trapped causing all sorts of fun.
 
rasband said:
Did you trill a hole in the top of the new thermostat (1/16"-1/8")? If it's not the thermostat itself it could be an issue burping the system where air bubbles are trapped causing all sorts of fun.
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Yes, I drilled the hole in the Tstat (I believe 1/8”) and positioned it top side upon install. Months later we drained the radiator and flushed the system and then brought it to run temp and squeezed the upper hose to help burp the system. It’s been good since then, which was back in the summer. Today I tried to burp it again. I didn’t get any bubbles to come up. We ordered a Mopar radiator cap tonight. I need to get on my wife’s car this week while we wait for the cap. In other news the Rubi springs came in. He wants to do the axles, shocks, springs, trackbars and all accessories to that project post Dec 20. That could be a bear. 😅 It’s cold too.
 
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The water pump is a centrifugal pump, as long as there is coolant on the inlet side there will be pressure on the outlet side so If the pump is pumping coolant the heater would circulate hot coolant, if it’s cavitating because of trapped air, no coolant moves until it gets so hot it percolates like a coffee pot. A stuck closed thermostat will boil the same way but the heater will still work because the coolant is still flowing from the pump. A stuck open thermostat will not let the heater warm up but it won’t boil over cause it won’t come up to temperature.
So it could have had an air bubble that never got released (burped) or;
Air is being introduced during engine operation, as in leaky head gasket, you can test for that with the test kit I linked.
Air is being introduced during cooldown because of a leak (hose, clamp, cap, radiator, heater core, return hose, pump, gasket, housing, or recovery tank) a pressure test like @Wildman suggested will identify that.
Or the pump is bad.
 
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It's another Damn It it's too Bad You are so Far Away. I've got the tester for headgaskets and the pressure tester.

@DrDmoney is spot on with all his info. Before you just throw parts at it IMO you need to identify what is wrong with the cooling system first.
 
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Start with the block test so you can rule that out and you won’t force coolant into the engine performing the pressure test.
 
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DrDmoney said:
Start with the block test so you can rule that out and you won’t force coolant into the engine performing the pressure test.
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Wildman said:
It's another Damn It it's too Bad You are so Far Away. I've got the tester for headgaskets and the pressure tester.

@DrDmoney is spot on with all his info. Before you just throw parts at it IMO you need to identify what is wrong with the cooling system first.
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Went out and checked coolant level this morning. At the radiator cap there's no coolant level visible. In the reservoir its at the full mark. Looks low to me. I like to see coolant when I remove the radiator cap.
 
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