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Cooling issue

1K views 13 replies 6 participants last post by  trippme 
#1 ·
I'm back - because you guys are so helpful - I searched and didn't see a solution so I'll ask it here.

Setup - I have a new radiator, upper and lower cooling hose, and transmission cooling connecting hoses. I filled the radiator with 50/50 and made sure there were no visible leaks at any of the hose ends.

I started the car and let it warm up to operating temp watching all the while checking the temperature with a IR thermometer. The thermostat housing hit about 200 and water started pouring out the overflow hose. I kill the engine and start re-measuring temps. Thermostat housing about 200, upper hose is stiff (pressurized) and hot. Top of the radiator HOT (ish) lower cooling hose - warm at MOST. I took some videos that I hope maybe gives a little better info.



I know cooling systems aren't that complicated but I don't know where to go next. I was guessing the water pump, but the cooling system used to work (I think at least). Would love some diagnostic help on what to look at next.
 
#3 ·
Actually, what you describe sounds normal...other than the overflow. That could be a faulty cap or a large air bubble trying to get out. I'd remove the cap and check the level (cold radiator), add as needed to about 1" above the fins, and reinstall the cap. A temperature of 200, if the reading is accurate, is "normal operating temp" and nothing to worry about. If it continues to puke coolant to the point where, when it cools off, that you have to add coolant to be above the level of the fins, and the top hose keeps getting very hard, then you might want to get a combustion gases test kit to check and see if you have leakage from the cylinders into the cooling system.
 
#4 ·
So, a little additional back story, I drove it last weekend after replacing the hoses and I think it did the same thing and then overheated and stranded me until it cooled and I added coolant.

Based on what I'm seeing tonight - kinda feels like it's not an air bubble and I hope it's not a combustion gas leak.

The coolant level was about 1" above fins this time I'll be more anal about paying attention to it.
 
#5 ·
+1 on the air bubble. Also check that the thermostat is not installed backwards.
Overheating can be caused by a leak in the cooling system as well. Regardless, it is always a good idea (and easy-peasy) to pressure test your coolant system... put a Mityvac on the radiator, pump up the pressure, and make sure it holds pressure.
 
#7 ·
Has coolant level been dropping?
Keep an eye on that.
What pressure cap psi are you using?

I switched to 16 # after original heater core had failed. Radiator and pump were fairly new when that happened.

How long was it sitting?
 
#9 ·
If the upper hose is pressurized and puking out the overflow there is a flow issue or something else pressurizing the system (such as a combustion chamber leak). Even a brand new radiator will clog quickly if there's a ton of particles/grime in your cooling system. If that's not the case, I'd get the combustion leak tester from your local parts store. It quickly identified a bad head gasket on mine which did exactly what you're describing.
 
#13 ·
No, I didn't. You may see air bubbles in the radiator though. I hope this isn't your issue but a head gasket isn't too terribly difficult to replace, just a lot of ancillary work.
I was having a hard time stopping my car from over heating. I replaced the head gaskets and it was still doing it. Ended up just replacing the heads. I never saw a color change in the coolant. But my upper hose would get rock hard, temps would creep to 230 and I would shut it down, and as the issue got worse it would shoot super hot pressurized coolant into my overflow. Enough that the overflow would overflow, lol. Since the new heads, no issues.
 
#12 ·
Thanks for your help and support my buddy Brad was right, was the thermostat. I replaced it yesterday (yet another run to Autozone because I had the wrong gasket) and let it heat up and not a drop of coolant came out anywhere. The car drove fine!
 
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