Frozen Heat Core

[birdo]

Me thinks my heater core is frozen.....engine overheats and nothing but cold air blows on the inside. Replaced thermostat yesterday. Jeep was inside for 3 hours while I replaced thermostat. Upon warm up, got lots of nice warm air thru the heater. This morning...no luck. She overheated but the heater hoses (top and lower) never got warm.  Have a sneaking hunch my coolant may not be up to snuff and that the heater core is frozen....sound about right? In the process of trying to thaw it out.

[dubbleJs]

Sounds like all of your coolant may be frozen if the motor overheats and no coolant is making the cycle through the hoses. Hopefully it did not crack your radiator (happened to me). I would thaw it, drain all the coolant and refill with a proper 50/50 mix.

[JackstandJohnny]

what Jonas said.  frozen coolant. get it in the garage and thaw it out, and hope you didn't do any damage

[EEP]

Be surprised that a frost plug isn't popped out. Guess you won't know until it's thawed out. Hopefully the block isn't cracked. Friend had a boat that wasn't winterized correctly, ended up with a cracked block.

[birdo]

Fortunately today I wasn't driving...just warming it up. I have a GoPoint OBD II reader so when it got to 95C and the temp. didn't fall back, I knew I was blocked. It's likely that I boo-booed when I changed the water pump in the fall and didn't get the coolant just right. Day 1 and 2 of the cold snap and it was ok...last night was just stupid cold and I don't have access to a garage. When she tried to overheat, I shut her down and released the pressure off the rad via the cap. Got a 200 watt work light mounted inside the tub to see if it will unthaw the core. If all starts flowing I will remove some coolant and replace with some full strength and do a mixture test. Fun, fun, fun.

[EEP]

You have a coolant tester? That will tell you what the coolant is good for temperature wise. Sounds like you have absolutely no coolant circulating. When you filled it after doing the water pump what was the ratio of water to antifreeze that you used?

[birdo]

Coolant tester is about the only tool I don't have so it's likely I have a bit more water in there than there should be. Hence the freeze up in the core especially with these past two really frigid days. Pretty confident I will get it un-thawed and put the correct coolant mix in there. Up until the real cold snap, I wasn't having any issues.

[cLAY]

If the coolant is fairly new you could just drain some out and then add some concentrate. Would help to have tester to know how off it is. Also having too much concentrate is bad as well.  I must be frozen somewhere else as well if its overheating. Usually if its just the core that is frozen the engine will run fine but you won't get any heat.

When filling/mixing antifreeze here is what I do to get a 50/50 mix. But two jugs of concentrate, pour half of one into the rad(2L), pour in 2L of water(pop bottle). Fill the 1/2jug of AF up with water(now its 50/50). Pour it in. Take 2nd jug(full) of AF concentrate and 1/2 fill the first jug, now fill both jugs with water and top off as needed. You will probably have a jug left over.

Also when buying your antifreeze look for bottles of distilled water. Canadian Tire usually has them right next to the antifreeze on the same shelf. Its about $2 a jug and much better for the system than tap water, Calgary has pretty hard water and my well water is really bad for mineral buildup.

[birdo]

All good.....the slightly warmer temperature sure helped.....got the right blend of coolant in there now.