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Randall C
Randall C, ASE Master Tech
Category: Kia
Satisfied Customers: 12803
Experience:  ASE Master Tech, 32 yrs. Diagnostic specialist
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2000 kia sephia, no heat, plenty of fluid and a brand new thermostat,

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2000 kia sephia, no heat, plenty of fluid and a brand new thermostat, seems the heater core may be clogged. in this modle the hoses seem hard to get to but it seems that maybe the core can come out through the engine cavity? is this true? and is there anything else I may be missing to check why I do not have heat? thank you
Hello, my name isXXXXX will do my best to assist you with your question

is there any possible way for you to get to the heater hoses and feel each when full warmed up and running? this is a big clue about the core or not core, Then let me know?
Customer: replied 4 years ago.

the bottom one is ice cold, the top one is slightly warmer,

how many miles on this car and.. are the other hoses ok temp wise when running>?
Customer: replied 4 years ago.

other hoses are significantly warmer, and engine temp is fine, car has 134000 on it

well, byt all the information you have sent, it really does sound like a heater core problem. the thing is, backflushing does not always work but,, is worth a try if you can do it.Otherwise?I do have to lean to blocked heater core, Warm in ,cold out are in fact the classic signs.the problem is, this is a 5.7 book time job. You have to remove the HVAC unit from behind the dash, so,, thus why I suggest a back flush as long as you can do it on the core asit may? work, If not? well tthe core will need changed unfortunatley
Core goes down top of case per say

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Customer: replied 4 years ago.

okay, back flush was possible and now clean water comes out both directions, but heat is not forth coming. when the hoses were pulled for the flush, little water came out, so where is the clog most likely now?

Unsure, can you back blow through the hoses? I have not yet seen one with a blockage in the heater hoses
Customer: replied 4 years ago.

in the engine itself maybe? seems strange that, that might be the case or a water pump issue if the temp stays okay, right?

rare for a pump issue. Correct. Normally temperature would run high with worn pump. In cases like this, we drain the coolant, used compressed air to back blow each heater hose being sure everything is open, Be sure stat is changed ( i know done) and then do refill , bleed air and top off and drive,. Now,, I can not say if little water from the hose is normal or not, really never had to pay attention to this. So, you can also use a PCV connector and bypass the core the best you can so all water goes ina loop in case the core is partially blocked restricting and not allowing full water flow, Craes can be flushed and still be blocked as a tank on each end of core with manyt tubbes connecting the tanks so,, 3/4 of the tubes could be blocked and the water that can, bypsses the blocked tubes thus why flushing does not always work
Customer: replied 4 years ago.

just drove a few miles and now engine runs hot, did I knock something loose?

I do not know. I am not sure what all you have done, just removed heater hoses? if so,, you may have air trapped
Customer: replied 4 years ago.

air was the issue, at least AN issue. after letting it circulate out for about 5 minutes with the cap off, the next 5 mile test yielded decent heat and no overheating engine, but after lunch on the way back it overheated again, how long do I have to circulate it to get all the air out? this car has never had an overheating problem before

you top off rad or leave a little lower, put cap on. run till hot, take cap back off when safely can, let car sit till cool, with cap off, the air will burp up and out. Then top off, put cap on and repaet this if necessary
Customer: replied 4 years ago.

how would i know if repeating is necessary without the overheating drive again like i just had?

I usually do this 2x to be sure, I really meant if still running hot, This is how the air is removed
Customer: replied 4 years ago.

okay, this is getting harder and harder. the last time I just topped it off, and started it, the resivoir overflow started dumping water at an alarming rate, where is this coming from and what, other than more air from who know where, is replacing all the water that it just dumped?

I am very confused, Your question was about lack of heat

You need to back up and start over and tell me what all happened, when , how, what you have tried etc

If water is beibng forced out like that, lack of circulation etc,, you could very easily have and internal problem

At no taime did I say leave cap off when running, I explained the steps so please resend information so ic an see how to help
Customer: replied 4 years ago.

heat problem was first concern, thought thermostat was most likely concern, changed that, still no heat.


2nd assummed heater core was next likely, and ended up flushing it, still likely not completely clean, but now have heat -- as long as we have water.


5 mile test out worked no overheating and had plenty of heat, but after a 30 min lunch, 2 miles back we started overheating, this is the first time this happened in this cars history, and at this time, no heat.


tried a couple times burping out the air and it drives fine for short distances and has heat until it overheats, then we stopped to check how high the water was and it took quite a bit this time. when restarted the car, instantly water was gushing from the resevoir overflow tube and when the engine cooled back down, it was very low on water again

if you have topped of, left cap off, let to cool, retopped off, put cap on and it pushes water out? you ahev an internal engine problem more than likely. its is not that difficult to remove the air,heat it up, take cap of, let sit till cool , fill and good to go, so if problems after this? then you may want to consider a combustion test as this sounds like a problem internally. You have made no menrtion of top and bottom rad hoses so if they are both hot? and feel hard, this is normal persay but is one is cool? then water not circultaing correct. I understand it never had overheat problem but if system bad enough to plug the core? it could have plugged the radiator or,, maybe after the flush you had more water in it , less air, then you got heat but original problem likes say headsgaket has surfaced. I can only shoot ideas, I am not there looking at it
Customer: replied 4 years ago.

okay whatever else is/ was wrong, the radiator does havee an obvious crack in the tank now, thank you for your help

with back pressure like that and now a crack? too much pressure and this can only come from say a headgasket etc thus a combistion test to confirm
This would explain no heat, cracks, pressure blow back ect. You have near all the clues.I hate to say this but I have to give as much info as i can
Customer: replied 4 years ago.

but with a head gasket issue, wouldnt there be either oil in the water or vice versa? it has never overheated either until I started messin with the thermostat and heater core today

I understand. I can only give the possibles for the symptoms. cracks. pressure blow back? and i still think there was an underlying issue thus why the no heat and now that you ahve flushed, added coolant, bled it etc,, it is circulatying different and the original problem has surfaced, No,, absolutely not on the water in oil. It all depends on area of the break, It can be a break in such a spot that only compression is getting into the cooling system. would lock the circutation some and if water goes a little low, it may not even overheat till, you ahev really filled and bled ait then,, the original problem shows, Agaim the funnel and dye setup and combustion test confrims this near 100%
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