I have a 2007 Kia Sedona 3.8L with 142,664 miles. It was leaking coolant near the thermostat housing, so I replaced all the gaskets and put in a new thermostat. Now it keeps overheating, even though I’ve pressure tested the system, done a chemical flush, and checked for exhaust gases in the coolant (none present). It runs fine at idle for over an hour, but it overheats after driving a half mile. Any ideas on what’s causing this?
Have you checked if the water pump is pushing coolant properly? If the fins are corroded or damaged, it might not be circulating coolant as it should.
Benard said:
Have you checked if the water pump is pushing coolant properly? If the fins are corroded or damaged, it might not be circulating coolant as it should.
Yeah, I pulled the water pump and it looks ok. The bearings are tight, no play, and it spins fine. Not sure if I missed something though.
@ForteFanatic
If the water pump looks good, it could be a coolant restriction somewhere in the system. Maybe the flush didn’t clear everything out.
Have you tried checking the upper radiator hose? If it’s easy to squeeze, that could mean there’s not enough pressure in the system.
ruth said:
Have you tried checking the upper radiator hose? If it’s easy to squeeze, that could mean there’s not enough pressure in the system.
Yeah, I noticed the upper hose doesn’t have a lot of pressure. Could that point to the water pump even if it looks fine?
@ForteFanatic
Possibly. If the pump isn’t moving coolant as it should, you won’t get enough pressure. Might want to replace it just to be sure.
Check for any debris in the radiator or AC condenser. Even if it looks clean, a small blockage could cause overheating.
Terryanne said:
Check for any debris in the radiator or AC condenser. Even if it looks clean, a small blockage could cause overheating.
I’ll give the radiator another look. It seemed clear, but maybe I missed something.
Did you do a block test for a possible head gasket issue? Sometimes those can fail but still pass the test.
TurboSoulMate said:
Did you do a block test for a possible head gasket issue? Sometimes those can fail but still pass the test.
Yeah, I did the block test and no exhaust gases were found. But I’ve heard it’s not always 100% accurate.
@ForteFanatic
Exactly. It’s rare, but I’ve seen head gaskets fail even after passing the block test.
If everything else checks out, you might want to try another coolant flush. Sometimes it takes a couple rounds to get rid of all the restrictions.
fabian said:
If everything else checks out, you might want to try another coolant flush. Sometimes it takes a couple rounds to get rid of all the restrictions.
Good idea, I’ll try another flush and see if that helps.