I've got a 1998 Sportage, manual transmission, 100+thousand miles, that has started running hot. The coolant is topped off. It use to have the typical temperature rise when running the AC, which shutting off the AC would cause the temp to drop back down to the normal range. That has stopped being a solution, when the temp guage starts to climb, shutting off the AC stops the climb, but the temp doesn't drop. It will sometimes get hot enough that the AC automaticly shuts off (this IS a feature of the '98s, right? <img src="/forums/images/graemlins/rolleyes.gif" alt="" />)

Its got a new heater core (1 year old). My knee jerk reaction is to replace the thermostat and radiator (us "shadetree mechanics just throw parts at 'em <img src="/forums/images/graemlins/smile.gif" alt="" />) but I thought I'd see if the collective knows of a specific cause for this issue. I know the cooling system on these vehicles are weak, mine has just gotten "weaker". The fan is spinning, but this occurs running down the highway also.

Is it possible that the system just needs a "burp" from when the heater core was replaced? If so, how do I go about doing that?

Thanks,

John

If you hadnt replaced them already I would vote for radiator been cloged..

anyway
first of all DONT let it overheat. the head is prone to crack.
second. your headgasket is been "eaten" slowly by the overheats and propably it will be burned in cilinder 4 the one on the firewall side - personal experience <img src="/forums/images/graemlins/smile.gif" alt="" />

so whatever you do dont let it overheat again.
to be on the safeside i would comlpetly remove the thermostat. The increased flow will keep things cool until you find what it is.

2 gueses ( if the new radiator isnt cloged by some kind of "debries" lets say)
radiator fan
and water pump
in this order.

throw the stupid fan mecanism away and do your car a favor and put an elektric one.

After remouving the thermo take the radiator cap of and with a cold engine start it and look if you see any strong flow of water

a less possible but cheap nevertheles is that the radiator cup is stuk and doesnt let the expanded water to flow to the expansion bottle ( and/or remove posible air by sycking water from the botle to fill it properly.

an other wild guess is that the so called cooling device on the base of your oil filter does not work right.
Dont forget oil also cools engine, spesialy in ours that has an oil jet underneeth the pistons spraying oil on them to cool them

As fokion said- DO NOT let her overheat. as for the problem- first check the radiator. it can get clogged with sludge - one of the symptoms is that your collant reservoir - the small coolant bottle with the blue cap that is located on the right side of the radiator will be empty from any coolant. so get the rediator well cleaned- unbolt the bottom coolant hose and insert water at high pressure. you wont believe what amounts of mud and dirt will come out of there!! then fill up with some quality coolant. i did it twice to make sure my system was water free because regular pap water can corrode your engine. if that does not work- replace thermostat. also- check your fan- and fan clutch. Also- as fokion said- why not consider a fan swap to an electric one?
better yet- if you dont want to do that-you can also install an extra fan up front next to your AC fan.

Thanks guys, good info.

I've checked the "obvious" stuff (coolant flow, fan function, etc) and hoped you had an "Oh yeah, this is the problem with that vehicle". I'll do the radiator "de-sludge" before I look at replacement.

Do you have the manufacturer/model number for the replacement electric fan off hand? Anything necessary other than unbolting the mechanical fan and attaching the electric?

Thanks.

look up on the page my sticky writeup conserning the fan
it will get you there
and if any questions please ask me

I don't know if you do any off-roading or not, but I was getting serious overheating because my radiator was packed with mud. I had to pull off my radiator fan shroud (I have an electric fan mounted in the shroud) and pretty much hold the nozzle of the garden hose right next to the engine side of the radiator to get it cleaned out.

After that, I installed a couple of relays behind my front fender and a switch in the dash to let me shut off the fan and also reverse it if need be (thought it might help push fresh mud out of the radiator after a nasty crossing).