Hey all, just thought I'd rack your brains a bit.

Today after a long day of driving, my car started to overheat. This was after noticing episodes of high idles (1000-1250 RPMs) that would come and go at random. It'd idle high for a couple seconds and then go to normal and would randomly do this. I recently cleaned the IACV, so I doubt that's the issue. High idles and overheating could be head gaskets, but there is no oil in the coolant, or no froth in the oil. No white smoke either. I recently replaced the upper hose a month ago after it blew out, but even with a pressurized system with coolant in the tank, I see no obvious leaks or spray like I did when I got a hole in the hose.

Any ideas?

(Sorry for the long messages >.>)

 

Did you bleed the air out of the cooling system? Air bubbles cause irratic idle and overheating problems.

 

x2 on what 4doorwagon said. Sounds like you just need to bleed the coolant. If you've done so already, when does the overheating occur? While driving, or at a stop?

 

It overheats when I drive. I haven't bled the system since the hose was replaced, but maybe I should. I am going to try that, but in the meantime, I still use it to get to work (it's my daily), and it is all of a sudden...not overheating? Not in the past few days since, and I've been monitoring it constantly. It is doing just fine, except for the idle now. I stopped at a light, 1500 RPMs in neutral. Parked at work, and I had 1100 RPM idle. I don't know if the symptoms are related, but I will say, when it overheated it was the hottest outside it's been in a while.

 

All i do which works fine, i have no rpm fluctuations or any problems doing it this way.

Open up your radiator cap while the engine is cold, turn on your car, let the car heat up to normal operating tempatures. Radiator fluid will start to disappear from top of radiator when thermostat opens. Keep topping it off until it begins to spill out of the radiator with no bubbles. It may take a few cycles of the thermostat opening, and if it starts spilling over, rev the engine a few times, if it continues to do so then cap it off and bleed it the regular way. I never had to bleed it through the bleeders or anything.

If you feel this is unsafe and you may get burned or whatever, dont attempt it then. But it works just like an old school car.

 

Well, if you changed out a rad hose, then of course you're going to have air in the system. Here is a detailed how to on bleeding your system.
If you don't have that bleeder screw (i don't) just leave your cap off. That spill free funnel is great to have btw. I would recommend it if you work with coolant a lot.

Come back for an update if it ever over heats after you bleed your system.

 

I tried this, but my coolant level never changed. I capped it, and waited (The car was warm at this point) and I felt my radiator hoses. My upper hose was hot and pressurized, and compared to that, my lower hose was cold. Maybe radiator is clogged, but I am going to start with a thermostat. Might just not be opening and letting coolant through, hence the cold hoses.

 

One fresh thermostat and re-bleeding the system again after I put the thermostat in, it seems to have all gone away.

It overheated yesterday after I got on it a bit (had to catch up with traffic)

After all the changes today, it has stable temps even after getting on it as hard as what caused issues yesterday. And both my hoses are hot now. Hopefully it stays this way!