running hot when driving

[PorkandBeans]

At idle, I can have the A/C on full, in 100 degree weather, and the temp needle stays at 12 o'clock. When I drive, even at 2k rpm on the highway the temp needle goes between 12 o'clock and the next mark on the gauge and stays there fairly consistently (never reaches the mark past 12). This is only an issue when the ambient temp is above 90 degrees or so with the a/c on. With a/c off, the car sits at a few ticks under 12 o'clock, regardless of ambient.

Is this too hot to be running this engine? Should I even worry about it? And why is it overheating while moving and ok at idle, usually it's the other way around.

I plan on replacing the 2 year old thermostat, flushing the system and refilling the coolant but thought I'd ask for advise here first.

I've bled the system per the instructions found all over this forum but I know my heater core is pretty clogged/low flow, I get very little heat in winter. Could this be a factor in properly bleeding the system?

Fan clutch is ok, aux fan works and has the low speed delete.

[Cronopoulos]

How new is the water pump and radiator?

[PorkandBeans]

How new is the water pump and radiator?

Water pump is three years, 32k miles. Radiator is approx 7 years, 90k miles.

I suspected radiator too but don't want to just throw parts at it. Car has 218k miles. It cools fine with airflow from just the fan, wouldn't highway speeds only help airflow? Cruising at 2k rpm in an eta isn't much different than 750 rpm idle as far as engine heat produced, is it?

[CarsSuck]

I think thats good logic there, it's able to dissipate the heat of driving, which means you have a flow problem. If the thermostat was stuck open it wouldnt do it. If it was stuck closed, it would be worse in traffic, I would think. I would replace it anyways and do a full flush of the cooling system.

Do you use distilled water in your mix?

[Quinthirty]

My car sits in bumper-to-bumper traffic at over 90 degree heat almost daily, and the temperature gauge creeps up to just before the 2/3 marker w/ the A/C on. I have flushed the radiator system and looked at the thermostat. Radiator is in good condition, all hoses relatively new, water pump still working well, and fans all working...These cars can sit in traffic for hours. I suggest that you should rev it a bit between 1200-1500 if you're sitting in long traffic and if it gets uncomfortably high. Temp easily goes down to 1/2 or below 1/2 when it starts running, even at 10miles / hr.

[PorkandBeans]

Do you use distilled water in your mix?

Coolant hasn't been changed since the new water pump. I'm assuming the problem is related to this. I've had to replace a couple coolant hoses and have just topped it up with pre-diluted stuff.

Just looking for some feedback before I got started, in case I'm missing something obvious or if someone else had a similar issue.

How hot can I run before I need to worry about headgasket/ head damage? Is running a couple ticks past 12 really going to hurt anything?

Thanks for the replies!

[Robotin]

sounds like your thermo isnt opening all the way. i would think about replacing it with a lower temp thermo.

it never gets above 85 here in los angeles. so i just run without a thermo. allows all the water and coolant to run freely. takes a little longer to warm up. but i have never had a overheating problem. i feel like if anything. my car runs a little cold.

[downernsp]

Simple pressure check it. If you don't have the tool go to auto zone they should be able to rent it cheap. That way if there is a problem you know where it is. Not worth the guessing game...

Sent from my HTC VLE_U using Tapatalk 2

[PorkandBeans]

My car has sat in bumper-to-bumper traffic at over 90 degree heat almost daily, and the temperature gauge creeps up to just before the 2/3 marker w/ the A/C on. I have flushed the radiator system and looked at the thermostat. Radiator is in good condition, all hoses relatively new, water pump still working well, and fans all working...These cars can sit in traffic for hours. I suggest that you should rev it a bit between 1200-1500 if you're sitting in long traffic and if it gets uncomfortably high. Temp easily goes down to 1/2 or below 1/2 when it starts running, even at 10miles / hr.

My temp goes down when sitting in traffic, up when running. Today I actually pulled off the highway and sat in a parking lot at idle (with the a/c on) in order to cool my temp down! That's what's weird.

[Robotin]

i still belive it is a thermostat problem. it may not b opening all the way.

try bleeding the system again. and also with the AC on, radio on u might just b starving the motor of power it could b heating up. u should see how it goes with the AC on. then try it with the AC off. and see if it differs at all.

[jlevie]

I'm a little confused by your original post. The gauge has three tic marks, one below, one at and one above the 12 o'clock position. If the gauge is getting to the upper tic mark the engine is running way too hot. And if that only happens at speed the logical candidates are the thermostat, radiator or a gunked up cooling system.

I'd replace the thermostat and radiator (and hoses, expansion tank and cap if they are over 7-8 years old). Then I'd run a detergent type flush followed by an oxalic acid flush to clean out the cooling system.

[PorkandBeans]

The gauge has three tic marks, one below, one at and one above the 12 o'clock position. If the gauge is getting to the upper tic mark the engine is running way too hot.

It never hits the upper tick, it gets halfway between 12 and the upper tick and holds there.

Thanks everyone, this is the info I needed. Looks like I'll be replacing a few parts along with the flush and refill.

[Quinthirty]

I'm a little confused by your original post. The gauge has three tic marks, one below, one at and one above the 12 o'clock position. If the gauge is getting to the upper tic mark the engine is running way too hot. And if that only happens at speed the logical candidates are the thermostat, radiator or a gunked up cooling system.

I'd replace the thermostat and radiator (and hoses, expansion tank and cap if they are over 7-8 years old). Then I'd run a detergent type flush followed by an oxalic acid flush to clean out the cooling system.

Hi Jim,

What about if its just sitting at idle and heating up to the 3rd mark? Would you recommend a change of the auxiliary fan? My radiator fan does not have a shroud. Would that help too? I just had the whole system cleaned, and the hoses and thermostat are still ok. No leaks. I just feel that with the over 100 degree temps here and lots of traffic 1-2 hours, it sometimes gets to the 3rd marker but it sticks there.

[noid]

http://www.rtsauto.com/diagnosing-and-fixing-cooling-system-and-overheating-issues/

See if that helps.

[jlevie]

Hi Jim,

What about if its just sitting at idle and heating up to the 3rd mark? Would you recommend a change of the auxiliary fan? My radiator fan does not have a shroud. Would that help too? I just had the whole system cleaned, and the hoses and thermostat are still ok. No leaks. I just feel that with the over 100 degree temps here and lots of traffic 1-2 hours, it sometimes gets to the 3rd marker but it sticks there.

The third mark is way too hot. The shroud is important and it sounds like you need a new clutch fan also. You should also find out why the aux fan isn't coming on as it is "airflow of last resort".