Overheating only while idling

Hi Adam,

Does the vehicle ever overheat when driving at highway speeds? If it only happens when at idle in traffic or not moving, chances are the cooling fans are not turning on. Have you checked if they work?

Let me know.

Joe

Hi Joe,

At any consistent speed, the car stays at or below halfway up the temperature gauge, so not overheating

Both fans are working. I'm not 100% sure if they're turning on and off at the appropriate times though (possible failing fan relay maybe). When the A/C compressor is running, they both seem to run. How do I test to see if they're turning on and off at the correct moment? BTW this is a problem I've had off and on literally since I got the car used in 2005. I had the seller have his mechanic looked at it for me for this very reason, and he basically just said "that's just the fan having to kick on, etc". It may mean there are just idle cooling issues with this car in general. But today it actually got up into the red zone for a minute before I turned on the heat to vent the engine heat a bit. The A/C was on and I was idling at a drive thru maybe 15-20 minutes. The A/C wasn't blowing cold either, seemed to be picking up heat from somewhere.

There really isn't any issues I'm aware of. The idea that it doesn't overheat when driving leads me to believe there is a problem with the fans turning on in time.

The cooling fan is designed to turn on at 230°F. The only way I could tell you to confirm it is with a live data scanner. Basically, you could watch the coolant temperature sensor's signal to the PCM as it warms up. Right around the 230 mark, it should turn the fan on. Actually, the fan module should allow the fan to run for up to 5 minutes after the key is off until the temperature drops below that 230 mark.

If the fan is working, what I would start with is simply replacing the thermostat and flushing the cooling system. Also, make sure there is no debris blocking any portion of the radiator.

Interestingly, the A/C was likely not working simply there wasn't enough air flow through the condenser which is in front of the radiator. Also, if the cooling fan wasn't running at that time, it will compound the issue because the condenser can't do its job.

Let me know if you are able to get your hands on a live data scanner.

Joe

Joe, I do have an ELM327 Bluetooth scanner now. From looking at the Car Scanner app, ECT sensor is one I'm able to get live data from. So from a cold start, watch the ECT temperature and see if the fan comes on at 230 degrees? Should I run the A/C or not? Also I do have two fans, I believe one is called radiator fan and the other is the engine cooling fan. Should I expect them to both come on at 230 or do they have separate parameters?

Hi,

Leave the A/C off. When you turn it on, one fan should always be turn on with it. That is the condenser fan. I want them to be off to see if they turn on automatically when they should.

Let me know what you find.

Joe

Hi Joe,

I ran my test today. The car started up at 113 Fahrenheit according to ECT, and the IAT stayed consistently at 113 to 115 Fahrenheit (it is a 90 degree day). Turning on and off the A/C got both fans to turn on and off properly. I had to drive the car around in a lot of stop and go to get the temperature up, it would only stay at 203 Fahrenheit while idling at first. After my drive and bringing it home, I got it up to 217 Fahrenheit, at which point both fans kicked on simultaneously. It stayed consistently at 217 to 220 Fahrenheit while idling, whether with A/C on or off. I've attached a picture of what my dash temperature gauge shows when it's at this level. This means the gauge is showing as 2/3 to overheating before the fans kick on. Based on your information about fans kicking on at about 230 Fahrenheit though, nothing seems abnormal here.

Anyway, there are a couple possibilities here, since I was unable to get it into the red again. First is unlikely, but I had the windshield replaced last night. It's possible the guy cleared up some debris blocking the little plastic vents beneath the windshield, and improved airflow. Do those vents have much effect though? The second, and more likely probability is it's an intermittent issue, and a component is beginning to fail but hasn't fully failed yet. You seemed to think possibly the thermostat? Do water pumps only ever completely fail, not partially or intermittently fail? Anyway I think it's safe to say the ECT, IAT, fans, and fan relays are all working correctly. I'm going to have to keep an eye on it and see if I can reproduce the issue. I suppose I partially reproduced it, since I got my gauge above the halfway mark. But what's the temperature where it really and truly is dangerous to your engine? 240 to 250 Fahrenheit? Thanks again, and I'll update you when I have any new info to share.

Adam

Hi,

The vents in the cowl below the windshield are basically for air intake to the HVAC system. As far as a danger zone, you don't want it to go more than 230 if possible. If you exceed that point, it becomes a concern.

For the water pump, usually they will leak when there is a problem or you will hear a bearing noise coming from them. They can't just totally stop working simply because they are belt driven. If it was to lock up and stop, you would know.

This may sound crazy, but have you tried replacing the radiator cap? If it isn't holding pressure, this can happen.

Let me know.
Joe

Joe, I did actually replace the radiator cap as an attempt at a cheap fix a month or so ago. Thanks for your explanations. When we replaced the timing belt 2 months ago, the water pump wasn't yet leaking from what we saw, so we didn't change it out.

This experience has me wishing for features on future cars... ability to leave the fans on at all times in hot weather. And the ability to vent heat right out of the engine when it's too hot, like what turning on the heater blower achieves, except without heating up the whole car. It seems like the fans just wait a bit long to kick on. Although when I went into the red zone the other day, the A/C was on, and so the fans were too.

I know this is a worst case scenario, but what are the symptoms of a leaking head gasket? I'm paranoid about that being an issue ever since one less than trustworthy mechanic tried to say it was leaking. He claimed to have chemically tested the coolant to see if it was contaminated by oil, and said that the test indicated that it was indeed contaminated. Of course, he was saying all this to avoid replacing my radiator under warranty. We had to take pictures of the leak in order to get him to honor it. So I've replaced the radiator in September 2016 and August 2019, and sometime between 2012-2014. So I've consistently been having similar issues with the engine cooling system. When it all exploded on me in September 2016, I was in stop and go traffic on a fairly hot day. It was similar to now where it was fine so long as I was moving. So anytime I see the gauge go above halfway, it has me worried about blowing up another radiator. I almost am considering trying an aftermarket fan or something to add, something that's just wired to be always on. Just a thought.

Joe I did actually replace the radiator cap as an attempt at a cheap fix a month or so ago. Thanks for your explanations. When we replaced the timing belt 2 months ago, the water pump wasn't yet leaking from what we saw, so we didn't change it out.

This experience has me wishing for features on future cars... ability to leave the fans on at all times in hot weather. And the ability to vent heat right out of the engine when it's too hot, like what turning on the heater blower achieves, except without heating up the whole car. It seems like the fans just wait a bit long to kick on. Although when I went into the red zone the other day, the A/C was on, and so the fans were too.

I know this is a worst case scenario, but what are the symptoms of a leaking head gasket? I'm paranoid about that being an issue ever since one less than trustworthy mechanic tried to say it was leaking. He claimed to have chemically tested the coolant to see if it was contaminated by oil, and said that the test indicated that it was indeed contaminated. Of course, he was saying all this to avoid replacing my radiator under warranty. We had to take pictures of the leak in order to get him to honor it. So I've replaced the radiator in September 2016 and August 2019, and sometime between 2012-2014. So I've consistently been having similar issues with the engine cooling system.

Interestingly, most chemical tests look for exhaust gases (carbon monoxide) in the coolant. You can see oil. LOL Have you ever noticed bubbles in the coolant after the vehicle was driven? Take a look through this link and see if you can do some of the checks.

https://www.2carpros.com/articles/head-gasket-blown-test

Joe

Lol. Okay that's probably just me misremembering what he said. Thanks for the link, I will try these tests out in the next couple days. I suppose the next part change I'll try is the thermostat as I've already got one. I've got a water pump too but I know that's way more of a hassle. I know there are some radiator additives too, head gasket sealers and some that supposedly increase the cooling power of the coolant or something. I think I know your stance on such products, but are any of those worth trying to see if I get a boost in engine cooling ability?

I checked the coolant about 40 minutes after driving today. I did not see any bubbles in the reserve tank. The coolant level of the reserve tank is sitting halfway between low and high. However, the radiator itself appeared bone dry. I still do not really understand whether I should be seeing coolant in there or not when it's not running. Because pretty much as long as I've been checking my radiator, it almost always has been empty when I checked it.

The radiator shouldn't be empty ever. The reservoir should only be a stopping location for coolant that expands into it and then is drawn back into the radiator when the engine cools.

Do me a favor. With the engine cold, fill the radiator. Start the engine and allow it to warm up. Let me know if the coolant continues to stay full or starts to drop. Also, do this with the heater on high and if you notice it dropping, add a little at a time to keep it full. When the engine reaches operating temp and the radiator stays full, then install the radiator cap and turn off the engine.

Note that when the thermostat opens, you should see some circulation in the radiator.

Let me know what you find.

Joe.

Low on coolant would explain overheating issues. Though I haven't noticed a coolant leak since I got the radiator replaced. Which would add credence to the head gasket leaking. I haven't noticed the oil being discolored, I'll have to check it tomorrow. I think I'm also gonna add some K Seal head gasket sealer. It has better reviews than the Blue Devil stuff, and it's 8 ounces you just pour in directly.

Hi,

Before you add the sealant, make sure that is the problem. Honestly, I have seen such products cause other issues. Try what I said. Once we know that the radiator is full, then we can check it again after you drive it and it cools off.

Note, if you are losing that much coolant, it shouldn't be hard to determine where it's going. Either the oil will be over full with indications of coolant mixing or you will see a lot of white steam coming from the exhaust.

Let me know.

Joe

Sure, I'll wait on the sealer.

So just to be clear, you want me to fill the radiator to the bottom of the neck of the radiator. Leave the cap off, run the engine with the heater on high, check to see if the fluid level goes down in the radiator. Then if it does, add a little more coolant. So it's safe to run the engine with the radiator cap off? It seems like it wouldn't pressurize correctly with the cap off.

Coolant sprayed out all over the place when I ran the car with the radiator cap off. So I've filled it back up, put the cap back on, am running the car with heat on full blast for 30 minutes, letting it cool down, then checking it again. I also found a coolant pressure tester in the closet so I'll check the pressure too once it's cool.

The coolant is/was definitely the problem. It's staying a lot cooler now and the fans are kicking on with the temp gauge reading below halfway. Having the coolant be low was screwing with the ECT reading probably. However, I was seeing some white smoke/steam coming out of the back of the radiator, see attached video. That said, I had spilled a lot of coolant all over the place, but at this point it had been about 30 minutes of running straight and I think all that had already burned off. What does it mean when the white steam is coming out of the grating on the back of the radiator?

Edit: I didn't see any leaks, just the white steam/smoke. I'm going to let it cool completely down for 2 to 3 hours then check the level and pressure, top up, and run it again to see if the smoke happens again.

Alright after letting it completely cool off, I checked the coolant in the radiator again... And the top of the radiator was totally empty again. I topped it off with 5 or 6 ounces of coolant, ran it again with the heater on full blast, and after 10 or so minutes, the white smoke started again. I'm attaching a new video of the smoke. The pressure tester was hard to get working right, but seemed to be within the higher side of the range, 260 to 265 boiling over point.

I checked the coolant level again. 30 minutes wasn't enough time for it to cool off apparently, and it was still very pressured and sprayed out as I opened it and was very hot. I used a rag though so it didn't scald me. It was over full at this point, the coolant went all the way up to the cap. But I guess since it was still pressurized, that's probably not a useful test. I'll have to check it again when it's fully cool.

I will say that the reservoir doesn't seem to budge at all. Just seems to always stay right in the middle of low and high, whether running or not.

Hi,

Yep, it needs done again. Listen, when you question if the cooling system is still pressurized, try to squeeze the upper radiator hose. If there is no pressure, it will be easy to do and soft. If there is still pressure in the system, it will be solid from the pressure.

Please be careful. Let me know what you find.

Joe

I was able to check it again after the radiator was cooled down. It went down again, but was at least at a visible level this time. I didn't get a chance to top it off and run it again. From looking at my manual, it says the car takes 7.4 quarts of 50/50 mixture coolant/water, with .69 quarts of that in the reserve tank. So about 6.7 quarts for the radiator and rest of cooling system. That is 1.675 gallons of coolant. I'm guessing most of that lives outside of the radiator. Anyway, it would seem the radiator was extremely low on coolant. We will see how long it holds the coolant once I top it off one last time tomorrow.

What did you make of the white smoke? I didn't see any coming out of the exhaust from what I could tell. I also didn't think that the oil on the dipstick looked "milky". So I really don't know what's going on here. I read maybe a leak in the heater core? My analysis would be that the coolant is being burned somehow, as I'm not seeing anything leaking on the ground, and there was the appearance of the white smoke. Also it does not appear the coolant is getting into the oil in large quantities.

Hi,

White smoke is produced when engine coolant is burned along with the fuel in the engine's combustion chambers. Can you video what you are seeing? Here is a link that explains what/why white smoke is created. In the beginning, it explains normal steam, but later in the link, it discusses what I mentioned.


https://www.2carpros.com/articles/white-smoke-or-steam-coming-from-the-exhaust-pipe

Let me know if I can help.

Joe

The white smoke is coming from the back of the radiator. I do not have steam or white smoke coming out of the tailpipe, at least not in large quantities. I attached 2 videos of the white smoke in the last 3 comments of page 1 of this thread.

Hi,

Okay, I watched them. Is that steam? Does it have any specific smell to it? Coolant will usually have a sweet smell. Oil can smoke like that as well.

I'm pretty sure it was a sweet smell. It was coming from the back of the radiator, behind the fan.

And yeah it is probably steam rather than smoke. Seemed lighter and wispier than smoke.

Then there is a leak in the radiator or one of the radiator hoses. You will need to pressurize the system to check it when the engine is cold. Here is a link that explains how that is done. You will need the right tool, but most parts stores will lend that to you. It appears this is where the coolant is going.

https://www.2carpros.com/articles/radiator-pressure-test

Let me know.
Joe

Yeah that makes sense. Although a leak in my 10 month old cooling system is a bit dumbfounding. Since I've been replacing the radiator about every 3 years lately, the head gasket seemed to possibly explain why I've been chewing through them so fast. But there's no coolant in the oil, no bubbles in the coolant, and no white steam coming out of the exhaust. So if the head gasket is leaking, it is only slightly, and not the main issue here. I just really don't get all my radiator problems. I suppose if I maintained the proper fluid level, then maybe they'd survive longer.

Alright it seems to be mostly retaining its coolant. I checked it again today and it was closer to the top of the radiator. Filled it maybe 2 to 4 ounces, ran it for 30 minutes with the heat on full blast, and let it cool off for an hour and a half. The level was pretty much still at the top, it was only down by maybe half an ounce or an ounce. It appears it's splashing up into the rim of the filler neck for the radiator, and that may explain why the level was slightly down. Is it possible coolant collecting here then evaporating could explain some coolant loss? I did not see the white smoke around the radiator this time each time I checked. So I'm not sure exactly what is going on. Not seeing any coolant leaking underneath either.

Try driving it for a few days and then check the coolant level. Hopefully it won't go down. Also, now that the radiator is full, does it overheat at idle?

Joe

Hi Joe,

There are no overheating at idle issues anymore. The temperature gauge stays a lot lower now and doesn't go above halfway. So it was definitely the low coolant, just a matter of whether it leaks/burns out or stays put I will be checking it regularly over the next week and report back what happens.

Adam

Sounds like a plan, Adam. Let me know. Also, if you find there is loss of coolant, we will have to do a chemical test on the coolant to see if there are any combustion gasses in the coolant.

I just hope it never goes low again.

Take care and keep in touch.

Joe

There does not seem to be an alarming amount of coolant loss going on. I will keep checking it. In total I added less than 1/2 gallon of 50/50 coolant/water mixture a couple weeks ago, and the level hasn't dropped much. I heard that running the heater can evaporate coolant, is that true? What about A/C or anything else?

The cooling system is sealed, so evaporation really shouldn't happen, regardless of what is being used. However, it isn't odd for some to evaporate over time. If you used a 1/2 gallon in a couple weeks, to me that is more than I would like to see. However, has it possibly slowed down? Are there any different symptoms?

Joe

What I meant by the 1/2 gallon was, that's how much I had to fill it up 2 weeks ago (which hadn't been filled since August 2019 when the radiator was replaced). And the level has not dropped nearly that badly, maybe half an inch from the the filler neck on the radiator. So this seems like an issue to just keep an eye on and top up as needed. My new issue is that the A/C stopped working today, which is in another thread, and obviously not related to this issue.

Okay, that sounds normal. I was worried at first. As far as the A/C issue, I hope someone is helping you. I have answered several already tonight. The heat has been difficult to deal with this year.

Take care,
Joe

Yes, and the oil from my oil change showed no signs of coolant. So it seems the engine cooling system is fine with no head gasket issues.

Roy is helping on the other issue, although feel free to take a stab at it as well.

Glad to hear the engine is okay. I'll look for the A/C question, but once they are answered, I may or may not be able to find it.

Take care of yourself. Let me know if I can help in the future.

Joe

Take care of yourself as well Joe. Thanks for all your help. The name of the thread is A/C stopped blowing cold, not sure compressor is running at all.