4RUNR

Highly doubt your thermostat is broken or is not fully opening. In 95F you would overheat in no time even at highway speeds.

Epic Ed

Alright! Test results are in...

I had to cut the test a bit shorter than mentioned, but it was still significant. I drove a full 20 minutes before threw it in park at 12:13 in the McDonald's parking lot with my Quater Pounder value meal. I did put my sun visor in the windshield to keep the glare out of my eyes, but other than that I had no cover of shade what-so-ever in the middle of a black asphalt sea.

The vehicle was already cool from the around-town drive and I left the fan on the second of four settings the entire time I was parked. At 12:54 I got a phone call that interrupted my nap and had to head back into work, but the temp gauge hadn't budged one bit from the normal spot and I never had to bump up the fan to keep it nice and cool in the cabin.

The temp outside right now is 102 with 28% humidity and a dew point of 58 (that's an important indicator for those of us in the desert -- it means that despite the seemingly low relative humidity, it feels mighty darn steamy).

Now, will those of you who are having over heating issues in rush hour traffic PLEASE go and get your vehicles serviced?! The rest of us who have well-functioning cooling systems are not defying the laws of thermodynamics.

Ed

-- edited to correct time I parked.

4RUNR

Well, here is empirical proof from today that you will run very hot, and most likely will overheat if sitting in traffic with AC on.

Meteorological conditions for the test: partly cloudy 96F, 44% humidity and 72F dew point.
Vehicle: 1999 4Runner, 4ECT, dark green, 100% distilled water in the radiator (marginally but more efficient than a coolant mix). Both the AC condenser and radiator are clean and in perfect shape, no broken/bent fins.




Relative engine load at idle in park 17%. Engine load with transmission in drive, e-brake on, AC on, fan on medium is 24%.

As you can see almost 13 minutes into the test the engine coolant temperature reached 223F. The thermostat opened at 190F. The temperature needle on the dash was right in the middle and didn’t move one bit from the beginning to the end of the test. It will start to move around 230-235F, but I wasn’t going to run that high with pure water, as it already boils at 212F in the open, and it was starting to smell like hot rubber.

There is nothing wrong with my truck, I know it inside out, and unless someone can show similar empirical proof that they stay much cooler in similar condition in a similar vehicle then we’ll talk.

4RUNR

A for effort. F for methodology.

Look at my chart, you sat in the car for 20 minutes, and if the temperature trend continued it shows that exactly around that time the needle would have just started to move higher at around 230-235F.

Haston

Amir: I notice you list a TJM bar and see that you also have big offroad lights in front of the grill. Are they new, at least new since last summer? If so, perhaps they are contributing to a less than optimum airflow. Just a thought. H

Epic Ed

Nope -- I drove for 20 minutes before parking for 40 minutes . I readily admit that emperical data is the best way to measure engine temps. My test was held in a non-controlled environment and the evidence is merely anecdotal, but even your conclusion indicates that after 20 minutes of testing that the temp gauge needle hadn't yet started to move. Is it running hotter than it would if you were moving? Of course. But you're still not "over heating." You're running within safe operating temperature parameters.

Those who are seeing that needle creep toward red and even get up to 3/4 of the way to red after a short drive are having problems and could improve their cooling system by fixing sumpthin.

That's my conclusion, anyways...

Ed

Epic Ed

THAT is a very valid concern. I have the same conditions on my '95 4Runner, and my mechanic believes it contributes significantly to the troubles I've had keeping it cool in the summer. We built an air dam at the bottom to funnel air up to the radiator and it seems to have helped.

Ed

4RUNR

I had my needle almost near the red when the coolant was around 245F after 45 minutes crawling in traffic. I wasn’t going to recreate a near overheat in my driveway today just to prove a point. From my observation of my 3rd generation 96’-02’ with the 3.4L truck, almost identical to the original poster of this thread, the needle is not purely an indicator of temperature, but rather time and temperature, that is even if the engine remains at the same temperature the needle will still climb, and that in this weather is perfectly normal to see the needle climb.

As far as lights and ARB, in my educated opinion they won’t influence cooling one bit while idling. Air is being sucked by the fan from behind the radiator, and there are still more than enough places for fresh air to enter, without creating a vacuum between the radiator and the bumper.

Epic Ed

I'd imagine you have been traveling home with dozens, maybe hundreds of other cars around you -- windows rolled up, A/C likely blasting full throttle. How many of them joined you on the side of the road to let their engines cool down? Or were you alone, like so many other motorist around here during rush hour. A smattering of hot vehicles pulled over on occasion, but most every one else is cruising on by on their way to completing another miserably long and hot commute. What do these "super vehicles" have going on with them to keep them cool and running in the same, exact conditions that are causing you to over heat and pull over? Or is everyone else running in the red?

Ed

4RUNR

Yes, I would say most everyone around that day was also running close to red. What I recreated in the driveway today was very hot, considering 190F is optimum and 265F is a boilover, it was half way between the two in under 13 minutes. The temperature would rise much slower of course as it is approaching the plateau which is the difference between engine temperature and cooling capacity.

My only point here is that a 3rd gen can be made to heat up and possible overheat on the hottest days while idling with AC on, even if the truck’s cooling is in perfect order.

Epic Ed

We're just gonna have to disagree on this one, buddy. No offense intended, and I appreciate the good debate.

Ed

4RUNR

Baseless disagreeing ehh? Show us some proof that won't be kicked out from even a high school science class

4RUNR

You have it backwards btw. Properly working fan will show resistance when cold, will spin almost freely at normal temperature, and will show resistance again if the engine is above normal.

marko3xl3

I am gonna be with Epic Ed on this one, cars shouldn't overheat in hot weather unless something is wrong with their system (which could be that the needle won't move higher?).

As I said before, I went off-roading in high heat, in 4-low & 1st gear for 30 minutes in very dusty conditions (lots of wheelspin) and I haven't had one single problem.

There are no "super-cars" just cars that don't work right. Designers don't make cars to go up 3/4, they make them so they stay at 1/2 most of the time.

Also, I don't believe that "most of the cars that day were running close to red"...absolutely no way, else people would be pulling over.

4RUNR

To be honest I’m not sure you understand what we are discussing. Roaring full throttle off-road with the fan spinning is not idling in crawling traffic.

You must be kidding. General population pulling over because some little needle is close to red? This discussion is about the 3rd gen, not other cars by the way.

I know a few people on this board have ODBII readers. Convince them to do the same test. I would be pleasantly surprises if the results vary greatly from mine.

Epic Ed

OK, now you're just being a jackass. Your lone example of a single experiment with your vehicle in non-controlled conditions isn't exactly sound methodology either, and you know it. Feel free to expand your test group to include a valid number of vehicles for your test sample under some strict controls and then you can brag about having testing methods that will get you past a high school classroom.

If you chose to believe that over heating (not just running hotter than usual) is a normal outcome of running the A/C in heavy traffic during summer temperatures, feel free. I'll go back to cruising around in my "miracle 4Runner" in complete ingnorant bliss.

Ed

4RUNR

Now this is comedy!
Accusing me of non-controlled conditions? More samples? You are not even sure how long you were parked!

All while during those 20 (or now supposedly 40) minutes looking at a gauge which is not designed to move with temperature in the first place. I presented a case using exact and verifiable measuring techniques.

When the needle goes into the red that is my definition of overheating, not complete and irreversible damage to the engine, and any stock 3rd gen will overheat after 45-55 minutes of sitting still in similar condition described in my test. Anyone is welcome to perform this on their own vehicle, just don’t ask Epic Ed to keep the time.

dragon564

4RUNR, Thank you.

Gents I think what 4RUNR is trying to say is what I did say....you do not have to a "problem" with any part of the cooling picture for this to happen. All the parts have a tolerence range, so by the book they can all pass with an "OKAY" yet added together cause an overheat.

EpicEd 4RUNR put the rig in drive which increased the load I do not see that in your test. I will AGREE with that it should not be happening.

I will state it again "Every part of engine can pass every test (nothing wrong) yet when combined with all the other parts create this problem."

In the begining of this everyone jumped on obvious and normal culprits, I just wanted to point out that sometimes it is not the obvious, and the obvious can be fully functional, yet other not so obvious parts that are functioning with in range when brought into the picture can create the problem.

For all we know he could have revved up the enginge in the morning dislodging some built up carbon desposits that shielded the EGT sensor which fooled the ECU into leaning out the mix, in turn creating more heat. The carbon later burned off the sensor and the problem corrected itself.......and nothing was wrong or not functioning......

Robinhood150

4runr, very impressive work, I like hard data. Now if we can only get 9 more people to do the same, we'll have some statistical data.

In the mean time, lets all settle down and try not to overheat (pun intended).

4RUNR

Robinhood150, why 9? Even 1 more with almost exact results will be very good statistical probability, and the chances of low variance between samples is a good bet, unless my truck is broken. Though the chances of that are also high if I were to look at some replies. Hehe.