Need Advice! Fluctuating Temperature & Intermittant Overheating.

[cajieboy]

I own a 2002 Toyota 4Runner SR5, V-6, 2WD. Presently, I'm in Colorado on a long trip from Florida. After stopping over in OKC to visit family over Memorial Weekend, I was driving north in Kansas when I first discovered the temperature gauge rising up, then easing back down to normal. I stopped at a rest Plaza for a short time, and the gauge returned to normal. I checked all the fluids, and everything was OK. I continued on to Lawrence, KS with no other problems. Leaving that area for Denver, CO, I experienced the same thing on several occaisons, but the gauge always returned to normal w/o ever having to actually stop the car. Over the next few weeks, I've been driving around Denver, sometimes on interstate highways for 30-45 minutes, other times around town. No problems. Temperature gauge remained normal. All fluids normal.

Today, I started to drive in the mountains towards Salida, and it had not been 15 minutes into it, that the temperature gauge began to climb upward to near the red mark. After pulling over, and just letting the engine run idle for a time, temps went back down to normal. Again, all fluids normal. This went on a few times more along a 3 hour drive in the mountains, and noticed that the temps seem to rise more on a steep grade and when it got close to the red mark, I pulled over to just idle for a period and temp would return to normal. During the last hour of driving, the temp remained normal, which is just below the halfway mark.

About 4 months ago, I had all belts replaced including timing belt, new water pump, plug, wire set, and tune-up. Looking back on the repair bill, I do not see any charge for a thermastat, which is what my first guess would be at this problem, but do not really know.

I called the shop back in Florida and spoke with the mechanic that had performed all the work from 4 months ago, and he stated that if it was a thermostat or faulty water pump then it would be having temp problems all the time, not intermittantly. The mechanic suggested that the radiator may be trying to get plugged-up. That doesn't ring correctly for me, but then I'm no mechanic. I would greatly appreciate any and all advice/help. Thanks.

 

[MAD 69]

It sounds like there might be a blockage in the rad, get a flush done on it and change the thermostat - 2 cheap solutions that can't hurt. You can always get a new radiator also. It's normal for the temp to go up a little when climbing but not to go to the redline.

 

[chitown40]

The general rule of thumb, at least with Toyota's is that if you had a bad thermostat, it will present as overheating all the time, including at idle, in-traffic, and at cruising speeds. If the fan clutch is not operating correctly, it will show by temps creeping up at idle or stopped in traffic only. If the radiator has a flow problem it will overheat at highway speeds. Also, there is the possibility of head gasket problems, cracked block, etc. But that's another issue.

I think the key to your post is the mountains. I'll explain.

Florida is a flat, warm state, so I'm going to guess that your mechanic, when he did your maintenance, didn't properly purge all the air out of your cooling system. Many mechanics is warmer climates often overlook the rear heater. He probably burped your cooling system pretty well on flat ground, but didn't get all the air out of the system. That would explain the sporadic temp spikes. You first started seeing the temps climb as you made it up north to some significant climbs. I'm speculating that on some of the extended uphills, air bubbles worked their way from hiding out by the rear heater causing the temp gauge to rise. I'll be you haven't moved your rear heater temp control in years, if ever.

So, you can try this to see if it fixes the problem. Park uphill and let the engine warm up with the radiator cap off. After the truck warms up turn both heaters to full hot and fans on high. Let it run a while. You can rev it up to 2500rpm occasionally for a few seconds as this sometimes helps get the little air bubbles moving. See if you can purge out some air.

That was the quicker method. In theory you can also just turn the rear heater temp control to full hot and turn on the rear heater fan and then just drive it for a while, including some good uphills, and the air bubbles SHOULD pass through to the reservoir tank.

Now with that said, your mechanic probably should have replaced the thermostat while everything was apart, assuming he actually changed the timing belt. Next time ask for the used parts in return with the truck and that will increase the chance that mechanic does what he said he does. Plus you can tuck that old timing belt away somewhere just in case it goes out on you on the road way in the future. You can always find a wrench, just not always a part.

If all this above is not the case, check for pinhole leaks on your radiator as well as either having it boiled out or replaced. I replaced the radiator in my 02 SR5 Sport Edition 4x4 right after I bought it. I used a performance radiator and I think it was about $150-$160 bucks.

Hope this helps. Good luck.

 

[cajieboy]

Thanks Mad & Chitown. My radiator was replaced about 4 years ago at a Toyota Dealership in Kansas City for about $800. This was shortly after I purchased the vehicle from another Toyota Dealership in Delray, FL which was supposed to be a "Certified" Preowned Toyota. Fortunately, I had also purchased an additional warranty from that dealer, and the faulty radiator replacement was covered after I paid the $50 deductable.
Could it be that I'm having ANOTHER radiator problem w/this 4Runner?

Geez, this is my 3rd 4Runner, as I've owned 1st & 2nd Gen 4Runner, and sold both after putting on over 350,000 miles. Most times, I had work done at the dealership because I did not know any local mechanics I felt I could trust to do the work properly. This last preventive maintenance work was done by a local shop that has a good rep. I had never had a radiator problem w/either of the previous two 4Runners. Chitown, where did you find a radiator for $150-$160?

 

[LittleCaesar]

Here is what you need if you want another one. I don't think you need it.
KOYO RADIATOR TOYOTA 4RUNNER NEW NIB | eBay

$800 for a radiator? And it doesn't have Lexus stamped on it?

You need to burp the system and all should be fine. There was a thread on here on this topic about a month ago. Use the search engine. I would follow Chitown's advice and proceed from there.

 

[cajieboy]

Here is what you need if you want another one. I don't think you need it.
KOYO RADIATOR TOYOTA 4RUNNER NEW NIB | eBay

$800 for a radiator? And it doesn't have Lexus stamped on it?

You need to burp the system and all should be fine. There was a thread on here on this topic about a month ago. Use the search engine. I would follow Chitown's advice and proceed from there.

Thanks Little Ceasar, I'll give the burping fix a try. I just spoke to Liberty Toyota in Colorado Springs, which is the town I'm heading tomorrow. The Service Advisor came up w/all kinds of scenarios that might be the culprit, ie. bad fan clutch, head gasket, spinning propellar on water pump..etc...etc..Scared the wholly sh*t outta me. Also, he remarked that it could be really bad that I did not use Toyota Coolant when I had the preventive maint. done 4 months ago. Is that factual?

 

[3.5inmag]

Yes and no.

Yes, because Toyota thinks/says that Universal coolant has phosphates which may cause problems in gaskets later on. Toyota red & pink coolant uses OAT ( Organic Aid Technology). The universal does not. Check out the link for more info.

No, because I'm reading on numerous sites where people have used Universal coolant and have had no problems. With that said, I have used universal coolant for the past 30K miles and have had no problems. My radiator cracked and was leaking coolant. Replaced radiator and put in universal coolant. No problems thus far.


http://donsnotes.com/home_garden/auto/antifreeze.html

 

[TheDurk]

One other simple stupid problem is a bum radiator pressure cap. Our trucks are at the age where they are starting to go. I say this because the caps are more important at altitude and you seem to have more trouble in the mountains.

I am of the opinion that universal coolant is ok as long as you keep your change interval to 30k (or less). If you want to go longer, stick to Toyota or Zerex Asian Formula.

 

[LittleCaesar]

I think the only drawback I have heard from folks not using the red coolant are having leaks at very high miles at the brass freeze plugs. Having never replaced one myself, I can't say what a good vs. bad one looks like, or if coolant really played any part in the leakage.

It could be a head gasket. Got any white smoke coming out the tailpipe in the morning? What does the underneath of the oil cap look like?

Ever had the water pump replaced before? If not, that is a slight possibility.

I still say air in the system.

Don't put much stock in what most service managers have to say. They can be and often are more ruthless in selling practices than car salesmen. Seen it more than once.

Follow Durk's advice as well.

 

[TheDurk]

Yes and no.

Yes, because Toyota thinks/says that Universal coolant has phosphates which may cause problems in gaskets later on. Toyota red & pink coolant uses OAT ( Organic Aid Technology). The universal does not. Check out the link for more info.

No, because I'm reading on numerous sites where people have used Universal coolant and have had no problems. With that said, I have used universal coolant for the past 30K miles and have had no problems. My radiator cracked and was leaking coolant. Replaced radiator and put in universal coolant. No problems thus far.


Coolant/Antifreeze

Actually, the bold part is backwards. Toyota likes phosphates and dislikes silicates and borates. The Pink Toyota is a p-HOAT (phosphated Hybrid Organic Acid Technology).

 

[3.5inmag]

Haha. My bad. I was in a bit of a hurry and got it transposed. Thanks Durk!

 

[MAD 69]

Let the Toy dealership look at it and get a price - but don't let them do the work. As the guys said, you can get a Radiator off of eBay for $120 - thats what I did too. There are a ton of guys on this site from Colorado and I'm sure they can hook you up with a shop that won't rob you if you have to replace the rad.

Try the burping/running heaters at full blast and then go for the flush, new thermostat and new rad cap. That might just be all it takes to fix your Runner.

 

[cajieboy]

The general rule of thumb, at least with Toyota's is that if you had a bad thermostat, it will present as overheating all the time, including at idle, in-traffic, and at cruising speeds. If the fan clutch is not operating correctly, it will show by temps creeping up at idle or stopped in traffic only. If the radiator has a flow problem it will overheat at highway speeds. Also, there is the possibility of head gasket problems, cracked block, etc. But that's another issue.

I think the key to your post is the mountains. I'll explain.

Florida is a flat, warm state, so I'm going to guess that your mechanic, when he did your maintenance, didn't properly purge all the air out of your cooling system. Many mechanics is warmer climates often overlook the rear heater. He probably burped your cooling system pretty well on flat ground, but didn't get all the air out of the system. That would explain the sporadic temp spikes. You first started seeing the temps climb as you made it up north to some significant climbs. I'm speculating that on some of the extended uphills, air bubbles worked their way from hiding out by the rear heater causing the temp gauge to rise. I'll be you haven't moved your rear heater temp control in years, if ever.

So, you can try this to see if it fixes the problem. Park uphill and let the engine warm up with the radiator cap off. After the truck warms up turn both heaters to full hot and fans on high. Let it run a while. You can rev it up to 2500rpm occasionally for a few seconds as this sometimes helps get the little air bubbles moving. See if you can purge out some air.

That was the quicker method. In theory you can also just turn the rear heater temp control to full hot and turn on the rear heater fan and then just drive it for a while, including some good uphills, and the air bubbles SHOULD pass through to the reservoir tank.

Now with that said, your mechanic probably should have replaced the thermostat while everything was apart, assuming he actually changed the timing belt. Next time ask for the used parts in return with the truck and that will increase the chance that mechanic does what he said he does. Plus you can tuck that old timing belt away somewhere just in case it goes out on you on the road way in the future. You can always find a wrench, just not always a part.

If all this above is not the case, check for pinhole leaks on your radiator as well as either having it boiled out or replaced. I replaced the radiator in my 02 SR5 Sport Edition 4x4 right after I bought it. I used a performance radiator and I think it was about $150-$160 bucks.

Hope this helps. Good luck.

Well guess what?...apparently I don't have any rear heater controls. I looked in my Owner's Manual and found a diagram of it, etc., but my SR5 does not have a rear heater. Sooooo, I'm wondering if this burping fix can be accomplished with only the main heater?

Yes Chitown, the water pump was replaced when I did all the belts, plugs, wireset, etc. The waterpump was not OEM, if that matters. Yes, I'm pretty angry about the thermostat not being done at the same time because I had a long discussion w/the mechanic about the preventive maintenance I wanted performed, and you would've thought he would have replaced that thermostat at the same time. I did look at the old belts, plugs, wireset and waterpump that was replaced. Everything looked pretty worn to me, but thinking back I forgot all about the thermostat, and it was not listed on the parts list I was charged. The mechanic just did not do it.

There is no white smoke, etc. when I crankup. In fact, the vehicle is running great, idling perfect, cranking up quick when cold or hot. Nothing else, except this intermittant overheating problem. I drove around Salida a bit yesterday, where we are about 8,000 feet up, and the 4Runner remained in normal temp. But I bet the first time I get into a heavy grade climb, this baby will start overheating.

I called Liberty Toyota Parts Dept. this morning, and they have all the parts I need in stock:
Thermostat - $21.13
Gasket - 5.77
1 gal. Toyota Coolant - $28.30
Radiator Cap - $14.10

Does anyone know of a reliable mechanic in Colorado Springs? Here's a rough estimate of what I was quoted from Liberty Toyota for this work:
Replace Thermostat - $190.00
Radiator Flush - $159.00

Seems really high to me. What do you guys think?

 

[cajieboy]

OK, did the burp fix w/only the one heater in the vehicle. Followed the instructions carefully, and I'll give it a test today on my trip to Colorado Springs. The coolant level was real high, up to the top, and some of it gently overflowed. When I revved-up to 2500 rpm's, the coolant went down a little bit, but did not stay there for long and creeped back up to the very top. I put the cap back on while the engine was running and parked back on level ground. Temp remained normal throughout the process.

 

[cajieboy]

Sad to say, the burp fix did not do the trick. The 4Runner overheated a few times on the way to Colorado Springs, but it did not seem as bad as before as it returned to normal temp more quickly after pulling off the highway for a bit. Most times, the car ran normal temp, but on the steeper mountain grades is when things got warmer for the engine.

 

[trovergraywilson]

Temp gauge question

Time for an old thread revival.

So this may just be me worrying about stuff, which I'm good @, but I've noticed over the past week in pictures from other members (@StreetCreeper and one other if not more) that the temp gauge on the far left of the instrument cluster seems to sit slightly below halfway, like 8-8:30p on a clock, for operating temp for y'all's engines. Bought my 2002 back in January and she had a coolant flush with Toyota Red right before I got her. No documentation on the Carfax or ToyotaOwners but I think the radiator was replaced recently (transmission is fine, no concerns about the PM). Really clean, fins on the front look new, cap seals and the overflow is fine. Zero leaks, no coolant in oil or vice-versa, no white smoke, no HG concerns. My temp gauge since January sits dead level, like 9p on a clock, for operating temp. Fan clutch works great, can hear it coming on and off and doing its job, drives like a dream, can idle in Chicago traffic for hours with the AC on full blast and no problems. No ScanGauge yet (all that would do is probably cause my mechanic to block my #, I call to ask enough questions as it is) so I can't quote the actual temps.

TL;DR: My engine temp gauge sits dead level, like 9p on a clock, for operating temp, and others look to be slightly lower. Thoughts?

Thanks y'all.

 

[shahsmerdis]

Best way is to get a 20 dollar OBDII and measure it that way. if its in the mid chances are you are fine, I was worrying about this last week as well.

 

[trovergraywilson]

Follow-up; with pictures, because they make everything better.

TL;DR: My engine temp gauge sits dead level, like 9p on a clock, for operating temp, and others look to be slightly lower. Thoughts?

This:
<a data-flickr-embed="true" href="https://www.flickr.com/photos/144040288@N08/26940681614/in/datetaken-public/" title="image"><img src="https://c7.staticflickr.com/8/7446/26940681614_8cedb239ea_z.jpg" width="480" height="640" alt="image"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>

Concerning? Thermostat jiggle valve @ 12 instead of 6? Or should I just go back to listening to 80s music in traffic?

 

[mtbtim]

Follow-up; with pictures, because they make everything better.

TL;DR: My engine temp gauge sits dead level, like 9p on a clock, for operating temp, and others look to be slightly lower. Thoughts?

This:
<a data-flickr-embed="true" href="https://www.flickr.com/photos/144040288@N08/26940681614/in/datetaken-public/" title="image"><img src="https://c7.staticflickr.com/8/7446/26940681614_8cedb239ea_z.jpg" width="480" height="640" alt="image"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>

Concerning? Thermostat jiggle valve @ 12 instead of 6? Or should I just go back to listening to 80s music in traffic?

Like somebody already suggested, get yourself a Bluetooth OBD II Sensor and use the Torque Pro app if you have an Android phone to monitor your coolant temp. If you have an I-phone, I'm sure you could find an app for that as well.

I changed my thermostat recently and the jiggle valve for the one I replaced was in the 3 o'clock position. I put the new one in the 6 o'clock position and the coolant temps are the same. I'm starting to think the jiggle valve position doesn't really matter.

 

[Diggo]

I may be way off here, but I had a issue with my engine getting warm. It turned out to be a valve. Have u had your valves checked?