Overheating again...

[spartacus]

I have an overheat problem with my 02 4Runner, v6, and wanted to see if anyone knows what it could be with these clues - this is my first time trying to fix a problem with this vehicle/any vehicle, which has 200k miles, I got from my parents
-first noticed the problem when the top radiator hose busted and steam came from under hood
-replaced the hose and when driving home noticed the coolant was boiling
-thought the radiator cap could not be holding pressure so I then replaced that, but still it got really hot (on the gauge and physically touching the new hose)
-replaced the thermostat and after driving a little more the temperature gauge was still going to max temp
-removed the radiator and seemed like there was no blockages because I flushed water in the top and it flowed out the bottom
-so I heard maybe the water pump, but my dad said he had that replaced not too long ago, and maybe a new radiator but if water flows through it maybe not, the guy at autozone said coolant temp sensor but I don't know enough about that, another friend/other posts say maybe fan clutch
-did not notice any leaks under the car
-radiator had some pink crud where the hose meets it

coolant temp sensor replacement

coolant temp sensor

 

[shadow247]

Get a surface read thermometer ( they sell one at CVS/Walgreens for like 20 bucks) and see what your actually water temp is at the water outlets coming from the engine. It's very possible your engine is not actually overheating, but that you have a faulty sensor. If the temp of the inlet/outlet is around 210, then you are good to go. A coolant temp sensor is cheap to replace, so I'd probably just throw one in.

It doesn't sound like a head gasket issue, as that usually presents as overheating during a long extended drive, or burning/sweet smell from the exhaust.

 

[3bears]

if you have a rear heater, you have waterlines higher than the radiator, thus able to trap air. If you have the rear heater, make sure it is on when flushing and filling system. I have the Leslie Spill free funnel. It puts the water sourse at the highest point. Burping has never been easier.
you can also put the car up on a ramps or up on a curb to make the radiator the highest point

 

[[email protected]]

1) Have you filled and purged the cooling system to make sure there's no air in it? Look up Lisle Spill Free Funnel.
2) Test your fan clutch.
3) Over pressure in the cooling system enough to blow a radiator hose off is indicative of a blown head gasket. Do a compression test to determine if any cylinder is low on compression, then do a cylinder leak down test to determine if you have a blown head gasket. Compression tester and leak down tester should be available for rent at parts stores. Check out Timmy the Toolman's youtube videos for help or any youtube video in general.
4)Autozone/Oreilly's/Advanced Auto/etc employees don't know any more than you do. All they have available to them is what their computer tells them. If they knew enough to be a mechanic, then they would be a mechanic and making more money.

1) So I got the Lisle spill free funnel, that works amazing.. lots of air pockets burping out... I was testing with just water and it seems to be staying cool, at least with thermostat removed... I put thermostat back in and will test more today
2) The fan is running strong when the engine is on
3) I did a compression test and all cylinders seem OK for that test
4) They probably still know more than me!


I am thinking maybe the air was my problem (not the original problem, but the problem after blowing a hose and replacing thermostat)... maybe the thermostat went bad, and when I put a new thermostat in I had too much air, and that's why it got hot again..

The radiator seemed to be flowing fine, so I never replaced that.. I just need to add more transmission fluid since I lost some in removing Radiator, then I will test more to see if it gets hot.

 

[Bad Luck]

[MENTION=407167][email protected][/MENTION]

That's good news that compression numbers are good. Not sure what brand thermostat you went with but I ended up changing my thermostat out for OEM. You might consider replacing the radiator cap as well since it "should" have released pressure in the cooling system before blowing a hose off. Just my $0.02 and hopefully all the air pockets were all of your issue.

 

[phattyduck]

I put a new thermostat in

Hopefully OEM, with the jiggle valve placed at the 6 o'clock position... (either of those missed may cause problems)

-Charlie

 

[Mommashark]

Won’t stop overheating

I don’t mean to hijack this thread. I have a 97, about 165k miles. I just bought it. Started overheating. Changed the cap, then the thermostat. Still overheated. Had it pressure tested. went back and replaced with OEM cap & thermostat at 6 o’clock. Still overheats. Replaced the fan, suspected maybe the clutch was tired. Still overheated. Replaced radiator & water pump. Still overheating. Mechanic said it’s like it is getting air in the system. Passes Multiple pressure tests. Did a chemical test. Not the head gaskets. He’s checked that possibility about 4 times. Someone please help me!!!

 

[spartacus]

I don’t mean to hijack this thread. I have a 97, about 165k miles. I just bought it. Started overheating. Changed the cap, then the thermostat. Still overheated. Had it pressure tested. went back and replaced with OEM cap & thermostat at 6 o’clock. Still overheats. Replaced the fan, suspected maybe the clutch was tired. Still overheated. Replaced radiator & water pump. Still overheating. Mechanic said it’s like it is getting air in the system. Passes Multiple pressure tests. Did a chemical test. Not the head gaskets. He’s checked that possibility about 4 times. Someone please help me!!!

Heater core or water pump not functioning properly.

 

[cashflow50]

I don’t mean to hijack this thread. I have a 97, about 165k miles. I just bought it. Started overheating. Changed the cap, then the thermostat. Still overheated. Had it pressure tested. went back and replaced with OEM cap & thermostat at 6 o’clock. Still overheats. Replaced the fan, suspected maybe the clutch was tired. Still overheated. Replaced radiator & water pump. Still overheating. Mechanic said it’s like it is getting air in the system. Passes Multiple pressure tests. Did a chemical test. Not the head gaskets. He’s checked that possibility about 4 times. Someone please help me!!!

Buy one of the coolant burp gizmo. Mechanic might be right. Air bubbles in system. Amazon for $20 or so

Sent from my iPhone using Tapatalk

 

[kball]

Is it actually overheating or just the gauge rising? Were the head gaskets ever done by previous owner?

 

[Mommashark]

I took it to the mechanic and he burped the system & used a vacuum then he drove it, 15 miles, right back to hot. It overheats, boiling coolant in the expansion tank. Is there a way for me to tell if the head gaskets have been replaced?

 

[thegipper]

You said your mechanic did a chemical test to check for a HG leak, in my experience, those tests are almost worthless unless you have a seriously blown head gasket. Have him do a leak down test. That is the best way to 100% rule out or confirm a bad HG. Also, are you losing any coolant?

 

[Mommashark]

It seems like after everything was done, there was air trapped in the heater core. They bypassed the heater core & drove the truck- no more overheating. So he pressure flushed everything, then filled everything with the rear heater on & said it’s been good for over 70 miles. So here to hoping the mystery has been solved.

 

[JJ994runner]

1999 4runner Overheating

I have a 1999 4runner 3.4l that I have been having overheating problems with. At first it was only when I would climb up steep dirt roads but it is starting to happen daily driving with any sort of strain on the motor uphill. I replaced the radiator and the thermostat and burped the coolant but none of that helped. The motor was also rebuilt about 15,000 miles ago.

Looking for some suggestions as to what the solution could be.

 

[plcfcng]

I have a 1999 4runner 3.4l that I have been having overheating problems with. At first it was only when I would climb up steep dirt roads but it is starting to happen daily driving with any sort of strain on the motor uphill. I replaced the radiator and the thermostat and burped the coolant but none of that helped. The motor was also rebuilt about 15,000 miles ago.

Looking for some suggestions as to what the solution could be.

If the Temp is 210 or below you should be ok if you can take a Temp reading you then you will truly know if it is overheating. Is the system loosing coolant or is the temp gauge reading hot. How long have you been driving this before the system started to show a over heating problem ? Somethings to consider is proper placement of thermostat proper flow direction and jiggle valve at 6 o clock. Is the radiator still cool even if the engine is hot ? Tell us more and good luck

 

[JJ994runner]

So I replaced the thermostat and made sure the jiggle valve was at 6 o’clock. The radiator also feels hot when the temp gauge says the engine is hot. The temp gauge has gone up 3/4 of the way before I shut it off to let it cool down there is a crack in the intake rubber but I didn’t think it could cause overheating that much. My coolant level has also stayed the same since I burped the system. It’s been happening for about a month now. The radiator is from autozone though so I don’t know if that could be faulty or if there were a way to tell whether or not it is. And my shroud is cracked at the top but I’ve heard that isn’t that big of a deal on the 4runners.

 

[kball]

Since you're saying it's getting worse I'm guessing it didn't start right after the engine rebuild? You also say that it's happening with strain on the engine so if you are cruising down the highway it's fine? If so my guess would be fan clutch not engaging, at least not enough under slower speeds with strain.

 

[spartacus]

I have a 1999 4runner 3.4l that I have been having overheating problems with. At first it was only when I would climb up steep dirt roads but it is starting to happen daily driving with any sort of strain on the motor uphill. I replaced the radiator and the thermostat and burped the coolant but none of that helped. The motor was also rebuilt about 15,000 miles ago.

Looking for some suggestions as to what the solution could be.

your fan should roar when you start your truck cold. I mean it should be loud and then settle just a bit after a minute or two. there are other methods for checking the fan clutch.
You might have a bad fan clutch. Get the asin brand clutch if that's the culprit.

 

[JJ994runner]

If the Temp is 210 or below you should be ok if you can take a Temp reading you then you will truly know if it is overheating. Is the system loosing coolant or is the temp gauge reading hot. How long have you been driving this before the system started to show a over heating problem ? Somethings to consider is proper placement of thermostat proper flow direction and jiggle valve at 6 o clock. Is the radiator still cool even if the engine is hot ? Tell us more and good luck

So I replaced the thermostat and made sure the jiggle valve was at 6 o’clock. The radiator also feels hot when the temp gauge says the engine is hot. The temp gauge has gone up 3/4 of the way before I shut it off to let it cool down there is a crack in the intake rubber but I didn’t think it could cause overheating that much. My coolant level has also stayed the same since I burped the system. It’s been happening for about a month now. The radiator is from autozone though so I don’t know if that could be faulty or if there were a way to tell whether or not it is. And my shroud is cracked at the top but I’ve heard that isn’t that big of a deal on the 4runners. Also it doesn’t even have to be running that long it will overheat if I put strain on it within 10 minutes of it being warmed up.

 

[JJ994runner]

your fan should roar when you start your truck cold. I mean it should be loud and then settle just a bit after a minute or two. there are other methods for checking the fan clutch.
You might have a bad fan clutch. Get the asin brand clutch if that's the culprit.

Yea my fan roars when I start it up and like you said then fades away I also checked by spinning the fan while it was cold to see if it would free spin and it didn’t.