02-20-2019, 10:29 PM
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#16
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Join Date: Sep 2016
Location: Bend, OR
Posts: 26
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Quote:
Originally Posted by norcalassassin
I had a very similar issue on my '98 in the snow as well... Ended up being the radiator cap. the one that had been on the truck for 20 yrs had a worn rubber seal allowing the system to lose pressure.
Replaced the cap about a year ago and no issues since.
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I need to replace mine as well. I was wrong to assume that a new radiator would come with a new cap.
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09-10-2019, 11:38 AM
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#17
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Junior Member
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Join Date: Sep 2019
Location: WASHINGTON DC
Posts: 8
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Mysterious overheating 2001 4Runner
I have had a similar prob with my 4Runner. Overheating on long uphill climbs (not necessarily steep) and/or after engine has been running at least an hour at highway speeds. Has happened twice while on the highway. Both times truck was not particularly overloaded or towing, but was full with luggage and 3 kids. Truck is 2001 with 102K miles.
Three separate mechanics (two Toyota dealers, one independent) have not found the problem. Did pressure test, which showed no leaks.
Last incident, it began to overheat while traveling to NY; luckily found nearby Toyota dealer; opened the hood and found overflow tank overflowing and boiling over but no actual leaks. In that instance, after pressure test, dealer speculated old radiator cap had some brittle rubber parts that fell down into radiator and blocked something, though he was only speculating; changed cap anyway and flushed system. Dealer also ruled out blown head gasket. We thought problem was resolved, got back on the road, and had gone about 30 miles when temp indicator started moving up near the red again. I slowed down, turned around and limped back home (about 75 miles).
The truck runs all day around town without a trace of overheating. Last week I purposely took it alone on a 90-minute drive up the highway to try to replicate overheating, but it didn't happen. However, I had no pax/luggage and the day wasn't very hot.
Radiator was replaced in 2016; coolant hose and thermostat less than a year ago; water pump reportedly replaced in '03. I am stumped, but i know very little about engines. The fact that three mechanics, including Toyota, can't figure it out, is more concerning. Sorry for the long post. Any thoughts?
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09-10-2019, 12:00 PM
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#18
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Join Date: Mar 2017
Location: Sacramento, Ca
Age: 36
Posts: 20
Real Name: Matt
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Junior Member
Join Date: Mar 2017
Location: Sacramento, Ca
Age: 36
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Real Name: Matt
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Quote:
Originally Posted by ED2001T4R
I have had a similar prob with my 4Runner. Overheating on long uphill climbs (not necessarily steep) and/or after engine has been running at least an hour at highway speeds. Has happened twice while on the highway. Both times truck was not particularly overloaded or towing, but was full with luggage and 3 kids. Truck is 2001 with 102K miles.
Three separate mechanics (two Toyota dealers, one independent) have not found the problem. Did pressure test, which showed no leaks.
Last incident, it began to overheat while traveling to NY; luckily found nearby Toyota dealer; opened the hood and found overflow tank overflowing and boiling over but no actual leaks. In that instance, after pressure test, dealer speculated old radiator cap had some brittle rubber parts that fell down into radiator and blocked something, though he was only speculating; changed cap anyway and flushed system. Dealer also ruled out blown head gasket. We thought problem was resolved, got back on the road, and had gone about 30 miles when temp indicator started moving up near the red again. I slowed down, turned around and limped back home (about 75 miles).
The truck runs all day around town without a trace of overheating. Last week I purposely took it alone on a 90-minute drive up the highway to try to replicate overheating, but it didn't happen. However, I had no pax/luggage and the day wasn't very hot.
Radiator was replaced in 2016; coolant hose and thermostat less than a year ago; water pump reportedly replaced in '03. I am stumped, but i know very little about engines. The fact that three mechanics, including Toyota, can't figure it out, is more concerning. Sorry for the long post. Any thoughts?
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Check your fan clutch, this happened to me on my Tacoma a few years back it drives fine around town but under load or highway speeds the fan cant move enough air to keep it from over heating.
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09-10-2019, 06:05 PM
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#19
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Elite Member
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Join Date: Oct 2014
Location: Citrus Heights, California
Age: 36
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Real Name: Jerod
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Quote:
Originally Posted by MK_98
Check your fan clutch, this happened to me on my Tacoma a few years back it drives fine around town but under load or highway speeds the fan cant move enough air to keep it from over heating.
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Around town this would definitely affect it but at highways speeds the air moving outside would quickly overcome whatever air the fan could move. So overheating at highway speeds is not a fan clutch issue. Seeing that he hasn't had the water pump replaced in 16 years, I'm saying the bearings in the water pump have gone bad and it isn't moving the coolant like it should. The cooling system is very simple, it's literally just radiator, hoses, water pump, thermostat and the coolant itself. That's it. Water pump is the only one he hasn't replaced.
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09-13-2019, 09:00 AM
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#20
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Join Date: May 2017
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Real Name: Jon
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When these engines are starting to warm up on a long climb. If your not milk shaking, loosing coolant. I would try the following:
Turn your heaters on full blast hot air and see if the temperature starts dropping. If it does. Then suspect the following few things.
1) radiator fins dirty or clogged with mud
2) radiator cap not pressurizing your coolant.
3) Theromstat starting to intermittently stick. [ seen this since the 1980s and very common]
4) Water pumps mostly start spewing coolant fluid when their bearings fail. However, not always. They mostly do get noisy when starting to go as well.
5) I would also look at the internal fins in the radiator [ through the cap ] making sure deposits are not building up. This is extremely rare these days but if someone exchanged the antifreeze and used very crappy water the radiator might be clogged with deposits.
Hope this helps. :]
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09-17-2019, 08:55 PM
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#21
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I have also had an issue similar too with my supercharged 3.4. The previous owner said the headgaskets went out and the truck overheated so he had the headgaskets replaced along with the timing belt, water pump, and radiator. The truck still was overheating so he swapped out the radiator for a champion radiator and drilled out the t-stat.
In this setup he said it doesn't overheat. Since I have had it, city driving is fine and the temps stay super low but at highway speeds going uphill, the gauge will read 3/4's almost to red. It was strange to me because the scanguage reads 190 when the temp gauge is at 3/4.
I am hoping it's a faulty water temp sender for the temp gauge and I can just install a 170 degree thermostat. What would cause the temps to rise at highway speeds with a new radiator and fluids?
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09-19-2019, 12:07 PM
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#22
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Join Date: Sep 2019
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Thank you all, guys. I am leaning toward a water pump issue, because it has been about 16 years since it was installed!
Just curious, and forgive my ignorance, but with the truck having been examined by two separate dealers, wouldn't a water pump issue be readily obvious, or does it need to be dismantled to see if it has failed?
Being a bit cynical, I am surprised two separate dealers didn't try to sell me an expensive water pump job, after all. I may have mistakenly told them the water pump was relatively new (which I thought at the time - long story!).
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09-19-2019, 01:15 PM
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#23
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Join Date: Oct 2014
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Quote:
Originally Posted by ProjectTrinity
I have also had an issue similar too with my supercharged 3.4. The previous owner said the headgaskets went out and the truck overheated so he had the headgaskets replaced along with the timing belt, water pump, and radiator. The truck still was overheating so he swapped out the radiator for a champion radiator and drilled out the t-stat.
In this setup he said it doesn't overheat. Since I have had it, city driving is fine and the temps stay super low but at highway speeds going uphill, the gauge will read 3/4's almost to red. It was strange to me because the scanguage reads 190 when the temp gauge is at 3/4.
I am hoping it's a faulty water temp sender for the temp gauge and I can just install a 170 degree thermostat. What would cause the temps to rise at highway speeds with a new radiator and fluids?
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Yeah, you're on to something there. Either the Engine Coolant Temperature Sender unit is bad, or the Engine Coolant Temperature Sensor is bad. If it's the sensor that's bad your engine is going to overheat again. If it's the sender, it's completely harmless and the dash gauge will be off. Replace the sender but if it still does it I would change out the ECT sensor next just to be safe.
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11-14-2019, 03:15 PM
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#24
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Quote:
Originally Posted by gamefreakgc
Yeah, you're on to something there. Either the Engine Coolant Temperature Sender unit is bad, or the Engine Coolant Temperature Sensor is bad. If it's the sensor that's bad your engine is going to overheat again. If it's the sender, it's completely harmless and the dash gauge will be off. Replace the sender but if it still does it I would change out the ECT sensor next just to be safe.
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Late response but mine ended up being the headgaskets being flipped. So the right HG was on the left side and left HG on right side, blocking a coolant port. Was an expensive fix but still less than a new engine at least. The shop who did the first job must have been blind. So now everything works fine and the engine stays 180-190 for the most part.
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11-14-2019, 04:46 PM
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#25
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Elite Member
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Join Date: Oct 2014
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Quote:
Originally Posted by ProjectTrinity
Late response but mine ended up being the headgaskets being flipped. So the right HG was on the left side and left HG on right side, blocking a coolant port. Was an expensive fix but still less than a new engine at least. The shop who did the first job must have been blind. So now everything works fine and the engine stays 180-190 for the most part.
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Wow, good catch! The accidental switch usually ends in a blown engine.
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11-15-2019, 11:38 PM
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#26
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Join Date: Apr 2019
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Quote:
Originally Posted by gamefreakgc
Wow, good catch! The accidental switch usually ends in a blown engine.
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I was really hoping it wasn't that lol. I also had a cracked head so had to get that fixed as well.
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07-16-2021, 05:28 AM
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#27
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Join Date: Jul 2021
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I need to know what ended up happening with your car, OP?
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07-16-2021, 04:44 PM
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#28
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if your temp is ok but you feel the engine is hotter than its supposed to be then replace the oil pump as well
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