Question about Toyota 4Runner

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Changed head gaskets @400,000 km. Now overheats. New rad, thermostat, water pump, removed thermostat, still continues to overheat.

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  • adhoc_laptop
    adhoc_laptop Aug 25, 2010

    Does the car overheat when driving? Or also when idle?

    Hook up a radiator flush T to your heater hose, this is the hose that leaves engine and goes into the firewall. Only hook the T to the firewall side so you can see if the coolant comes all the way threw the system back to the T. Make sure the cap is on. If the coolant does not come out of the heater hose thats still hooked to the engine you have a blockage somewhere.

    It is possible you did not torque the head gasket right and exhaust is getting into the coolant.
    It is also possible such a small thing like the radiator cap is bad. Rent a pressure checker from autozone and pump it up to the pressure on the cap. If the pressure leaks down look for coolant anywhere under the car. If you do not see coolant and the pressure leaks down, either you didnt do the gasket right or the lower intake gasket is leaking.

  • rogeshir Aug 25, 2010

    How is the timing. What size engine?



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Unclip topmost hot hose when engine is running to vent any airlock.
have you checked fan rotation......?

Posted on Aug 25, 2010


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We changed thermostat sensor and thermostat, still over heating. What could it be?

overheating has many symptoms, not just green on the ground
do tell?

temp gauge lies its buns off... use a real tool called a thermometer to see real temps. we use a IR pyro gun to see it and not GET burnt.

gauges is telling truth, so......................

a bad rad cap, or bad thermostat are common fails.
test one: (dead cold engine) never hot.
radiator tank filler cap off , you look down there, is the level really low?
(forget the silly side expansion tank for now)
if found low , then fill it and burp it. no air allowed there
running 50% antifreeze now? no?, that its WRONG.
the tool is $2, test it. (Prestone sells it)
the coolant is all rusty color, (ill not comment ) try service.

  1. Green on the ground,? for passengers feet.
  2. Water exploding from overfill side tank? ( oil in RAD or Milky engine oil) (same milk in transmission pan?)Exploding gases, on cold start is bad head gasket or warped head or cracked head/block, or just simple overheating, The Rad leak down test and the exhaust test (green/blue ) tests solve this riddle easy.
  3. Steam rising from hood or Radcap, or hose to Cap and recovery tank. Over heating or leaks.
  4. Dash gauge pegged. (or WILD GAUGE swings "air pockets below thermostat") or gauge bad. sender bad.
  5. Motor pinging and loss of power. (do not allow pinging, it will wreck the engine)
  6. Pistons landing on ground? (just joking....)
  7. A/C dies?, does it?, due to A/C engine overheat switch ,tripping off. a 235 ?F (spec) see FSM. A/C means Air conditioner clutch dead.
  8. Does the engine over heat , if left idling a long time (30min-1hr). or only at stop signs or red lights? (clutch fan not activating , check it, this way.)
  9. Does it only over heat while moving ? ( a bad pump, or Rad)
  10. Overheats, only on hills? (bad RAD)
  11. Only overheats pulling heavy loads ? (inside, full of bricks, or pulling a 1000 trailer ? ONLY?
  12. Never overheats moving fast on flat ground. (so the RAD fan is dead, no mater if stock or hacked in electric fan, it's DEAD)
  13. Do you have carbon or oil floating around in the Rad, filler CAP neck top tank ? yes?, that is bad head gasket or worse cracked block/head. Do the Exhaust test.
  14. Overheats under all conditions, Catastrophic overheat. ( can be bad pump (rotor gone) or RAD or system is packed up)
  15. Seems to overheat , even at first start , in 1min or less I have gases shooting into the overfill tank, that is a bad head gasket (mostly a warped head, at least)
  16. Antifreeze (and water) in the pans, Engine or Transmission.
  17. The RAD fan is DEAD ( just because a mechanical RAD fan coasts, don't mean it WORKS RIGHT.) See the clutch tests below. if electric fan , there is a test in the FSM covers this 100% the fan must come on over heated,.
  18. my electric fan , starts to run idling engine long time at 225F. It kicks on, some cars have 2 fan and staged, come on trip points.
  19. RTM read the manual the FSM>
  20. there is more im sure, cant think of them all now.

That pyro gun allows me to test any RAD easy , ask.
ok , i check all rad tube top and bottom and bingo find any tube clogged fast. if all are equally clogged.(partial) i cant find that.
that is caused by zero service, so...and there are signs for that too.

Jul 02, 2014 | Cars & Trucks

1 Answer

Causes overheating

no year? who hot, does hot mean only the gauge when high?
engine overheats or passengers.?? LOL'
overheats parked, ???? or moving fast or BOTH?
where are you that needs A/C , Key West>? im clueless.
it was 72 hear yesterday, no A/C needed.??
so how warm was it? out side?
Any engine with a weak cooling system will in fact overheat
if the A/C is used, because of the heat the A/C dumps in front
of the engine cooling radiator. (a silly design but practical)
think of the straw that finally broke the camels back.
its perfect.
top reasons, lots:
coolant low? look in the RAD neck, dead cold, is the RAD FULL??
for now ignore side tank, levels, assume its not working at all , use RAD actual levels.

1: belts slipping, on water pump pulley
2: debris, in the 2 cores up front, in the front nose of car.
3: radiator tubes clogged, making RAD , weak.
4: not running 50% antifreeze, with boilover protection.
mine boils 265" (i just changed mine yesterday)
5: water pump bad, blades inside rusted thru, (bad service)
6: serious engine problems causing cooling system failure.
a: blown head gasket, forcing exhause gases to the water jackets.
B: same with cracked head, or block. (freeze protection ignored)
7: Engine RAD fan dead. (will cause parked , overheating for SURE)
8: a bad thermostat. they dont last forever. 5 years?
I have a video that shows what fails in a thermostat. very revealing.
did i cover it?

check out the 17 signs of overheat here. and 24 causes.

Jan 21, 2014 | Suzuki Grand Vitara Cars & Trucks

2 Answers

Car is over heating. antifreeze leaks out the top of the reserve.

can be caused by many things.
does it leak (overheat) all the time.
does it do it at first start, parked, idling, for 5mi, or 30min.?
or only after engine warmup ,then i drive and only at stop signs
does it overheat moving fast , steady 45mph speed?
there are many tests, all are easy.
first off , it can be bad RAD,thermostat, lost coolant (ignored service) bad water pump, bad RAD CAP.(replace if bad)
or cracked engine bock, cracked head, bad head to block gasket.
to name a few.
if it only fails at stops signs look for RAD tube blockage
i use an IR pyro gun to find these.
there are 3 more tests, ask.

Oct 16, 2013 | 1999 Chrysler 300M

1 Answer

2001 impala overheating replaced water pump ,thermostat,after driving 6 miles heater stops blowing warm air car overheats?

sounds like head gasket, shes putting pressure out into your rad, check your big hose when idling see if they swell up with pressure,another way to check is to leave rad cap loose.

Dec 23, 2012 | 2004 Chevrolet Impala

1 Answer

Can the power steering pump on a 92 camry cause an engine to overheat


Dec 17, 2011 | 1992 Toyota Camry V6

1 Answer

My o1 grand am v6 overheats , just put in new t/stat and still overheats . how can i tell if the rad cap is bad

Where does water come out,if at all?It probably is a water pump since you already changed thermostat.Probably takes 15-20 minutes of good running speed to overheat?Greg

Nov 17, 2010 | 2001 Pontiac Grand Am SE

2 Answers

2002 pontiac montana overheats but rad is cool.Thermostat has been replaced and still overheats in less than 10 km. Rad over flows and pressure fills the overflow. Coolant is warm. Possible water pump...

Either you have not bled the system, or possible fan not working, or head gasket problem. Solution

Step by Step
1. Check both hoses, do both have equal amount of pressure?
2. Run the vehicle where your gauge shows in the middle, shut the vehicle off then open the bleed valve near the heater line and wait till fluid comes out like a steady stream. Make sure you do not go low on coolant.
3. Turn on vehicle, turn on A/C high maximum blow check to make sure both fans are on. We are testing to make sure the fans at least work!.
4. After all this and you are still boiling over make sure your radiator cap is good if not then replace. Last but not least get a block tester to test for exhaust gases in the coolant. Rent one from autozone. $25.00 plus fluid which is about $8.00.

Sep 15, 2010 | 2002 Pontiac Montana

2 Answers

What is the possible response to a 1991 Toyota Corolla that has the tendency to overheat. Gaskets are new and it just had repair work done within the last two days. Sensor has been changed. Timing has been...

You either need a new thermostat or the water pump impeller is worn out,this is if the rad fan is working,if the rad fan is not working then you likely need a coolant sensor or a rad fan relay.the water pump impeller is not a serviceable part ,so of it is worn you will need to replace the pump.

Sep 04, 2010 | 1991 Toyota Corolla

2 Answers

1995 Isuzu, 2.3L engine overheats, chnaged rad cap, water remians

head gasket, if a crean collor is on the oil cap, lools like water pump etc are good

Apr 14, 2010 | 1995 Isuzu Pickup

1 Answer

1999 grand am se v6 3.4

tranny fluid low this could cause the over heat
flushing the rad doesnt always clear the clog sometimes it can make things worst
water pump not flowing properly too much calcium build up inside
if a/c compressor connected the bearings could be seizing slowly maken a drag on the engine to overheat
these are somethings i can think of off the top of my head at this time i hope this helped

Jun 03, 2008 | 1999 Pontiac Grand Am GT

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