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Diagnosing Cooling problems

Discussion in 'Diagnosis/Help' started by Stig, Apr 17, 2009.

  1. Stig

    Stig ST162 Guru Donated!

    When in doubt - Change the thermostat, they are cheap and responsible for 40% of cooling problems. 40% is due to corrosion and buildup and the rest is mechanical failure, gaskets etc.
    Always keep the radiator water green (glycol) - prevents rust (read MUD), icing and shows your system is clean.It also raises the boiling point of the water, ie it will not boil at 100 deg/C.
    Remove all hoses, thermostat etc and blow out all hoses, radiator, head, heater at least once a year from all directions.
    On cars fitted with factory oil coolers, remove & clean it out as well (a pain), you cannot blow it clean in the system and it is a collecting point for mud.
    NEVER put water into a steaming radiator! - It will crack/warp your head and/or radiator.Let it cool down first!
    Never open a hot radiator! - leave it for 15min or ground the fan for a few minutes first. You will burn yourself and those around you. If it has boiled, it could vomit hot water at any time!
    Put a small amount of grease on all fittings before re-fitting the hoses - prevents rusting and will make removing hoses easier (No it won't leak).
    NEVER throw glycol (antifreeze) on the ground (kills the grass) or leave it lying around, animals (esp kids, dogs, cats, birds) will try to drink it (smells nice) and it's lethal!
    Do not mix diffent types of antifreeze, always empty into a pan and flush the system first.
    Always check new thermostats in boiling water first!
    Fill the system slowly, squeeze the hoses to check no air is in the system.
    Before upgrading your motor, seriously consider fitting a thicker, aftermarket radiator as well!
    Periodically check your fans are working.
    In sub zero temperatures and your car is not heating up properly - tape a piece of board or thick plastic over part of your radiator, experiment with different sizes.

    Mysterious loss of water and eventual overheating.
    Let car idle for 10 min and then check for water under the car, around the radiator (the top tank is suspectable to small cracks which leak under pressure)
    and the bottom of the cambelt cover and inside the car around the passenger footwell.
    Check exhaust for white smoke, white smoke = head gasket leak.Exhaust will be wet and sweet smelling.
    Check spark plugs - Any "clean" plugs will show where gasket is leaking.
    Check engine oil - white/milky oil indicates water in the oil.
    Check fan operation
    Check around engine block, welsh plugs will usually rust through and start seeping from the centre of the plug. They are bastards to find as the water will boil away on the hot block. Look for stains under the plugs. Same goes for small leaks around the water pump

    Gauge moves up and then comes down
    Thermostat is sticking and not opening fast enough, in that time the pressure has risen and dumped water into the overflow bottle. If the fan is faulty it could blow a hose or head gasket.

    Dumping water into overflow bottle
    Radiator cap faulty, replace
    Thermostat faulty, replace
    Fans not working - sender, fuse, relay, motor faulty
    Radiator blocked - clean entire system.
    Head gasket leaking gas into water - bubbles in radiator, steam. Perform pressure test.

    Burst Hose
    Thermostat stuck closed - remove it and immerse it in boiling water, if it does not open - chuck it.
    Major water leak - fill system and check for leaks
    Perform steps under tips to remove any potential obstructions.
    Check fan operation.

    Radiator cold in places
    Radiator tubes blocked

    It's overheating and I'm miles from home
    If there's a leak - fix the leak! - any water you put in will be pumped out in seconds. Refer to tips section before burning yourself.
    Make sure you have plenty of water and spare water in the trunk, keep the revs down (shortshift), coasting on flats, switch the motor off on downhills and WATCH THAT GAUGE!
    Frequent stops to check the water and grounding the fan sensor will help.
    Switch the heater to high heat and open the windows, it will help cool the motor.
    Spraying the radiator with cold water will also help
    DO NOT spray a hot engine block with cold water - you risk cracking it!
    If you can - remove the thermostat till you get home/garage.

    Fan/s not working
    Sender unit on thermostat housing faulty?
    Remove wire from sender and touch it to the motor, fan should switch on.If not it could be a fuse, sender, relay or fan motor.
    NOTE - fans will not work when radiator is empty, sender can only work when immersed in water not steam.

    Heater not working
    Heater valve on firewall jammed
    Heater radiator blocked - remove two hoses and blow out repeatedly with water.
    Heater radiator control flaps stuck, can be a cable or electric motor fault.

    Car takes ages to warm up
    Either your thermostat is jammed open, or
    Your motor is so worn, there's hardly any friction and it's running rich.

    Car takes ages to warm up and gauge drops lower than normal at speed
    Your thermostat is jammed open, not good. Refer to Thermostat section.

    Always check new thermostats in boiling water first
    Never run without a thermostat or modify the thermostat, the engine temp will not be constant and take longer to warm up. Causes accelerated engine wear & gasket problems.
    Yeah I know race cars don't have them - don't do it
    a) they modify (restrict) the housing
    b) they are flat out all the time
    c) the motor is pre-warmed
    d) most use electric water pumps

    Water Pump
    The water pump bearing and seal will eventually go. When it does it will scream on startup and start to leak water or start/stop screaming loudly while driving - CHANGE IT IMMEDIATELY!- The water pump on these motors runs off the cambelt, if it seizes - it could destroy your motor
    There is an O-ring on the rear of the pump and a gasket on the front, if either leaks it is advisable to change the pump as well.
  2. NightCrawler

    NightCrawler Member

    Depending on your location having a Thermostat is pointless... ie: People whom live in Hot- Dry places don't need a Thermostat, which in turn the celica's already have a slight hating issue and with Thermostat removed the antifreeze/water flows more freely keeping the engine cooler- for those in cooler snowy areas a Thermostat is very important to have installed.

    One additional side note- When replacing antifreeze always do a cycle run, turn the engine on and make sure you water pump is flowing the water thru the op of the radiator hole- this will also "Purge" the system, getting out the air that has been trapped, Air in the system can actually cause your car to over heat.

    A major issue our Celica's have with Heat is 2 things-
    1st: The position of the exhaust manifold/Cat is very close to the a/c Cooling fan and also the Radiator which is producing the most heat for the heating issue.- Soultion us a Heat Wrap the ones used for the Turbo exhaust Manifolds it will reduce a lot of heat making the car run cooler.
    2nd: the Airflow to the radiator is made very odd from toyota- the grills on the celica's are in a downward angle causing a lot of air to flow away from the radiator, The front bumper has a huge area that no air can get thru, and the lower valance has holes but dos not direct the airflow to the radiator it continues its flow under the car...
    So that being said a Airflow system is needed for the front- installing a "Ramp" style panel on the lower valance will direct a massive amount of air to the radiator Yes it may hurt your MPG by a few miles but hey it keeps the needle from the hot !!!!
  3. Stig

    Stig ST162 Guru Donated!

    Everyone on the road needs a thermostat!

    It's job is to speed up warm-up time before you go revving the crap out of it
    Also it keeps the temp constant while running, without it your temp will
    range up/down depending on your speed and revs - even in hot areas, worse in cold areas.

    Your engine parts expand and contract according to the temperature, not good in terms of
    wear and reliability. They are designed & measured to work together at around 85 deg C

    The exhaust isn't affecting the radiator - the car moves forward, not backward
    Heat wrap is designed to speed up exhaust gas flow by keeping the gas hot, not to cool

    The "S" motor is a 30yr old design, the heat issue is because water flows from cyl #1 to cyl #4,
    getting hotter and hotter instead of across each cylinder evenly and out the back of the block.
    At that time engines that used this design had wet liners, not dry like the "S".
    The cylinder bores are also hopelessly too close to each other, the water can only cool the
    front and back of the bores and can't get between them

    Your car is supposed to have a "ramp" below the front bumper, it's probably been ripped off
    like on many cars.
  4. NightCrawler

    NightCrawler Member

    I have found it is better to run without a themostat simply due to the restriction the part has towards waterflow- it will open when the vehicle gets to a certain tempature but if you examine the diameter of the stat you will see where the restriction is coming from... keep in mind this is only directed towards HOT and DRY areas not you snowmobiling people!
    But I live in california where its 85 degrees at 7:30 am but its debateable--- I will be on later to rebut your prior post lololol
  5. Stig

    Stig ST162 Guru Donated!


    Even in race engines which run at redline all the time we remove the plunger but
    still run with the restrictor plate (Mafix had this problem a while back - refer to his thread)
    and block the circulator pipe


    Because the water has to pass through the radiator at a certain speed in order to cool -
    too fast (ie without the plate) and it doesn't have time to cool in the radiator.
    You'll find that race engines also run with a bigger pump pulley to slow the water down
    to normal (ie street speed) and save some ponies for the wheels.
    Too fast and the water cavitates in the pump and flow is lost

    Things are not as simple as you think

    I bet your fans are working overtime trying to keep things cool and suggest you look
    elsewhere for your problem (clogged radiator/head maybe?, running lean? faulty fan/sensor etc)

    Another thing to bear in mind is that when you mod the thermostat, you MUST block the circulator
    pipe behind your exhaust with a plug or else it just pumps boiling water straight back into the motor!

    Nice to see someone thinking outside the box for a change and asking questions
  6. Mafix

    Mafix Owner Staff Member Administrator Donated!

    i'm running a race motor (pretty much) and you cannot run without a thermostat/restrictor plate. you have to have it.
  7. 86CelicaGT-S

    86CelicaGT-S Well-Known Member

    Hey Stig, great post!!!! Learned a lot.

    Got a couple questions:

    1. When you said to check your fan you said to take the sender wire and ground it to the motor; what wire is this? I know mine works but unsure if my brother's fan works; want to check it.

    2. For the cycle-run to see if air is in the system; it says to turn it "on"; does this mean to have the engine running or just turned to the "on" position? Also, do you do this cycle-run after changing the coolant or before or both? - This question is for NightCrawlers post. Thanks NC as well for the info!!!

    3. Last one, is the thermostat located inside the water pump?

    Thanks again!!!

  8. Stig

    Stig ST162 Guru Donated!

    1) Thats a mistake - you only need to unplug the wire and the fans come on if the ignition is switched on
    It's the one on the water hose below your alternator, GT4's, 182's etc have the
    switch at the bottom of the radiator
    (a much safer place for it)

    2) After changing, it's to eliminate air and check for leaks. Water won't circulate unless the motor is turning

    3)No, its under the alternator as well, inside the bulge. The pump is on the cambelt side
  9. Stig

    Stig ST162 Guru Donated!

    Running too cold?

    The temp gauge is one of my least liked items on the car.
    11pm is normal, 12pm is "I'm going into meltdown now!" mode

    The gauge should be redlined from the 12 oclock mark

    In bad winter conditions (below zero) it's possible the engine takes too long to warm up and runs cold
    when moving, esp with a larger rad fitted - The solution is to tape a piece of plastic card or cardboard
    in front of the radiator, provided you never cover more than 1/2 the radiator
  10. bluestreak

    bluestreak Guest

    I have a factory oil cooler on my donor car that I plan to swap over any tips for cleaning it before I put it on my car??
  11. Stig

    Stig ST162 Guru Donated!

    wash it out with acetone, kerosene, thinners or similar and make sure it's clean inside

    Handy Cooling Tip
    For those suffering from cooling problems there is a cheap & easy solution

    The manual ST162 has a single core radiator and a low power fan
    The auto versions have a 2 core radiator with an inbuilt oil cooler and high power fan.
    The Diesel Corona auto ST160/ST191 has a 3 core radiator with inbuilt oil cooler and high power fan.
    Bolts straight in using your exsisting brackets & top hoses from a 202 will work

    These radiators can sometimes be bought cheaply and are a worthwile investment.
    The 182, 202 radiator will not fit in your car without moving the bottom & top brackets.
  12. Seank90

    Seank90 Well-Known Member Donated!

    great tip!! but what would be the best to go for??? :thumbsup:
  13. Stig

    Stig ST162 Guru Donated!

    The auto version is easy to find and works with Gen2/3 headers as well
    The Corona version is hard to find and clearance probs with the hose/fans and
    later headers

    I've switched the Deisel ver to my FE motor with stock exhaust and it's a good fit.
    My GE is now much happier with the 2 core auto rad and gen2 exhaust - I was getting an error 42
    so filled the oil cooler with oil, closed the pipes and it helps to stop the temp swinging wildly when the fans kick in.
  14. Alwayzsidewayz

    Alwayzsidewayz ST162 Guru Donated!

    man I wish that upgrade was so easy for the turbo cars...

    Dam water cooled turbos.
  15. Seank90

    Seank90 Well-Known Member Donated!

    so would that give a bit more of a kick due to the engine being cooler???
  16. Stig

    Stig ST162 Guru Donated!

    No, but it will make things more stable, prevent blown hoses & H/G and keep engine wear down
    Optimum temp for these motors is 85-90deg C

    Handy Tip
    Tried 2 new thermostats this week and the car kept overheating! :twisted:

    Before fitting a thermostat - take both thermostats and place them in a coffee cup,
    pot etc and cover them both with boiling water.
    They should open at the same time, if not - the one that opens 1st is the one to use
  17. Seank90

    Seank90 Well-Known Member Donated!

    hmm... i get what your saying and with my engine build there would be a bit of a need to keep the temp cooler! and more stable..
  18. Stig

    Stig ST162 Guru Donated!

    You don't need anything fancy to clean the heater radiator, some pliers and a hosepipe is all.
    Disconnect the 2 firewall hoses and blow out the radiator from both sides till all mud is gone

    Here's the heater/ventilation problems I found & fixed on mine, leaking dash fix is on another page
    My problem (as shown) was a combination of dirty radiator, leaves and a stuck heater valve
  19. ST165-2765

    ST165-2765 Well-Known Member Donated!

    Thats not going to help. The area you want to get to is all welded up and concealed.
    The only way to get to it is to remove the blower motor and go from the inside. If you
    have air conditioning it's a pita because the AC radiator should come out first which means
    draining the AC coolant.

    So you should really answer my previous question before you cause yourself a lot of grief.

    You have 2 options to get air into the heating system. You can recirculate the air in which
    case a blocked fresh air intake (as you suspect) would make no difference. Or you can draw
    air from the outside through the opening picture I posted earlier.

    If you switch between fresh air and recirculate and do not notice a difference in the interior
    temperature then a blocked fresh air intake is not your problem. Once I know the answer to
    this question I can give you other options
  20. ST165-2765

    ST165-2765 Well-Known Member Donated!

    I doubt your cable is seized it just still attached to the motor inside the car and that is preventing
    it from sliding

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