Engine & Internal Chat about beefing up your engine's insides here.

overheating problem

  #1  
Old 08-10-2018, 11:42 AM
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Default overheating problem

Hey guys I have a 97 with the 2.2L and the 4 speed auto trans. I bought it from a family member that said they replaced the rad and the water pump but they never told me why. Here lately I have been noticing that the car will start to over heat when it sits at idle like at red lights and such. I havent pressure tested the system yet (planing on doing that this weekend) but I seem to be losing a good amount of coolant, I having to refill my rad once every two weeks or so. Any insight is greatly appreciated.
 
  #2  
Old 08-10-2018, 02:04 PM
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The OEM radiator had plastic upper and lower tanks. The tank can crack and leak over time leading to much bigger cracks if the radiator is not replaced.

Check the coolant system for signs of coolant leakage. Hoses can crack with age and leak but not to the point of total failure.

If possible pressure test the coolant system for leaks. An auto parts store may lend out the pressure testing tools.

If no leaks determine if the radiator fans works. The fans draw air through the radiator when the coolant becomes to hot such as with stop and go driving.

Operate the engine and turn on the AC. The fans should turn on/off when the AC compressor turns on/off. The fans should come on when the coolant temp reaches 199F.

Obtain a thermometer and with engine cold remove radiator cap. Start engine and let coolant heat up. Fans should come on when temp is over 199F.

It can happen that if the engine is overheated the head gasket fails. If this happens the engine can overheat for no obvious apparent reason and lose coolant. A "block test" can test for exhaust gases in the coolant.
 
  #3  
Old 08-10-2018, 03:33 PM
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I'm hoping to get the pressure test and also a compression test done this weekend. I keep leaning towards a head gasket because I cant see any visible signs of a coolant leak anywhere on or around the engine. Id like to flush the block and the rad and I had found a thread with a really nice step by step on how to do both. Any chance you can point me back towards that thread, and as for my car I'll keep you posted with the results from the pressure and compression test. Really hoping that if I have to do the head gasket I wont have to have the head machined lol cause thats when it really get pricey.
 
  #4  
Old 08-11-2018, 04:49 PM
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Can't find it. Suggest using the "search" function.
 
  #5  
Old 08-17-2018, 07:17 AM
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Finally got it figured out haha. Thermostat wasnt opening until it reached a little over 220 degrees Fahrenheit. Put a new Autozone 180 degree thermostat in and havent had a problem since.
 
  #6  
Old 08-17-2018, 11:45 AM
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Good job on finding the problem!
 
  #7  
Old 01-01-2019, 10:50 AM
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Unhappy My wife must feel jinxed

I have some similar issues to this thread. The car is a high mileage 1996 LE 2.2 and is fairly well maintained. It sits outside. About a week ago, the car heater stopped working for my wife and it began to overheat after about 6 miles of driving. Ambient temperature was about 45 degrees. It was way down on coolant so I added more and when I test drove it everything worked perfectly including the heater. My thought was that it was so low on coolant that it wasn't getting much to the heater core. Like the others on this thread, I've been unable to find any evidence of leaking, including at the heater core, so I was hoping I'd see something pop up now that I was looking for it. The car runs very well without any loss of power so a blown head gasket doesn't seem likely. It has a fairly recent timing belt and water pump. The thermostat is also fairly recent as are the hoses. The radiator is an almost new Denso (replaced new about a year ago) and I flushed everything and put in new Toyota red coolant at a 50:50 mix.

This morning it was much colder out, about 0 degrees when my wife left for work. She made it to work but the heater wasn't working again and the engine started to overheat. It didn't reach the red but it rose pretty high. About the time she got there the electric fans kicked on. I drove to her work about two hours later and found that the overflow tank was low again but the radiator barely took any coolant. Again no evidence of leaking. The car started and ran fine. I drove it home and the gauge stayed at exactly normal. However the heater still didn't work. When I opened the hood at home, the radiator cap was showing steaming but the engine took no coolant from the overflow tank like it did a week ago.

My gut reaction is that I have a bad heater core (maybe plugged) since that seems to be the wildcard here. I'm pretty sure it has never been touched and the car is around 240k miles. It seems strange that I'm not seeing or feeling any leakage at the core. I haven't done any of the other items on toyomoho's checklist other than what I've listed above. My hope is that my fact pattern would give some obvious clues. Working on the car is a bit of a hassle right now since it's so cold and my garage is now taken with another immobile project car. Thanks in advance for your help.
 
  #8  
Old 01-01-2019, 12:05 PM
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Heater core coolant picks up and returns to the engine coolant circuit. One heater hose going to the core has a valve to control coolant flow and cabin heat. The coolant system should not be tasked (overheat) by a plugged heater core or closed control valve. However a heater core can add to engine cooling (lower coolant temp) as it's just another radiator.

As you state, the lack of cabin heat and engine over heating occurred at the same time, it's possible the coolant dropped low enough to cause both. This seems to be the cause here. The question is why the coolant level dropped.

A few common issues with this car/engine:

You state the radiator cap was steaming. Has the cap been pressure tested? Perhaps it's not holding the designed pressure.

An engine coolant hose can have a leak but its small (for now) or only happens when the coolant system has pressure! Check ALL hoses, large and small particularly the smaller bypass hose (about 1 inch in dia) which can be hard to see/inspect. Squeeze the hoses and feel for coolant.

The lower large radiator hose can fail by collapsing (coolant being drawn through it) and cause a lack of flow.

The radiator coolant fans should turn on when the coolant temp reaches approx 199F. The fan switch is located at the bottom of the radiator and should have contact with the coolant unless dry. It's common for the fans to turn on/off if the engine has prolonged idling.

A thermometer can be inserted into the radiator fill port (engine cold) to determine temp when the fans start. The engine is then started and allowed to idle until the fans turn on. if they do. If the air temp is too cold, use cardboard to the block radiator air flow and heat the.coolant up. The engine should be able to constantly idle without overheating (temp gauge needle not moving from the normal position) if the fans are working properly.

An engine can have an internal coolant leak and run just fine. The symptom is loss of coolant.

If you think it's a blown head gasket these is test called a "block test" that will check for exhaust gases in the coolant. Blown head gaskets can cause all kinds of strange issues, irregular overheating being one.

The coolant overflow tank can crack and leak.

A engine "freeze" plug can corrode and leak. There are also plugs in the back of the engine.

There are florescent dies that can be put into the coolant. An external coolant leak will glow under a black light.

It has happened the water pump impeller blades degrade to the point of resulting in low coolant flow or the impeller break loose from the water pump drive shaft.

Thermostat issues.
 
  #9  
Old 01-01-2019, 02:47 PM
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Unhappy Wow, that's quite a list Joey

More info and questions in bold italic below.

Originally Posted by toyomoho View Post
Heater core coolant picks up and returns to the engine coolant circuit. One heater hose going to the core has a valve to control coolant flow and cabin heat. The coolant system should not be tasked (overheat) by a plugged heater core or closed control valve. However a heater core can add to engine cooling (lower coolant temp) as it's just another radiator. It is something of a relief that the heater core is the unlikely overheating culprit. Does a bad valve or plugged up core explain the sporadic heater performance however?

As you state, the lack of cabin heat and engine over heating occurred at the same time, it's possible the coolant dropped low enough to cause both. This seems to be the cause here. The question is why the coolant level dropped. It hasn't taken any new coolant since the episode a week ago or so. It took a lot then but it hasn't taken any/much this time. Low coolant level seems to be less likely this time although it definitely made a big difference last time.

A few common issues with this car/engine:

You state the radiator cap was steaming. Has the cap been pressure tested? Perhaps it's not holding the designed pressure. The cap is Genuine Toyota and was bought May 2015. That doesn't mean it hasn't failed.

An engine coolant hose can have a leak but its small (for now) or only happens when the coolant system has pressure! Check ALL hoses, large and small particularly the smaller bypass hose (about 1 inch in dia) which can be hard to see/inspect. Squeeze the hoses and feel for coolant. I will check.

The lower large radiator hose can fail by collapsing (coolant being drawn through it) and cause a lack of flow. I will check. Hoses are fairly new however.

The radiator coolant fans should turn on when the coolant temp reaches approx 199F. The fan switch is located at the bottom of the radiator and should have contact with the coolant unless dry. It's common for the fans to turn on/off if the engine has prolonged idling. The fans did turn on but it's hard to know how hot the coolant was. Given when they started, it could be that they are not starting early enough. Your recommended test below makes sense.

A thermometer can be inserted into the radiator fill port (engine cold) to determine temp when the fans start. The engine is then started and allowed to idle until the fans turn on. if they do. If the air temp is too cold, use cardboard to the block radiator air flow and heat the.coolant up. The engine should be able to constantly idle without overheating (temp gauge needle not moving from the normal position) if the fans are working properly.

An engine can have an internal coolant leak and run just fine. The symptom is loss of coolant. I may be thinking old school but I always thought a blown head gasket makes a car run terribly due to loss of compression. I'll try the exhaust gas test and see what happens.

There are florescent dies that can be put into the coolant. An external coolant leak will glow under a black light. This makes a lot of sense to do, too. Any particular product you prefer?

It has happened the water pump impeller blades degrade to the point of resulting in low coolant flow or the impeller break loose from the water pump drive shaft. The water pump is not that old but it could still have failed. My recollection is that this approaches a catastrophic failure because it is hard to find the little impeller pieces.

Thermostat issues. Also pretty new and Genuine Toyota if member serves. Still could have failed.







 
  #10  
Old 01-01-2019, 07:03 PM
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A partially plugged heater core can still produce heat. The lack of heat noticed when outside air temps are very cold. The climate control system mixes heated outside air with unheated outside air to get the proper cabin temp. If the outside air is cold enough and the heater core partially plugged, the resulting air mix temp is too cold and now noticed by the driver.

The heater valve mechanism can break. One result can be the valves control rod can move but the valve itself does not. The push/pull rod to the control rod can also fail. The valve can also leak coolant. If a manual heater control system, have someone move the temp control in the car while you watch if the valve body is actually rotating with cabin control movement.

If you ever drain the coolant system again. Disconnect the hoses going to the core and try back flushing the core with a garden hose.

Are you stating the coolant level is now OK but the temp gauge still goes above normal and the heater is not hot enough?

There is no coolant bleed valve to get the air out. When an empty coolant system is filled up, the upper and lower radiator hoses can then be squeezed to purge out air and add more coolant. The overflow tank is filled to the proper level. The engine is then operated until hot and then once cool again, make up coolant is added to the overflow reservoir to replace any air that has escaped.

Toyota makes great parts. Would be unusual for them to fail in just a short time.

Check the smaller coolant lines that are approx 1 inch in diameter such as below:
https://www.rockauto.com/en/moreinfo...273520&jsn=382

Head gasket failures symptoms can range from severe to minor and can be very illusive!

For coolant dyes, I use what is available at auto parts stores, auto section of department stores, etc.

Its rare but does happen the water pump blades deteriorate (less area to move the coolant). The impeller can also come loose from the pump drive shaft. The pump still moves coolant be less of it.

The radiator switch for the fans tends to either work or not. You can test the fan system by disconnecting this switch with ign switch on. The fans should now work. The switch turns off the fans, it doesn't turn them on.

Has the outside air temp ranged wildly in temperature? The cold air temps hiding a coolant and or heater system that is not up to par. This issue showing when the air temps rise.

A block test should be a yes/no indication of head gasket issues. If you are up to it get a pressure tester and check for leaks over time. The pressure tester can also check the cap relief valve.
 

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