2000 Camry overheating

[jaggudada]

Hey guys,

My Camry seems to be overheating. When I'm driving the gauge maintains and reads 6/10, when the engine is idling, it goes upto 8/10, radiator fans kick in and then temperature goes down to 6/10 and keeps cycling over a period of 5 mins.

It's got 100K miles, water pump has not been replaced yet.

I checked the hose temperature; top hose 210 F, bottom hose 192, fans kick in when top hose is around 215 F.

I checked the engine temperature where the sender is installed and it was reading 205 F. Coolant level is OK. I burped the system. Previous owner told me, he had thermostat replaced by dealer.

Is the reading off?

[Brian R.]

It's time to replace the timing belt, water pump, thermostat, and hoses. The problem is probably in the thermostat.

I doubt the reading is off.

[jaggudada]

Originally Posted by Brian R.

It's time to replace the timing belt, water pump, thermostat, and hoses. The problem is probably in the thermostat.

I doubt the reading is off.

Hi Brian : I checked the hose temperature again this morning

Top hose 190F
Bottom hose 170F

May I know why you think there is a problem with the thermostat? The t-stat was just changed 2 months ago. If the t-stat wasn't working, would you still feel top and bottom hoses hot to touch?

[Brian R.]

My opinion on the thermostat is mostly just historical problems. They are the first thing to go which may cause engine temperature issues. You seem to have inadequate coolant circulation. If the thermostat is not able to open all the way, it may cause a problem like you are experiencing (strange temperature fluctuations). If there is logic or consistency to your temperature readings which I am unaware of, then perhaps a better opinion is at hand.

Since you have to replace the timing belt around now, it would be a good idea to replace the water pump, thermostat and hoses all at one time and not worry about this problem further. If you have recently replaced the timing belt, then the issue becomes more complex.

Thermostats don't necessarily last a long time, particularly if the engine has not had the coolant changed regularly and there is a build-up of deposits in the cooling system. Also, the thermostat is extremely easy to replace in your engine, and rather cheap. Given one fix, I would replace the thermostat. If you need a timing belt, go for the complete cooling system replacement.

The blades in water pumps corrode (with infrequent coolant changes) and can cause problems with cooling, but then you are looking at the timing belt all over again. Also, the lower (suction) radiator hose can collapse on the inside and cause intermittent restrictions in coolant circulation. These are both much less common than the thermostat failing.

It is not common for the engine temperature meter to only partially work. Check the connection, but again, it is not common and that's why I didn't think to advise this in the first post. It's just a simple thermocouple which either works or not.

[jaggudada]

Just to give you a little history. Coolant temperature gauge was pegging all the way to H even if the engine is not ON. I found no ground reference on brown wire behind cluster panel. Instead of finding where the ground wire got disconnected, I just took a piece of wire and push that on the top of brown wire through the connecter and grounded it to the chassis screw right behind cluster panel.

After this the gauge started working, prior to this, thinking there was problem with oirgional sending unit, I replaced that with Auto zone one perhaps non OEM.

I ordered OEM sending unit just to rule out any discrepancies here. That's why I was thinking there may be issue with the reading.

[Brian R.]

See if you can't make a good ground connection to the engine from the meter.

[jaggudada]

Originally Posted by Brian R.

See if you can't make a good ground connection to the engine from the meter.

I did run a temporary wire from dashboard to engine block, engine block side was secured tight, the cluster side the wire was just slipped through connector on top of existing ground wire. I got the same results.

Only other thing left is to cut the brown wire and splice it tight. I wanted to make sure everything works before I cut the brown wire.

Do you know what the corresponding temperature in degrees is for 5/10, 7.5/10, 10/10? In other words what is the scale for C to H on temperature gauge.

Should it be even reading 6/10 when measured top hose temperature was 190F?

Any recommendation on the timing belt/water pump kit?

[Brian R.]

Originally Posted by jaggudada

Should it be even reading 6/10 when measured top hose temperature was 190F?

Any recommendation on the timing belt/water pump kit?

Reading 6/10 is quite reasonable for 190F. Might be a little high. I would expect a horizontal needle at normal operating temperature.

Assuming you have the 5S-FE 4 cylinder.

http://www.amazon.com/ACDelco-TCKWP1...toyota%3Acamry

or

http://www.amazon.com/Gates-TCKWP199...toyota%3Acamry

If you're buying the kit locally, I prefer higher end NAPA parts.

Neither of the above includes a thermostat or radiator hoses. I guess you can always install a thermostat later if the above don't fix your problem. Unless they are rather new, I would replace the radiator hoses.

(You may also need cam or crank seals and/or accessory belts)

[jaggudada]

Brian,
Lots of good info. Thanks

While I was driving home I saw my gauge was reading 6-7/10 on a 20 min commute. I got home, left the engine idling and shot Top and bottom hose with infrared gun just to check. Top hose was 190F, bottom was 130F meaning t-stat was not opened yet. after about 2 mins of idling perhaps the temperature had risen further and then I felt bottom hose getting hot (175 F)

This definitely sounds like a t-stat problem. If the gauge had been reading 6/10, the coolant temperature is hot enough for t-stat to open. do you agree? On a 75 degree day, you would think t-stat should open on 20 min drive.

After few more mins of idling, gauge read 8/10 and fans came on. If gauge is reading right, wouldn't you expect fans to come on around 5/10? On a car where it maintains normal temperature (less than 5), fans do come on and off?

One other thing, the temperature reaches 4/10 within half a mile of starting engine from cold. I thought this should take few mins.

what does all of the above tell you?

[Brian R.]

Originally Posted by jaggudada

This definitely sounds like a t-stat problem. If the gauge had been reading 6/10, the coolant temperature is hot enough for t-stat to open. do you agree? On a 75 degree day, you would think t-stat should open on 20 min drive.

To me, it may mean that the thermostat was not open at the time you took the measurement. It may open and close at various times based on the block temperature. It might mean the thermostat is unresponsive.

Originally Posted by jaggudada

After few more mins of idling, gauge read 8/10 and fans came on. If gauge is reading right, wouldn't you expect fans to come on around 5/10? On a car where it maintains normal temperature (less than 5), fans do come on and off?

Fans are controlled by thermocouple in lower radiator hose. If coolant in radiator is relatively cool, they will not come on. They are not controlled by the block temperature. The fans turn on and off unpredictably.

Originally Posted by jaggudada

One other thing, the temperature reaches 4/10 within half a mile of starting engine from cold. I thought this should take few mins.

There is no set time for this to occur. What you are seeing may be normal. There is not much coolant in your engine.

[jaggudada]

This morning the top hose was showing 170F/bottom 100F(t-stat no open yet)after driving for 15 mins , but gauge showed 6/10. There is no way the gauge should indicate 6/10. correct? and if the gauge is reading correctly then 6/10 is hot enough for the t-stats and fans to come on.

Also on a normal running engine, the gauge doesn't read past half way mark yet we know fans come on and off before that. It seems to me the problem is with reading?

The reason I want to make some logical sense here is I have known lots of people replace lots of things and problem still remains, especially when it comes to cooling.

[Brian R.]

Originally Posted by jaggudada

This morning the top hose was showing 170F/bottom 100F(t-stat no open yet)after driving for 15 mins , but gauge showed 6/10. There is no way the gauge should indicate 6/10. correct? and if the gauge is reading correctly then 6/10 is hot enough for the t-stats and fans to come on.

The gauge shows local block temperature. The fans react to the lower radiator coolant temperature. The thermostat reacts to it's local block temperature which may be different than the gauge and the lower radiator temperature. That soon after starting means you can't judge anything by comparing these temperatures. They only mean something after the engine has reached operating temperature and the engine is at a relatively steady condition.

Originally Posted by jaggudada

Also on a normal running engine, the gauge doesn't read past half way mark yet we know fans come on and off before that. It seems to me the problem is with reading?

The reason I want to make some logical sense here is I have known lots of people replace lots of things and problem still remains, especially when it comes to cooling.

The fans turn on and off at unpredictable times. Don't use them as a diagnostic tool unless they are always on or always off. If you replace the timing belt/water pump/thermostat, there is basically nothing left to replace. If you don't want to replace the water pump, then remove the thermostat and test it in hot water.

Immerse the thermostat in warm water and heat the water and monitor the water temperature at which the thermostat opens. The temp is marked on the thermostat. The valve lift at greatest opening should be 8 mm or more. The thermostat should also be closed at lower than operating temperature.

[jaggudada]

Originally Posted by Brian R.

there is basically nothing left to replace.

I agree with what you are saying. Most likely the problem is with water pump/thermostat. What about the radiator? What about the poor heat transfer? or the engine is running hotter than usual because of incorrect air/fuel mix etc?
If heat produced itself is higher than component design the temperature is going to rise. Correct?


Is it possible that when I check the block temperature may be below the t-stat setpoint and hence it is closed but as I was driving the t-stat might have opened if required? once t-stat is opened, even if it is closed, you should still be able to feel the host somewhat hot. Not at 100 degrees correct?

If the t-stat is closed, water pump is still running? where does it put water?

[Brian R.]

Originally Posted by jaggudada

What about the radiator? What about the poor heat transfer? or the engine is running hotter than usual because of incorrect air/fuel mix etc?
If heat produced itself is higher than component design the temperature is going to rise. Correct?

"My Camry seems to be overheating. When I'm driving the gauge maintains and reads 6/10, when the engine is idling, it goes upto 8/10, radiator fans kick in and then temperature goes down to 6/10 and keeps cycling over a period of 5 mins." <= Not the radiator

Poor heat transfer is seldom an issue unless you never change the coolant and corrosion has almost completely filled the water jackets. This is an abnormal situation for an average engine.

Incorrect fuel/air will not cause overheating. Your cooling system is designed to remove much more heat than that produced by your engine at highway speeds (90 mph).

Originally Posted by jaggudada

Is it possible that when I check the block temperature may be below the t-stat setpoint and hence it is closed but as I was driving the t-stat might have opened if required?

The above sounds like normal operation to me.

Originally Posted by jaggudada

...once t-stat is opened, even if it is closed, you should still be able to feel the host somewhat hot. Not at 100 degrees correct? If the t-stat is closed, water pump is still running? where does it put water?

Normally the bottom hose should be fairly hot. But that is at normal operating temperature. The thermostat has to open a few times before the engine is really hot.

The water pump moves water around internally without pumping water through the block. There is a jiggle valve on the thermostat which always perrmits minimal coolant flow through the thermostat. The purpose of this valve is to permit air to escape when filling the system with coolant.

Just test the thermostat. If you're concerned about the radiator, feel that there is heat being emitted from the entire radiator when the engine is hot, and not just the top or bottom. Also, make sure your coolant level is sufficient to fill the radiator and have a moderate amount in the overflow tank. You might also consider buying a new radiator cap.

[jaggudada]

Brian,

You certainly have wealth of knowledge!! What coolant would you recommend for Camry? I think Toyota recommended coolant is their long life RED but it is expensive. Is it okay to use Zerex Asian vehicle formula?

Right now I have red and little green mix and once I resolve this overheating issue, I would like to get rid of this, put distilled water twice, run it for a day or so and finally fill it with 50/50 mix. Will this work? Do you have any recommendation on the flushing procedure?