Overheating - Please Help, Unusual ?

[danw77]

I am trying to help out a friend with his 1995 4cyl Camry that has been over heating. I had started this in another thread (Overheating - Head Gasket?) but the problem seems to have changed so I', reposting.

The background: Car was overheating, he took it to a mechanic, the mechanic said it was a head gasket, I didn't believe him, etc. There is no power loss, no steam from exhaust, no coolant in oil or oil in coolant. I drove the car about 10 mins from his house to mine with the A/C on and couldn't get it to overheat. i turned the heat on and i was getting plenty of heat out of the vents (i took this to mean the water pump was working). I turned the A/C off and it overheated. Thats when I noticed the electric fan was only coming on when the A/C was on. I checked the fan switch, and as far as I could tell it was bad, so i replaced it.

I was hoping this was the problem all along, so I filled it with coolant and tested it out. The fans never came on and it overheated. The fan came on with the A/C again, but this time it wouldn't stop it from overheating. When I reached down to check the connection at the fan switch, I noticed the bottom half of the radiator was cold, including the lower radiator hose. the upper hose was hot. i figured maybe the thermostat was bad so i replaced that. same thing. this time i left the cap off the radiator as i let it warm up, and the coolant boiled out.

Where I am now: I'm thinking maybe it's the water pump. But I can't explain how I was getting heat from the vents when I drove it the first time. And I was certain that the fan switch should have fixed the problem. I'm wondering if maybe there is some air in the system somewhere that isn't letting the pump circulate the coolant? I'm not hearing any noise coming from the water pump however.

any ideas? i don't want to change a water pump if all it is is some air in the hoses somwhere. would a bad head gasket (like the mechanic said) cause these problems? i'm truly at a loss with this and don't know what to do next. thanks in advance.

To recap, my main ?'s are these:
1) Is it possible there is air in the system that is preventing the water pump from doing it's job?
2) If the water pump is bad, why was I able to get heat from the vents before?
3) Is it possible that the mechanic was right all along, and it needs a new head gasket?

[danw77]

please.... someone...... anyone..... any ideas?

[Nad1370]

Originally Posted by danw77

The fans never came on and it overheated.

^^
Here's your first problem. Even though you replaced it and the fans still didn't kick on means that there is still a problem.....electrically meaning a short in the harness.

Usually the fans should kick on when the fan switch connector is disconnected with the Key "ON" or engine running .
Fan switch is a single wire that completes ground to de-activate the fans. When temps get up, the thermistor in the fan switch creates an "open circuit" then operates the fans.

Turning on the ac bypasses everything and kicks the fans on.

I believe it is a wiring problem on the fan switch. Trace the wire down and look for open wires touching each other or grounding out.

[toyomoho]

If the T-stat was installed with the hole or jiggle pin up the air should bleed out of the system on its own.

As the engine heats up eventually the lower hose hose should also be hot. Obtain a thermometer and check the coolant temp as the engine warms up. At around 199F the fans should kick in. You should be able to see the coolant circulate inside the radiator.

The radiator could be partly plugged (not uncommon), it should flow from a garden hose freely out the bottom. The pump can fail at the impeller (happens but not common).

If a head gasket the engine would have other symptoms besides over heating. A test of the coolant can be done for exhaust gases.

[500KCamry]

Originally Posted by toyomoho

If the T-stat was installed with the hole or jiggle pin up the air should bleed out of the system on its own.

Yep.

Also, some after market replacements for the thermostat don't have a jiggle pin and shouldn't be used.

[danw77]

Originally Posted by Nad1370

Usually the fans should kick on when the fan switch connector is disconnected with the Key "ON" or engine running .

The fans do kick on with the switch disconnected. I originally suspected an electrical problem with the fans, but have ruled that out.

Originally Posted by toyomoho

If the T-stat was installed with the hole or jiggle pin up the air should bleed out of the system on its own.

i triple checked the t-stat, and it is good, with the hole in the correct place.

Originally Posted by toyomoho

The radiator could be partly plugged (not uncommon), it should flow from a garden hose freely out the bottom. The pump can fail at the impeller (happens but not common).

water flows freely from the top to the bottom of the radiator. i'm thinking maybe the pump did fail at the impeller?

Originally Posted by toyomoho

If a head gasket the engine would have other symptoms besides over heating. A test of the coolant can be done for exhaust gases.

there are no other symptoms. i have not tested the coolant for exhaust gases, but even if they were there, would that explain the lack of coolant circulation?

the thing about this problem that has me the most stumped is that the problem seems intermittant. sometimes it will overheat in five minutes, sometimes it takes 20-30 minutes.

i think my only remaining question is this: is it possible that these symptoms are a result of ONLY the head gasket being bad? is it at all possible that the water pump is fine? i am no expert here, but everything i see points me towards the water pump. i just don't want to waste a saturday doing a water pump, only to find that the water pump was fine and i have to tear everything apart again to do a head gasket. after all, that's what the mechanic said was wrong in the first place.

[toyomoho]

Typically a blown head gasket results in exhaust leakage into the coolant, then stream and a back flush of coolant into the over flow tank. Does then engine have this problem?

Suggest if not already tried to pull out the T-stat. Back flush the system, block, heater core, radiator, etc. Check the inside of the radiator hoses for damage and signs of internal collapsing. Fill the engine with water with T-star removed.

The coolant should start flowing from engine cold start. If it does not circulate the issue is pump, something is plugging up the block coolant ports or radiator.

Have known 2 Camry owners whose WP failed, one at the shaft/impeller joint, the other had broken impeller blades. Thus WP failure is possible.

[danw77]

no, there is no backflow into the coolant bottle. i stopped by a local mechanic this afternoon and explained the situation to him. he said it is possible that if the head gasket is blown, the exhaust gases will form air pockets in the cooling system. if the air pocket forms near the water pump and is large enough, it can make it look like the water pump is not working. that the pump will basically be spinning in air and not force the coolant to flow. he said the only way to tell for sure was to test for hydrcarbons in the coolant (for $85), but he couldn't do that for a couple days.

at first this made a little bit of sense, but the more i thought about it the less likely it seemed. so i went back home and took the car out for a drive to see what would happen (i hadn't driven it since i did any of the work, only let it idle in my driveway). much to my surprise, everything worked fine. both hoses got hot, the t-stat opened when it was supposed to, the electric fan came on and off at the right times, and i had heat out of the heater vents. i drove around for 45 minutes doing everything i could to try and make it overheat, and the needle didn't budge from the middle of the gauge.

now i'm wondering if the problem was the fan switch all along. perhaps i had an air bubble in the system? maybe taking it out for a drive dislodged the bubble? i looked at the overflow after it cooled down and it was down about half way from full. i filled it up, took it for another drive (same thing, no overheat) and it's right at the full mark. everything seems to working perfectly now!

i know my way around an engine pretty well (really, i do) and i have never had a harder time tracking down a problem and getting it fixed. i am hoping and praying that this is the end of this, but i'm trying not to get my hopes up. is any of this possible, or is this just the strangest cooling issue ever? or maybe i just don't know what i'm doing?

[danw77]

anyone?

[lloydrobbins]

Hi, Dan - did you ever figure this out? Trying to diagnose a 94 Camry that overheats at stoplights - think it might be the fan switch.

[msm15]

HI I have the same problem on my camry I just had the head gasket and radiator redone, it was fine for 4 months then it just started to heat up again, it can take about a half hour before it gets up there but the temp goes up and down, and then eventually stays up at first I put the heat and and it helped, but then it stopped blowing hot air and only cold air, things I havent checked yet are the T-stat, fans and water pump, I was told the timing was done a little while ago but they way I got this car it was abused really badly oil hadnt been changed, trans fluid was bad, it had a slew of problems.

If you figure you problem out it would probably be a great help to me.

thanks

oh and by the way there is tons of coolant in the overflow, I couldnt check the radiator itself it was too hot at the time, but the coolant was a thick brown not green - the way it started out - what does that mean ?

[Kingdom934]

Originally Posted by msm15

HI I have the same problem on my camry I just had the head gasket and radiator redone, it was fine for 4 months then it just started to heat up again, it can take about a half hour before it gets up there but the temp goes up and down, and then eventually stays up at first I put the heat and and it helped, but then it stopped blowing hot air and only cold air, things I havent checked yet are the T-stat, fans and water pump, I was told the timing was done a little while ago but they way I got this car it was abused really badly oil hadnt been changed, trans fluid was bad, it had a slew of problems.

If you figure you problem out it would probably be a great help to me.

thanks

oh and by the way there is tons of coolant in the overflow, I couldnt check the radiator itself it was too hot at the time, but the coolant was a thick brown not green - the way it started out - what does that mean ?

I hope the coolant was flushed when the head gasket was redone. If it was and it is thick brown again...that could be a serious problem.

Is the car blowing white smoke? Is there any chocolate milkshake color under the oil cap?

[msm15]

ok dont know if the system was flushed or not but I just opened the radiator cap and the thing was so overly cacked with the rusty garbage there is no way the coolant was circulating properly, the radiator - new was put in aroung 3k miles ago and it had more junk build up in it then the original had on 139k.

I havent checked the white smoke yet, but I dont think i will see it it takes at least a half hour from warm up for the engine to ever heat

[stereo]

I'm battleing a overheating problem in my brothers 2k solara with the 1MZ-FE motor it would overheat after a few weeks of hot weather with the a/c on then after with it off and it would boil the coolant out of the overflow before it makes it to the H mark so far I've replaced the t-stat it had some scratch marks where it could be sticking thing it fixed the problem but...after 2 weeks and a few 101-104 degree days it happened again ...so I suggested to replace the radiator (orginal with 270k on it) even tho water flowed through it fine fans worked like it should , so far so good 3 weeks and going .... when I get a time thinking about breaking it open to see when it looks like inside!