Delurking for help with overheating issue

[SafetyThird]

I've been lurking, well, searching in these fora for the past 2 years, trouble-shooting on my 1995 Toyota Camry, which seems to have had a multitude of overheating problems.

Through TN I was able to replace my radiator by myself! Later, when a hose broke, I was able to glean enough info from diagrams and threads to figure out it was the coolant by-pass hose, and replaced that. I had already been to our local library, and the Chilton & Haines didn't have the diagrams that I needed, by TN did!

And now, another overheating, in our 114-degree phx heat.

This came on suddenly, and would only allow 1/2-mile before going red, so I assumed it was the thermostat - AGAIN -- but it wasn't. Now I see that the two fans are not coming on when it gets hot. From reading, I see that there are several possibilities -- fan relay, fan switch, and temperature sensor. Since my funds are extremely limited, I don't want to buy extra stuff.

I've been trying to figure out how to test or check the relays, and how and where to disconnect the fan switch, which, it seems, would have it run all the time? And then there's the sensor switch -- where exactly is it, and where to disconnect?

Thanks!

I'm stuck at home, no car, in boiling weather.

[96ToyoCam164K]

I don't blame you for being pissed. Last week I had to drive from Albuquerque to Denver in 90+ degree heat with the heater full blast half of the way because mine kept overheating slightly but intermittently. I flushed coolant and replaced radiator cap so...we'll see how it holds up on the next 500..........mile.

I had an issue like this some years ago with this same car. Non of the fans were cutting on. Turns out some wires were actually cut...snapped during an accident.

[ghettosled]

do you have a multimeter?

i dont know off hand with other systems in the camry use the same relay, but if you can find one that is working that you dont "need" - try swapping the relays. can anyone verify if you can jump the fan switch and/or temp sensor?

[SafetyThird]

Originally Posted by ghettosled

do you have a multimeter?

i dont know off hand with other systems in the camry use the same relay, but if you can find one that is working that you dont "need" - try swapping the relays. can anyone verify if you can jump the fan switch and/or temp sensor?

Update: The fans did not come on, either one. I checked all the fuses, from the 7.5 to the 30A ones - all fine. A friend came by, and did a direct-to-the-battery connection for the fans with some Romex I had, and they both worked. he also checked the relay, and they were functioning. But fans did not come on. So he disconnected the link to the sensor in the radiator -- and they came on! and stayed on after the sensor was reconnected.

However, the overheating (nears red in 1/2 mile) continues.

Recap: New radiator & t-stat 6 mos ago, new t-stat 2 days ago, fans working, no water in oil (and there was not any coolant loss anyway), does not seem to be coolant loss from water pump...but it's so dirty from underside oil leak that it would be hard to tell. Water pump does not seem to be noisy, but coolant is flowing through the heater hoses, so there's flow. I don't run the A/C since it's clutch went out years ago.
http://www.toyotanation.com/forum/im...s/headbang.gif
What could be causing the overheating?

[SafetyThird]

OK -more updates: Just on the off-hand chance it was the radiator cap that was causing the overheating, I replaced it. The old one was definitely damaged, but the new one made no difference. Still boiling overflow at 1/2-2/3 miles

A friend had checked the flow to the heater, which there was, so the assumption was that the water pump was working, at least partially.

The curious thing, however, was that the lower hose never got hot -- remained "warm" as if the thermostat had never opened, and the cooling water from the radiator is not getting through. of course the fans would not come on! So -- I removed the thermostat and ran it without. As expected, the lower hose warmed up, and with that, the fans came on.
So I tested both thermostats - they both opened, hanging in boiling water on the stove.

I was able to drive 2 miles in our heat with the thermostat out. Initially, the temp (gauge on dash) climbed, and then (I assume) when the fans came on, it dropped back to near operating temps. If the water pump is bad, it's clear that the passive movement has some cooling capacity.

But I'm left with a paradox: How is the thermostat not experiencing 195-degree water, when it's open to both the bypass coolant (back from the heater and some from the engine) AND the water pump fluids? From what I understand, when it opens it blocks one of the bypass pathways, so it has to be experiencing that coolant warm-up. Which boils pretty quickly. Or does the by-pass at the t-stat get minimal flow/mixing so that it's never able to open?

This diagram in post #10 was helpful: 96 Camry overheating

And does this definitely mean the water pump is bad?

While they say to change the timing belt with the water pump (or vice-versa) I have no funds for the t-belt and all that it requires. I understand that the water pump works off the t-belt -- when it's bad, do the bearings just disengage while the t-belt turns it, with no motion of the impellers? And can we get away with just the water pump replacement?

Since a friend -- well, a kind & generous acquaintance -- might be doing the work, I want to cover all bases so that I'll have a working system after his generous labors. WHich, with the work involved, and our 114+ heat this weekend, is not inconsiderable!

again -- no water in oil, no whitish at oil cap. And no fluid loss from radiator prior to this sudden fail.

[hill8570]

Are these Toyota thermostats? Aftermarket's good for some stuff, but most aftermarket thermostats tend to be pretty shoddy. Need to make sure that jiggle valve is placed correctly, too -- if an air bubble gets trapped up against the thermostat you'll get really flakey behavior.

[SafetyThird]

SO I understand. However, both tested good. So the first one was actually fine for 6 months (no bubble). I replaced it, hoping that it was the reason. Burped the lower hose multiple times to remove any air bubble, and ran the system and burped each time the replacement one was put back in.

[tmauldin]

when u have on the heater or a/c does the car still get hot?

[tmauldin]

only thing that comes to mind is
thermostat stuck open
radiator
intake gasket/ small leak not enough for oil to look milky/ does white steam come out of tailpipe,


head gasket/ any leak causing block to get hotter faster

cracked head


heater core, not sure bout that

[SafetyThird]

Turned on both the A/C and the heater in the beginning (as part of the check of the second fan) and neither affects the overheating. And 6 mos ago, when I replaced the radiator & t-stat, either of them being on had little-to-no affect on the overheating.

No white smoke from tailpipe.

no loss of coolant before the sudden overheating, so leaking head gasket is unlikely. (BTW, I never let it get in the red -- I'd pull over and let it cool down. That's why it took 2 hours for 10 miles in 112-degree heat!)

radiator is 6 mos old & worked perfectly with no leaks. and with t-stat out, as I said, there is a certain degree of cooling, so it's flowing.

Big immediate problem is t-stat sticks closed, not that it's open. SO I'm trying to figure out how that phenomenon could possibly relate to a possibly failed water pump.

and, intake gasket??? --- how could that relate?

[hill8570]

OK, clarifying question. Since you're running with the thermostat completely out, is your temp gauge somewhat below 1/2 scale or lower? Or does it still seem to be running hot?

[SafetyThird]

Originally Posted by hill8570

OK, clarifying question. Since you're running with the thermostat completely out, is your temp gauge somewhat below 1/2 scale or lower? Or does it still seem to be running hot?

It initially got 3/4+ up, then dropped back down, I'm assuming, when the temp sensor in the radiator felt the heat and turned on.

After that, it dropped back down to the typical operating temp, which is a hair below midline. But I only drove 2 miles, not wanting to get into trouble. I just needed to get to the closest groc store!

I don't know how long it would stay there, tho. When the t-stat was off, I tried to feel into the water pump are to feel the impellers, or if they move, but I couldn't feel anything. So I don't know if the coolant (now mostly water after multiple on-off's with the hoses) is moving into the engine in the proper direction past freely-moving water pump blades, or backwards, from the bypass hose/ heater hose junction area.

Added note: with t-stat out yesterday, the friend suggested disconnecting the upper hose from the radiator, and see if a burst of coolant came out when I turned on the engine. It just flooded out the end of the hose with the disconnect, but no burble or burst indicating pump action. (and would it give a burst?)

[hill8570]

3/4 scale before the fans kick? Those fans are supposed to kick on at 200F. Sounds like your coolant is circulating w-a-a-a-y slower than it should -- either you've got one heck of a restriction in your coolant path, or your water pump ain't doing it's job.

[SafetyThird]

Originally Posted by hill8570

3/4 scale before the fans kick? Those fans are supposed to kick on at 200F. Sounds like your coolant is circulating w-a-a-a-y slower than it should -- either you've got one heck of a restriction in your coolant path, or your water pump ain't doing it's job.

SInce I was driving down the road with one eye on the t-gauge, I don't know when exactly the fans kicked in. But, without the t-stat in, at least it dropped down, albeit slowly.

It most likely IS the water pump, but that's a hefty replacement effort if it isn't.

As a published scientist, I'm expected to track down all possibilities, and explain why or why not their effects were felt. So, it SEEMS like a water pump issue. However, I would really like to know why a bad water pump would prevent a t-stat from opening when it seems to be also subjected to the hot coolant by-passed from the heater and the coolant exit end on the engine.

My understanding is that the water pump circulates to the engine, and when the t-stat senses THAT warmth, it opens and blocks off one of the by-pass holes (it seems the other one stays open). But when the engine is hot from no pump action, the t-stat should still sense that increase in temp in the by-pass coolant temps, shouldn't it? So it seems the t-stat should open whether or not the water pump is pumping. That's the paradox.

and then my other question if anyone actually knows the direction of flow when a pump stops working. Does it still passively let the blades turn, or are they seized and thus totally blacked, and so without a t-stat in, the coolant is going on a reverse path?

Like I said, I want to completely nail down that it's the water pump.

Not trying to be snarky, just trying to explain why I track down all possibilities to their (to me) logical conclusion.

My experience on cars has been that some people just replace until it works...I'm one who wants to know it WILL work! parts cost money! plus it's some else's time....and I'd hate for that to be wasted.

[02whiteLE]

Sounds like you're having the exact same problem i'm having with my old '94. Will be replacing water pump this weekend, after having replaced every other possibility already. Although, after reading this, the t-stat isn't a toyota one, it's a cheap $13.49 O'reillys one.