why is my car’s cold & hot meter keep going to hot

[Adam]

Here’s the thing; my car is a 2001 Toyota Celica GT automatic. It has 316,000 miles. I do speed on the highway at least 80-90 mph. One thing I noticed just recently was that the cold (C) and hot (H) meter on the dashboard has been on H (hot). It was blinking telling me that the engine was getting hot. The engine wasn’t smoking since I knew I had to pull over. So I added some 50/50 prediluted antifreeze since I didn’t realize it was almost out. Now here’s the thing; I filled up the fluid compartment to the “full” line yet just about a week later, the H (hot) sign started blinking again as if it’s telling me I’m out of antifreeze, which the car is. I do not see a leak anywhere. I filled it up again. Is this due to me running my engine hot (i.e. speeding on the highway when my car already has 316,000 miles?). Also, 3 days ago I just replaced my spark plugs because when I was driving on the highway the car was running as if I only had 3 cylinders. The check engine light started blinking so I thought it was the ignition coils. I unplugged each one and the problem wasn’t ignition coils. So I had the check engine light get checked up at Advanced Auto parts and it was suggested to me that it could be the spark plugs, they were right since I already checked the ignition coils and they weren’t the problem. So spark plugs are new, but why is my engine seem to be using up the antifreeze a lot faster than it should? Is this due to speeding? My car may be on its last leg according to some guy I know, but I also thought my car was about to go when it was only 250,000 miles. The car still runs well at 316,000 miles.

The order of incidence as it happened was that the hot (h) meter on the dashboard started blinking, a few days after that is when the spark plug issue became a problem. I’m assuming the engine getting hot may have ruined the spark plugs a lot faster than it should? It has only been about less than a year since my last spark plug change. So now the spark plugs have been replaced and antifreeze filled up, I still don’t get why the antifreeze would get used up too quick. I also noticed that my AC light sometimes would blink, it could be unrelated to anything but cold air works but no heat (when the antifreeze was empty). Now there is heat after I had added some antifreeze. I don’t get what an antifreeze’s role is in giving my car heating.

Topic

[Mike]

overheating enough to pin the temp gauge to hot commonly causes the cylinder head to warp, at which point you will have symptoms of a failed headgasket such as coolant consumption, repeated overheating, and a consistent or inconsistent misfire. It has nothing to do with speeding. Your engine in normal working order will support 90 mph all day long. A headgasket failure may have been the original cause of the overheat, because it doesn’t overheat until the coolant level is too low to carry enough heat away from the engine. It didn’t just overheat randomly and then the headgasket starts leaking coolant into the cylinders.

To diagnose the issue on your own, you can get a block tester from NAPA or a auto parts store that sells a lot of tools too. The block tester goes is like a test tube that holds a blue liquid and you put it over the radiator cap with the engine running. If combustion gasses are being expelled thru the cooling system, the fluid in the block tester will change color or a clearer yellow-green color. This would mean that the headgasket is almost certainly leaking. No way to know if the head is warped without taking it apart. You could also look at your spark plugs and see if any of them are cleaner than the others due to the steam cleaning action of coolant getting into a cylinder, but the block test is going to need to be done.

If you pay to have it looked at, they will do a block test. A block tester is about $60, which is less than you should be paying to have it diagnosed, so that’s why I’ve suggested a DIY. The procedure is very simple and requires no tools, and demonstration videos of it are around.

BTW, your interior heat comes from hot coolant which is why the heat doesn’t work if there’s no coolant in it. There is a feed and return hose that come into the dashboard from the engine, and there is a small radiator in there called a heater core. The hot coolant flows through it, and the blower in the dash blows air thru it and the air picks up the heat and then comes out the vents as hot air. It’s exactly the same as how air coming in the front of the car is directed thru the radiator, picks up heat from it and then just takes it away and adds the heat into the air surrounding the car. The heater core and the radiator both have hot coolant from the engine flow into them, air takes some of the heat out of it, and the coolant comes out colder to go back into the engine to re-absorb more heat and repeat the cycle of transferring heat away.

Also, you said you filled the coolant reservoir to the full line. I’m almost sure on your car that the coolant reservoir functions as an overflow tank, which is the case if it’s got only one small hose that goes into the radiator under the cap. In that type of system, checking and filling coolant needs to be done thru the hole that the radiator cap seals, as the overflow tank is isolated from the cooling system unless pressure/vacuum occurs that overcomes the springs in the radiator cap. If you remove the cap and look at the hole in the filler neck that goes out to the overflow tank, you’ll see that the hole is above the lower sealing surface of the radiator cap which means that whole thing is outside the cooling system during normal operation.

[Brian Compton]

If you are running out of antifreeze you need to locate and fix the leak…

My suggestion is learn a bit about the cooling of an engine (actually all of the basic sub systems of vehicles…they basically are all the same, well do the same thing)…if you over heat your car bad things happen…as in head warping, cracks, really not good stuff

Think of the radiator fluid as the cars “sweat” but in an enclosed system…if YOU stop sweating but keep running you greatly increase the risk of heat stroke…you as flesh and blood can possibly recover from heat stroke…a car engine made out of aluminum or steel usually won’t.

[Adam]

we looked for leaks and found none. I had been told before my water pump may be bad/is bad. Could the issue be a water pump? Must I replace my head gasket as well? The way I filled my antifreeze is as simple as topping off an oil – pour and fill. But I was just reading under the hood that there seem to be more to filling/replacing coolants. I think it goes something like this; leave engine running while pouring coolant into the reservoir, wait for the coolant fan to turn off then cut the engine out, so this way the fluid gets sucked inside the engine? I’ve almost used up 1 gallon of coolant yet the reservoir keeps becoming empty. Someone said something about air being replaced with coolant etc. I forgot the exact words. But before when I topped off my coolant, it only used about a glass of coolant, not sure why now that almost 1 gallon would be used up.

[Bluesnut]

The system could be pressure tested for coolant leaks. Some of the auto parts houses such as AutoZone rent out (money returned when the tool is brought back) a pressure tester I believe.

Fan operation should be verified; both as to cycling on with high engine temps and with the A/C on.

Consider a weak radiator pressure cap. They age and weaken like anything else and it could be that the cap is surrendering coolant at temps much lower than it does when the cap is new. Caps are cheap; you could just buy one and stick on there to see what happens.

[Brian Compton]

[quote=”Bluesnut” post=144883]The system could be pressure tested for coolant leaks. Some of the auto parts houses such as AutoZone rent out (money returned when the tool is brought back) a pressure tester I believe.

Fan operation should be verified; both as to cycling on with high engine temps and with the A/C on.

Consider a weak radiator pressure cap. They age and weaken like anything else and it could be that the cap is surrendering coolant at temps much lower than it does when the cap is new. Caps are cheap; you could just buy one and stick on there to see what happens.[/quote]
Yep…antifreeze could also be called anti-boil, on pressurized systems each 2 psi you increase over atmospheric pressure you raise the boiling point of the system by 1 degrees, a 50/50 mix already raises the boiling point to approx 140C, so add 6 or more to that with a proper pressurized system the water shouldn’t boil off, cheapest way to check is get a new $5 radiator cap with a pressure bleed lever on it.

To the op with a suspected water pump problem, there is a small hole in the housing of the pump, it has a gasket and seal inside that the impeller shaft goes thru…if that is leaking the radiator fluid will run out that “weep hole” and you will see tale tell signs of leakage as a stain near that hole, if you see that, time to replace the water pump. but before you do that have a pressure test done on the system…if it doesn’t hold pressure that is an issue too

[Adam]

I will try a new radiator cap, but I don’t get why the fluids from the compartment would disappear. Last night we checked and seems as if one of the hose keeps getting spit out of the liquid compartment, suggesting a leak then which Jiffy Lube did not see because it wasn’t there at the time they checked, maybe this is a new problem that the hose keeps getting spit out of the compartment, Turns out the plastic that was supposed to be on the compartment that goes inside the hose broke off the compartment, so the guy I know suggested to get a new antifreeze compartment.

While I don’t get why when I had the coolant at full that the dashboard would tell me the engine is getting hot (H), could this be a thermostat problem not being able to read properly? Which then could lead to a gasket problem then a water pump? I was told that if the coolant turns brown then it is a gasket problem since oil and coolant are mixing. The coolant isn’t brown. I shall first try installing a new coolant compartment to see if that fixes the problem. It may have been just the hose coming off? Not sure how that happened, if it was due to my car running funny when my spark plugs was bad.

[Ben]

have you checked that your thermostat is working, It could be stuck in the closed position which would cause the coolant not to circulate.

[Adam]

I’ll let someone check it since I don’t know how to. I’m not sure exactly if it’s outward or inward but I think it’s hiding somewhere behind the engine or hose.

If it is in the closed position, how did that happen and why did that happen just now and never before? is that the reason why the coolant level keep disappearing from the reservoir or is it also the loose hose?

[Ben]

Well when your car is cold the thermostat remains closed until the temperature gets to a certain degrees, once it gets to that certain degrees it opens up to allow the coolant to circulate around the engine, They usually fail with age or dirty coolant, Sometimes they stay open in which the car will have trouble when the engine is cold because its allowing the coolant through to early.

Well if you think about it, if its stuck in the closed position then the coolant can not circulate therefore the engine would over heat.

The thermostat is usually in front of the water pump.

You can test the thermostat by taking it out and placing it in a bowl of boiling water and see if it opens, usually within around 10 seconds. if it doesn’t open then its faulty. Pretty cheap to replace. about 10$

the thermostat looks like this
differ slightly from car to car

[Adam]

I had called up every Autozone and Advance Auto parts in my area and seems as if the radiator overflow tank is either dealer only or junkyard. If anyone here knows where I can get one online let me know please. I even tried my favorite Rockauto and they don’t have it. Even Pepboys do not have it. Curious if I could use any (made for another car) and would it work for my car (2001 Toyota Celica GT)?

I’m curious if I could use any radiator overflow tanks meant for other toyota cars listed on this link below?

http://www.1aauto.com/toyota-radiator-overflow-tank/ma-c/46-38

Considering the Avalon and Camry uses the same. This one actually looks like one on my car:

http://www.1aauto.com/radiator-overflow-bottle/i/1arob00033

I guess I’d have to see what kind of part # or OE part # that’s on my car? I’m assuming something from a Camry, Corolla, or Avalon could work on mine? I wish there was such a thing as universal? It’s just a compartment for liquid after all.

I don’t know if this product below is even a radiator overflow tank but Advance is selling it as OE/Universal, yet it looks nothing like the one on my car:

http://shop.advanceautoparts.com/p/dorman-oe-solutions-universal-603-001/17191312-P?vehicleIdFromReq=50078&isAllVehicle=false&vehicleIdSearch=50078&searchTerm=603-001&showTitle=

The pic below is called a radiator overflow tank, right?

Attachments:

• oft.jpg

[Adam]

looks like my last resort to buy a coolant reservoir is the junkyard since all toyota dealerships have told me that for the coolant reservoir it cost about $220-$240, ridiculous considering it’s just a plastic thing. They know no one else has it other than junkyard so they jack up the price.

Anyway, while the leak had been taken care of temporarily, I kept putting coolant into the reservoir and it keeps disappearing overnight, but I wonder why the engine isn’t overheating? Could it be that the coolant is actually going into the return tank and my car really has coolant in it despite the coolant reservoir being empty? I notice that when I put coolant into the reservoir it slowly gets lower yet I see no leak, where could this liquid be going to? I could also use water right since it’s summer time so that way I don’t waste buying a $10 antifreeze bottle?

I bought a new coolant reservoir cap just to see what happens. I bought a thermostat as well and hopefully this is easy to install.

[EricTheCarGuy]

I’d go salvage for the coolant reservoir. In fact, you may find one on eBay.

That said, I’d table the thermostat theory. It’s not likely that’s the cause of the overheat. There are several things to check for with an overheat condition. I cover them here in this article. BTW there’s also a video on how thermostats work and how to test them in there as well.

http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats

I recommend you read it over and watch the videos on how to diagnose that problem.

Good luck and let us know what you find.

[Adam]

Found one on Ebay for about $100 used. The links I posted above may have what I’m looking for. I think what I can do is ask the dealership what the item or product # is of what’s used in my car so I can see if the item or product # matches with the products sold on the websites I posted above. Some of them do look like the one in my car, plus those are new and cheaper than the Ebay one I found.

[quote=”EricTheCarGuy” post=145026]I’d go salvage for the coolant reservoir. In fact, you may find one on eBay.

That said, I’d table the thermostat theory. It’s not likely that’s the cause of the overheat. There are several things to check for with an overheat condition. I cover them here in this article. BTW there’s also a video on how thermostats work and how to test them in there as well.

http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats

I recommend you read it over and watch the videos on how to diagnose that problem.

Good luck and let us know what you find.[/quote]

[Adam]

So I got my water pump and thermostat replaced. The car is running fine so far. I’m still using water as my coolant until I get the coolant reservoir replaced. The hose that kept coming off was tightened up using a zip ties. It works for now.

Once I find the coolant reservoir, how do I do a radiator flush? Part of the instructions is under the hood but I’d probably need to look into the manual. From what I understand some of the coolant (or in my case at the moment, water) is in the radiator. How do I remove all that out of there so I’d be using pure antifreeze/coolant? I may just go to Jiffy Lube for a radiator flush but I guess it’s also a good idea to learn this my self.

Another thing; I noticed that my engine oil usually becomes almost “empty” after about 500 miles of driving. I was told there may be a leak, but I haven’t really found it. So considering that per oil change the oil in the engine should last about 3000 miles to 5000 miles at least yet every 500 miles I need to top it off because it’s almost empty. Is it possible that since I believe that my water pump had been bad for as long as my engine oil keeps disappearing, that this was caused NOT by a leak but by a bad water pump? Which I think is making the engine hot enough that the engine oil evaporates and or gets used up quicker than it should, although the engine never really overheated.

the water pump I bought is for car’s with gasket, does that mean that the water pump I bought has a gasket attached to it? Or must I buy a gasket separately? From what I have been told that if my coolant turns brown then gasket is bad since oil and coolant are mixing.

[Author]

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