Toyota Avalon Radiator/Cooling System Questions

mbt1mbt1 Member Posts: 33
I noticed on my 2000 Avalon XL that the coolant level in the overflow reservoir drops a couple inches every year. I understand that temperature affects the level reading; however, I usually check first thing in the morning and compare the readings in similar ambient conditions (i.e., similar weather conditions, etc.). I've had the system flushed once already and pressure checked by the dealer, and no leak was found. Is a slight coolant drop a normal part of all cars or should the amount of coolant in the system remain constant between flushes when there is no leakage? Personally, I don't understand how a closed system like the coolant system can lose fluids when there is no obvious leakage. I would appreciate an explanation.


  • bjk2001bjk2001 Member Posts: 358
    Have you checked the radiator cap?
  • hawiianavownerhawiianavowner Member Posts: 76
    As well as the torque on the drain valves. The service tech who refilled your system may have failed to tighten these to spec.
  • armtdmarmtdm Member Posts: 2,057
    Common. I have two where it will drop as you noted in a year. Also, may not be entirely closed as many overflow tanks have a air outlet or overflow outlet where air can come in

    2 inches a month or week a major issue. 2 inches a year, really no problem
  • carjunky1carjunky1 Member Posts: 3
    mbt1 Sep 29, 2002 7:17pm
    Yes, your system is "closed", but it's not "sealed". In other words, if the pressure from expanding fluids gets high enough, the radiator cap releases coolant into the overflow reservoir. When the engine cools, the fluid is supposed to siphon back into the radiator, but that needs a lot of luck. Here is some background information. Coolant is better than water because it stays liquid below water's freezing point and above it's boiling point. But it does have a nasty tendency to expand more than water when it gets hot. That is why you need a mixture of water and coolant. If you use straight coolant it would expand too much and overflow even the reservoir under normal engine temperatures. The water actually helps the coolant work better in your car. Second, coolant can vaporize in the presence of oxygen, so if it is in the reservoir, and its hot, it will evaporate. It will also weep out of the hose that leads back to the radiator from the reservoir. That is why the siphon thing doesn't always happen, air gets in the line. So, MBT1 What your experiencing is relatively normal. It is possible that your coolant mix is a little rich and you have more expansion going on, and therefore more evaporation. I hope you are using water to top off your radiator, because if you are using coolant, you are making matters worse. You can buy a device that will indicate the range of temperature your coolant mix will be effective in, some mechanics have them (Hygrometer), but I'm not sure this is a problem worth investing money in. "Just add water". Fun Fact, Fog machines use coolant to make the fog. It actually works the same way an iron makes steam to press your clothes. Coolant drips from a reservoir onto a hot plate and a fan pushes the white smoke down a hose. Just like in your car, the coolant combines with oxygen and dissipates.
  • betrayedbetrayed Member Posts: 3
    18 months ago,we purchased a 2000 Avalon,one owner 65,000 miles.We have been loyal to the Toyota brand since 1973,so we REALLY know the brand and what to expect.We have often bought brand new and loaded,kept the cars 10 years or more by passing them on to our sons with complete confidence.Our son in Michigan has our 1992 Medalist forerunner which still looks great and runs well.SO, when we bought the Avalon XLS, we expected no less than what we always experienced.WHAT A LET DOWN.The car now has 78000 miles and had its 75,000 mile inspection at Toyota
    One evening,we came out to the car and found a steady flow of coolant running out fom under the car.,
    The problem was that the thermostat stuck in the closed position,caused the engine to overheat ,causing the frost plugs to pop out ,and causing a leak in the heater core.There was green coolant fluid on the ground outside the car,and what we couldn't see,the same fluid INSIDE the car absolutely sopping the rugs
    In order to replace the heater core and replace the frost plugs,the car had to literally taken apart,like a body having all the organs removed and then put back .We are still putting full rolls of paper towel on the floor in the back of the car to sop up more coolant which is still not all gone after repairs and cleaning.It seems to be drying out now,and the smell is almost gone
    Total cost? Over $2000.
    I have tried to find out why this happened.The Toyota dealers that I spoke to anonymously,and the newspape car journalists that I E mailed all said they had never heard of such a thing in a Toyota carof this age .Dealers said they don't even keep the parts in stock because this never happens
    I called the Toyota hotline and it was suggested that this car was "too sophisticated" for me.I had asked why it was so difficult to replace $17 frost plugs [whole dashboard taken apart and airbags removed and later put back]I said I suspected that was a bad design flaw and wondered if Toyota has changed design in recent years.

    One repair man said that the newer Avalons don't have the pan that would guide any leaking coolant OUTSIDE and prevent it going INSIDE. He said the other Toyotas do have this. Is this true?If it is,wouldn't that be a design flaw ?
    Our biggest problem is that we have lost faith in the brand after a love affair 30 years and feel betrayed.Will this car be ok now it is fixed? Did we get a lemon? Has Toyota made changes in design?

    Has anyone else out there had this problem?
  • finfin atlantaMember Posts: 594
    Here's one opinion:

    Your years of Toyota success are the norm. The unlikely failure of a thermostat is the exception. It happens. Unfortunate and expensive, but it happens.

    My '99 XL was perfect. Like new when traded at 92k miles. But, the '03 XL I purchased got a new battery at 18 months (original totally dead in a parking lot, the case had split?). Then, going over a bump, the rear view mirror bracket broke and the mirror falls off. Cost almost $200. to fix, and again, no warranty.

    Each car is different. This rare thermostat event is not a design flaw. Probably will happen only once in a model year, if that often. The Avalon, any model year, is a great car from a great company. I still enjoy mine, even with the battery and mirror expenses.

    Keep the faith. My .02 worth... :-)
  • abfischabfisch Member Posts: 591

    Thanks for sharing your story above. I have an 02 without that problem and have 63K on it. I wish their was some advice that could have come out of this. Toyota response seems underwhelming, and I like their vehicles but have not love lost for loyalty to that corporation.

    I can say to you that the 2000 model year, was the FIRST year of the past Avalon model, and buying one especially a used one presents a higher incidence of problems, when looking at CR statistics.

  • jim3jim3 Member Posts: 19
    My 2000 Avalon with 140 thousand miles will overheat on a hot day, at least the gauge shows so. On a long hill the needle will rise almost to the red. A couple times it was in the bottom of the red. I had it into the dealer last summer he drained and replaced the anti-freeze and could find nothing wrong. All year long it read normal. Now with hot weather back it's at it again. Dealer replaced thermostat, no improvement. I raised the hood the other day, turned off the engine, but could not hear it boiling. Any ideas?
  • wwestwwest Member Posts: 10,706
    If your Avalon uses an electric fan to move air through the A/C condensor/radiator assembly then the fan motor itself might be suspect or even the thermostatic switch that turns the fan on as the coolant temperature level begins to rise.

    You can also reduce the heat load on the radiator by running the A/C in the most, more efficient mode. Turn the cooling down to maximum and then manually adjust the blower speed to maintain the cabin comfort level.
  • finfin atlantaMember Posts: 594
    This is a problem that needs to be fixed. You can toast the engine and stress other parts unnecessarily.

    The fan, or a part of the fan such as the switch, may be bad (see *wwest* comments above). Easy check: Is the fan running when you overheat and shut down the engine? If you warm up the car in the driveway, does the fan come on? It should.

    Did you change coolant regularly? It is possible that the radiator, water pump, internal engine coolant passages or a radiator hose are partially blocked or a hose is collapsing slightly under heavy demand.

    Last, how old is the water pump? And the hoses? Is the radiator clear of trash from the road? How about the AC condenser fins, are they clear? That air goes thru the radiator also... Check it out, post your results. Good luck.... :)
  • domenickdomenick Member Posts: 1

    When I worked as a mechanic, we would go through changing the thermostat, flushing the radiator and when that did not work sometime the problem is caused by road film build up on the core where the air passes through. Try flushing the radiator from both sides with a hose and maybe some detergent soap or degreaser. If air will not flow you do not get a cooling effect. Make sure the engine is turned off so that the fan is not turning.

    Also try shinning a bright light behind the radiator to see if it is plugged with road grime or oil grit.

  • dresbachdresbach Member Posts: 1
    In preparation for a road trip I got an oil change and coolant flush at Jiffy Lube and replaced the spark plugs myself in my '99 Avalon XLS. Before getting off on the trip a 60 mile highway drive followed by a couple miles of stop-and-go city traffic caused the temperature needle to peg out and the overflow reservoir boiled vigorously. My local mechanic said Jiffy Lube didn't "burp" the cooling system properly so they took care of it and sent me on my way. 500 miles into my road trip I experienced the same overheating. Since I could keep it under control at highway speeds, I limped home to the Toyota dealer who said they couldn't find anything wrong, burped and refilled the coolant, took my money and sent me on my way. A few days later... overheating again. Returning to the dealer they said they detected CO2 in the coolant which indicated a head gasket leak which would cause the coolant to be forced into the reservoir and overflow until there's not enough circulating to properly cool the engine. I sought a 2nd opinion and when they concurred I let them do the work. In the end it was $2900. I expect some of the "extra" work they did was just good protocol, but MY QUESTION: how much of this was necessary or practical... cam shaft belt, timing belt, water pump thermostat, valve cover gasket, head gasket set & bolt set, upper & lower radiator hose, new spark plugs, new radiator cap? Points of contention:
    1. The car only has 65,000 miles and timing belt service isn't recommended until 90,000. I may have sold before 90k and wanted to avoid the investment.
    2. I'd just replaced the spark plugs a month before. Are they inherently damaged when doing the required work and need to be replaced? If not, did they just assume I needed new ones based on the ~60k mileage regardless of their new appearance? And charging $127?
    3. I had already let the Toyota dealer replace the radiator cap when it was in their shop. Is it reasonable to suspect the cap needs to be replaced regardless of appearance when working the cooling system (without asking the owner)
    4. Hoses... did I really need $60 worth of hoses if a visual inspection showed no cracking or faults - especially if they could be replaced later without regard to the invasive procedures currently at hand?
    5. Two occurrences of labor itemized as "machine shop labor" for $225 and "R&R cylinder heads" for $1079. Is this in the right ballpark?

    Incidentally, the first day after I paid the bill it overheated. They kept it for another day to burp and refill the coolant. Then a week later I had to take it back because the coolant reservoir was bone dry (hadn't overheated) and the car would only start with a jump. They kept it for a couple of days to replace the water pump - saying it was leaking (nothing on my garage floor or driveway though) and tried to charge me $100 for a new battery. I replaced the battery myself, but wonder if the charging system wasn't reassembled properly causing the battery to drain and short (if that's possible). I'll find out soon enough if this battery bites it also.

    Sorry for the long post, but thanks for any information based on your experiences.
  • stonecold0715stonecold0715 Member Posts: 1
    I have a 2002 avalon. Car is overheating. someone told me burnt head gasket. I have no water in the oil and no water is leaking out the exhaust. where is the thermastat located? Please help
  • 1fishaholic1fishaholic Member Posts: 3
    Is your radiator cooling fan functioning? You can go to the following link and download the Toyota Avalon Service Manual for your car and go to the section on cooling to begin trouble shooting where your problem is...I found this site immensely helpful...some very knowledgeable and helpful people there...
  • holmandouglasholmandouglas Member Posts: 1
    My avalon just keeps losing water. It rarely get's hot, although when I first got it it used to. although it was few and far between. I had a stroke a few years ago and I'm alright now except rh arm and leg don't cooperate. I just drive the car locally except on the rare occasion, last time it mysteriously was running real rough. The thermostat was showing that it was fine, so I didn't think much about it. The dealer where I bought the car kindly said that they would fix the problem. They did, so I thought! I think that all they did was put some water in the car, supposively it was the cold air return AND they fixed it. I've now come to the conclusion that the car has a coolant leak. The reason I know this is because I put some antifreeze in it the other day and the check engine light went off and then I began to smell antifreeze for a couple of days, then mysteriosly the check engine light came back on. And when I checked the fluid resevoir was empty again. The car obviously has a small leak somewhere, the ground was wet in a couple of areas and the check engine light stays lit up after a couple after putting fluid in the car. HELP. I know that eventually that it will get worse, is it the thermostat, or the radiator, heater core?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    If it were the heater core and you were losing THAT much coolant, the interior of the car would have a horrendous stink to it.

    The only sure way to get at this is have the shop pressurize the cooling system with a hand pump(or buy the tool yourself). The best way would be to pressurize it and then lift the car and see what's dripping.

    If you see no external leaks (but you say you do), then you'd have to suspect a head gasket. Hopefully not. But the rough running is a troublesome sign. Hopefully not related to coolant loss.
  • wwestwwest Member Posts: 10,706
    "... causing the frost plugs to pop out..."

    IMMHO that just does NOT happen absent an actual coolant freezing event..!

    Have you checked with the previous owner on that being a possibility sometime during their ownership..??

    ".. causing a leak in the heater core.."

    If the engine coolant got HOT enough to do all this damage then the engine life will be foreshortened significantly. I'm betting the previous owner allowed the coolant freeze level to get too low and the coolant froze. Makeshift repairs to the freeze plugs and a can or two of Barrs stop leak and the car was good to go for another...what, 13,000 miles..??

    Even if, like you say, the thermostat stuck closed the radiator cap pressure relief arrangement would not allow enough coolant pressure to build up in the system to force the freeze plugs out, the water heater core...yes, maybe.
  • wwestwwest Member Posts: 10,706

    A few weeks ago my daughter allowed Jiffy Lube, ("with this many miles it needs to be") to drain and flush her car's coolant. Within days the water pump developed a serious leak and had to be replaced.

    No coolant system should subjected to more than 12-15 PSI of pressure.

    Nuff said.
  • wwestwwest Member Posts: 10,706
    Maybe I'm getting too old and my sense of smell is failing but it seems to me that these newer coolants do not smell nearly as strong as those of yesteryear.

    Ethylene Glycol no longer being used..?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    You may be right but even so, if you had a substantial heater core leak your windshield would be full of condensation as soon as you hit the defroster. In that case the coolant would be pretty much in your face.
  • finfin atlantaMember Posts: 594
    There is another antifreeze, propylene glycol, that is not as dangerous to people and pets. It works to 50 below also if mixed properly. No ideas on whether it is used in all cars, or Avalons, or if it smells better or not at all.
  • wwestwwest Member Posts: 10,706
    "..windshield would be full of condensation.."

    That only requires past use, yesterday, of the A/C for dehumidifcation, no heater leak necessary.
  • rmiska1rmiska1 Member Posts: 3
    I had a Toyota Avalon 97 XLS. It overheated at 205
    K miles. The radiator cracked. I had it replaced at a local mechanic shop. It was 100+ miles away from home. After the new radiator and coolant it still over heated in about 8 highway miles. He told me it might be a headgasket. I thought possible but wasn't sure. It needed a new Timing belt on my PM schedule so I drove it to our cabin (20 miles and 3 stops to cool)and changed the timing belt. I found the water pump was broken. The shaft let the timing belt turn but not the impeller. I changed the waterpump (I had it apart for the timing belt at this point.) The pump was $50. When I put it back together it worked great. My son drove it to 275K with no other trouble. It got totalled in a rear end accident but it was still running good and giving 25mpg and no oil added between changes. It was a great car.
  • azadminazadmin Member Posts: 4
    My son's 98 XLS with 145,000+ miles has a new home---Portland, Oregon--quite a change from Phoenix, Arizona. AC works great! Heater does not appear to work at all.

    Turning the heat/temperature dial from low to high and back causes the fan and control panel lights to change and there's the sound of a door flap opening and closing BUT the car and air coming in to it does not warm up.

    It was serviced and checked out before he left but no one thought to check out the heater---it was 104 or so when he left. During the 1,500+ mile trip, the temperature gauge was right in the middle and no coolant was added. We have generally followed the recommended maintenance schedule since purchasing the car used with about 28,000 miles on it several years ago.

    Any thoughts, ideas, experiences, suggestions, remedies or fixes anyone can suggest from personal experience--even what NOT to do--will be appreciated.

    Limited income, new job, start up housing expenses are all in his immediate future so knowing what he can do to get this fixed and not get too badly screwed in the process is important. A new (or newer) car right now is not an option but spending the coming winter freezing in his car because the fix is too expensive does open the door to the need to consider options.

    Thanks to all who can provide information!

  • popsavalonpopsavalon Member Posts: 231
    I would bet that the valve that shifts hot engine water to the heater core is simply cruded up and stuck in the off position. I haven't had enough experience with Toyotas to know exactly where this valve is in the "water in" heater hose, but a check of web sites about "flushing the heater core on an Avalon" might reveal the location. The recommendation for most cars a few years ago was to move all controls to heat a couple of times during the summer (all the time in Arizona?) to keep the valve and heater core flushed out.

    Any competent radiator shop that can perform flushing of heater cores should be able to fix the problem. I would not let a Toyota service dept. do this because of what they would charge!
  • azadminazadmin Member Posts: 4
    Pops--thanks for the input. I'll have him do that in the next couple of days. And yes, we do stay away from Toyota service since I checked my lottery tickets this morning and...
  • djohnson1djohnson1 Member Posts: 54
    I know a lot of mechanics who work at a dealer (not Toyo), and they all say some evaporation is normal. The water gets hot and it's going to evaporate some over time ... usually quicker than a year. It's not totally sealed, only when hot. It should be checked monthly, along with all fluids ... engine oil, trannie, brake fluid, PS fluid.
    Whatever you do, if you add fluid, use only what it's filled with, and it should only be filled with Toyo antifreeze. That way you won't be paying for new coolant system parts. Don't believe the lie that they are all compatable. The chemistry of a cooling system is very complicated and Toyo has spend millions to minimize corrosion.
  • concern1concern1 Member Posts: 1
    you are absolutly right,it did happen to my wife car.chevy cavelier,we just flushed the radiator at Jefiy lube in Palmdale ca ,after that,the water pump start leaking,whats the secret here,to replace this water pump will cost about $ 600. yes,need t romove half of the engine and replace also timing belt and others,we gave up on it,it must be a chemical in the liquid they use ,i was told there was no chemical in the liquid. and i will never go back to Jefiy any more
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