I have a 2005 Toyota solora, I went up the mountains a couple days ago and my car ended up over heating. It kept over heating til I replaced the reserve tank. My car was working perfectly again til today. It started to over heat but not dramatically. I got home, parked my car and the temp of my a lot. What could it be

  • Welcome to Motor Vehicle Maintenance & Repair! Apr 17 '19 at 22:50
  • What do you mean you "replaced the reserve tank"? Do you mean you filled it up or actually installed a new unit? Apr 17 '19 at 23:15

Car will not overheat because of res tank. I'd suggest the following diagnostic steps, in this order: 1. Check to make sure the fan is operating, radiator is not plugged (outside) and is not blocked by anything. 2. Replace the thermostat. 3. Check the radiator for having free flow.

  • Why would you replace anything prior to seeing if the radiator has free flow or not? Apr 17 '19 at 22:50
  • @Pᴀᴜʟsᴛᴇʀ2, thermostat is cheaper and normally easier to replace than paying a shop to diagnose radiator flow. In addition to a lot more likely to be the cause of the problem.
    – EᑎOT
    Apr 17 '19 at 22:58
  • Not if you check it yourself. People come here to get self help. The last thing we do is to encourage someone to take it to a shop. Let them decide if they are going to take it to a shop or not. Besides, in your scenario, wouldn't they also be taking the car to the shop to get the thermostat changed? As far as your answer, always do the no cost option first. Also, diagnose whether you need to change a part, just don't change it. That's called "Remove and Replace" (or R&R) mechanics which gets expensive very fast and solves nothing. Apr 17 '19 at 23:06
  • @Pᴀᴜʟsᴛᴇʀ2, people come here to get advice. I am sure you had to occasionally give people advice which required them to turn to third parties to be properly done. Nothing wrong with that as long as everyone's informed. Testing radiator flow and pressure may be difficult without specialized equipment which most people won't have. A thermostat on the other hand is 10 - 15 bucks and on many vehicles takes 5 to 15 minutes to replace yourself.
    – EᑎOT
    Apr 22 '19 at 16:17
  • 1
    Cars can absolutely overheat because of the tank. In vehicles which pressurize the overflow tank (really a surge tank in that case), a bad seal can let the coolant boil.
    – 3Dave
    Jan 13 '20 at 22:29

Overheating is typically caused by one (or more) of 3 things; insufficient coolant flow (including from too little coolant), inefficient coolant system (blocked radiator fins, bad fan, etc), or a mechanical failure/leak like a bad gasket.

A few thing to check if you haven't :

  1. Are your upper and lower hoses in good condition? How to check radiator hoses If they are too old and weak, the suction can cause them to collapse and block flow. They are also a good place to check for leaks.

  2. Do you have sufficient coolant of the correct type? How to check coolant levels This could be caused by a few things, such as a bad house or loose connection, a cracked hose port, cracked housing, or even just an open drain plug or petcock.

  3. Is coolant being circulated?

A DIY way of testing is with the car on and at temperature squeeze the top radiator hose somewhere in the middle. If you can squeeze and let it go and feel the coolant rushing through the hose then you're fine. If you can't squeeze it or it feels too firm then you likely have a stuck thermostat.

NOTE: If your car is not warmed up at all, then the top radiator hose should be firm. So that is an important distinction to make.

  1. Do you have a head gasket leak? The most visible indicators of a possible head gasket leak are milky engine oil, or white smoke from the exhaust and consistently losing coolant without a major visible leak. There is more info here : What are the symptoms of a Blown Head Gasket?

If everything seems to check out on the basic things you can check easily, then I'd consider getting into doing some actual work.

There are many more potential causes for overheating, but they pretty much all boil down to the 3 I mentioned at the beginning.

Past this, you're looking at possibly buying parts, so if do, I'd do that on a cost gradient myself. Easiest/cheapest things first, I'd probably do radiator flush, clean exterior of radiator, replace radiator cap, replace hoses and clamps, replace thermostat, replace coolant pump - giving a few hours of use between each action to make sure the problem has been handled, or is persisting - and only continuing off the problem persists.

After at of those steps, you've really only got a few more steps, which would be replacing the radiator and replacing all the gaskets, most likely you'd go to a shop for those, because they are pretty hefty jobs (although the radiator replacement could be DIY if you wanted to).

If I get any specific ideas for your car I'll update my answer.

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