I replaced my thermostat about 10 months ago as the car was having a very difficult time heating up and in cold weather no heat from the heater. The heat situation improved dramatically and immediately and my engine has been warming up quickly ever since till it got really hot one day and I found I had to add and add water as it was very close to dry but the water could not be added all at once but only in little bits as the radiator would get full and then I could add some more later. It seems to be loosing water but I do not know where. It is not in the oil or Tx fluid or apparent anywhere but it has been going some where and not the overflow reservoir either as it is completely dry. I have been adding water as needed. Now I am back to the situation where the engine will not heat up and I just replaced the thermostat again but the temp is not coming up any better with the new thermostat. What else could be the problem?
You may have an air blockage preventing you from filling it up all the way. Park on an incline with engine at higher end. Remove radiator cap (engine cold) and let engine warm to operating temp. Keep an eye on it and when the air burps out top it off with antifreeze. Make sure the cooling fans come on and go off as they should . Check all the hoses( there are alot on back side of engine) radiator, water pump for leaks. Could also be a leaky head gasket or even heater core . Has the radiator cap ever been replaced?
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No, the radiator cap has not been replaced. I took a 4000 mile trip with no cooling problems at all in early summer and added no fluid. Then the car sat for 1.5 months and over a short distance it overheated one day, as mentioned with the fluid way down. Now it has been consuming water but overheated one more time before I started checking it often. I think it has almost no antifreeze since everything boiled out. Can that be part of the problem? I have checked for water everywhere and it is bone dry on the outside. I am not as concerned with the water consumption as the fact that it is not heating up correctly and I was betting it was the thermostat...
Burp the air, fill with antifreeeze, replace the cap and check the level frequently thereafter for any more loss. Keep a close eye on temp gauge (should read in middle when warmed up). If the level drops again you have probable head gasket failure issues which if not fixed will ruin that engine.That antifreeze is leaking into combustion chambers getting burned and diluting oil on cylinder walls which isn't good for pistons and cylinder walls.
The engine is a 4A-FE if I did not mention it. To see how things might be inside the engine, I took a look at the plugs and they were perfect and all similar. I checked the compression and it is running OK for this altitude 4500, feet, and has not gone down since many months ago. I think it has very little antifreeze. I guess that will be my next step.
Give it a flush out then bleed the system as previously explained... I had same sorta thing, so I jacked the front up a little and there ya go, big bubble came out.
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Thanks for all of the info.
I topped it off with distilled water, filled the reservoir with antifreeze, and just covered about 160 miles and the level seems to be stable for the time being. It did use some antifreeze. Maybe the water tends to evaporate without the proper amount of antifreeze? I have been putting off loading it with the proper amount of antifreeze till I get this warm up issue taken care of and I have to drain it again.
The real dilemma at this time seems to be that it will not warm like it should and that would seem to be the thermostat which keeps allowing coolant to circulate before it gets hot. I just put in a new thermostat however. The weather is getting cooler and it needs to warm up much more quickly.
Did you burp the air and replace cap? Also even though has been replaced your new stat could be a dud. The toyota brand stat has a valve that should be in a certain position when installed to allow air to bleed. If you bought an aftermarket brand it may not have it. I have a hunch your old cap isn't sealing tightly and the system isn't building up pressure and no heat. The heater core could also be full of junk. Remove hoses going into it and flush it out . Is your temp gauge reading normal?
Last edited by 90 GP; 10-15-2010 at 10:58 AM.
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I do need more theory understanding on this stuff. Is there anyway to test the thermostat? I think the temp gauge is OK. I think I know the little valve you are referring to in the original thermostat. Is it the little bleed hole with the pin in it? I presume the hole goes at the top? The new one does not have it. I think the cooling system is pretty clean inside. The heater works great when there is enough hot water. The heater and temp gauge correspond.
Once it gets to normal operating temp it stays right where it should in the middle.
I have not gotten to burping it yet.
No I just added distiled water for the moment but I am getting around to the antifreeze. I do not know what sensor you are talking about. The one on the thermostat?
Go to toy and buy a new stat and rad cap. Get a prestone flush kit and an additional length of heater hose and temporarily install the kit on the inlet heater hose (the one with cable operated valve). Remove rad cap , hook up kit using garden hose for water supply turn heater on full. Run till engine gets warm and water runs clear. Disconnect kit ,drain radiator of all water and tighten radiator drain. Remove and install new stat. Fill with antifreeze till full. Run car till warm to expell air (park on incline) and top off radiator and overfow. Unless you have a major blockage in radiator or other component that is impeding the coolant flow or internal issues that should fix the problem.
Last edited by 90 GP; 10-16-2010 at 04:28 AM.
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