I have a 2.4 2004 Camry. It was over heating. I replaced thermostat, water pump and radiator. Still has temp issues. It's not over heating but running hotter than usual. At lower rpms it will run hot. Rpms higher than 2000 it will start to cool.

I just tried to bleed the coolant system and no bubbles. Infact the coolant slowly overflowed the radiator fill point till the thermostat opened. It lowered slightly. I noticed no coolant movement as far as circulation from radiator to overflow or vice versa. Recently had a hydrocarbon test which showed no signs of head/gasket failure.

Back story on this vehicle. My mom was the previous owner and used 2 or 3 cans of stop leak over the course of two years. The car up untill 6 months ago had sat for about 2 or 3 years.

Should I bypass/replace the heater core? I have no idea what is causing the temperature issues. Any insight would be appreciated.

 

My guess is that you have air trapped in the system. Unless you used one of those funnels that extend about 15" above the top of the radiator when you filled it, you did not get all the air out of the system. I had to buy one of those, which work really great, when I replaced the thermostat on my 2.2 and I am assuming that your engine is not that different in this respect. An easy way to tell is to see if any part of the cooling system where water (or now air) might be is higher than the top of your radiator which I am guessing it is. Other people on here might know if there are bleeders located near the top of your engine somewhere to open and bleed out the air until coolant comes out but the funnel system is easy to use, fast and works very well. This video shows what I am talking about:

Just make sure the one you buy has the adapter that will fit your toyota. Also, shop around as I think I paid about $25 for mine and I see them online for almost $50 in some places.

Bill
PS When you say it is still "running hotter than normal", does this mean the temp gauge is shower a higher than normal reading? If so, that can be another indication of air trapped in the system because if the temp. sensor is near the top of the cooling system on your engine, that is where the air would be and it will make the temp gauge read incorrectly. That happened on my 1995 Mercury Villager (Really a Nissan Quest) and my gauge showed cold even though I had been driving for an hour then it sometime shot up to full hot then back down, etc. Are you losing coolant anywhere through obvious leaks? Is the level getting lower in the overflow container or radiator? If not, I am still going with the trapped air theory.

 

slightly higher. Again dropping under higher rpm. I did notice the top hose was hot to touch and lower was cool. I did delete the heater core and bleed the system. I'm suspecting possible faulted thermostat. I noticed when I changed the radiator there was like a silicone chunk (rvt red in color) melted to the thermostat.

Any ideas past air lock?

 

How did you "bleed" the system? Hot water in the hose is no indication of a system not having air in it. The reason it probably cools down on the gauge when the rpms increase is because the water pump is pushing the water through faster and more water instead of air is contacting the sensor. Yes you may have bought a faulty thermostat but the odds are against that. Do you have a service manual for this engine? If you do or have access to one online it will describe the proper bleeding procedure. The only two ways I know to remove the air from a modern car engine's cooling system is to open the bleeder valve (s) which would be located at the highest point in the cooling system, or use a funnel bucket raised higher than the top of the cooling system. My Toyota 2.2 does not have any bleeder valves so that is why I bought that special funnel. You can easily test your water temperature using a cooking thermometer which is about $4.00 in a grocery store. You can dip it into the coolant at the radiator once at temperature. I would bring it up to temp. with the cap off so you do not get sprayed when you take it off when it pressurizes. These are made to measure liquid temps so it will be easy to use for this. (I would not use for food afterward as antifreeze is poisonous) If you installed a 180 degree F thermostat, then the thermometer should read pretty close to that when totally warmed up. If it does and your gauge still reads high then it is air in the system messing with the sending unit/sensor for sure. If it reads much higher than that then it might be possible that your thermostat is not opening as much as it should when at temperature. With everything you replaced you introduced a ton of air into the system and it will take some effort to get it all out. Not hard to do at all just takes some time using one of the 2 methods I mentioned. One other possibility is that the temp. sensor is bad or partially bad. I forget how many ohms it is supposed to have but you can research that and test it pretty easily if everything else checks out ok. Chances are it is fine if the car was overheating before you did all of this work and the gauge showed that it was overheating.

Bill

 

I bled it using the funnel method. It gurgled and bubbled. A lot.
I didn't think about the coolant temp being measured like that.
I really do appreciate the advice.

 

No problem. Well, as long as the funnel was sealed to the radiator with a cap designed to hold pressure for bleeding and it was elevated above the highest part of the system it should have removed all the air. Did you install the new thermostat with the little valve facing up? (12:00 position when looking at it) This helps in getting the air out of the system. I think most of the time, if the temperature sensor is bad it will show a check engine light and log a OBDII code PO117. Is your coolant still filled up to the top of the radiator neck? One of the very knowledgeable moderators here, Toyomoho, mentioned on a similar topic that the 2.4 is known for the head bolts to pull out from the block which will cause a head gasket leak. Hopefully, this is not the case. You can have it pressure tested and also they can check for exhaust gases in the coolant too. IF the coolant level stays right up to the top after driving around for a few days I don't think the head gasket would be leaking. Maybe some others here will chime in with suggestions?

Bill

 

I did a hydrocarbon test so no exhaust gases detected. I have no oil discoloration and no oil in the coolant. No white smoke. I'm pretty sure the head and head gasket are good. I'm going to test the temp sensor and possibly remove the thermostat and see if it effects temp raising past 50c. If no indication I will install a new thermostat and chalk it up to bad luck. Though I do feel that when I flushed the system I may have missed some debris and clogged the thermostat.