Hi...

New to the forum but have been lurking for some time. My complete frustration over this issue led to posting. I have a 2007 V8 Limited with 175,000 mile. Had timing belt and water pump changed by Toyota at 125,000 (18 months ago). The car overheated about two weeks ago and a friend changed out the radiator. Yesterday the car overheated and lost all coolant. I changed the thermostat out. Today, same thing.

The weather has been cold and the heater was only blowing hot when the car was at 2000+ RPM's before overheating. I re-filled the coolant and noticed only a small leak after the car cooled, which could have been residual coolant that was dripping. It seems that when overheated, the coolant is escaping from the reservoir.

Any thoughts...cracked head?

Thanks

Take out the thermostat and put it back together. See what happens.

Link 12

Thanks for the reply. Put a new thermostat on and problem continued. Had mechanic take entire engine apart and saw that the intake manifold had been melted due to overheating. Mechanic says that the replace all gaskets and other items will only lead to more problems given the heat the motor has been exposed to and suggested a new engine. I am weighing this option now.

Ed

I am betting you have a major blockage in tubes in the core.
You need a real radiator shop, to do a real cleaning and testing of your radiator. Many small repair shops try to just flush out a radiator,many time this just makes thing worse or you just pay for nothing.

Sadly it might be time to just junk it out,and find a new truck.

No heat produced when truck is "warm" is indicative of a low coolant situation. Overheating an engine can have catastrophic results, and this may or may not have long term effects. I've never heard of melting an intake manifold, but I'm not a mechanic. I assume it's made out of aluminum, (as is the head I assume on our v8s) so questioning the validity of those claims myself. Id be tempted to pull the thermostat altogether to take that out of the equation. I'm also wondering if you could have a catastrophically failed water pump. These engines aren't cheap and unless you truly trust this mechanic, a second opinion might be worthwhile.

drop the thermostat in boiling hot water and observe it open......that way you can rule out the thermostat......

For starters how hot did you let it overheat? These engines are extremely tough and very forgiving but they can only handle so much.

This sounds like a typical low coolant or a pretty good size air pocket. Sometimes after I do a timing belt job I can get these. This is my procedure after I have drained all coolant and such for whatever reason on any vehicle I work on.

Fill radiator to the top.
Fill recovery tank/Degas bottle to the full mark or if it has an H mark.
Start engine and put heat on HIGH
Allow engine to idle with heat on for about 5 to 8 minutes. Watch the temp gauge and feel for warm air to begin to blow.
Once you begin to feel warm air let it idle for about 2 more minutes and then shut it down.
Just let it sit and allow the coolant to start soaking in the engine heat for about 10 minutes.
Go ahead and start engine, verify heat at vents, raise idle to 2K for 90 seconds.
If the temp gauge is doing fine then go for a short drive with heater on, turn in complete 360 degree circles both ways. Try to get on an incline for a moment, etc. What you are doing is trying to get any air pockets you have to burp out.
If you have heat, temp gauge is still good then stop engine, raise hood, check recovery bottle to make sure coolant is present and at the proper level. Do NOT open the radiator! Now just walk away and allow the engine to cool down to ambient temperature.
What you want it to do is pull any coolant the radiator needs from the recovery tank. It acts under a siphon pressure. If you open the tadiator or there's a leak it will not use that vacuum. The coolant level in your recovery tank is always moving for the most part. The hotter your engine gets the more coolant that you will see in your bottle. In the morning it will be at a lower level.

I know this sounds like a lot of stuff, but it's really not. Just take your time and follow what I said. I do ALOT of timing belts and coolant repairs with my auto business and have learned some good tricks.

I also replaced the items (water pump, radiator, thermostat) shown in this thread - 2006 4runner - V6. I hooked a scan gauge and OBD app- Dashcommand and it is showing coolant operating temps from 189 up 194. The temps will mainly stay around the 189 - 190 range most of the time. The thermostat is aftermarket. No other noticeable issues.

Is this operating temp normal.

Thanks

That's the temp I normally see using my Utragauge.

Just a little from my experience with a timing belt and water pump change on my V8. It's been a long time, but if I remember correct I ordered and returned 3 or 4 Toyota dealership water pumps before I received the correct matching pump. It turned out to be a water pump from the Lexus SUV that matched up. Maybe the replacement pump was not the correct match. Unfortunately I can't remember if it was just a case of it not lining up or simply visually not the exact same.

You probably don't have the original pump to compare what Toyota removed and what they replaced with, but if you can identify this it might help prove if 18 months ago Toyota didn't use the proper water pump and are a result it messed up your engine.