2005 Tacoma overheating

I have a 2005 Tacoma that I have owned since new. I have oil changes every 3000 to 4000 mi since 2005. I now have a company truck and don't drive Tacoma very much. Having overheating problems, started with heater blowing hot air for 20min then cool air for while. Checked fluid level, was ok.
2014 fall it overheated, limped back home took thermostat out took to repair shop. They replaced thermostat, radiator ,hoses, water-pump clutch-fan, flushed heater. Toyota dealer said it was ready, picked up drove 7 miles, heater went from hot air to cool air then temp gage went toward hot. pulled over called dealer. They towed to shop, got me rental car. I HAVE TRIED EVERYTHING, NOT SURE WHAT ELSE TO CHECK.

ANY CLUES, thanks

 

That hot air to cool air makes me wonder if you have an air bubble in the system.

 

sounds like something is restricting the flow of coolant somewhere. if overheating started before you changed radiator, then air bubble would have been flushed after the install. does it do the same thing when heater is on and off? you tried bypassing the heater core? hose that goes to the over flow? over flow cap? are you losing coolant? does level drop in radiator? is water coming out of tailpipe? you ever put any additive in radiator like a sealant or anything? any chance fan shrowd is damaged or cut? kinda stumped here...

 

I would have thought that and air bubble in system would have been taken out when refilling system. I have noticed the thermostat is not opening when this happens. Top radiator hose is hot bottom is cold. I have had this truck to 3 different places, 2 were small repair shops the 3rd was the Toyota Dealer where it was purchased. The truck has 200,000 mi now, I was thinking Head-Gasket, no smell from exhaust, no leakage under truck. No symptoms of head gasket gone bad. This is really strange.

 

Head gasket failure or cracked head leaking compression into the cooling system causing a vapour pocket would be my guess based on what you're saying. When the heater goes cold and it heats up, does it push coolant out into the overflow reservoir?

We can eliminate the radiator, thermostat, and fan clutch as possibilities, not only because they are new, but a failure with one of them would make the heater blow hotter air, not cooler. There is a coolant flow issue through the bypass circuit of the cooling system within the engine and to the heater core, and since the water pump is new and it's doing the same thing as before, its most likely a vapour pocket. And since this assumed vapour pocket keeps coming back, the vapour is likely being introduced from within - back to my earlier comment of HG or cracked head. Have the cooling system checked for combustion gasses.

 

I will be talking to the Tacoma service mgr on Monday. They get 1 more chance and then I am going to remove the thermostat and just run it like that. The 2 times that I had to do that to drive the 40mi to the shops that worked on it, It didn't overheat or act strange at all.

Getting mad about this, kind of like the truck just acts up when it wants to.

 

sounds like a head gasket. seems like early 2nd gens are prone to this problem.

 

We had a car come into our shop that was overheating. It had a new waterpump put on at another shop. Naturally we put a new thermostat and then a radiator and it still overheated. We were about to tell the owners that it was probably the head gasket when the boss told me to pull the new waterpump out and take a look at it. Here it had a plastic impeller and it was cracked where it atached to the shaft and was not spinning all the time. Before pulling the heads off double check the waterpump. Hope this helps.

 

No CEL? In the process of doing the HG on my 04 4R, similar mileage. 04 4R and 05 tacos are notorious for the HG. Are you losing coolant?

 

NO COOLANT LOSS, HAS A NEW WATER PUMP ON AS OF LAST WEEK. I GOING TO LET THE DEALERSHIP WORRY FOR A WHILE, I TOLD THEM TODAY, WHEN THEY GET IT READY, TO DRIVE IT 45 MILES TO MY FARM AND I WILL TAKE THEM BACK TO DEALERSHIP IN THE TRUCK, THEN BACK HOME. TOTAL OF 135 MI, I AM GUESSING IF I HAVE PROBLEMS THIS WILL TEST IT.

 

sweeeeeet! i like your style bro!

 

did the dealership figure out what was going on with your truck?

 

NO, THEY SAID THEY THOUGHT THERE WAS A BLOCKAGE IN ENGINE BLOCK.

I'M THINKING OF TAKING TO A SHOP THAT CAN REBUILD MOTOR.
HAVIG THEM PULL MOTOR AND GO THRU REPLACE ROD BEARINGS AND CAM.
THAT IS A LOT CHEEPER THAN NEW TRUCK.

 

Do a leakdown test and get right to the cause.

 

This. ^^^
You can borrow a leakdown test kit from most parts stores. I borrowed one from advance that worked well. Deposit was $200

Or try a reverse flush. Maybe disconnect all hoses and flush from both sides. I would not be pulling the engine just yet. Sounds like you can't find a good mechanic. Was the dealership Dan Cava in Fairmont?

 

Before you go through the big expense you've outlined, trying burping the system. Remove any trapped air inside the cooling path.

Elevate the front of the truck. Top up coolant - not all the way up, but make sure your radiator is close to full. Turn on truck and set heat control to max heat. Let engine warm up fully. Now quickly depress and release accelerator pedal - wait a sec or 2; then do again 3 or 4 times. Put a sock around the radiator fill neck before you do this to keep coolant from flying all over the engine bay.

This will cause the water pump to push coolant thru the system and any trapped air out the top of the radiator fill neck. Elevating the front of the truck helps get air out.

 

I WILL TRY THE LEAK-DOWN TEST AND THEN TRY TO PURGE OUT ANY AIR POCKETS. I WOULD HAVE THOUGHT THAT THE TOYOTA DEALER ( BERT WOLFE--CHARLESTON,WV ) OR ONE OF THE 3 SHOPS THAT THE TRUCK WAS IN WOULD HAVE DONE THESE THINGS. PRETTY SAD IF NOT.

 

I'd jack up front and purge first then leak down test second.