Strange Cooling System Issue

Hey guys, first time looking for advice. I bought a 2006 Tundra Double Cab off the auction and am having some strange issues with it.

First thing is the coolant is boiling in the reservoir after a drive. The temperature stays in the middle and never overheats. I also noticed that the upper and lower radiator hoses are hard as a rock after a longer drive. I replaced the radiator cap, radiator, and thermostat today and still have the same issue.

On top of all that, there is no heat coming from the vents. I suspected a bad head gasket but I did a compression check and found 145-170 compression in all cylinders. I also did a block test with the fluid and it never changed color to indicate that there are exhaust gases in the coolant system.

Is it possible there is a clog in the heater core causing all these issues or where else should I start looking?

Thanks

 

Could be air in the system, truck take like 3 warm ups to properly burp.

Are you sure the thermostats is good and installed correctly in the right orientation.

possible bad water pump. Any signs of the timing belt being replaced? How many miles does the truck have?

what brand radiator and thermostat did you buy and from where? OEM or Denso ?

How much coolant did it take to fill?

 

98k miles but has been standing a while as it was a theft recovery. Thermostat is correctly installed and opens and closes properly. Radiator is Denso and it took about 2.5 gallons to fill fully.

Curious how a bad water pump would cause it to not overheat but to have pressure in the system and no heat?

 

Boiling in the res doesn't sound like 195deg. Get an OBD2 reader and see what IT tells you the temp is. Gently flush your core backwards if you think it's plugged, but burping it on a hill for 20 30 min worked for me. What did the original coolant look like when you drained it?

 

Could be that it's blowing air out the expansion hose, causing the coolant to bubble as if boiling. Buy a new OEM/Denso radiator cap if you did not do so already.

 

99% chance a new OEM radiator cap will solve the issue - its boiling over because the spring is weak not allowing pressure to build - you remember from science class water under pressure will boil at a much higher temp than not under pressure.

BTW since you just bought this - if the radiator tank is over 10 yrs old (look for date stamp) it needs to be replaced. Luck.

 

First off, if you've never owned a 1st Gen Tundra read this before you invest any money, especially if the truck has ever spent any time in the rust belt, because it may not be worth fixing: https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

A lot of people have gotten conned from auctions with rusty/perforated frames. Some go waaaay out of their way to cover things up.

Your problem could be two issues. Sounds like air bubble in the coolant system or other similar blockage, but "No heat" is a big clue which could be related, or could be its own issue. "No heat" means hot water isn't making it to the heater core.

No heat could be for a few reasons, like or (A) the heat valve control on the firewall isn't opening via the cable that's in the dash, (B) there's blockage somewhere down the line including potentially inside the heater core, (C) you've got the infamous problem of the blend trap door breaking.

This pic shows the flow of hot water out of the block (on the right), to the valve that controls whether the heater core gets heat, and then through the heater core, and back in into the block. Obviously the heater core is inside the dash, that valve is inside the engine bay, but actuated via a cable/pull inside the dash IIRC.

What I would do is this... I drew three distinct segments in red here. Fire up the engine to heat it up to temp, turn on the heat full blast, then check the right-hand segment from engine block to heat valve is hot/firm. If so, check the 2nd segment from the heat valve to the heater core. If that's OK, check the last segment from the heater core to the block. If all three are hot, your vent door is probably broken.

I'd replace the radiator cap as others have said, but I'd also burp the system. And make sure some fucktard didn't put non-pink/non-red coolant in the engine. If it has anything other than pink/red coolant, you may've just found your issue.

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