Sudden Coolant loss

You can call up water pump operation w good scan tool . And wen ya do you can hear pump sounding like it's running but a trained ear will hear other things like the 800 rpm it's saying it's spinning is actually half that or similar antics going on . It's a real thing . No water pump will solve leaking HG. But a slow spinner can certainly bring temps up . Usually peeling impeller try the 35 dollar solution first. That could help save ya thousands. Operative word being could... Good luck

 

What’s the miles?

 

What water pump and thermostat did you buy? OEM or aftermarket?

I would replace the water pump to see if that fixes the overheating. While you wait for the water pump to arrive, I would monitor the engine coolant temperature by using an ODB2 Bluetooth dongle and an app.

 

What is a HG compression kit test? Are you saying you did a compression test on all 4 cyclinders or did you just put in some chemical indicator in the coolant and that's negative?
In the meantime. refill the coolant level and burp the system. After all the bubbles are out, mark coolant level, then monitor.

Hope this helps.

 

I'm guessing he bought the gizmo that checks for exhaust gas in coolant, which is not what usually happens with gen 3 head gasket failure, at least not in the early stage.

 

This is exactly what happened to me. Second time it happened, read the code and it was the water pump failing. Replaced the thermostat for good measures. Problem solved. Think you are on the right track. Hope it all works out.

 

Yes, that's neither a compression test or head gasket leak test. It simply tells you if exhaust gases is leaking into your coolant. IT DOESN'T TELL YOU WHERE THE LEAK IS. Making an assumption leap like that can cost you serious money and wasted time. IMHO

 

That is a very good question.

When the engine water pump goes bad on this engine (not enough coolant flow through the engine), the engine overheats, and pressure builds up in the coolant system. When that occurs, the cap on top of the reservoir releases the pressure just like it is designed to do, and coolant is pushed out the overflow.

Take a look at the two pictures below.



Take a look at your car for evidence of dried pink coolant around the reservoir.

 

What water pump and thermostat did you buy? OEM or aftermarket? I hope you got OEM. If not, you may be replacing it again in about one year.

 

Hose-off and clean that coolant bottle area when everything is cold. That way you'll be able to tell if the coolant is still boiling out, without the temperature light flashing at you. I'm assuming your not going to actively monitor the ECT.

hope this helps....

 

Did you buy the car new or used? I am asking to determine if the water pump you took off was the original OEM pump or was it an aftermarket pump? You can tell the OEM pump by "TOYOTA" and "AISIN" cast into the pump. See picture below.

If the old pump was OEM and you still have it, I would try to remove the rotor from the shaft and then buy a replacement rotor on Amazon ($22) or eBay. Then you will have a replacement pump for the next time you need it.

 

By the way there are two temperature sensors on this car, one sensing the coolant temp after the exhaust heat recirculation system (which caused the B1503 at 248f - normal high about 205f). AND the second coolant temp sensor on the head just below the largest coolant hose on the drivers side.

Clearly the engine hit 248f or higher. As indicated above, you hope the reservoir on the passenger side relieved pressure and dumped coolant. Otherwise it is head gasket or a rare leak in the exhaust heat recirculation system.