Massive Coolant Leak!!! Please help. (Now $4,000 Engine Repair!!!). Fixed! (Post #48)

Toyota believes it's because they programmed the ECM to tell the water pump to run at the wrong speeds at the wrong times. That by itself can't be blamed on the pump; you can have a brand new, perfectly-functioning pump and it will run at the wrong speed at the wrong times if the ECM tells it to. (In that case, of course, the target RPM and actual RPM will show an ok match.)

Of course water pumps do also fail, and that will also cause overheating. But "bad water pumps" isn't the whole story for overheating and head gaskets, because until the ECM firmware is updated, even good water pumps will still be running at the wrong speeds at the wrong times.

 

That's wild our two here seemingly struggled to get up top rating temperature until it's 110° out

 

If that were true, they would have issued a firmware update. That doesn't explain that overheating is very rare in the first 100,000 miles.

 

Did you, by any chance, take the teeniest look at the linked technical service bulletin showing the updated firmware versions?

You might also notice the TSB doesn't say anything about reaching the overheat warning light threshold of 120℃ where you would see an indication of overheating. The TSB is talking about "certain areas of the engine block" getting too different in temperature from others, to the detriment of the gasket, and that can be happening over a long period of time with no red overheat lights or symptoms of "overheating".

 

I have observed my temps in realtime for years and find the first 2.5 “severe” conditions cited actually causes the engine to cool off. Which is all I do since I don’t do high load or towing. I call it Thermal Cycling, sometimes as much as 50f swing. While still staying below 205f. The two separate coolant sensors do differ but only by a few degrees with the exhaust Heat Recirc sensor reacting faster.

 

I saw that after I wrote that. However, the TSB applies to severe service conditions and in Europe. Are you saying we should all get the TSB done? Is there a US version of the TSB?

 

Looking at what it calls "severe conditions", plenty of people drive that way. (Kind of like the related business in the warranty and maintenance guide, where it says to change the oil at 5k miles under "special operating conditions" or 10k otherwise, but the "special" conditions aren't all that special.)

Well, clearly the ECM firmware calibration IDs for Europe aren't exactly the same ones used in this market. And here in the US, when Toyota mentions a firmware update in a TSB, they often skirt around saying what they changed, compared to the clear statement in that European TSB. This may reflect a difference in what the respective regulatory agencies let them get away with.

In any case, it looks like an issue they didn't correct in Europe until 2014, and they were selling Prii here during those same years also, and there have been TSBs released here that included ECM firmware updates, even if they didn't come out here and say what they changed.

Sure sounds to me like a prudent person might want to be running the recent ECM firmware.

 

OK I'll check with the dealer to see if they can flash the latest version of the ECM firmware. Hopefully they won't give me any grief because I can't reference a US TSB.

 

No grief just a $150 service charge.

 

I wonder if I had this update? I had a firmware update when I had the inverter recall years ago since the date on the TSB was 2014 and my vehicle is a 2013.


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