2019- heat exchanger done- cap popped off

It's in the exhaust pipe, behind both catalytic converters.

(In gen 4, the first catalytic converter is built into the exhaust manifold. So the exhaust pipe starts with the second catalytic converter, followed by the heat exchanger.)

 

Engine takes a bit longer to warm up.

 

If the exhaust heat exchanger failed there is now an exhaust leak into your "capped" coolant lines. I would probably securely cap it.

You should also ensure the thermostatic valve is secure in an open position to reduce exhaust restriction.

 

You've got your answer in this thread....
Looking for help doing the heat exchanger bypass | PriusChat

Your more than likely creating another future problem by bypassing a perfectly good EGHE, and pretending to tell us you have a leak. Think about it - if it's leaking, why did it blow off the cap??? Wouldn't the excess pressure just leak into the exhaust system? Path of least resistance. That's why problems needs to be tested, rather than going by assumptions alone....

 

Assuming your bypass fixed the coolant loss, cause and bypass effect was determined.

A 2019 would take longer than a 2016 to experience the issue if it was going to happen.

Another member forced the exhaust heat exchanger valve into the straight through open position here:
Need help with Custom PIDs for Gen 3 Electric Water Pump (21D7) in Torque Pro | PriusChat
That was on a gen3 so your gen4 could be slightly different.

To find a recent post from a member click on their name and then "recent posts". One issue with Priuschat is the post title may have nothing to do with the solution. This is because the op was guessing at first about the problem and edit ability is quickly locked out for admin paranoia reasons. In the link above the member started looking for custom scanner pids to diagnose a water pump but it was a stuck exhaust heat exchanger valve.

 

He missed your update. It happens.

This forum has a refresh problem on Iphone and other ios devices. Meaning a post may be missed without a manual refresh.

 

@rjparker ; Thanks....

@C Clay If the issue is resolved, what's the question? The day before you started this thread you posted wanting to proactively bypass the EGHE (see link), even though 2019 was at the end of the recall/failure list. That's why I was confused that all of a sudden you developed a leak. As I've always stated; you should test your assumptions before taking action; so you don't waste your time and money, chasing ghosts and assumptions.

Looking for help doing the heat exchanger bypass | PriusChat

Happy you've resolved your issue......

 

Pressure test it to see if there's an actual leak - simple as that.... I've already stated why I don't think it's leaking there in thread #8. I've only got your observations and test results to form my conclusions. I'm not there; those are your tests and observations - I'm just pointing out inconsistencies that you should probably double check.

 

You have an exhaust leak pressurizing it, more so if the exhaust heat exchanger valve is closed. On top of that the coolant is vaporizing which adds volume. But that vapor will quickly exit at the rear exhaust pipe if the cap is secure.

 

Those old steam powered locomotives was easily 5x+-10x+ the weight of your current car. It's going to push on the weakest spot and escape.