4th Gen DIY heat exchanger bypass solution

You're overthinking it. Yes, that hose runs from the exchanger into the engine. You can also point to the hose where the coolant comes out of the engine on its way to the exchanger (it does visit the cabin heater first). Because it's a loop.

If coolant is leaking out of the system, then you will eventually have not enough coolant in the system to cool the engine or make cabin heat—regardless of where in the loop it happens to be leaking out.

Keep in mind that most leaks are a lot smaller than the flow rate of the circulating coolant. It's not leaking the way it would if you took that hose right off and the full two gallons of coolant pumps out into a lake on the driveway the moment the pump starts and none circulates back to the engine. The leak is slower than that, and the rest of the coolant keeps going around the loop.

Until enough has leaked out, and then you're just running the system with too little coolant. You get there eventually no matter where the leak is.

 

I don't have access to a special Canadian TSB of the heat exchanger issue.
@bryanpenn the issue as I see it, is not included in any of the regular warranties issued by Toyota.
It is predicated on the conditions the service department finds yout Prius exhibiting when they hook it up to techstream, and if those conditions meet the stated conditions in the TSB for coverage.

 

Yes, and my issue of no cabin heat followed by seeing coolant levels low is what led me to the issue. Glad that I caught it before engine got too warm or seeing any further issues.

 

..."APPLICABLE WARRANTY  This repair is covered under the Toyota Federal Emission Warranty. This warranty is in effect for 96 months or 80,000 miles, whichever occurs first, from the vehicle’s in-service date.  Warranty application is limited to occurrence of the specified condition described in this bulletin.  For 2016 and 2017 model year Prius and 2017 – 2019 model year Prius Prime vehicles, sold, registered, and normally operated in California, Connecticut, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Rhode Island, and Vermont. The California Emissions Defect and Performance Warranty coverage is 180 months from the date of first use or 150,000 miles (whichever occurs first)."

So does this mean if I go to NJ where I purchased the vehicle (used from a owner) that they will fix it Free of Charge?

 

I wonder why NO ONE has done a POST MORTEM of one of these exhaust systems to show EXACTLY what the defect is.
If the repair is so expensive, why not just cut the exchange cover off and see what it is and then FIX it and re-weld it back.
SOMEONE has to have thought about this.

 

Why then not just block the exhaust gas control actuator from activating the exhaust control valve rather than going through all this trouble??? ref: 20:10...

 

Good question.

 

Had to post this, because of the cool factor, plus this guy seems really awesome:

Almost Misdiagnosed This Mysterious Engine Coolant Leak!
The Car Care Nut

He scopes the engine... I mean, we all know why it is leaking... but I like the way he rules it out and uses an endoscope!

 

What are you thinking that would accomplish?

 

With forcing the valve to remain closed, the coolant will not enter the heat exchanger and therefore not leak inside. Maybe, this could be an easier fix than disconnecting the hoses and plugging them together.

 

That valve has no effect on where the coolant goes.

 

Yeah you're right, it's the exhaust heat that the valve controls


Waste Heat Recovery

 

Besides, even if the valve did shut off coolant flow through the heat exchanger, it wouldn't block both inlet and outlet tubing, so you'd still have the leak when the cooling system builds up pressure.

 

thing is... this is only a temp solution until your appointment at the dealership for the fix to be covered under warranty. POST MORTEM is dealer fixed free of of charge.

https://black.jmyntrn.com/2023/12/02/prius-prime-p148f-00-was-unrelated-to-engine-coolant-pump/?utm_source=PriusChat&utm_medium=weblinkt&utm_campaign=commentlink

 

if the valve that sends coolant to the heat exchange was cut off... so no coolant could get by... then how is it going to leak... coolant has to get by the valve to get to the exchanger.... no? Also, that loop shown seems to do nothing. If it were to work, it would be attached to both the supply and the return... not just inline... or maybe there is something I do not understand going on here???

 

I called NJ and they said there was a pzev pef warranty... registered to my car, but I live in NC.
I might consider re-registering the car in NJ and then re-registering it here again to get it fixed... but that is a pain.
Called corperate... and they will not let you email them... they will not give you an email address to contact them. So they have you by the cohones. I mentioned T-SB-0135-19 and they say it is not associated with my 2017 prius... HOW CAN THAT BE???



No doubt I will be getting a bypass, but I Have to wonder how that will affect the catalytic converter not having liquid and air on it instead.

 

No matter how often we cover it, people keep on thinking the exhaust heat recovery system somehow involves the catalytic converter.

It doesn't. When you look at the exhaust pipe, the first lump (after the exhaust manifold) is a catalytic converter. (It's the second catalytic converter, in a gen 4, because the first one is part of the exhaust manifold).

The next lump, after the catalytic converter, is the EHRS exchanger. That's where the coolant lines connect. It's not a catalytic converter at all.

 

It's expensive for not being a catalytic converter...

 

What you mean by "it"? Toyota only sells you the whole front pipe assembly:



The first lump is the catalytic converter. The middle lump is the exhaust heat recovery exchanger, where the coolant lines attach. (You can see in the drawing where they attach.) The last lump is a resonator.

The whole assembly is expensive because there is a catalytic converter as part of the assembly, in the first lump.

The catalytic converter just isn't where any of the coolant goes, and it isn't where the hoses attach, and it isn't what leaks the coolant.

 

That old catalytic converter belongs to the owner, right? Which mean could it be retrieved by the owner and legally sold to offset some of the cost?