Anyone done a heat exchanger bypass on a 2016?

So my 2016 Prius 4 Touring has been at the shop for 2 weeks. First I thought it was a blown head gasket (overheating, white smoke, burning coolant) but based on the advice of this forum that it might be the heat exchanger I went back armed with the Toyota TSB on that topic and a youtube video and the mechanic went back through the diagnosis and confirmed it was the heat exchanger.

It turns out that this part is on national backorder with Toyota with no known date that it will be available and there is no approved aftermarket part to use as an alternative. So I can't get it fixed now anyway and who knows when I might. The did quote me that a heat exchanger replacement is a $2100 repair job parts and labor which is half the cost of head gasket but still not cheap.

So question. Has anyone just bypassed this piece of junk equipment and left their car that way permanently or temporarily? I'm ready and willing to give it a go if I knew exactly how to go about it. It is June and I don't care about the heater anyway.

Advice?

 

Well, I'll have to do it myself. The shop wasn't interested in doing that sort of unauthorized repair. Upon further research there isn't an actual Toyota Prius part called a heat exchanger. It is just the catalytic converter assembly that has a heat exchanger built into it. So what you need to do is replace the whole d*mn catalytic converter which is still perfectly good. So very stupid on Toyota's part to design it that way. I'm not sure why they are all out of stock. I'll probably call around and see if I can locate one.

I couldn't find a u-shaped pipe to fit between those two hoses but I can rig something up with two brass elbow pipes. And then wire it up in place so the hoses don't flop around.

This is apparently what you have to buy: https://www.ebay.com/itm/134070734784

 

Another update.

Today I called my local Toyota dealer and they confirmed that catalytic converters are on national backorder with no indication whatsoever of when they might ever be available. They don't even have a waiting list, you just have to keep calling back to check every so often. They also won't install any used or ebay part you might be able to scare up on your own. Nor will they do any sort of bypass that isn't authorized by Toyota. And also said that because no specific recalls or TSBs are coming up under my VIN this is not something that Toyota is going to cover.

Bottom line? If I ever want to drive my car in the near future I'm going to either have to buy an $825 used catalytic converter on ebay and install it myself. Or construct a u-shaped hose fitting to bypass the heat exchanger and install it myself. No mechanic, Toyota or otherwise is going to get my car running for me.

So I'm choosing the latter option. I bought some ramps at Harbor Freight to elevate the car and make it easier to work under. An this weekend I will be installing some hose fittings to bypass the heat exchanger and will just wire or clamp the whole mess out of the way so it doesn't flop around or get damaged under there. And then just hope for the best. This is mostly an around town car, not something we take on long road trips. So I'll just keep a close eye on the coolant level and exhaust and hope that was actually the problem. While I curse Toyota for this stupidity and vow once again that this will be the last ICE vehicle that I ever buy.

I've got my eye on the new Nissan Ariya as the next car as I'm also tiring of of all the Elon Musk fanboy nonsense but hopefully that is still some time off. If I ever get this car properly and permanently fixed I'm sending it off with the youngest child when she goes off to college in two years and getting a new EV then.

I'll keep you all updated on the proposed fix and see how it goes.

 

The heat exchanger is part of the catalytic converter assembly so you all you are doing is replacing the catalytic converter and then just hooking up the two coolant hoses. Doesn't actually look like a very hard repair to DIY. The problem is getting a new catalytic converter as they are on nationwide back order. There might be an individual dealer some place that still has some on their shelf. But they can't order any new ones. The parts guy at the dealership says he can't even place the order, the system won't take it because they no future delivery date.

The other alternative is to find a used one from a junk yard off a wrecked Gen-4 Prius but those are running north of $800 on ebay because the junkyards know what they have. And then you don't have any assurance that it is going to be a good one anyway. I'd rather just wait and pay for a new Toyota one so at least there is some kind of parts warrantee if the problem repeats.

I'll be doing a bypass this weekend by myself which will actually tell me 100% for certain that this is the actual problem and not the head gasket. And if it turns out to run just fine with the heat exchanger bypassed I might just leave it that way permanently, or for a long time. I keep the car garaged at night and we don't live in a really brutally cold climate so this isn't really feature I need anyway.

 

Update guys.

I couldn't find any perfect fitting to bypass the heat exchanger. One hose is about 1" longer than the other so you need a u-shaped fitting that is 1" longer on one end. As a "kludge" repair I found a 90-degree brass PEX fitting in 3/4" size which is the appropriate bar size to fit on these hoses and just bent the longer one so that they could be connected together. Then took some wire to secure it so it wouldn't flop around and rub against the hot catalytic converter. This is the part: Apollo 3/4 in. Brass PEX Barb 90-Degree Elbow APXE3434

I also used proper stainless steel hose clamps with a bolt tightener rather than the OEM spring-loaded ones just to make sure it was very very secure.

I drove it around about 20 miles today and it isn't using up a drop of coolant anymore. Previously the entire reservoir of coolant would drain after about 5 miles of driving. So I think that was the problem and the fix. Driving on the flats I get no white smoke but driving back up the steep hill to my house after about 20 miles of highway use I suddenly started to get white smoke again which alarmed me. But since the coolant level hasn't budged I'm guessing and hoping that there was just some coolant left in the heat exchanger that drained back into the exhaust when I drove up an incline. It was only on the final steep uphill that I got white smoke. None at all for 20 miles of highway driving at 70 mph.

I will figure out how to cap and plug the intake tubes as suggested upstream. And after looking at the bottom of the car I think the better bypass would be to pull the hoses completely off and then fashion a small u-shaped hose or pipe to attach to the hose barbs at the other end which are nicely positioned side-by-side. Maybe some sort of small flexible metal hose that I can bend into a u-shape and fasten there. It will be cleaner than having the long hoses flop around

BTW, these cars are REALLY LOW to work under. I went and bought a set of ramps at Harbor Freight but they turned out to be unusable because the front cowling of the car would hit the ramp before the tire. So in the end I just jacked up one side of the car really high and put two jack stands under the sides for safety in order to work under it.