Any Gen 4 Owners Out There With Blown Head Gasket ??

Well they just internally leak in the exhaust. People will just mistakenly think their headgaskets are shot as there is a coolant smell in exhaust with no leaks apparent but a low coolant level and low heat output from the heater. Now, to be honest, we just did a headgasket on a 2018 Prime but it's far from a common occurance. Far less than those heat teaps. We have 3 used/defective ones right here as we speak. I told my waranty guy that i want one when they will be cleared as i want that trap portion. I want to see how it's made. Will post pics when i'll have it but i know there is a thermostat on to open/close a flapper door to divert exhaust gases in that trap..

Is my english good btw? Just want to be sure you understand me as english is a second language i don't use enough...

 

Internal leak so heat trap must be changed along with that 2nd cat.

Yup.

My 2012 Civic Si is dangerously near 300k miles. Original engine that maybe consume half a cup of oil per OCI. Never had high mileage oils in..

 

Just to keep us wanting for more..

 

Eheheh

 

Bonjour, je suis de la ville de Québec moi aussi. J'ai acheté ma Prius chez Ste-Foy Toyota...

When I bought my Gen 4, I was worried about that heat exchanger inside the exhaust. Now, you just confirmed my suspicion. Having a coolant line near a super hot exhaust isn't such a good idea. Corrosion in the exhaust is always a concern, especially with those winters in Quebec. How many of them do you see each month and at what mileage? I wonder if we could simply bypass the heat exchanger when it start to leak instead of replacing the whole piece?

 

Well actually the heat trap is a very good thing, efficiency wise, as it allows the engines to get up to temps soo much faster by using waste heat that's getting dumped right up the tailpipe. A nice warm engine is a happy one, a cold one isn't.. and as the engine tends to go on and off on the highway, i'd like to have it warm fast please. Also, it dumps exhaust heat right in the heater core so the heat pump works much better during winter time. For that reason, i won't be bypassing mine if it fails. More so as it will likely trigger a bunch of Check Engine codes as there are a TON of coolant sensors on a prime. Like 5 or 6 of them. 1 being monitoring the heat trap. Exhaust corrosion isn't an issue here as it's leaking from the inside, probably because of repeated heat cycles.. i will learn more when i dissect one sometime later on.. What i also think, judging as how Toyota works is they will likely get an upgraded part later if they get enough warranty claims.. to be honest, it's more like "how many do i see per year" (3 or 4..) and 100-110k miles and up. Some delivery cars/taxis have more then 300/400k km and never had that problem too.. really, it's not a death sentence but it occurs more then headgaskets for sure. If you feel unsure, buy a gallon of coolant at your dealership in case you need to top it off and DO NOT allow coolant level to go below the low mark.. Coolant is cheap and having some fluids handy in the shed/trunk is never a bad idea anyway.

Thanks! Well coolant leak is never good but if i had to choose, i'll let coolant drip in my exhaust each day, every day before it drips in my motor oil. Repairing a trap, i guess, would be a huge job is you're not a welder with proper equipment. Something i might want to try for fun as an experiment but don't expect it to last a long time after that as it would likely fail elsewhere.. as for sniffing the exhaust, as i said, keeping an eye on your coolant level when you add windshield wiper fluid and/or check engine oil, is never a bad idea.

Really guys, don't loose sleep over the heat trap.. hell, if you have a high milleage Prime (110/120k miles..), i would consider replacing the inverter/transmission cooler water pump as it's a relatively inexpensive part (more or less 220$ canadian) and if that one fails, it will cast doom on that inverter pretty much quickly! And THAT costs a hell of a lot more then any heat trap does.

 

What puzzles me is that the exhaust heat recirculation system was introduced a dozen years ago in Gen 3, and yet I just haven't been hearing such reports about the Gen 3 version leaking. I wonder what changed about the heat exchanger for Gen 4?

 

Toyota 17410-37B72

 

Actually, it's 17410-37B52 for the 2017-2019 Primes and 17410-37C60 for 2020-up Primes. Also note that Toyota improves that 2017-2019 part as it was 17410-37B50 and it changed to 37B52. Most likely Toyota improved/corrected the part..

Also worthy of mention is we always change them on 2017-2019 Primes. Most likely that 37B50 part that fail. We never changed one on a 2020-current Primes. Is it because the 37C60 part never break or is just not old enough remains to be seen..

On those pics, the first one is the earlier style 37B5x part, the latter is of the current 37C60 variant.. notice the difference.

 

Good reason for buying into a generation in the waning years; (hopefully) the bugs get worked out.

 

And here's the -37300 version from 2010. I wonder how come we haven't had stories about that one leaking?

 

My 2012 Prius v was purchased in February 2012. It was recalled and replaced in March of the same year. No issues with leaks for the past 10 years.

 

Judging by the pictures, i would'nt see why the 2020+ heat traps could'nt be installed on a 2017-2019 car. Everything looks compatible.

 

Gen 4 owner here, unfortunately I'm on the same boat, coolant loss, no heat and white smoke coming from the tailpipe. Dealership said its heat exchanger failure, still wanting for parts.

TSB: Coolant leakage at front exhaust pipe (Prius & Prius Prime) | PriusChat

Heater not working | Page 2 | PriusChat

Engine coolant inside catalytic converter | Page 3 | PriusChat

After seeing these threads, it seems like the problem is actually prevalent among gen4 prius (including prime?).

 

Here at my dealership, it's mostly afflicting 2017-2019 Primes. Never changed one on a 2020+ Prime that has another type of heat trap. I would think that both are compatible but never had 2 besides one another to compare. See above pics. ...oh.. and 2020+ part is a bit less expensive too!

 

Well it appears that 17410-37B52 again changed to 17410-37D40 per TSB TCI-5257..

 

This is exactly what my mechanic did when my exhuast heat exchanger failed and started leaking coolant into the exhaust. The replacement part had a two-month lead time, so to make the car driveable in the meantime he just disconnected the coolant hoses from the heat exchanger and connected them together with a bit of spare pipe. The vehicle drove fine in this condition, no lights or codes. The only perceptible difference was the cabin heat taking longer to warm up. Mileage probably suffered a bit but it wasn't noticeable to me, a non-hypermiler.

If I hadn't had the money for the replacement part, I believe I could have left it bypassed indefinitely.

EDIT: For what it's worth, my Toyota dealership initially (mis)diagnosed my coolant leak as a head gasket failure. Fortunately I got a second opinion from a local independent mechanic before replacing my ICE like the dealership wanted to do. The mechanic I found happens to drive a Prius himself, and he was able to properly diagnose the heat exchanger as the culprit.

 

Had the same issue. Check my video

TSB: Coolant leakage at front exhaust pipe (Prius & Prius Prime) | PriusChat

 

Seeing all those having issues with that system , I'm glad some models including ours didn't come equipped with such system .

I really hope a sound quick solution will be found soon .