So my sister has a 2018 Prius IV, 90k miles. Head gasket blew. It's been drinking coolant and she took it to the dealer. They quoted something like $6k for head gasket, $8k for new engine. Has anyone heard of this kind of failure before? Shes had all the service done at the dealer, and the 2 independent Dallas area repair shops I've called can't believe a 4th gen would blow one at that low miles. K3S gave a much more reasonable quote, but wanted to see if anyone had any input on this crazy issue.
You should call Toyota corporate (their toll free number) and ask for them to assist in the repair cost. There is no way a properly maintained car from Toyota should have this failure.
Is "they" a dealership? Not that it matters much, dealerships have been misdiagnosing 4th gen coolant leaks in the exhaust heat recover system, as reported here quite regularly. How did they diagnose the head gasket failure? Was the possibility of coolant leak in the exhaust heat recovery system mentioned? It is much more prevalent, and there's a Technical Service Bulletin (or similar) on it. There have been several reports of failed head gaskets in 4th gens here, and as far as I know, they all turned out to the exhaust heat recovery system. Also, the replacement parts for the exhaust problem are largely unavailable. The workaround seems to be connecting the intake to outlet, bypassing the system. Dealerships are all refusing to do this; it's disabling a pollution control. So owners DIY or go to independents.
For future people, I found the TSB for this: https://static.nhtsa.gov/odi/tsbs/2019/MC-10166037-9999.pdf Yes it was a Toyota dealer. Her heater hasn't been working good so it looks like this may be the problem. Her compression actually tested good at the dealer too. Do you happen to have the procedure listed out anywhere or a link to what to do?
If compression tested good on all cylinders, most likely isn't a BHG. They need to put the car on a lift to look at the exhaust heat recovery system; it cannot be diagnosed with a cursory look at the engine bay.
Dealer is checking it out, sister sent them the TSB. The code tripped apparently didn't match but symptoms did so they're gonna look. So hopefully that's it. Will let you guys know, thanks so much for the help!
Dealer quoted $2k for the heat exchanger fix, sisters going with the $30 bypass. Thanks for all the help, will let you know how it turns out. Documented for future people with this problem:
I've read here that it's part of the emissions and the fix should be covered and performed under warranty.
The TSB was only to 80k miles, power train is just to 60k, she's at 90k. Toyota corporate and the dealer didn't want to help. She's in Texas so I don't think it will hurt her mpg too much.
What’s the trick for sizing those? I got some, measured OD of hose, ordered that size, and that’s what the ID of clamp was, at rest. So just snug, next to no clamping action. You want them with ID a mm or two smaller than hose OD. And that would be when pushed onto spigot or barb connector?
I don't rightly know. Online ordering makes it harder. I might walk into the local auto job shop with the hose and the barb in my hand and say "what springy hose clamp for this?" Or look for a similar-sized hose used in the car, and pick up the Toyota part number called out for that.
So follow up, she did a road trip on it, no coolant loss so looks like that did fix it. Thanks a ton Mendel, you saved my sister since she did not have the cash to waste on a dealer swapping out a good motor!
