prius heater core without dash removal (the easy way) (read description for more information)

I bought a 2012 Prius V that had the notorious head gasket failure. Mine was caused by the clogged EGR valve that also clogged the intake ports. That combined with the crappy head gasket they used in this generation Prius all led to the head gasket failure.

This car was very well maintained. Service records show it was in every 5k for oil change and service since it was new off the lot. (I think it's worth noting that this car doesn't use a drop of oil like many of the others that had their oil changed every 10k). Why the EGR valve cleaning isn't part of the preventative maintenance list is beyond me,
as Toyota clearly knows it's a problem. Maybe since it makes it past the warranty period before it fails means that Toyota doesn't care to address it. They did make some computer adjustments that did help but it just seems like cleaning the EGR at 100k would make sense. If you don't want this problem with your Prius make sure you get the EGR valve, cooler, and intake ports cleaned about every 50k ...maybe you could go 100k but I wouldn't go past that without cleaning it. (Note, My car had almost 170k on the clock before the head gasket failed..)

The problem I had, that I assume the majority of you watching this are in the middle of dealing with too, is that the previous owner put some type of head gasket sealer into the coolant reservoir which clogged up the rest of the cooling system. When I replaced the head gasket, I found a bunch of the sandy pink residue in all the cooling ports on the block and head.

After replacing the head gasket and cleaning out as much of this crap as I could, I found myself dealing with an overheating condition. So I assumed there was a plug somewhere else. I opted to replace everything in the cooling system, and flush out all the lines. One, so I could just eliminate the problem all together in one shot instead of messing around with it, and two, why not? It has 172k on it and it's 12 years old. I just decided to refresh it. I replaced the water pump, thermostat, and radiator, plus cleaned the temperature sensors since they had the pink crap on them too. The problem is solved. The car runs great. No more over heating.

Then, comes a brisk morning here in the Midwest. It got cold enough to run the heater for the first time and I found the heat was hardly warm. It was almost hot coming out of the driver's side vent but just cold air coming out of the rest of them. Given the known history of the car's recent activities I knew right away it was a restricted heater core.

After many days of research on how to change the heater core, everyone says the dash has to be completely removed. I really didn't want to go down that rabbit hole if I didn't have to because that is a highly labor intensive job and it takes a long time. Plus there is 47,212.5 electrical connectors, not to mention the pressurized A/C lines and refrigerant to deal with, I was just dead set on finding another way to do it.

I searched high and low for anyone who has found an alternate way to change it. I couldn't find a single video on any other way to do it.

That's why I'm posting this video. This is to show you that yes there is another way but you have to be willing to cut some insulation out of your way. You can cut it in a manor that you can just fold it out of the way and put it back when you're done so you can't even notice. Also, you'll need to pound the firewall out towards the engine bay just a little bit to gain the little bit of extra clearance needed to slide the old heater core out. Don't worry, it doesn't hurt anything and you really don't even notice.

The only other thing that you need to do is either cut or detach the hard aluminum pipes from the heater core that stick through the firewall, because you can't slide the core out with the pipes protruding through the firewall. When you put the new core in you'll need to cut or remove those ones too so you can slide the new core back in, then splice or reattach the pipes depending on the method you chose. If you opted to cut them like I did, then you'll need to splice them together with a few inches of 5/8 heater core hose and some spring clamps. If I were to do it again, I wouldn't cut them, I would just remove them from the heater core and reattached them after it was back in.

Do this at your own risk. Be careful, and use your brains. There is a risk of the pipes leaking or the connection blowing off under pressure. That's 200+°F water that will be spraying under your dash and probably on to your legs and feet, and it will continue spraying until the cooling system is empty or the car is shut off. That will be a bad day if that happens so use your best judgement if you choose to proceed. I can tell you that the method I chose is working great so far. It has been a week and I have no leaks and my heat blows 170°F from all the vents when it's fully warmed up.

Good luck with your project