engine coolant mystery leak 4th gen USA

[CarstenAlmskaar]

Hi all, Just signed up.

I bought my Prius a month ago and love it.

4 days ago I was driving home and noticed the engine temp light was on. Popped the hood and saw the engine coolant reservoir almost completely empty (Perhaps it can never completely empty while in the vehicle due to the position of the hose). Bought some 50/50 put it in and light goes off.

Yesterday evening, after putting 150 - 200 miles on since last adding coolant, temp and check engine light came on. Popped the hood, reservoir almost empty and droplets of coolant on underside of car, however not dripping on ground. Got Engine code P0117 - ECT sensor. No sign of leakage at sensor. I figured first I'd address the low reservoir issue.

Took off splash shields, found a few droplets between the engine and the firewall (driver's side) and on those plates under the cat. Added coolant, ran motor, and could find no leaks. The reservoir was again almost empty so cycled thru running the motor, letting it cool, and adding coolant. There was a horrible sound coming from the water pump when the engine shut off and the car was still on, but this went away as I added more coolant. At this point I assume the P0117 code came up due to air in the system. Used 3/4 gallon 50/50. Still not seeing any leak.

Checked oil - looks fine, the exhaust heat exchanger had already been disconnected, some condensation at tail pipe but no sign of coolant. Seems like that rules out internal leak.

My other suspicion would be the lines to the heater core, I put the cabin temp on high, never smelled any coolant, no window fogging.

So uh yeah kinda stumped. 

[Devon Aygo]

Early MK4 can suffer a coolant leak into the exhaust heat exchanger 

 

[Harters]

Check out PriusChat (US forum) as there are lots of people over there who have the issue.  There is a TSB for US residents which get the heat exchanger replaced under warranty providing you are within the desired mileage (80,000 iirc) and within a time period (can't remember).

There is one user from the UK on that forum @TheProfessor (and this) that had the heat exchanger problem too, but it is not covered under the UK warranty, but he wrote to Toyota UK and after a bit of negotiation managed to get the replacement part fitted FOC, but had to pay for ancillary items.

I understand that in the US the heat exchanger forms part of a SMOG/Emissions test and is therefore covered.

I hope that helps.

[Harters]

5 minutes ago, Harters said:

Check out PriusChat (US forum) as there are lots of people over there who have the issue.  There is a TSB for US residents which get the heat exchanger replaced under warranty providing you are within the desired mileage (80,000 iirc) and within a time period (can't remember).

There is one user from the UK on that forum @TheProfessor (and this) that had the heat exchanger problem too, but it is not covered under the UK warranty, but he wrote to Toyota UK and after a bit of negotiation managed to get the replacement part fitted FOC, but had to pay for ancillary items.

I understand that in the US the heat exchanger forms part of a SMOG/Emissions test and is therefore covered.

I hope that helps.

EDIT

I notice you have already posted on PriusChat, hopefully they can help you better over there 😀

[CarstenAlmskaar]

Issue resolved...(time will tell for sure)

Drove to work and found some drips on the undercarriage, so when I got home I jacked it up again and was able to see some coolant on a plastic cover on the engine side of the firewall. Removed the metal shelf where the wiper motor sits and could see that one of the lines to the heater core was damp. Removed the hose and discovered the line was partly squished (Lame!), tried to reshape is some. Took the factory clamp off the hose and put it back on with 2 pipe clamps, so far so good.