Bought 2008 Prius - Overheating (Red Triangle)

I bought a used Prius cheap off Facebook Marketplace to use for gig work. It drives great other than losing coolant then overheating / red triangle. Has 340K miles.

What I know so far (also pic of scan from AutoZone attached).

Has the following codes: P1121, P1150, P1151, P0300, P0302, P0304, P0420.

Coolant Flow Control Valve seems dead as the P1121 suggests. Tried jumping it via the relay and it won’t come on (the car was completely off when I tried to jump it - not sure if that matters).

12v battery seems fine based on the check signal screen. Reads 12.4-12.5 and 12.2 with slight load. Goes up to 14.4 when car is started up.

There is the smell of coolant around the car, I can’t tell for sure if the smell is in the interior

I drove it about 130 miles the other day after refilling the coolant via the radiator cap and letting some of the air burp out. After that got the red triangle, let it cool down and added more fluid.

Keeping it parked for now until I replace the Coolant Flow Control Valve and radiator cap, plus bleed out all the air via the radiator cap.

Toyota told the prior owner it needed new radiator, coolant heat storage tank, coolant flow control valve.

Based on the scan from AutoZone looks like it also needs some new spark plugs.

Anyone see something here that suggests I will need to do more to stop the overheating than just replacing the coolant flow control valve / bleeding the system?

 

Yeah the red triangle goes away once you add coolant. It comes in intermittently and goes away when you slow down (when the engine cools down I guess.

The details of the codes are shown in the photo - 1150 and 1151 are coolant heat storage tank and 1121 is control flow valve. The 0300-0304 codes are misfires and 0420 I think is related to the catalytic converter

 

I do think the hose connected to radiator may be loose (just eyeballing) - the clamp is rusted and it does not sit flush with the radiator. Can see maybe a half inch or inch (can’t remember off hand) of the right side of metal pipe you connect the hose to. Will have to take pics and find out if there are any leaks (I have spilled fluid on accident a few times so can’t tell if there is any leak at the moment)

To clarify my last post - the triangle didn’t show up the other day when I drove it until 130 miles in … then adding coolant (via radiator cap) made the triangles stop, and I was able to drive it back home.

 

Originally I posted that the Coolant Flow Control Valve is dead. I thought that was the noise when you turn on the vehicle … turns out the noise is the pump for the Coolant Heat Storage Tank. The coolant heat storage pump still comes on when I turn on the vehicle, or if I press the brake pedal several times with the car off. However, I can’t seem to jump the pump using the relay. Tried replacing fuse 44 for the CHS W/P and still cannot jump the pump using my multimeter set to 10 amps.

This morning I burped the Coolant Heat Storage tank then worked on burping air out of the heater core. I followed the process shown by the Youtube channel Eyeonaiman that goes pretty in depth about bleeding the system - except I had to keep using the brake pedal to turn on (for about 5 sec each time) the pump since I can’t seem to jump it.

There was definitely a lot of air in the system, think it took about 2 quarts. This did not solve the problem - drove around 80 miles today and red triangle was back. Added more coolant - triangle gone - parked it.

Tomorrow I’ll try to tighten that loose looking hose and bleed again. I do wonder if that hose could be leaking and/or letting air into the system. May have my answer tomorrow morning as I cleaned up the garage floor so that it was dry before parking.

The radiator hoses are hot when the car comes to temp - so it does seem like the coolant is flowing. From what I am reading - despite my P1121 - the Coolant Flow Control Valve is unlikely to solve my problem … is that correct?

I suppose Toyota’s diagnosis for previous owner could be correct (needs new radiator and coolant heat storage tank)

 

Here are pics of the hoses I suspect may be loose. Is it normal for that much of the metal to be exposed? Seems like it should be pushed all the way on so that it sits flush?

 

There does seem to be a slight leak, around the driver side, right where the potentially loose hose is I showed earlier. Maybe it could be leaking more while under pressure or could be coming from somewhere else?

I checked the dipstick too, not knowing what to look for and based on very quick Google search looks ok? Could definitely be wrong about that.

Taking it to a mechanic is unfortunately not possible for now. This is basically a gamble that it will last long enough to at least pay for itself and then some. I just don’t have the funds to do that right now, even if it ultimately means it blows up. If I get another month or two out of it, maybe.

 

Did what you suggested. Here are both sides of the dipstick … doesn’t look milky to me but again not sure exactly what it would look like if it was milky … I saw some that looked more like jelly on Google but not sure if that was an extreme example of coolant mixing with oil.

Prior owner claimed to change oil 2K miles ago (2700 now)

 

Little update on my situation. Since buying, have now put ~5K miles on it.

Got an oil change the other day, they didn’t see coolant in the old oil.

Today I found several spots in the engine bay with coolant residue (see photos), so maybe there is a leak? (or would a head gasket issue cause this?)

I also kind of suspect heater core could be the issue but it’s hard to tell if coolant smell from vents is just due to coolant being in the engine bay or if it’s actually heater core. Both AC/Heater work. Also not sure how likely it would be in light of the coolant residue I found today.

 

It is definitely losing lots of coolant. Going through about 1 jug every 3-4 days

 

I am going to replace the 3 way pump and see what happens … the leak is near-ish to the pump and I already bought the pump a while back so it’s too late to return it, and I do have P1121. There are a lot of corroded pieces of metal around the 3 way pump.

The leak / pink crust build up I posted photos of is on the inverter side of the engine bay - but doesn’t seem to make sense that part of the inverter loop would be related … since it’s losing coolant in the engine coolant loop.

If this doesn’t work then I’ll try replacing some hoses (trying to find info on how many hoses / where to buy / cost etc.) and/or the coolant heat storage pump, as I also have P1150.

Could blown head gasket cause the residue/crust on inverter side ?

 

Accidentally double posted