2008 Prius Overheating Issue

Ok. So I've been dealing with a coolant overheating issue for a bit. I previously changed the water pump, which was leaking. I now realize that from the pump failing, air bubbles got into the system.

So yesterday, I put in a new radiator cap and changed the thermostat. Using the Lisle funnel I took an hour in maintenance mode and did my best to get all the air out.

Today, when I was driving, everything seemed fine at first. Then eventually the car began to overheat again.

Here is what I am noticing.

1. Most of the air bubble noises i have been hearing in the dash are gone. Except when I turn on the AC. When I initially start the AC I hear some sloshing in the dash.

2. Yesterday, in maintenance mode the fans were clicking on at 96C like clockwork. Today, they are not coming on in temps over 100C. When I turn on the AC to check the fans, they turn on for about 10 seconds then click off. Then intermittently turn on and off.

So, all in all...
Is this normal fan behavior? If not, what could be the problem?

Secondly, could the sloshing in the dash when I turn on the AC mean there is still air trapped in the system?

Should I go for another bleeding/burping session? Or something else?

Thank you.

 

I checked it this morning and it was good. I'll check again tomorrow.

 

There is water coming out of the drain line. And this noise it happening when the car is stationary.

The coolant temps are getting over 120c and the problem light comes on. The car is definitely overheating.

 

Update. I checked the coolant level in the morning and it was down a bit. So I refilled and started burping it again.

I noticed that when I was pushing the accelerator to the floor for an extended period of time that the coolant in the funnel would begin to rise significantly.

Then when I looked at the cool and I noticed an oil sheen on top.

So it's pretty clear my head gasket is blown. Now to figure out what to do to this car. Junk yard. Or try to get someone to fix the head gasket.

 

Thank you for that thread.

Last night I was driving the car, and the temps stayed fine the whole time(drove around 70 miles).

Today, when I went out for a spin, them temps immediately started climbing. I managed to limp home without overheating, but in the process my check engine light came on and the the p1150 code.

So I got the block tester to be sure, and sure enough it turned yellow and confirmed a blown head gasket.

Since I only need the car to last me another 3 months and 10k miles, I decided to give the blue devil a shot after reading about the success story there.

Since the coolant was new and I have a spare thermostat, I decided to add the blue devil as the instructions on the bottle.

Somewhere near the end of the 50 minutes in maintenance mode I got a new p1121 code.

After letting the car cool down for 6 hours, I decided to take the car on a test drive.

Initially, when pressing the accelerator I was still hearing the sloshing sounds in the dash. But after about 5 minutes, they went away. (Hopefully a good sign)

I only drove the car about 20 miles and went as fast as 20mph, but the temps stayed in a good range. One thing I was noticing that I never noticed before was the temps dropped really fast after accelerating. For example would drop from 96C to 80C in a few seconds. I don't know if this is good or bad, but never seen it before.

The car is still a little low on coolant and needs to be bleed, but I ran out of new coolant through all this. So I hope to make it to the dealership tomorrow to pick up a gallon or 2.

Then I will bleed it again properly and keep updating this thread on how it turns out.

 

Update.

So I drove it to the dealership today to get some more coolant so I can fill and burp the system.

The initial startup was really rough. So much so that it threw 3 misfire codes. Random misfire. Misfire cylinder 2. And misfire cylinder 4. Not sure if this is related to the blue devil or the p1121 3-way valve.

Regardless, right now all I care about it the head gasket seal and overheating. I can deal with all these issues after I know the head gasket is sealed and the car is not going to overheat.

Will keep the thread updated.

 

Update.

Took it for another test drive last night. A little longer and a little further. Got speeds up to 55mph.

Temps were running a little on the high side (got up to 101C) but still far from overheating.

After checking the car afterwards, I noticed that the lower pipe was cold. So today I went to change the thermostat.

And when I pulled it out it was heavily gunked up. All the blue devil got caught in the thermostat and seized it up.

In hindsight, I should have put the blue devil in with a pulled thermostat and brand new coolant.

But live and learn.

I am still proceeding forward as I have no other option in the meantime. I am an uber driver, so i am out of work and cannot rent or use another car in my area. In other words, I got the time and a few hundred dollars to try and salvage this thing.

Regardless, it seems like the head gasket is at least partially (if not all the way) sealed up for now.

So I am going to replace the thermostat and 3-way valve today. Then do some more test drives.

 

Could you elaborate on the thinking behind that? And why that vs just closing it up without a thermostat in?

 

Thank you for that. That was a whole lot of information I didn't know. I appreciate it.

I wish I would have done that before I added the blue devil. That makes the most sense to me instead of leaving it completely out, or putting it in and risking it getting gunked up.

 

Ok. So today's update.

Drained coolant, replaced thermostat, and bled coolant.

Noticed while burping the coolant that the temperature would rise when not applying throttle, and then come down a bit when I pressed on the gas.

Took it for a test drive of about 40 miles with speeds hitting 60mph. Stop and go driving.

Temps stayed elevated again, but no where near overheating. Maxed out around 103C again. Same as when still, the temps rise when stopped and no throttle, and drop when accelerating.

Afterwards, lower hose was warm(not hot) this time.

So I am suspecting that the radiator is partially clogged. And maybe some other stuff too considering how bad the thermostat was gunked up.

I can get a used radiator off an old prius for $50. The replacement didn't look the easiest though. And not sure if I'd have to replace fan assembly or fin assembly as well.

Decisions decisions.

I'll update when I decide, it might be a few days since I think I'm getting a rental so I can drive Uber for the holiday weekend.

 

Update. So basically everything is running normal at this point, except when I am running the A/C.

When the A/C is on, and I am pressing the gas pedal, there is bubbles in the coolant.

When I am driving with the A/C on, the coolant gets pushed out of the overflow tank and it overflows.

When the A/C is off, there are no bubbles and the coolant overflow tank stays within a normal range and I don't lose coolant.

I got a borescope and am renting a pressure tool from advance auto parts and I am going to look for leaks and take a peak inside the cylinders to check out the head gasket.

If anyone knows how the A/C system is introducing air into the coolant system, that would be great.