Head gasket blown. Pink/orange tapioca. Have a few questions as to cleanup before proceeding.

ASRDogman · Jun 26, 2026 at 7:44 AM

Yes, you made it very confusing.
Now it's too much to read.

Hope that whatever it is doesn't happen again and that you don't have a bad head gasket.
You should change it BEFORE it fails, when you can decide the time and place.

weapon said: ↑

You think you are confused , you need to look at it from my point of view. HAHA
Have to read the replies to multiple people in the correct order, if possible. Which can be confusing on its own with all the injections of off topic questions, theories and multiple conversations going at the same time. I have no idea what is going on so I am trying to just answer to the multiple possibilities.

Here is a tighter synopsis:
I noticed the goop when a check engine light came on (dirty air MAF sensor code). I was in the process of getting ready to perform all of the neglected maintenance for my 2 prius(s). The majority of the goop was floating on the top level of the reservoir. I parked the car and started to diagnose. I used a syphon pump to suck the goop out of the reservoir until there was just dirty pink coolant. I pinched off the 2 hoses that lead to the reservoir so the system still had coolant in it. I then used the ultrasonic to throughly clean the reservoir. Reinstalled and then filled it with water to get it back to the correct level since i was going to do a complete flush anyway and did not want to waste $30 of new coolant to do it. The water stayed clear in the reservoir while i ran the car around my neighborhood on few short laps. It did not do what I wanted which was to circulate the system and push any goop to the surface. So I decided to take it out for a longer trip today as it was worth the risk to me. I drove around doing errands, stopping/starting, engine on/off, Idling and driving. At each stop I popped the hood and checked on the system. The coolant did mix with the water and the reservoir became a light pink (too much water to coolant ratio now). There was some minimal goop residue that made its way to the reservoir. So I returned home and removed the reservoir again and cleaned it one more time in the ultrasonic, I also cleaned the hoses as far as I could without taking apart the whole system yet. Now we are up to date.

At no time has there been a consensus idea of what is happening from the group or someone who has seen this before, just a bunch of educated guesses (which i do appreciate the comments, still it is confusing) but I am listening to all possibilities and not ruling anything out at this point.

Some suggest that incorrect coolant was added. I am the second owner but have owned it for over 10 years and bought it at 70k miles so the coolant has never been flushed as far as I know. That does not mean that coolant has not been added to keep the system full but I only used the toyota long life. And it has never been in the shop/dealership since I have owned it as It has had no problems up until this issue. Could that coolant in the toyota jug been bad or contaminated while it sat on the shelf for years. Maybe?

Some think it is a stop leak but again that is not really possible unless it was done by the original owner over 10 years ago and took that long to reveal itself. Again not likely.

If you look at the photo of the milk jug, it is separating like oil and water. The goop is oily and makes my hands slick. That is why I assumed it was a head gasket and oil was mixing with the coolant. But there is no coolant in the oil pan, just oily substance in the coolant reservoir.

So I have decided after all the testing and cleaning that I will flush the whole cooling system. If there is more goop that come out during the flush then we know it is deeper in more parts of the system (right now it seems to only be in the reservoir and down the adjacent hoses a few inches but that makes no sense). The coolant change needed to happen either way. But if it is just residue, then I will run it as usual since it is not throwing any codes and the engine is performing solid. A cleaned egr cooler and manifold will be installed at this time also as those are already on my bench and ready to go.

At that point I will monitor closely and wait to see if it happens again. I do have the gasket kit on the bench ready if it truly is a head gasket failure.

Either way, I am still up for listening to more theories as I continue to clean the systems.

Thanks in advance.
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Head gasket blown. Pink/orange tapioca. Have a few questions as to cleanup before proceeding.

ASRDogman Senior Member

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Head gasket blown. Pink/orange tapioca. Have a few questions as to cleanup before proceeding.

ASRDogman Senior Member