A couple of weeks ago error code P1151 popped up. This code indicates an issue with the Coolant Heat Storage (CHS) system. Anyway, I then noticed that there was almost no coolant in my radiator reservoir so I filled that up and reset the code. The code has not resurfaced. Yesterday, I checked the radiator reservoir again and it was just below the low mark. I again filled it up and then on further examination of the engine bay, I noticed pink residue from coolant on what looks like a pump - initially I thought it might be the inverter water pump, but it appears to be the 3 way coolant control valve. I started the car up and drove it around the block - I couldn't see any coolant actively leaking from this valve or the connecting hoses. I still haven't had any codes return. Does anyone have any tips for replacing this 3 way valve. How about for bleeding afterwards - can I assume that this valve is only connected to the engine coolant loop and not the inverter loop? I'm also thinking of purchasing the Autel AP200 to do the bleeding procedure afterwards - anyone have success using this tool? I've attached pics taken from the top view, facing the front of the car: the pump is in front/below the right side of the inverter. Additional pics taken after cleaning off the reservoir as well as a pic from under the car.
That is probably where it is leaking, but since you didn't actually see any fluid there, you might want to find out for sure before replacing it. That could be from an old leak. Knock off the bigger chunks and then wash off the rest. If it comes back, now you know for sure. You should also get a mirror and inspect the water pump, the one that is belt driven over on the passenger side of the motor. In any case, keep a close eye on the fluid level. You should top it off in the radiator neck (don't just assume that is the level in there) and then mark the halfway point in the overflow tank with a Sharpie, and fill to that point. You can then just check the level against that mark each morning. If there is a little trapped air, and there probably is given the code you saw, the level in the overflow will fall a bit for a couple of days, just bring it back to the mark. Run the heater a few times, there could be air in there too. Once all the air is out it will be stable - if there are no leaks. As long as the tank doesn't empty the radiator should still be full to the top and following the overflow tank will be good enough. Hmm, or not. If there is a head gasket issue that can introduce gas into the cooling system. It can actually force fluid out of the overflow tube on the overflow tank. Which you may not ever actually witness since if it happens on the road it will just blow out under the car.
What are the visual cues that would indicate a bad engine water pump? I can't see any leaks or pink residue by that pump - belt is still attached.
Sounds like it is not leaking. If it was really pouring out it might also fling coolant in the plane of the drive belt, pool coolant on the plastic shields on the bottom of the engine compartment, or puddle under the car. All of those would have been pretty obvious.
It's definitely leaking from the coolant control valve - I can see coolant beading on the valve and there are some drips that accumulated on the plastic guards below. My one question remaining is that the fault code that originally popped up is specifically for the Coolant Heat Storage tank P1151... although one of the coolant control valve outlet pipes leads to the CHS tank, all reports of the 3 way coolant valve failure reference a different fault code (none have mentioned P1151). Is it possible (likely/unlikely) that some failure of the CHS system caused the 3 way coolant valve to fail. Or is it more likely that the coolant valve failure resulted in the P1151 code? I cannot see any leakage coming from the CHS tank - but I have limited access to that area.
If the three way valve is leaking you need to replace it no matter what codes you see. With the caveat that you should attempt to figure out if the fluid is coming out of the valve itself or from a deteriorating hose or clamp. You may already know which as you have seen it, but we have not.
IIRC, that code is specifically about the temperature coming out of the CHRS. It certainly could be triggered by little to insufficient coolant coming out of the CHS tank, which could be due to low coolant. If that leak at the CCV was sucking in air to the CHR tank, then maybe there is insufficient coolant in the tank to hold the temperature with the required parameters, or even provide sufficient flow. Just spitballing here. In any case, you need to stop the leak by whatever means is necessary, then see where you land.
Maybe also take a peak under and near the CHS tank and make sure that the plumbing there isn't leaking. Remove the 4 fasteners on the bottom/front of the driver's side wheel well liner and pull it down and back to get access. If the coolant was changed it's possible that the drain valve there wasn't closed all the way. It is also somewhat exposed to road debris, although I would expect a hit hard enough to break things would also have ripped up that liner.
What's the correct bleeding procedure for the coolant valve replacement? I'm going to clamp all 3 hoses before removing to reduce the amount of coolant lost... but I'm assuming I'll still need to bleed the system afterwards.
Watch these: If the overflow tank does not already have the midpoint marked (use a Sharpie) do that first and adjust the level to that point. This is a good idea in any case since it makes it much easier to detect when coolant is being lost. Then if you only lose a tiny amount of fluid during this procedure you can just drive normally and each morning refill to that mark. In a couple of days all of the air will be out. A larger amount of air should be bled though. Check if the coolant is due for a change. If so do that at the same time. With all the coolant out first you won't have to plug the 3 hoses, which is actually a little bit of a pain because there is so little room in and around that valve. Replace the valve and refill the coolant. Do the full bleeding procedure as above. Use an airlift device if you have one. A couple of us have filled from the bottom, which worked better, in terms of trapped air, for the first person who tried it than it did for me. https://priuschat.com/threads/refill-engine-coolant-without-trapped-air-unique-method-gen-2.257664
Well, I replaced the valve - much tougher than I thought it would be which is pretty much always the case! The clamp holding one of the hoses was positioned facing the bottom so took me 45 minutes alone to get that thing off! Getting the coolant valve bracket bolt threaded and tightened was also a @!%@#. I also somehow lost a 10mm socket. I clamped all the hoses but still lost a significant amount of coolant - maybe 2+ quarts... I had bought a set of clamping pliers off Amazon that obviously did not work that well! After the replacement, I filled up the coolant reservoir to the halfway mark, then I attached a Lisl funnel to the radiator and opened the radiator bleeder port a few times. Following that, I used the jumper trick to force the CHS pump to cycle and I repeated this a few times - the reading I got on my multimeter was around 3.8 and not the 3.99 or 4 shown in that video. Lastly, I started the car and cranked up the heat. At this point no further coolant was going into the radiator and I couldn't see any more bubbles. When I crank up the heat (which I did for only about 5 minutes) I'm assuming I should still have the Lisl funnel connected and filled with coolant instead of replacing the radiator cap when doing this? Also, does the low multimeter reading mean I still have air in the system? I never ran the car in inspection mode so is that something that might help or is there something else I should try tomorrow? Thanks
I wouldn’t read anything into the difference in that reading. You’re talking about 0.19 to 0.20 of (presumably) an amp. That is within the margin of error for both meters. If the multimeter shown in the first video of post #10 is the one used, it is not going to be highly accurate, just accurate enough for most around-the-home tasks.
Good to know. So my plan is one of two things - just start driving and periodically check the radiator and reservoir levels, topping up if low. Hopefully, this will expel the air over time? Or, I can try bleed one more time in the morning... but this time crank up the heat when in inspection mode and let the car run for longer - at least 10 minutes. I'll have the lisl funnel attached with coolant in it for this procedure... unless one of you suggests something else!
It should be enough to check the radiator neck once a day, for a week, in the morning before the first drive of the day. Then check once every week for a couple of weeks. After that just keep an eye on the overflow tank periodically.
