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Sorry for the clickbait, but I have a real mechanical dilemma that I've had trouble getting a response to in the past. (Hopefully) now that I have your attention, I just want to say that I love my CT and it's actually one of my favorite cars, but I am having an mechanical/existential crisis at the moment. I am really hoping to get some expert or at least sound advice here, so if you know anything please weigh in!

The car: 2012 ct200h base, 174k miles, 3rd owner, 2-3k miles driven were mine
The issue(s): Engine overheating, stop leak in the cooling system, Code P148F, triangle of death (check hybrid system), check engine light, white smoky exhaust, no heat on passenger side or windshield defrost (fixed)
Other factors: Cooling system flush performed, thermostat replaced, water pump replaced (neither were bad it seems), code reset, no coolant or water in oil, no shake or rough start, no actual leak (unless the stop leak solved this, but I can't know for sure)
The story:
My car has been trying to overheat intermittently since I bought it almost a year ago. The coolant temp. warning light would flash then go away before I even had a chance to pull over, so I thought it's probably a bad sensor and didn't rush to address it. Instead, I did a bunch of digging over time and never found any useful information, so I took a wait and see approach. Last month it finally took a **** and gave me the triangle of death. It tripped the fail safe to run exclusively on the ICE so it wouldn’t overheat the hybrid battery. The code it gave was P148F - engine coolant pump over revolution. I unhooked the battery and no more code, no more warning lights, car performs normally again, but still overheating.

I took it to Lexus where they charged me $130 to do exactly nothing. They wanted to charge me another $400 to do a coolant flush after they found stop leak in the reservoir that the last idiot of an owner botched whatever job they were trying to perform by not flushing it out of the system (and using it to begin with.) I did it myself instead for maybe $30 total, dumped the sludge, flushed under pressure with one of those hose kits, replaced the thermostat, then flushed the system normally while getting the engine up to temp to open the thermostat about 10 times with distilled water until it ran completely clear. Plus I did a blue devil coolant flush for about 2-4 hours and drove it (or whatever was close to the max time recommended in the instructions,) then replaced with coolant and continued with testing in maintenance mode ever since. During this process I also ran the heater which would blow very hot throughout the cabin after the car was up to temp, but during some tests it would blow cold just before it started to overheat. I would then stop the car, and found the coolant boiling and overflowing out of the reservoir, which could be what the last owner mistook for a leak. The flush seemed to solve the heater problem, so I don't think the core could be clogged. I was draining the system from the radiator petcock, so that wasn't clogged either. My last resort was replacing the water pump, which did not help either. BY THE WAY, the first replacement pump I got from Amazon was seized, so if you order from them be on the lookout for defective parts. Just a final note, I did not start to get smoky exhaust until after I had flushed the system. Again, I am not seeing any other tell tail signs of a bad head gasket, but what else could it be?? As far as having the head gasket replaced, I am considering doing it myself, but also entertaining the option of a whole new engine when I can get one with 50k miles for $1400. A HG fix upwards of $2k just doesn't make much sense to me as a first resort if that is indeed the problem. I figure that if someone wants to charge me $2k to fix a head gasket vs. replacing the engine with something much newer for the same price then I might as well try to do the head gasket myself first, then possibly replace with a newer engine. Also, does anyone know of or recommend a good head gasket kit? Thoughts please! Thanks for reading.
 

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So no oil in water and vice versa?
Are you losing coolant now?
Stop leak is hideous and should never be put in this system. Does more harm than good.
If all is well how about checking the radiator itself. It might be partially clear and flowing but could also be clogged with Stop Leak that the previous owner used. Maybe the rad got struck and holed somewhere?
If you can access a bore scope it might be worth looking inside each cylinder with the plugs removed for signs of coolant or bore wash.
Good luck


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Discussion Starter #3
So no oil in water and vice versa?
Are you losing coolant now?
Stop leak is hideous and should never be put in this system. Does more harm than good.
If all is well how about checking the radiator itself. It might be partially clear and flowing but could also be clogged with Stop Leak that the previous owner used. Maybe the rad got struck and holed somewhere?
If you can access a bore scope it might be worth looking inside each cylinder with the plugs removed for signs of coolant or bore wash.
Good luck


Sent from my iPhone using Tapatalk
Thanks for the quick reply! You don’t have to talk me how bad stop leak is, it kills me that someone did this. No, there is no coolant in the oil and vice versa. It could be the radiator or the core still, perhaps? There is definitely no leaks that I have noticed and I’m not losing coolant—besides the small amount that is burning off from the excess heat. What really baffles me at this point is the white smoke in the exhaust, which is the newer development after doing the flushes. Have any ideas about what it could mean? I guess I’ll try to get my hands on a bore scope next.
 

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It’s quite possible that there could be a small seepage of coolant getting into one of the cylinders hence the smoke.
Without being able to look into the bores for now maybe look for any differences with the spark plugs.


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Sorry for the clickbait, but I have a real mechanical dilemma that I've had trouble getting a response to in the past. (Hopefully) now that I have your attention, I just want to say that I love my CT and it's actually one of my favorite cars, but I am having an mechanical/existential crisis at the moment. I am really hoping to get some expert or at least sound advice here, so if you know anything please weigh in!

The car: 2012 ct200h base, 174k miles, 3rd owner, 2-3k miles driven were mine
The issue(s): Engine overheating, stop leak in the cooling system, Code P148F, triangle of death (check hybrid system), check engine light, white smoky exhaust, no heat on passenger side or windshield defrost (fixed)
Other factors: Cooling system flush performed, thermostat replaced, water pump replaced (neither were bad it seems), code reset, no coolant or water in oil, no shake or rough start, no actual leak (unless the stop leak solved this, but I can't know for sure)
The story:
My car has been trying to overheat intermittently since I bought it almost a year ago. The coolant temp. warning light would flash then go away before I even had a chance to pull over, so I thought it's probably a bad sensor and didn't rush to address it. Instead, I did a bunch of digging over time and never found any useful information, so I took a wait and see approach. Last month it finally took a **** and gave me the triangle of death. It tripped the fail safe to run exclusively on the ICE so it wouldn’t overheat the hybrid battery. The code it gave was P148F - engine coolant pump over revolution. I unhooked the battery and no more code, no more warning lights, car performs normally again, but still overheating.

I took it to Lexus where they charged me $130 to do exactly nothing. They wanted to charge me another $400 to do a coolant flush after they found stop leak in the reservoir that the last idiot of an owner botched whatever job they were trying to perform by not flushing it out of the system (and using it to begin with.) I did it myself instead for maybe $30 total, dumped the sludge, flushed under pressure with one of those hose kits, replaced the thermostat, then flushed the system normally while getting the engine up to temp to open the thermostat about 10 times with distilled water until it ran completely clear. Plus I did a blue devil coolant flush for about 2-4 hours and drove it (or whatever was close to the max time recommended in the instructions,) then replaced with coolant and continued with testing in maintenance mode ever since. During this process I also ran the heater which would blow very hot throughout the cabin after the car was up to temp, but during some tests it would blow cold just before it started to overheat. I would then stop the car, and found the coolant boiling and overflowing out of the reservoir, which could be what the last owner mistook for a leak. The flush seemed to solve the heater problem, so I don't think the core could be clogged. I was draining the system from the radiator petcock, so that wasn't clogged either. My last resort was replacing the water pump, which did not help either. BY THE WAY, the first replacement pump I got from Amazon was seized, so if you order from them be on the lookout for defective parts. Just a final note, I did not start to get smoky exhaust until after I had flushed the system. Again, I am not seeing any other tell tail signs of a bad head gasket, but what else could it be?? As far as having the head gasket replaced, I am considering doing it myself, but also entertaining the option of a whole new engine when I can get one with 50k miles for $1400. A HG fix upwards of $2k just doesn't make much sense to me as a first resort if that is indeed the problem. I figure that if someone wants to charge me $2k to fix a head gasket vs. replacing the engine with something much newer for the same price then I might as well try to do the head gasket myself first, then possibly replace with a newer engine. Also, does anyone know of or recommend a good head gasket kit? Thoughts please! Thanks for reading.
See post #76 here: Bad head gasket or bad head due to violent shudder This was a great solution for relatively low cost.
 

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Discussion Starter #6
See post #76 here: Bad head gasket or bad head due to violent shudder This was a great solution for relatively low cost.
Hi Tom, thanks for the input. That does make me think more that it’s a head gasket, I really have no other explanation. And now that I think about it, one of the last times that I drove it-after the system flush- it did get some engine shake so I shut it off immediately. I completely forgot about that because otherwise I have not experienced any shake, only the temp warning and coolant overflow, which is what causes me to question it. I’m going to have to get some estimates this week.
 

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Hi Tom, thanks for the input. That does make me think more that it’s a head gasket, I really have no other explanation. And now that I think about it, one of the last times that I drove it-after the system flush- it did get some engine shake so I shut it off immediately. I completely forgot about that because otherwise I have not experienced any shake, only the temp warning and coolant overflow, which is what causes me to question it. I’m going to have to get some estimates this week.
Hi MammaMia
I wasn’t at all sure I wanted to fix the car when I got those big estimates. Sell it, maybe, on Craigslist as a “mechanics special”. That all changed when I found these guys who would fix it in front of my house for 1/3 the price the local shop charged. So I guess It depends on how much it will cost you. Here’sa link to their video of how they do it.
. If you’re in the SF Bay Area, is highly recommend you use them. If not, still an interesting video to demystify the whole thing.
 

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That’s funny that you posted that. My brother sent me that same video a week or two ago and I was just rewatching this morning it to see if I want to take that on. You’re pretty lucky to have that resource nearby, I can’t seem to find anything of the sort here in central Virginia. I’m no master mechanic, but it’s a pretty fantastic guide, so I think I’m gonna give it a go. I figure that I have little to lose at this point... wish me luck!
 
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