07 TCH Temp gauge drops quickly when gas engine shuts off/Occasional Rough Start

[Mario81587]

I have a 2007 TCH with 103,000 miles on it. A few weeks ago, I noticed while I was sitting in a parking lot with the car idling (after driving 20 miles), as soon as the gas engine shut off, the temperature gauge dropped almost all the way to cold within a matter of minutes. I am a college student and I sit in my car between classes and typically leave it running and it has never done this before. What could be causing this? It has this issue every time the car idles with the gas engine off. The car has a very slow water pump leak (it took 6 months to leak out all of the coolant in the overflow tank). However, I don't think there's any connection between the two. I attached a picture of the temperature gauge that I had taken a few minutes after the gas engine shut off while it was running on electric only. My first guess was a bad thermostat, but to my knowledge a bad thermostat would do the exact opposite of what my car is doing. I also am considering the fact that it could be a bad coolant temperature sensor/sender. I went to O'Reilly's Auto Parts and talked to one of the guys that worked there. He was a complete moron. First off, he told me that the gas engine never fully warms up because it's barely used, the car mainly uses battery power at all speeds, so the little 1.5 liter engine would lose temperature quickly when it shuts off (IDIOT). In addition to that, I tried getting him to look up the coolant capacity of the car, because I plan on flushing the cooling system. He told me that it probably only takes about half a gallon because the batteries don't really need much cooling. I corrected him on the engine size, informing him that it uses the same 2.4L engine found in the regular Camry and I also explained to him how a hybrid vehicle works and that there is a separate cooling system for the electric motor and gas motor... he didn't believe me. It's sad that someone like that is actually giving advice to customers that walk in there completely clueless. Anyways, I'm getting off topic.

In addition to the temperature gauge problem, a few months ago I started up my car and a few seconds later, the gas engine came on, shaking violently as if it were running on 2 or 3 cylinders. I shut it off and restarted it two more times and it did the same thing both of those times as well, just not as bad. The fourth start up was perfect. I pulled the spark plugs (needed to be changed anyway) and noticed oil on the spark plug threads from cylinders 1 and 2. Should I be concerned about this?

Any help would be greatly appreciated seeing as my warranty just expired. Thanks!

Mario

[WhiteSands]

I did read where the radiator coolant should be replaced at 100K miles. They also recommended using the same type coolant that was originally in the system. I'm sure it's the same pink toyota coolant used to cool the inverter and MG1 and MG2. I don't know the price, but i'm sure it cost more than the standard coolants.

[ukrkoz]

well, on TCH, engine does not really idle, or work in any manner, when it shuts off. All your gauges and fans run off auxiliary battery then, and water pump is not spinning.
sort of common sense thinking, no engine running, no heat produced, right?
if you have leaky water pump (welcome to the club) and it's no being spun with engine not spinning, there is no heat exchange between engine and radiator.
coming from cold country, I know that engine temp drops down very fast, if you turn engine off and it is cold outside.
what I am suspicious of is that your coolant level is simply low, or you have air plug somewhere in the system. if you ran out of coolant in expansion canister, you bet air was sucked into the system and needed to be purged.
what you need to do is to fix the pump, which is - replace it. hate to sound corny and cold, but it's expensive car to own for a college student. 95 Civic would have been a much much better option.
and agree with me, if gas engine is not running, there's nothing to produce heat, right? plus, you prolly have fan running while you inside, and then heater core becomes a 2nd radiator.

[WhiteSands]

Once the engine and heater is fully heated, I set the fan speed to 1 or 2 graph marks. I find when sitting still in a cold parking lot with the heater on and engine off, the slower fan speed, allows the heat to last longer.

[Mario81587]

I was going to get a cheaper car, but I could not resist getting this car when I saw the price - $14,899 in July 2010 at CarMax with 65k miles and it has every option available on the 2007 model year. The exterior does not have a single dent and the interior is almost perfect, aside from the unusually heavy wear on the driver's seat. At the time, it was nearly $6k below blue book. I figured with the amount of gas I'd be saving, it'd be a win-win situation. As for the temperature gauge issue, the temperature was in the 70s outside when it started having this problem. I have filled the coolant reservoir back up about two weeks ago and have been keeping and eye on how fast the coolant level is dropping. As of right now, it moved down maybe 1/4 of an inch. I have a new water pump and thermostat, I just haven't had time to install them because of me always being at school. I'm also going to drain and fill the transmission fluid while I'm down there. I guess my main concern is the temperature gauge suddenly dropping as quickly as does and the oil on the spark plug threads. I'm on the coast of North Carolina, so the weather isn't cold just yet and the temperature gauge hasn't always done this.

[ukrkoz]

sorry to be this way - there's always (never good) reason it costs what it costs. good cars are keepers. no one sells keepers.

I just can't rid of memories of my Russian car Moskvitch. It was badly overheating and boiling. when it'll boil, it'll expel water (what coolant?) out through a drain hose in radiator neck (what expansion canisters?) and the temp on temp gauge will radically drop down right away. mof, I knew I was low on water because of that temp drop.

with that being said, I am repeating myself on 2 points.
1. you very likely have air in the cooling system. this may easily cause poor circulation and temp drops. air is very poor heat conductor plus it badly influences circulation.
2. like I said. It's hybrid engine. IT DOES NOT IDLE per se. ICE kicks in to warm up cat and whatever else is needed to stay warm, turns off - your heat source is shut down. even better, even if you want to rev engine and keep it that way to stay warm, - it won't. It's computer controlled engine, you gas pedal is nothing more than a potentiometer. You can press it to the metal all you want to, ECM will allow only short RPM boost, followed by normal idle speed to ICE shut down.

it is virtually impossible to keep that engine running for "keep me warm" purpose.

oil on spark plugs means leaking valve cover gaskets and seals, and rocker arm towers seals. It's about 30 minute job if you know what you doing. on a regular car. that being a hybrid and I-VVTE engine, who knows how long and complicated it may be.

[rainbowchaser]

I'm., not sure if the "bleeding" process to get air out of the coolant system is the same in the TCH as other vehicles. The normal process is:

1. Raise the front of the car a few inches (a modest incline or some wood blocks under the front tires will suffice)

2. With the engine cool (no pressure in the coolant), carefully release the radiator cap.

3. Make sure the overflow is filled to above the "low".

4. Start the car and run it until it is fully warm (this is the hard part for the TCH). As the coolant warms up the level at the radiator cap should rise. Ideally you want to warm it until the thermostat opens and this could be the point that a good air bubble will "perk" out of the coolant system.

5 Put the radiator cap back on, making sure the coolant level is all the way full in the radiator.

6. Confirm the coolant level in the expansion tank is between low (cold) and full (hot).

In your case, if you have not yet replaced the water pump, you will want the coolant level in the expansion tank at the higher level you are now already filling it to.

[AML]

That much of a temperature drop in such a short amount of time is definitely not normal. Even in the winter if I sit in the car with all accessories and heat off, the ICE will stay off until it drops about two bars from normal before kicking back on (if I'm sitting at idle).

The violent shaking upon starting is probably your water pump. I noticed that same startup violence in mine a while back. I had the dealer check the water pump specifically, but they didn't notice anything out of the ordinary. A couple months later I was losing a lot of coolant and noticing the pink spray everywhere in the engine compartment. Replaced the pump and haven't noticed it since. Initial ICE startup is going to be rough no matter what in the winter, but it should not be violent or making abnormal noises (in my case I had a grinding noise that sounded like dragging plastic across rough asphalt).

As for the O'Reilly's guy. Those guys make little more than minimum wage and the typical person visiting their store isn't likely to be driving a Hybrid. You can't expect them to have in-depth knowledge of a Hybrid system.

Originally Posted by ukrkoz

sorry to be this way - there's always (never good) reason it costs what it costs. good cars are keepers. no one sells keepers.

Of course people sell good cars all the time. What if they wanted to get into something different? I sold a perfectly good Mercedes because I wanted to give the Hybrid a try.

[Mario81587]

Thank you everyone for all the help. I plan on installing a new thermostat, water pump, and properly draining and refilling the cooling system asap. I know that sometimes people get rid of their cars because they start having problems, however, this is the first time this car has given me any major trouble at all. I've put 40,000 miles on it so far and aside from finding oil on two of the spark plug threads and the current issue I'm having with it, it has been a great car. It does not burn any oil at all and after having the transmission fluid changed yesterday, it drives perfectly. Everyone that sees my car thinks that it is brand new. My best friend didn't even know that it had 103,000 miles on it. Actually, the guy that drained and filled my transmission fluid yesterday thought it was brand new and was shocked when I told him that mileage. I have owned a lot of cars since I was 16 (I currently have 2), and I must say that this is the best car I have ever owned.
I bought this car without shopping around much because my other car, which was my only car at the time, sucked up water through the intake and locked up the engine. I didn't think my insurance company would pay to fix that, even though they eventually did, so I bought the Camry from CarMax. I still can't believe how low the price was. They had a base model 07 Camry LE sitting next to it for the exact same price. The rest of the Camry Hybrids and regular Camry's were over $20k (mine was $14,899).
On the other hand, I have bought a used car before that ended up being a flood vehicle. I returned it to the dealer that I bought it from and complained until they refunded my down payment. So I guess there's always a risk in buying a used car versus buying a new one.