Overheating issues

[modmonster2008]

perhaps upgrading to a higher pressure radiator cap may help? idk as our family van always varies in temp after driving for a long time starts off at 1/4 temp then goes all the way up to 3/4 but not close to the red area yet then slowly falls back down after turning a/c off

 

[CyFi6]

http://www.supramania.com/forums/showthread.php?77282-radiator-seem-credible&highlight=koyo+overheat

Well i read all through that thread and a lot of the info there from very knowledgeable people seems to be contradictory to some of the info in this thread. Basically they are discussing that if temp goes over the thermostat temp and is rising, you are out of cooling capacity, and changing to a lower temp stat will merely make it take a little longer to get to the overheating temp ("30 seconds"). Sitting in traffic yesterday, no ac (condenser not even in the car), about 105 deg outside, stop and go, temps were hitting ~203 slowly rising unless i started moving. The fan would sound like a semi truck, roaring, bring temps down very slightly, then they would slowly start rising again at idle. This is all with a 180 degree superstat t stat(tested before putting it in). Once the car was moving again at ~50mph temps went back to about 183. Still not understanding what is wrong here. The other thread says anything over the thermostat temp is overheating, this thread says anything up to about 230 is fine and nothing to worry about.

Trying not to over analyze but my car seems to have an obvious problem, and with ac on in stop and go traffic temps would hit 225 still slowly rising and i just don't feel comfortable with that.

If i check radiator temperature at the top and bottom, sitting idle in about 105 ambient, what should the temperature drop be? Only thing i can think to test is the radiator, even though it is brand new. (Read somewhere to check temp drop across radiator just after shutdown, and it should be around 50 degrees F, is this accurate?

EDIT: I can see coolant temp rising significantly at idle, and pretty fast. Even at a stoplight that doesn't take a huge amount of time, i can see the gauge rising pretty quickly from ~183 up to 185 to 190 to 195 and by then i am usually on my way and temps come back down.

 

[SupraCorwin]

Have you tried un-blocking off the heater core? Might get you a few degrees cooler, even with out turning the heat on.

 

[crisp]

So... I reread a few pages back, and can't remember if we answered the question: Does the STOCK gauge wander above "mid-point" (rise toward the red) at any point in time? (Or was it REPLACED altogether with the aftermarket, and subsequently more responsive gauge?) ...not always HELPFUL if the several degree variance is alarming yet completely within the sensitivity of the oem unit...


(Although my aftermarket DOES wander... I am not seeing temps in the 200* range... even with pretty aggressive setup. On the other hand, KOYO radiator and other tuning elements keekp me on the "rich" and "safe" side in many respects, including cam timing and ignition, so perhaps I can't judge the oem/aftermarket gauge relativity next to a mostly stock vehicle...)


Still curious where your issues lies... be sure to post if there IS a EUREKA! moment to this whole thing!


-crisp

 

[CyFi6]

Have you tried un-blocking off the heater core? Might get you a few degrees cooler, even with out turning the heat on.

Have not done that, but the heater core ports are not blocked, the heater core is bypassed, so coolant still flows, just through a hose not a heater core.

So... I reread a few pages back, and can't remember if we answered the question: Does the STOCK gauge wander above "mid-point" (rise toward the red) at any point in time? (Or was it REPLACED altogether with the aftermarket, and subsequently more responsive gauge?) ...not always HELPFUL if the several degree variance is alarming yet completely within the sensitivity of the oem unit...


(Although my aftermarket DOES wander... I am not seeing temps in the 200* range... even with pretty aggressive setup. On the other hand, KOYO radiator and other tuning elements keekp me on the "rich" and "safe" side in many respects, including cam timing and ignition, so perhaps I can't judge the oem/aftermarket gauge relativity next to a mostly stock vehicle...)


Still curious where your issues lies... be sure to post if there IS a EUREKA! moment to this whole thing!


-crisp

Stock gauge was completely replaced. If i had the stock gauge still it wouldn't even move, because someone did some testing and the stock gauge doesn't even move until about 240 degrees, but people say by that time you are already in trouble. Many people are running aftermarket gauges and not reaching temps this high. I can understand the stock gauge is meant to hide normal fluctuations in temperature for instance exiting off the freeway on a hot day with ac on sitting idle, but to be running at the temps i am on a regular basis doesn't seem right.

Il keep searching, im going to check the radiator temp drop today while its running hot or right after shutdown like i remember reading and post up the results.

 

[3p141592654]

I see no conflict between the two threads.

If coolant rises above the thermostat opening temp then you are out of coolant capacity, but that capacity limit can be mitigated, for example by turning on an electric fan, if air flow limited such as at idle or low speeds.

At idle, cooling systems are air flow limited, so even the largest rad will be ineffective if the air flow through it is insufficient. The 7M uses a mechanical primary fan, which has limited flow at idle. It is augmented by up to three electric fans that turn on at various temperature thresholds (e.g. condenser fan temp switch no 2 goes on at T=212F). So clearly, Toyota has no issues with temperatures rising above 192F, and when it happens they uses electric fans to mitigate the rise. If your goal is to have the temperature stay at 192F regardless of conditions, good luck.

 

[Nick M]

Still not understanding what is wrong here.

Neither am I.

Trying not to over analyze but my car seems to have an obvious problem

But you are. What makes you think the temperature will sit in one spot and not move when you increase heat in the radiator, and there isn't an increase in airflow over the radiator?

But just for fun, is your timing at 10 degrees?

 

[CyFi6]

I see no conflict between the two threads.

If coolant rises above the thermostat opening temp then you are out of coolant capacity, but that capacity limit can be mitigated, for example by turning on an electric fan, if air flow limited such as at idle or low speeds.

At idle, cooling systems are air flow limited, so even the largest rad will be ineffective if the air flow through it is insufficient. The 7M uses a mechanical primary fan, which has limited flow at idle. It is augmented by up to three electric fans that turn on at various temperature thresholds (e.g. condenser fan temp switch no 2 goes on at T=212F). So clearly, Toyota has no issues with temperatures rising above 192F, and when it happens they uses electric fans to mitigate the rise. If your goal is to have the temperature stay at 192F regardless of conditions, good luck.

I understand, but my goal is not to stay at 192F regardless of condition, my goal is to not consistently run 220+ when the system is designed to run at 180 with a 180 t stat. Basically, this thread seems to say temps of 225+ and rising with a 180 stat is normal, whereas the other thread seems to state it is not.

Neither am I.



But you are. What makes you think the temperature will sit in one spot and not move when you increase heat in the radiator, and there isn't an increase in airflow over the radiator?

But just for fun, is your timing at 10 degrees?

Timing is at stock 10 deg BTDC. I don't expect it to stay the same, but i don't expect to have an increase of 40+ degrees over thermostat temp and still slowly rising. I would expect the stock cooling system to be able to pull enough air to prevent that.

220 is pretty bad.... 240 is well into the danger zone.

YOU ARE GAINING NO MARGIN. YOUR COOLING SYSTEM IS ALREADY MARGINAL. THE T-STAT CAN NOT MAKE THE ENGINE COOLER ONLY THE RADIATOR AND WATER PUMP CAN.

get a fan shroud on there and I can almost guarantee you won't go over the T-stat's opening setting. That is the way the system is supposed to work. If that doesn't help you have other issues you need to track down.

Cooling system on a 7M is not something to assume is up to the task. One overheat and you have a warped head and a BHG...

If you have excess cooling capacity temp doesn't rise.

These are some of the things that seem to conflict.


BTW please nobody take this as me arguing against you in any way. Im just trying to get the facts and they don't seem to add up. All im worried about in the end is my engine overheating, whatever overheating really means. At what temp do things start seeing damage? What exactly is it that sees the damage first? The aluminum head? If im sitting at 225 degrees and i shut my engine down and leave the car, who knows how much temps will rise because of heat soak, maybe to the point of damage? No idea... Everything just tells me running an aluminum head engine that hot isn't right, but then again what do i really know.

 

[te72]

Cy, I have seen temps as high as ~120*C on my 1j, due to the fact that my fan doesn't kick on by it's own free will until around 118 or so. I've since added a manual switch and just keep an eye on it, but my issue is probably different from yours. Anyway, to answer your question about damage, I can't honestly say that getting mine that hot caused any permanent damage to anything. Still running fine after it did that a couple times in April, and I drive the shit out of my car more or less daily.

7m though... I never had much luck with them and heat, gotta say.

 

[CyFi6]

Now that summer is approaching again...I just want to confirm- It is OK and perfectly safe for coolant temp to rise above 225-230 degrees Fahrenheit with the engine idling and the A/C on. Yes or no? That is all I need to know...

 

[jetjock]

Mine never did but assuming you've got the standard .9 bar cap you're good to nearly 250 F...

 

[CyFi6]

Thanks JJ that is all I need to know. As long as I am not doing any physical damage to the aluminum head etc!

 

[grimreaper]

AC should kick off at 212*. Are all the sensors in the water neck hooked up properly? I've had my ac kick off once due to temps. extended idle in bumper to bumper traffic last summer or the summer before. Temps stabilized and started dropping slowly after the ac kicked off.

 

[3p141592654]

More likely over-pressure, not temps, although obviously there is a relation.

 

[CyFi6]

Now that you mention it you are right. When things started getting hot the ac was kicking on and off from high side pressures being too high and wasn't cooling very well at all anymore. Apparently the stock fan pulls more air than any electric could but its still not enough for idling in the summer with the ac?

 

[te72]

Lemme ask you this, how often has your house's a/c been unable to cope with the temperatures of Phoenix? A/c has a tough job to do down there man, especially when it's in an underhood environment along with a turbocharged engine... just saying, perhaps you're asking a bit too much out of it? I can't say I've known too many guys down there with working a/c in a turbo car, although I can understand why you still want it.

 

[CyFi6]

Lemme ask you this, how often has your house's a/c been unable to cope with the temperatures of Phoenix? A/c has a tough job to do down there man, especially when it's in an underhood environment along with a turbocharged engine... just saying, perhaps you're asking a bit too much out of it? I can't say I've known too many guys down there with working a/c in a turbo car, although I can understand why you still want it.

I like things on my car to work as they should from the factory, and as far as i know, they never issued a warning upon purchase that stated AC will not function properly in Arizona during the summer.

 

[3p141592654]

Since the condenser is in front of the radiator, the only reason it would not be cooling sufficiently is if there is inadequate air flow from a fan/shroud issue, blockage from debris, or corrosion and damage to the condenser fins, assuming the A/C is in otherwise good working order.

 

[CyFi6]

Since the condenser is in front of the radiator, the only reason it would not be cooling sufficiently is if there is inadequate air flow from a fan/shroud issue, blockage from debris, or corrosion and damage to the condenser fins, assuming the A/C is in otherwise good working order.

Trust me i have been battling with this forever. Every shroud/undercover is in place, brand new Tundra fan clutch, stock dual electric fans, strait fins on condenser and radiator, entire system flushed, all new seals, new compressor, new txv, new drier, new hoses, fresh R12 charge, everything... The system is still sub par IMO and quite honestly fails at stop and go low speed performance (keep in mind I'm referring to 95-116 ambient temps here). Next to IMPROVING the stock system somehow, there is nothing else left to fix... You must also realize i tend to be picky about things, but in this case I hardly feel I am being over critical. Get in a GM truck and you have instant ice cubes pouring out the vents no matter how fast you are traveling, no matter how long the car has been baking in the sun. Get in my car after work and by the time I get home (only a few miles) the vent temps are barely cool enough to yield any kind of relief. I have poured many hundreds of dollars into it trying to get it to work right, doing anything from attempting to fix it myself to giving the car to a reputable high end A/C shop, only to get nowhere. They claim the system is working as well as its going to... Unfortunately, the system works great with the hood up, in the shop, and sitting at 2000 rpms like it is supposed to, but sadly there is no on the road low speed performance tests listed by the manufacturer therefore those tests are invalid. The system does everything the manufacturer says it should, but it doesn't do what many people i have heard on here claim it should. See where my frustration comes from?

If there is any info in regards to how to approach the issue (if it is actually an issue, rather than a weak system) i would gladly accept any input.

 

[3p141592654]

What is your subcooling on one of these hot days?