Overheating issues

[jetjock]

I applaud his thoughtfulness but without solid metrology it's just that. Me thinks he thinks too much.

Crisp: Too much instrumentation and data, or having it presented in wrong way, can be more hindrance than help. Even when it's installed and displayed correctly it can show all sorts of "problems" that were always there but aren't cause for concern. This has been studied to death and proven time and again in the aerospace sector. Course, I can't say for sure what the OP's problem is (or if one exists at all) but imho he's approaching this issue the wrong way.

 

[CyFi6]

Haha, i do admit that i am overly worried about things with my car most of the time, but its mostly because i see people all the time that aren't worried enough, and end up losing their engine because of a careless mistake. Not to mention the time and money put into the engine, and the fact that i rely on it for getting around.

The statement about the thermostat being fully open was based upon the assumption that my thermostat was working properly. I have not physically tested it, but i could also hear my fan roaring with temps going up which led me to believe the hot coolant was getting to the radiator. I cant get a good shot of the radiator with a temp gun because i have the condenser in front of it, and i don't think i will get accurate readings shooting it through the moving fan blade.

This was originally an NA Manual trans car, so i upgraded from the single aux fan to the dual aux fan, and they do not come on with engine temperature(not sure if this is specific to the body or what, but there was not even a connector for it in my harness), they are only triggered by the AC high pressure switch, and they only come on if the ac is turned on. In other words, the AC can be on with the fans running but as soon as i turn off the ac the fans kick off. I watched a manifold gauge and they seemed to turn on when the high side pressure reached around 275psi IIRC. I also don't have a pusher fan, which IIRC was only for the automatics.

I am fine with it as long as its nothing to be concerned with, i just don't want to toast a motor because i neglected to fix an apparent issue. What temp exactly would be considered harmful for the engine to be running at? From searching it seems that around 220 deg is when you should be shutting down and pulling over, but that's also if you are driving, maybe for idling in the heat its normal.

I will give the thermostat a shot regardless and see how it works for me.

 

[3p141592654]

I routinely see 225F on my wife's Volvo using the OBD2 logger on a hot day typically after a freeway run followed by city driving. I don't think 220F is anything to worry about.

You may find this interesting. The factory gauge will start to rise at 240F (115C).
http://www.supramania.com/forums/showthread.php?47479-Temp-Gauge-Calibration

 

[te72]

I discovered the 115C thing about the stock gauge a few months ago... I'm more or less in the same boat as Cyrus here, blown up enough 7m's to be paranoid about that temp gauge haha! It seems to reason that removing the rear seal where the hood meets the firewall is a good way to alleviate heat, is it not?

 

[crisp]

I discovered the 115C thing about the stock gauge a few months ago... I'm more or less in the same boat as Cyrus here, blown up enough 7m's to be paranoid about that temp gauge haha! It seems to reason that removing the rear seal where the hood meets the firewall is a good way to alleviate heat, is it not?

Hmmm... I've never read that! Is that a "suggested" mod somewhere??? What are the caveats to doing so?


-crisp

 

[jetjock]

It won't do much other than allow engine stink into the fresh air vents.

Keep up on maintenance and there's no need for worry. In 22 years of driving under all sorts of conditions the Sonalert wired to the #2 water temp switch on my car never once sounded. That means the coolant never went above 234. As long as I didn't hear that thing beeping I didn't care...

 

[crisp]

It won't do much other than allow engine stink into the fresh air vents.

Keep up on maintenance and there's no need for worry. In 22 years of driving under all sorts of conditions the Sonalert wired to the #2 water temp switch on my car never once sounded. That means the coolant never went above 234. As long as I didn't hear that thing beeping I didn't care...

DONE! (My rear hood seal policy is now firm.)


-crisp

 

[jetjock]

People can do as they wish but Toyota put it there for a reason and I'd personally rather not be inhaling CO should an exhaust leak develop. I suppose the argument could also be made that removal cuts airflow over the bell housing and transmission (assuming the undercover is in place) but I'm not going there. Not much if any gain me thinks. Like trying to empty a bucket under a waterfall with a spoon...

 

[te72]

Hmm... makes sense. My car never came with one when I bought it, nor did it have an under tray. The tray has been on my list of things to get at some point, think I might reinstall that seal too. I stand corrected.

JJ, what are your thoughts on the Stout hood's ability to alleviate heat?

 

[crisp]

People can do as they wish but Toyota put it there for a reason and I'd personally rather not be inhaling CO should an exhaust leak develop. I suppose the argument could also be made that removal cuts airflow over the bell housing and transmission (assuming the undercover is in place) but I'm not going there. Not much if any gain me thinks. Like trying to empty a bucket under a waterfall with a spoon...

For the more stubborn yet visually cognizant among us, JJ... love your imagery!



-crisp

 

[CyFi6]

Well i changed my thermostat to a 180 superstat. Also tested the OEM stat that i pulled out, and it was good going to full open after about 200-205 deg i believe. it runs cooler during normal driving but again at a standstill it continues to climb, just takes longer to get to the same temp. I think the problem is the AC though. I have tried searching all over the net for what condenser temp should be but i get nothing besides how much of a drop there should be across the condenser, but at idle when heating up, condenser inlet fitting is at ~230deg F, which i think is hotter than its meant to be with r12 (its r134a right now). Im getting the system converted back to r12 soon hopefully so i hope that helps. I may try to source a pusher fan to aid in idle airflow as well.

 

[te72]

Our cars came with condenser fans between the intercooler and condenser, but I have seen VERY few cars that still have them. You have one on yours Cyrus? Might help explain the problem being a/c related...

 

[CyFi6]

I have the two auxiliary fans behind the radiator (converted from the single aux fan) but no condenser fan in front of the condenser. I know which fan you are talking about, but since my car is originally an NA Manual trans car, it never did come with one from the factory. Also, supras that had that fan have the receiver/dryer for the ac on the left side of the car, but mine has it on the right side of the car, so it wouldn't be a bolt in affair if i did get my hands on one.

 

[Nick M]

I have tried searching all over the net for what condenser temp should be but i get nothing besides how much of a drop there should be across the condenser

When the A/C is running, it is taking heat from the cabin and putting in the condensor. From there, it radiates to the atmosphere, right in front of the radiator. It is going to be hot when the A/C is on. This should help.

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=144

Our cars came with condenser fans between the intercooler and condenser, but I have seen VERY few cars that still have them. You have one on yours Cyrus? Might help explain the problem being a/c related...

The third fan is for automatic cars which have an additional cooler for the trans fluid.

 

[CyFi6]

It is going to be hot when the A/C is on. .

I understand its it going to be "hot". "Hot" could be anything from 100 deg to 1000+ deg. Seeing how R134a is said to run "higher pressures and temperatures", its my theory that my condenser is getting hotter with r134a than it would with r12, causing more heat to be expelled and pulled through the radiator, possibly reducing the temperature differential for my radiator and causing my engine to run hot at low airflow situations.

 

[3p141592654]

In order to generate more heat it would presumably need to be removing more heat from the cabin, an unlikely scenario given that R134 conversions are less efficient than with the original R12 charge.

 

[CyFi6]

Thats what i was thinking too, but with the pressures this thing is reaching on the high side(gets high enough to shut the compressor off when idling long periods in direct heat) i would think temps would be higher than normal too. All i really dont know is, what a properly charged r12 system runs condenser temperature wise on a hot day, just seems like 230 deg is very high. Regardless, im converting to R12, so i will see what kind of changes it makes.

 

[grimreaper]

never saw over 200*F coolant temps even with a BHG in 100*F ambient stop and go traffic with ac on.

 

[3p141592654]

A general rule of thumb for R12/R134 is to keep the condenser below 125-135C.

 

[CyFi6]

never saw over 200*F coolant temps even with a BHG in 100*F ambient stop and go traffic with ac on.

I dont know how you did it lol. My temps start going up at idle. New fan clutch new shroud huge radiator...whole cooling system is brand new. I dont understand. Are you sure your gauge was accurate?

A general rule of thumb for R12/R134 is to keep the condenser below 125-135C.

Thats good to know, thank you