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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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 how cool is too cool?
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Thu, 17 February 2005 05:52
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Need some info on what the running temperature ranges are supposed to be on internal combustion engines. I found my limits on running a hot engine, now I just want to know if there's any adverse side-effects of having the engine running cool.
Thanks.
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Location:
Epping, Sydney
Registered:
April 2003
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Re: how cool is too cool?
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Thu, 17 February 2005 06:03
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hey andrew! long time no talk.
I am no scientist, but this is my understanding (and also relates to thrashing your car when cold)
Any temperature except for the temperature the car is designed to run at is either too hot or too cold.
When the ol' girl was designed they calculate tolerances based on expansion (or contraction) based on metal temps. So, when it's cool, then the clearances will be larger than ideal, and given the oil pressure of X things might tend to bang around a bit.
Which is one reason why cars wear out more when cold, because there are larger clearances and blah blah?????
I could be wrong, but it's my understanding yeah
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Location:
Perth, WA
Registered:
December 2004
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Re: how cool is too cool?
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Thu, 17 February 2005 06:04
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youll never get the engine up to operating temp, which... how to describe it...
if you have access to a carby car..
get in at about 6 in the morning, after a cool night, and start it, get it running by revving it for a few short pumps, and take off, and thats how your engine will perform, youll see it lacks power and throttle response..
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Location:
England
Registered:
November 2004
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Re: how cool is too cool?
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Thu, 17 February 2005 07:20
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Most cars operate at around 90 deg'C (water temp)
Most competition cars operate at an even lower temperature, usually 70 - 75 deg'C.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: how cool is too cool?
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Thu, 17 February 2005 07:52
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the problem of too low a temp is that the oil never heats up enough to allow the volatiles (like fuel etc) to vapourise, and that leads to faster oil breakdown.
keeping a thermostat and elec controlled fan will mean you will not be too cold... i had a 90deg thermostat and car ran ok with carb.. changed from an 82 deg, as the manifold was not heating enough to prevent fuel dropout (and build-up), but with EFI, car sits on 82 degrees all day (except when outside temps are over 40)
i would guess 80-85 is a good operating temp..
you also need to match your grade of oil (the hot number, ie 40, 50, 60 etc) to your operating temps..
Cya, Stewart
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: how cool is too cool?
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Thu, 17 February 2005 10:43
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Thanks for the replies guys. 
I'm only asking because I have my thermo fans setup to run fulltime after getting a major scare when we took it out to tune it last year (before the head work). The Power FC shut itself off after it got up to 120°C only because the coolant was being forced out of the system by the crack in the head, thereby allowing it to overheat.
Now I think I've gone the opposite way by over-compensating.  The engine is a hot bitch to be sure... but I have a 71°C thermostat in there and it doesn't get to opening temperature on most days, except for hot ones (the temp needle sticks to around 75°C at that point). The engine feels hot if you put your hand up against it, but the temp gauge says otherwise.
How hard is it to implement a thermo-switch? I'm after a decent one not one of those old-style ones that look like a copper probe you stick in the pipe with a pot on the other end to adjust the temp. 
What to do?..
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Location:
tas
Registered:
June 2002
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Re: how cool is too cool?
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Thu, 17 February 2005 12:24
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"you also need to match your grade of oil (the hot number, ie 40, 50, 60 etc) to your operating temps.."
Can you clarify that bit of info, that's very interesting what you say there, But i'm pretty sure you don't mean to match your operating temp of say 80C to an oil raing of 80?
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: how cool is too cool?
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Thu, 17 February 2005 13:24
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Get a thermo switch from most FWD Toyota's.
Camry's, Corolla's.
Most are switch controlled. Some are ECU controlled.
Screw this into the radiator, or somewhere in the water jacket, you might have somewhere, otherwise, get a short section of pipe to replace a radiator hose made up, and screw it in that.
Not sure what temp they run at, but I'd hazard a guess its in the late 80's.
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Location:
Brisbane
Registered:
June 2003
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Re: how cool is too cool?
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Thu, 17 February 2005 13:33
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i run an SV21 or AE92 one in my ma70 - im sure it cuts in at 90'C ill be running the same one in the ma61
Its as bad or worse to run an engine cold as it is hot...the oil doesnt heat up properly hence it doesnt lube properly...
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Location:
tas
Registered:
June 2002
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Re: how cool is too cool?
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Thu, 17 February 2005 14:06
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blake, was that much of a job to set a thermo switch from a carmy in the ma70? do you have the thermo running the stock ma70 fans? just wondering how you did it, as my fans don't come on at all, the relays must be shot, so i have a manual switch in the cabin. :(- it sux, but i gotta cool my car down somwhow.
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Location:
Land of Oz
Registered:
June 2004
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Re: how cool is too cool?
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Thu, 17 February 2005 20:36
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Hi,
Mine runs at 78C. It goes to 82C then the thermostat opens and it drops down to 78. On a stinking hot day, with the air-con running and in slow traffic she can go up to 82C and stay there.
It runs a belt-driven viscous (however its spelt) fan, but compared to newer cars the engine bay is pretty open and there's not a million pipes and conenctions everywhere, nor a big hot turbo in there.
All the newer engines seems to run hotter and I haven't figured out why this is so.
seeyuzz
river
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Location:
c'town, NSW
Registered:
May 2002
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Re: how cool is too cool?
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Thu, 17 February 2005 21:58
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most if not all toyota engines run 82deg thermostats.
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: how cool is too cool?
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Thu, 17 February 2005 22:03
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My mum says I'm cool.
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Location:
Adelaide
Registered:
September 2003
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Re: how cool is too cool?
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Thu, 17 February 2005 22:06
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| river wrote on Fri, 18 February 2005 07:06 |
All the newer engines seems to run hotter and I haven't figured out why this is so.
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It is a function of engine design, emissions etc.
It is also as you mentioned, underbonnet space. You'll also notice all of the new cars have bazillions of heatshields, and it is getting worse !!!
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Location:
Adelaide
Registered:
July 2002
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Re: how cool is too cool?
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Thu, 17 February 2005 22:41
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not to mention the huge amount of plastic crap in there too!
my corolla used to run at 200F, but would get up to 215-220 then the fans cut in and bring it back down
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Location:
Brisbane
Registered:
June 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 00:10
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| dingaling wrote on Fri, 18 February 2005 00:06 |
blake, was that much of a job to set a thermo switch from a carmy in the ma70? do you have the thermo running the stock ma70 fans? just wondering how you did it, as my fans don't come on at all, the relays must be shot, so i have a manual switch in the cabin. :(- it sux, but i gotta cool my car down somwhow.
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its a piece of piss to hook them up. i ditched the belt fan all together and just now use a pair of fans i made a bracket up for..one is a 13, one an 11. they keep her cool as a cucumber. its currently got an ma61 manual radiator in it...as that is what i originally made the fan bracket for when the ma61 had the 5m in it. What else did you need to know? for intersts sake mine never goes past say 40 to 45% of the wag on the gauge.
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 01:21
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How is it possible for a car to run colder than a thermostat's opening temperature?
River says his car runs at 78, but his thermostat opens at 82.
RavGT4 says his car runs at 68, but his thermastat opens at 71.
How is this possible?
Am I missing something?
But to me, as soon at the thermostat completey closes, the water would heat up really quickly as its not getting cooled in any way.
I can see the running temp being a couple of degrees above thermostat temp, but not a couple below.
Any ideas why?
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Location:
Sydney
Registered:
May 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 02:11
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ummm if your thermos are always on and have an oversized radiator.. (hypothecially) you could end up with it running below thermostat temp as they start opening before their listed temp.
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 02:13
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| Bugman wrote on Fri, 18 February 2005 10:11 |
ummm if your thermos are always on and have an oversized radiator.. (hypothecially) you could end up with it running below thermostat temp as they start opening before their listed temp.
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No, they start opening AT their listed temp.
And then fully open 8-10degC after the listed temp.
Unless the t/s is faulty
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Location:
brisbane
Registered:
December 2004
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Re: how cool is too cool?
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Fri, 18 February 2005 02:17
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mine barely makes it to operating temps.. my thermo fan just one.. runs all the time but its only 3 or 4 degrees off operating temp.. one seems to cool enough if its on all the time i think 2 on all the time might be a bit much.. but im no expert
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Location:
Sydney
Registered:
May 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 02:17
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have you actually tested this?
I know i have. twice.. cos I had a dead one.. and two good ones on the shelf one was 88deg and one was 82. cos I remember buying them but not which is which, using my nada certafied fluke digi temp. I had one begging to open at 78deg and other at 83deg.
ofcourse... you would need the supply water to be real cold to make it run at them temps.. thats why I said in hypothecially,
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 02:31
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| Bugman wrote on Fri, 18 February 2005 10:17 |
have you actually tested this?
I know i have. twice.. cos I had a dead one.. and two good ones on the shelf one was 88deg and one was 82. cos I remember buying them but not which is which, using my nada certafied fluke digi temp. I had one begging to open at 78deg and other at 83deg.
ofcourse... you would need the supply water to be real cold to make it run at them temps.. thats why I said in hypothecially,
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Yes, I have tested it with a thermometer.
Brand new (been in car for a few hours running), tested it because I didnt think it was working.
It began opening at 82degC, and stopped around 90ish, can't remember.
It even stats this in toyota manuals.
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Location:
Sydney
Registered:
May 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 02:35
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interesting.. maybe I have the wrong temp tstats or they just decided to operate at different temps. (that'll teach me to take things out of the packets to save space.
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Location:
Sydney
Registered:
July 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 02:47
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If you want to run your car a FEW degrees cooler (like 5 degrees) you'll get a slight power increase. You'll also get a similarly slight emissions increase.
I don't believe any cars in this thread run UNDER the thermostat temps. If they do, then the thermostats are faulty. A car should run on or just over the thermostat temp.
If its under, then your not getting enough water circulating round your block (no flow) and you'll get hot-spots and cause a BHG or worse.
Running thermos full time is a bit silly (depending on car etc.), you'll always have COLD water entering a HOT engine instead of WARM water entering a HOT engine. COLD water into HOT engine = cracks. Which is also why you don't put cold water into a radiator when you've just changed the thermostat and the engine is still HOT.
Points of interest:
- Holden commodores running temp is around 100 degrees (maybe higher, but couldn't find it on google).
- 1UZ-FE engines have the thermostat in the hose between engine EXIT and radiator ENTRY. They have a nifty recirculate pipe so there are no hot-spots when the engine is warming up.
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Location:
Sydney
Registered:
July 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 02:54
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| CrUZsida wrote on Fri, 18 February 2005 13:31 |
It began opening at 82degC, and stopped around 90ish, can't remember.
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What was the number stamped on the thermostat?
It sounds like what your saying is the number on a thermostat is the temperature that its FULLY opened at.
Where as I always believed (and still do frankly) that its when it STARTS opening.
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 02:55
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82degC is stamped on the T/S
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Location:
Sydney
Registered:
July 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 02:57
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wow.
What we need is a highschool science teacher to setup a beaker on gasburner experiment with a thermostat inside and watch through the glass very closely.
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 02:59
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Thats what I did, with a pot, on the stove, because I didn't think it was working properly.
Turns out it was.
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Location:
Sydney
Registered:
July 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 03:00
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again - wow
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 05:22
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| dingaling wrote on Thu, 17 February 2005 23:24 |
"you also need to match your grade of oil (the hot number, ie 40, 50, 60 etc) to your operating temps.."
Can you clarify that bit of info, that's very interesting what you say there, But i'm pretty sure you don't mean to match your operating temp of say 80C to an oil raing of 80?
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oil (and most other liquids) viscosity is a function of temperature.. thats why there is a cold and hot rating on oil. higher number for h8igher operating temp, and no, don't match the numbers
as for the opening thing, i used an LM35CZ precision temperature sensor with a pico ADC16 datalogger
it definitely begins to open very close to the rated temp, sometimes 1 or 2 deg under, and sometimes a couple over, but not more than 1 or 2...
with my fan on all the time, i had vastly changing temps.. (the thermostat is before radiator inlet, and temp sensor is just below thermostat. temp would sit at 82 for a while and slowly creep up , but then would start to increase faster.. this would take a couple of minutes.. and then temp would go down to 82 in about 3 seconds.
i attribute this to a thermostat that is sealing too well. the water was not circulating much, and so the temp reading and thermostat temp didn't rise quickly... initially, block water is stationary. temp warms up, tiny amount of water escapes past thermostat and temp appears to rise slowly, but the water in block is getting heated. then thermostat opens slightly, the hot block water starts escaping, and the thermo opens more, letting more hot water escape.. hence the faster temp rise... during this time, the water in the radiator was cold, and it gets let into the block... so eventually, when water is exiting fastest thru the thermostat, cold water is rushing in... when the cold water hits the thermostat, the temp suddnely drops, and the thermostat suddenly closes....
so long long story short, i drilled a 3mm hole in the thermostat and now the temp changes aremuch more gradual.
Cya, Stewart
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Location:
Sydney
Registered:
July 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 06:00
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Which way was your thermostat "pointing". Sounds like the spring is on the radiator (cold) side.
What engine was it on the entry to the radiator?
I think *most* cars benefit from a hole in the thermostat. especially when coupled with a large non-standard thermo fan.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 06:03
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pointing toward engine "hot" side, as on all K motors
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Location:
Land of Oz
Registered:
June 2004
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Re: how cool is too cool?
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Fri, 18 February 2005 06:52
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Hi,
It also depends where your water-temp sensor is placed. The water around the engine block will always be hotter than the water in the radiator.
I'll have to check where my sensor is placed in relationship to the thermostat.
seeyuzz
river
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Location:
Land of Oz
Registered:
June 2004
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Re: how cool is too cool?
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Fri, 18 February 2005 08:59
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Hi,
Shmeee again...
Here's the blurb from the Toyota 2T engine (2T, 2TB & 2TG) manual. These engines use an 82C t/s.
1 - Replace t/s if valve is open at normal temp (20C) or if not tight when closed.
2 - Place t/s in water heated to 78C for at least 4 minutes. If the valve does not open, then t/s is satisfactory.
3 - Immerse t/s in water and test for opening temp by gradually increasing water temp. The t/s is satisfactory if the valve starts to open at 80.5-83.5C and opens more than 8mm at 95C.
The actual t/s specs are...
Opening temp - 80.5 - 83.5C
Opening temp for cold area - 86.5 - 89.5C
Full open temp - 95C
Full open temp for cold area - 100C
Valve lift - Over 8mm
I dunno about other engines (and their relevant t/s), but at least it gives you an idea of the opening temp ranges of a fairly typical t/s.
seeyuzz
river
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Location:
Sydney
Registered:
May 2002
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Re: how cool is too cool?
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Fri, 18 February 2005 20:27
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oldcorollas got same results as me with equally accurate temperature monitoring devices.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: how cool is too cool?
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Fri, 18 February 2005 23:01
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| Bugman wrote on Sat, 19 February 2005 07:27 |
oldcorollas got same results as me with equally accurate temperature monitoring devices.
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we rock dude!!!
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