Supra ST Myster Posted February 8, 2008 Share Posted February 8, 2008 Shouldnt a radiator be red hot after a drive? just my previous rad was stone cold after a drive, but it developed the usual crack near the rad cap, so just changed it to another one and that is the same, yet the pipe at the top and the pipe from the bottom are red hot?? I have a after market water temp sensor mounted in the top pipe and reads 85-90, can see it go to 100 initially then it drops down so thats the thermostat opening? Quote Link to comment Share on other sites More sharing options...
Alex Posted February 8, 2008 Share Posted February 8, 2008 A blocked radiator would have cold spots... Did you put your hand over all of it? It shouldn't ever go above 90degC...to go over and drop back would infer you have a cooling system issue...could be the thermostat. Quote Link to comment Share on other sites More sharing options...
dannypunto Posted February 8, 2008 Share Posted February 8, 2008 sounds like air in the rad, needs bleeding Quote Link to comment Share on other sites More sharing options...
Jake Posted February 8, 2008 Share Posted February 8, 2008 It shouldn't ever go above 90degC Really? That wasn't my understanding. I thought temps in excess of 100°C were not unusual. Quote Link to comment Share on other sites More sharing options...
Alex Posted February 8, 2008 Share Posted February 8, 2008 Really? That wasn't my understanding. I thought temps in excess of 100°C were not unusual. Oil should definately. But I don't think water is supposed to get to 100degC...80-90 is optimum for combustion. Happy to be corrected but that's what I understand atm. Quote Link to comment Share on other sites More sharing options...
Kranz Posted February 8, 2008 Share Posted February 8, 2008 Over 100 from cold when you're driving depends if its idling at the time or driving HARD Idling the thermostat will have time to open slowly & control the temps nicely. On power the stat may lag a little, but then catch up bringing the temps back to the controlled temp. Top & bottom hose feeling hot (too hot to hold) is normal after a drive. The previous rad was probably cold because the top section had no coolant in it due to the crack? Quote Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 8, 2008 Author Share Posted February 8, 2008 i thought the stat opens at 100, and that is indicated becasue the gauge goes to 100, then goes straight done to around 85-90 while im driving, may go up to 92-94 when driving hard and then leaving it idling, the top section say about an inch is hot but then the rest is cold, is it air then do you think, best to try and bleed it by taking top off and reving it a bit then topping up, i take it the whole rad should be hot?? cant belive the two i have had have been cold.. Quote Link to comment Share on other sites More sharing options...
TLicense Posted February 8, 2008 Share Posted February 8, 2008 When idling mine stays between 82-88degrees. Never seems to go above 88 unless I'm driving hard. Quote Link to comment Share on other sites More sharing options...
Kranz Posted February 9, 2008 Share Posted February 9, 2008 I think the stat is normally 89. During warmup engine temp may peak before the stat opens fully, then settle down During full throttle driving the temps can go higher even though the stat is fully open.... its then up to the rad capacity and airflow to control the temps, if the rad isn't up to it & the power output of the engine is significantly higher than stock then its possibly overheat time. A rad at 1 bar should boil at around 125C IIRC. You may have an air lock, or just a lazy stat The top of the rad being hot is ok, it getting cooler as you get lower is also good as it shows its working. You may not have a problem. Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted February 9, 2008 Share Posted February 9, 2008 Sounds like a lazy stat to me. Just be wary of the stat failing completely. Mine runs at ~90 at steady dc speeds and ~100 on a track day. The bottom of the rad will always be colder than the top (if it's working correctly). This may be of interest re top hose v bottom hose temps. http://www.mkivsupra.net/vbb/showthread.php?t=80363&highlight=bottom+hose Quote Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 9, 2008 Author Share Posted February 9, 2008 i was under the impression that the coolant circulates around around the whole system and passes through the rad so dont get why the bottom will be colder than the top? Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted February 9, 2008 Share Posted February 9, 2008 i was under the impression that the coolant circulates around around the whole system and passes through the rad so dont get why the bottom will be colder than the top? Hot water from the engine enters the top of the rad via the top hose and travels down through the rad. As it flows through the rad it cools (loosing heat to the rad and thence to the air flowing through the rad). The cooler water from the rad enters the engine via the bottom hose and gets heated by the engine as it travels through the water jacket (so cooling the engine in the process). Imagine if the water coming out of the rad and back into the engine was the same temperature as the top hose. The engine would put more heat into the water, and the temp would spiral upwards. Although the temperature appears to be stable in your top hose, it's actually fluctuating as it circulates through the whole system. HTH:) Quote Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 9, 2008 Author Share Posted February 9, 2008 just been for a nice drive, and checked it, top hose very hot, half the top of the rad is hot but the bottom half is luke warm so think its doing its job right, Quote Link to comment Share on other sites More sharing options...
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