HELP! Overheating coolant
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 47
Likes: 0
From: San Antonio Texas
Is there air flowing THROUGH the AC Condenser and Radiator?????
There is a very common problem with our C5s. There is a 1" space between the AC Condenser and Radiator. It commonly gets clogged with grass/trash/sand/dirt. You need to pull the air bridge and the plastic cover over the radiator and inspect that space.
BACK Flush the cooling fins with a garden hose on direct stream and see what all comes out. After that procedure see if it returns back to normal.
Also look at the cool air intake in front of the car and make sure its clean and not blocked with trash/leaves/dirt.
There is a very common problem with our C5s. There is a 1" space between the AC Condenser and Radiator. It commonly gets clogged with grass/trash/sand/dirt. You need to pull the air bridge and the plastic cover over the radiator and inspect that space.
BACK Flush the cooling fins with a garden hose on direct stream and see what all comes out. After that procedure see if it returns back to normal.
Also look at the cool air intake in front of the car and make sure its clean and not blocked with trash/leaves/dirt.
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 47
Likes: 0
From: San Antonio Texas
It seems the Low Speed mode is not kicking in. That would explain what's happening!Both fans are supposed to start in low speed at 226°F. If temperature continues to raise and reaches 235°F then they change to high speed. Once temperature drops back to 226°F they change to low speed again, and if temperature reaches 219°F they are turned off.
And yes, the scoop is still installed under the bumper.
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 47
Likes: 0
From: San Antonio Texas
Take out the thermostat and put the housing back on..;;;;Fill it back up. Fire up the motor and see what happens. If it still overheats, then you have a restriction somewhere. Did you verify that the radiator would flow collant?.....Hose in one end and watch flow at other end?? Run water through the block with a garden hose. Hose in the top hose and watch water come out the bottom. It would be nice if you could put an A/C thermometer in the radiator somewhere and run the motor. Compare block heat to radiator heat. Im leaning towards that radiator,,,, As they get old, they loose their ability to transfer heat from the tubes to the fins. Usually they dont go bad instantly.. It takes a period of time. Try these things and see what happens. My bet is on that 16 year old radiator.
I actually can't do that thermostat trick since I have one with the integrated housing...
Melting Slicks
Joined: Jan 2009
Posts: 3,275
Likes: 739
From: Miami FL
It seems the Low Speed mode is not kicking in. That would explain what's happening!Both fans are supposed to start in low speed at 226°F. If temperature continues to raise and reaches 235°F then they change to high speed. Once temperature drops back to 226°F they change to low speed again, and if temperature reaches 219°F they are turned off.
But that being said, it seems something is wrong with the Low Speed mode that is compounding the problem.
Last edited by GCG; Jul 15, 2019 at 04:02 PM.
Drifting
Joined: Jul 2015
Posts: 1,844
Likes: 376
From: San Jose, CA
Yes - if you are driving 40mph, that should provide enough cooling and the fans should be off.
Yes - you should pop the hood and idle it and listen/observe for low speed fans turning on at 226F.
Yes - a thermostat housing with no thermostat is a good thing to try just in case, but you may not want to destroy yours if it's integrated ...
One thing at a time. I think the easiest, least-effort thing is to idle the car with the hood open, keeping track of temperatures, and see if the fans turn on low speed at 226F. (You can also turn the AC on - cold air - and at, I believe, 185F coolant temp, they should cause the fans to start. Someone correct me if that temperature is wrong.)
Another question: what are the oil temps doing? When your coolant gets to 250F, what does the oil temperature read?
Yes - you should pop the hood and idle it and listen/observe for low speed fans turning on at 226F.
Yes - a thermostat housing with no thermostat is a good thing to try just in case, but you may not want to destroy yours if it's integrated ...
One thing at a time. I think the easiest, least-effort thing is to idle the car with the hood open, keeping track of temperatures, and see if the fans turn on low speed at 226F. (You can also turn the AC on - cold air - and at, I believe, 185F coolant temp, they should cause the fans to start. Someone correct me if that temperature is wrong.)
Another question: what are the oil temps doing? When your coolant gets to 250F, what does the oil temperature read?
Burning Brakes
Joined: Jul 2005
Posts: 1,147
Likes: 7
From: Motor City area Michigan
Stealing thread re: correct T-stat and pump
Problem I have is on the highway the car is running ice cold, like in the 130's. It is not a problem of no coolant at the sensor because I can grab the rad hose and it is cold with no pressure as if the car were actually over heating. Sitting and idling the temp comes up to 210 ish as expected.
So, the old T-stat and housing on a new pump is a problem?
TIA
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Burning Brakes
Joined: Jul 2005
Posts: 1,147
Likes: 7
From: Motor City area Michigan
Upon further investigation, Apparently the old integral stat is shorter than a stat and housing unit so the combo of old integral stat and new pump will not work as it does not stop water flow to build heat. maybe this is a good trick for a track car??
Last edited by greendot; Feb 5, 2020 at 03:17 PM.
Drifting
Joined: May 2008
Posts: 1,696
Likes: 491
From: Denver, NC
Then see if your new one has no compression in the new pump - like the disk isn't hitting the ledge. I have seen different size disks on the t-stats, and have seen some with combinations of what should work that I have doubts about. Feel free to PM me. I have seen where the new thermostat disk doesn't touch the surface inside the pump.
Last edited by Ed Ramberger; Feb 4, 2020 at 09:51 PM.
Burning Brakes
Joined: Jul 2005
Posts: 1,147
Likes: 7
From: Motor City area Michigan
Exactly right. I have found the old integral stat is shorter than a stat and housing unit so the combo of old integral stat and new pump will not work as it does not stop water flow to build heat. maybe this is a good trick for a track car??
Melting Slicks
Joined: Mar 2018
Posts: 2,502
Likes: 187
From: California
Thermostat needs replacing ! Let it run if continues over heat and you know it the spring in the thermostat is opening ! Check the heater as well as you will not have heat ! You will most likely need to drain or replace coolant ! Be a good idea to get a water pump given it’s right there and easy! Fill it up let it recirculate with the heat full blast to remove any air pockets !