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OVER HEATING IN TRAFFIC

 
Barbaras90vette
I love my Chevy Chevette!
Posts: 1
Joined: 06/09
Posted: 06/16/09 12:48 PM

I gave my wife a 1990 Corvette convertible for a wedding present.  It has the L98 engine and recently received $1,454.30 in repairs at a local Chevrolet dealer due to blown gaskets (head gasket, manifold gasket etc. etc.)  mainly due to OVERHEATING in traffic (Dallas).  The dealer purportedly put a new thermostat in addition to replacing all the gaskets, changing the oil (I had coolant in the oil) and flushing and refilling the cooling system.  UNFORTUNATELY, the thing still overheats badly (240 degrees and up) in any traffic or slow driving.  I called the dealer, they said the fans don't come on until 237 degrees.   Any ideas??  Any suggestions??  Does this sound normal?  I had a 1996 Corvette coupe with the Grand Sport engine and a 6 speed manual that did the same exact thing - every time I got stuck in any kind of traffic snarl.  

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waynep712
V-6 Camaros rule!
Posts: 77
Joined: 10/08
Posted: 06/16/09 08:02 PM

does it blow the coolant out the radiator???    

if you are loosing coolant...  with the engine cold... take off the radiator cap.. examine it... is the brass disc in the middle of the rubber seal pulled up tight against the rubber??? or does it flop loose?????   if it is one of the flop loose versions... change it for one that is not...    16 PSI...

does the fan actually come on.. you can tell if the fan is being commanded on with a OBD1 scan tool....    they do come on as commanded by the ecm at 228 or higher...  237 is possible...  i just don't remember that number .. but it is floating in the back of my mind as being a number for corvettes..

how is your air dam and under bumper areas...    so any ram air will be forced through the radiator..  not leaked to the side...  is the a/c condenser filled with dirt and sand from dusty roads... blocking the cooling air..

is your cooling fan running at high speed/????   has anybody replaced it with an aftermarket unit...  not all are up to the full power specs.. once size fits all in the aftermarket...   no so with all of the gm or delco units...     i have also seen some aftermarket units missing the spacer between the drive flange and the front bearing... so when the fan is bolted on tight.. the drive plate comes loose... slips down the shaft.. rubs the motor case... and the shaft just spins as the drive plate is past the splines ...  

how slow is the idle speed?????    how many idle air counts are there at idle ??  20 to 50 would be in the normal range...  yes this is scan tool data..
if the engine is idling too slow.. slower than normal... there might not be enough coolant circulation to properly cool the motor...


on earlier models... the aux cooling fan switch is in the right cylinder head between spark plugs 6 and 8...   green wire...  so if the ecm fails to turn on the cooling fan... this switch will...  edit... just took a good look at the wiring diagram.. this system is totally controlled by the ecm...  

here is the wiring diagram for the 90 radiator fans

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/08/fd/ad/large/0900c1528008fdad.gif

this component locator will also help

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/08/fc/a5/large/0900c1528008fca5.gif  

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aruba608
I love my Chevy Chevette!
Posts: 14
Joined: 07/08
Posted: 12/13/09 11:19 AM

I have a 91 corvette with l98 motor and had the same problem this is what i did to solve it ..I bought a 160 degree thermostat then  i got a after market fan switch that turns the fan on at 165 degree and turns off at 180 and it seems to have worked  also my next step was to swap out the radiator with a BECOOL radiator and fan set but so far looks like its working fine. Cool  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/13/09 04:47 PM

with a scan tool... look at your block learn memory... if the car is running in a normal range.. it will be close to 128.... usually within 2 or 3 if there are not any mods to the car..    when you put in a 160 thermostat.. you are running it below normal operating temp...    this will decrease the air fuel ratio.. make it run rich... reduce fuel economy..   melt your cats...  reduce power levels..  

if the cars don't loose coolant under normal temps.. and normal temps on a vette are 215 to 245F....

if you had a carb..  would you run around with your choke part way on...????  

if you want to run the lower temp stat.. you really want to have some reprogramming done...  new chip.. or what ever it takes...  

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hawkeyejjl
I love my Chevy Chevette!
Posts: 1
Joined: 04/10
Posted: 04/18/10 02:13 PM

Hi:
I have a 1996 six speed grand sport and it will heat up to 235 degree at a stop sign.  I replaced the thermostat
and same problem.  The chev dealership looked at the car and said all is fine.  The senior mechanic said the big engine will be hot on stop lights.
Jeff  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/18/10 02:57 PM

235F is just find for that car...

as long as it does not loose coolant..


with a proper mix of coolant and the 15 or 16 pounds of pressure raises the boiling point of the coolant to over 260F...


i hope that you installed a 192/195 thermostat..       they are marked on the end of the brass bulb...  

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sean39
I love my Chevy Chevette!
Posts: 6
Joined: 04/10
Posted: 04/18/10 03:27 PM

try replacing the radiator cap if the cap is bad the coolant will b ble to boil at a much lower boiling point  

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mediumquazarblue
I love my Chevy Chevette!
Posts: 3
Joined: 09/09
Posted: 07/29/10 02:01 PM

I have one, and if you have the AC on both fans engage which should keep it cooler  

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