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Looking for insight on 249 degree coolant temps today..Thanks in advance

JBsC5

Well-known member
Joined
Nov 28, 2001
Messages
1,219
Location
Northern NJ
For the past few days I 've noticed my coolant temps higher than usual but figured it was the much hotter temperatures we've been seeing...but today.....

Today .....I'm cruising at 75 mph in sixth gear and the coolant temps are 207 degrees..(usually 192 degrees)

I turn off the a/c and put the defroster on heat.....and it brings the temps down to 198 degrees..

I'm thinking since I put the stock air box on saturday and found out my aftermarket coupling to the maf was letting some air in...I'd run the stock air box for a few days and sure enough the cars running much much better...but hotter...

So this afternoon I put the aftermarket air filter back in and thought....that would resolve the issue...

Low and behold in 15 minutes of around the town driving...

The car is running 243 or 249 degrees coolant...so I quickly turn off the road onto a side street...turn the car off...and park....turn the key just for a D. I .C reading of coolant about 5 minutes later and the D. I. C says....253 degrees...

I'm like holly ****..so

Wait ten to 20 minutes...start the car and then the coolant goes down about 2 degrees every few minutes..

Now the car seems to be running about 217 to 230 degreess for the most part..sometimes down to 208 degrees but the car really used to run 190 degrees pretty much all the time except maybe bumper to bumper traffic..

I could let the car idle now and it settles in at 208 degrees...and then if I drive it rather gently it climbs to 221 degrees..drive it a little harder and the temps climb to 230...

I didn't sit in traffic today so I'm dumbfounded...

No codes in D. I . C either....

Could it be a fuse for the fan blown..(the passenger side one seems to work...I can't see the driverside one so I can't tell.)

Could it be a slipping water pump belt?

Could it be a bad thermostat?

Could it be the water pump?

Could it be worse like a head gasket?

Could it be the tuning? (found the maf connector to air filter was leaking air in...and fixed it...)

What do you guys think? Any insight would be appreciated...
 

Mr. Lucky

Well-known member
Joined
Aug 30, 2004
Messages
405
Location
Orange, CA
Corvette
2004 MY stroker Coupe
Since your car is an '01, it's possible that enough time has passed that your foam radiator seal has degraded. Depending on how much you had to wrestle with parts to reinstall your stock airbox, it may have gotten dislodged or flaked away. The foam seals the area around the radiator by the shroud. I guess the theory is that it is supposed to direct airflow through the radiator rather than around it. Check that area, and adjust/replace as needed. I've heard of people using conventional bulb rubber weatherstripping with good results.

GL!
 
Joined
Mar 27, 2003
Messages
3,664
Location
Mustang, OK
Corvette
'13 427 60th vert - '21 Silver Flare Coupe - CTS V Wagon(4-door Vette)
The first thing to do is check the radiator for blockage. It's amazing how much junk from plastic bags to leaves get sucked up into the radiator area blocking air flow through it.

While under the nose, check to center air dam piece and make sure it is still there and working. If the center piece is missing or loose, it will not direct air up through the radiator as it should when cruising at freeway speeds.
 
Joined
Apr 18, 2002
Messages
1,441
Location
Staten Island, NY
Corvette
1999 Torch Red Coupe
Check to see if the electric fans are actually coming on. (One is usally on with the A/c and the other should go to full speed over 228 degrees, or around there)

Another problem can be some air in the cooling system. When I changed my thermostat I had to bleed the system multiple times, using the bleeder screw on the thermostat housing.

You can also test the fans by grounding pin 86 on relay 1 and 3, located in the fuse box next to the battery.

My 99 did almost the same thing, so I installed a fan switch.
 

mqqn

Well-known member
Joined
Apr 12, 2004
Messages
437
Location
In The Cornfield
Corvette
02 EB Z06 / 99 BLK Coupe
Hi JBsC5 -

Good advice from the previous two posts -

Check to ensure the radiator is not blocked, and the rubber airdam is in place -

Your car seems to be running too hot - mine runs much cooler, but my fans have been tuned to kick on sooner.

Please let us know what you find out -

best regards -

mqqn
 
R

Robert YellowVette

Guest
mqqn said:
Hi JBsC5 -

Good advice from the previous two posts -

Check to ensure the radiator is not blocked, and the rubber airdam is in place -

Your car seems to be running too hot - mine runs much cooler, but my fans have been tuned to kick on sooner.

Please let us know what you find out -

best regards -

mqqn
My money is on the t-stat going south, possibly the water pump. Check your drive belt tension.

Try pulling your t-stat out and testing it in a pot of water on the stove, it should be fully open at 195-200 F. While unlikely, something in the cooling passages could have come loose and is blocking the valve from moving fully open.
 

JBsC5

Well-known member
Joined
Nov 28, 2001
Messages
1,219
Location
Northern NJ
Thanks guys..

I've been very busy so I've parked the car until a GM tech professional can take a look see.

I'm hoping its just the thermostat or water pump. Maybe a radiator fan not going to high speed operation. ETC...

I dig the internet and all the good friends who offer advice in situations like this.

Corvette owners are top notch!
 

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