Overheating after idling for a while.
Thread Starter
Instructor
Joined: May 2002
Posts: 145
Likes: 0
From: Long Island NY
Overheating after idling for a while.
I'll get to the point here.
After the first overheating(coolant boiling into overflow tank, I've done the following:
Flushed system
replaced radiator, cap and water pump(leaking)
Burbed the system of air.
While idling in garage, after a couple of cycles where the fans come on at 227 deg and the temp dropping back down to 204 the temp goes past 230 and never comes back down. High speed fan comes on too. I hear the system gurgling aftem shutting the car down. I have no codes and no coolant leaks. There appears to be no coolant in the oil and no evidence of coolant at the exhaust. I am trying to get my hands on a Block Test Kit before I start pulling the plugs. Am I missing anything here to checkout? I'm leaning towards a blown head gasket or worst, a warped head!
96 CE
After the first overheating(coolant boiling into overflow tank, I've done the following:
Flushed system
replaced radiator, cap and water pump(leaking)
Burbed the system of air.
While idling in garage, after a couple of cycles where the fans come on at 227 deg and the temp dropping back down to 204 the temp goes past 230 and never comes back down. High speed fan comes on too. I hear the system gurgling aftem shutting the car down. I have no codes and no coolant leaks. There appears to be no coolant in the oil and no evidence of coolant at the exhaust. I am trying to get my hands on a Block Test Kit before I start pulling the plugs. Am I missing anything here to checkout? I'm leaning towards a blown head gasket or worst, a warped head!
96 CE
Last edited by john3154; May 10, 2007 at 08:03 PM.
Racer
Joined: Jan 2001
Posts: 452
Likes: 0
From: The Dark Side of the Moon
Checked your profile and you have an LT1, right? LT1's run hot and 230 is not unheard of, especially for me. I had similar problems, kept the coolant full, and ultimately replaced the radiator with an all aluminum one. It made the problem better. I run about 180-200 on the highway and see 220 in traffic. Are you running the factory thermostat? If not, go back to the factory one as that seems to confuse the computer.
Race Director
Joined: Feb 2003
Posts: 16,475
Likes: 270
From: Kingman AZ
Cruise-In VII Veteran
Cruise-In VIII
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Take a bright light and look in between the radiator and the AC condensor from the passenger side. Clean out any junk you find in there.
Instructor
Joined: Apr 2007
Posts: 136
Likes: 0
From: Fountain CO
Our cars are like vacuums. Check to make sure you don't have a bunch of debris in front of the radiator. I had a bunch of leaves, coke can and part of a retread stuck up there 
. Worth looking into 
. Worth looking into
Thread Starter
Instructor
Joined: May 2002
Posts: 145
Likes: 0
From: Long Island NY
Sorry guys, I guess I wasn't clear. I installed a new radiator, water pump and radiator cap. I'm using whatever thermostat came with the WP. I've tripled check everything and I don't see any leaks.
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
make sure both your fans are coming on.. Also, don't forget to bleed the system via the bleed screw on the top of the thermostat housing. Also, check the condition of the condenser. Make sure all the fins are straight and everything is clean in front of it and in it.. little rocks get stuck between the fins over time and cause havok.
From there you might want to also flush the system.. you might have crap gunking it up.. mixing brown coolant and green coolant will cause it to congeal.
hook up a scanner and make sure your not running rich.. check your oil for little chocolate milkshake spots on the dip stick. dont forget to check for oil in the coolant also (little black spots at the high point - under the cap).
next start pulling plugs..
oh try something.. try it with your AC system off and see what the temps read.. if they are back to what you consider normal your AC could be over/under charged or your compressor clutch could be on the fritz..
did i forget anything..
good luck..
From there you might want to also flush the system.. you might have crap gunking it up.. mixing brown coolant and green coolant will cause it to congeal.
hook up a scanner and make sure your not running rich.. check your oil for little chocolate milkshake spots on the dip stick. dont forget to check for oil in the coolant also (little black spots at the high point - under the cap).
next start pulling plugs..
oh try something.. try it with your AC system off and see what the temps read.. if they are back to what you consider normal your AC could be over/under charged or your compressor clutch could be on the fritz..
did i forget anything..
good luck..
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Thread Starter
Instructor
Joined: May 2002
Posts: 145
Likes: 0
From: Long Island NY
I've burbed the system many times with the front of car raised and engine rev'd up. I've flushed the system by removing the knock sensors and ran water through system until clear. No brown sludge but I didn't use any flushing chemicals. Should I? A/C condeser is clean. With A/C off, it still overheats.
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
I was thinking one of the powerflush machines that any oil change place has.. have them flush it a few times.. it gets in the upper part of the system./. like the crossover pipe in the back of the heads, the passages in the heads..etc..etc.. there is also a small orifice flow restricter in line with the hoses comming out of the heater box under the reservoir that the radiator cap is on.. take that out and make sure its not plugged.. it dosent take much.. check for any collapsed hoses..
well.. get goin.. it aint gonna fix itself!
well.. get goin.. it aint gonna fix itself!
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
oh.. and get yourself a factory service manual from www.helmsinc.com (or is it just helms.com) it is more than worth the 150 bucks it runs.. it literally worth its weight with these cars if you plan on driving them alot..
trust me...
I've had my daily driver for 176k miles.. shes in better condition than most current cars with half that.. I follow everything to the letter in that book!
trust me...
I've had my daily driver for 176k miles.. shes in better condition than most current cars with half that.. I follow everything to the letter in that book!
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
You can not burp an Lt1 by raising the front of the car. You must burp the system using the bleeder screw on the t/stat housing or it will continue to have air trapped and overheat. Burp it at least twice, engine cool, motor running, engine hot, t/stat open.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Seems like you've done everything to return it to the way it left the Factory. The only thing you don't mention is the mix - 50/50? Also, what is the temp? 230 is ok with the proper mix. Assuming everything else is right and it's overheating, you can start by scanning it - coolant in the combustion chamber will make it run lean, not rich. Otherwise, compression and leakdown tests are in order.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Sun has a good point, 50/50 mix especially during warmer months makes a noticeable difference. Too much or too little antifreeze can make it run warmer. I try torun 50/50 year round. Your results may vary.
Thread Starter
Instructor
Joined: May 2002
Posts: 145
Likes: 0
From: Long Island NY
Well, it looks like a head gasket. I drained oil again and this time it looks a little brownish. I'm getting air into the system when the car gets good and hot. While the temp was creeping up even when the fans came on, I burbed the system but this time lots of air(gas?) came out. As soon as all the air burbed out, the temperature went down to 210. Also, I'm seeing water dropping only out of right exhaust pipe. I guess by me running the car trying to find the problem, it's getting worst. Unless there is another way air can get into the coolant system, I quess I have a blown gasket.
That doesn't sound good. 
