Overheating... Thinking thermostat.
Thread Starter
Le Mans Master
Joined: Jul 2009
Posts: 9,526
Likes: 12
From: Los Angeles California
Overheating... Thinking thermostat.
I just drove about 300 miles today with no problem. I got home no problem. Then I left my house to meet up with friends and suddenly my coolant temp shot up and pegged itself VERY fast. Got the warning light and all.
I immediately pulled over and shut down. I checked to see if it was leaking coolant, and it was not. But there was a LOT of pressure built up in the reservoir. Both fans are working and on when the AC is on. (Checked all the fuses while I was at it.)
After letting the car sit for a while to cool down, I turned it back on and ran the heater. Cold air. The coolant temp started rising again very fast. Turned the car off again and called for a tow truck.
So it sounds like the motor isn't getting any coolant which makes me think the thermostat is stuck. Last time I changed a thermostat, it was on an L98. LOL
Do you guys think it's the thermostat or is this something else? If you think it's the thermostat, is the thermostat housing on my LS6 on the passenger side of the motor?
Thanks in advance!
P.S.
The car isn't throwing any codes.
I immediately pulled over and shut down. I checked to see if it was leaking coolant, and it was not. But there was a LOT of pressure built up in the reservoir. Both fans are working and on when the AC is on. (Checked all the fuses while I was at it.)
After letting the car sit for a while to cool down, I turned it back on and ran the heater. Cold air. The coolant temp started rising again very fast. Turned the car off again and called for a tow truck.
So it sounds like the motor isn't getting any coolant which makes me think the thermostat is stuck. Last time I changed a thermostat, it was on an L98. LOL
Do you guys think it's the thermostat or is this something else? If you think it's the thermostat, is the thermostat housing on my LS6 on the passenger side of the motor?
Thanks in advance!
P.S.
The car isn't throwing any codes.
Race Director
Joined: Jul 2007
Posts: 18,681
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From: Reno is so close to Hell you can see Sparks , State Of Confusion
St. Jude Donor '12-'13-'14
Are you by chance using Amsoil 0-30?
That will do it..
Just kidding, I would first check the air flow to the radiator and if that is ok, I would then change the Stat, The easy things first.
Mr.Bill
That will do it..
Just kidding, I would first check the air flow to the radiator and if that is ok, I would then change the Stat, The easy things first.
Mr.Bill
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Le Mans Master
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From: The line waiting to see Santa Claus stretched all the way back to Terre Haute, and I was at the end, Indiana
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16-'17-'18
I WOULD CHECK FOR DEBRIS BEFORE CHANGING THE STAT.
Thread Starter
Le Mans Master
Joined: Jul 2009
Posts: 9,526
Likes: 12
From: Los Angeles California
OK.. So here's what's happening at the moment.
I checked to make sure nothing was obstructing the radiator. There was nothing. I'm sure the radiator can use a good cleaning, but nothing that's stopping it from getting air.
I replaced the t-stat and there's been no change.
I drained all the old Dex out, flushed with and drained distilled water, then began to fill with 50/50 mix of Dex again. Here's the problem: I can't get more than 1 gallon in. The car doesn't seem to be cycling the coolant. However, I'm 99% sure that the water pump is working because the exit pipe on the radiator is hot. The car gets up to 225 and kicks on the fans. I shut down at that point and let the car cool.
With the surge tank's cap on, I run the car. I've also run it with the cap off. In both situations the coolant wants to bubble out. A lot of pressure gets built up with the cap on. Cap off, the Dex just boils out.
At one point I saw the temp drop from 218 to 210... Then it began to rise again.
When the temp starts to go up, it does so very fast. Like 2-3 degrees every 20 seconds.
Any thoughts?
I checked to make sure nothing was obstructing the radiator. There was nothing. I'm sure the radiator can use a good cleaning, but nothing that's stopping it from getting air.
I replaced the t-stat and there's been no change.
I drained all the old Dex out, flushed with and drained distilled water, then began to fill with 50/50 mix of Dex again. Here's the problem: I can't get more than 1 gallon in. The car doesn't seem to be cycling the coolant. However, I'm 99% sure that the water pump is working because the exit pipe on the radiator is hot. The car gets up to 225 and kicks on the fans. I shut down at that point and let the car cool.
With the surge tank's cap on, I run the car. I've also run it with the cap off. In both situations the coolant wants to bubble out. A lot of pressure gets built up with the cap on. Cap off, the Dex just boils out.
At one point I saw the temp drop from 218 to 210... Then it began to rise again.
When the temp starts to go up, it does so very fast. Like 2-3 degrees every 20 seconds.
Any thoughts?
Drifting
Joined: Nov 2008
Posts: 1,450
Likes: 140
From: Palm Beach Florida
There is a blockage somewhere. The water pump is also a good candidate. The fact that your that hot, and you have cold air at the heater core means blockage or water pump. If the dexcool isn't gelled which can happen, I would be looking into the water pump. You caught it as soon as it happened so something broke. Heater control valve also?? Did you burp out any air pockets, disconnecting the coolant line to the air intake at the throttle.
Last edited by seamus2154; Nov 20, 2010 at 10:40 PM.
Le Mans Master
Joined: Jun 2007
Posts: 6,301
Likes: 6
From: LAND OF OZ Kansas
Interesting, my thermostat got stuck open, and I was out of town when it happened. The car did about 235-240F when I drove it at 55-65mph. It sounds to me like your water pump is gone. If it's not circulating coolant, the impeller must be stripped. Yeah, I'm with 87VETTE7, did you burp the system?
Thread Starter
Le Mans Master
Joined: Jul 2009
Posts: 9,526
Likes: 12
From: Los Angeles California
I thought I burped the system for the most part... I'll try both suggestions right now and see how that goes.
I knew I was going to be replacing the thermostat, so I drained the radiator first (by the way it drained really slow. Not sure if that's normal). Once everything was out I pulled the t-stat and LOTS of coolant flowed out very fast. Then I replaced the t-stat with the new one, and reconnected the hose. I assume about a half-to-full gallon flowed out when that happened.
I'll be back in 30 minutes to post the results of my second "burp" attempt.
I knew I was going to be replacing the thermostat, so I drained the radiator first (by the way it drained really slow. Not sure if that's normal). Once everything was out I pulled the t-stat and LOTS of coolant flowed out very fast. Then I replaced the t-stat with the new one, and reconnected the hose. I assume about a half-to-full gallon flowed out when that happened.
I'll be back in 30 minutes to post the results of my second "burp" attempt.
Thread Starter
Le Mans Master
Joined: Jul 2009
Posts: 9,526
Likes: 12
From: Los Angeles California
OK... Results weren't good.
These steps went normal:
Then while opening the cap, the dex wanted to boil out... I waited a few minutes while it slowly decompressed... Then the level went down a little, but not a lot.
If I start the car with the cap off, it will boil out again. (as I tried this before)
These steps went normal:
Start w/ a cold engine
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
If I start the car with the cap off, it will boil out again. (as I tried this before)
Thread Starter
Le Mans Master
Joined: Jul 2009
Posts: 9,526
Likes: 12
From: Los Angeles California
LOL BTW, I checked the oil during all this because I had a thought that maybe I had a blown head gasket and wanted to see if there was coolant in the oil... The oil looks great. Almost exactly the same as when I put it in. Good times.