Cooling system - Help
 

Ok, so I've been having some issues with my cooling system.

I just attempted to burp the radiator... it went badly.

- Removed radiator reservoir cap
- started car, let it warm up
- Nothing happened.. reservoir never drained no burping,etc
- THEN, when Temp hit 214 degrees, hot dexcool overflowed all over the place.

? T-stat not opening up?

Help. :P

Ok here's some more info:

I topped up the coolant, replaced the overflow cap and started the car - Car began to overheat

Facts:

- The upper hose on the drivers side going into the rad seems empty. If I squeeze it I see bubbles in the overflow tank, but it never gets firm or heats up

- The car overheated a few days ago into dangerous territory, could this have roasted the t-stat?

- The problem is intermittent. After it overheated on friday and completely cooled down, I was able to drive it home.. operated as normal for a while, then the temp spiked and it over heated again.

- Both cooling fans work. The first turns on at around 225 degrees and the second comes on at 234, as they are supposed to.

It seems my problem is the movement of water.. but I just had the water pump replaced last year.

Ok I've either made the problem a lot worse or discovered the source.

I drained the system and took out the t-stat. I tested it and it is working.

Replaced the t-stat, refilled the system with 50/50 dexcool to distilled water.

Removed the overflow rad cap, started the car and brought it up to temp. Once t-stat opened there was a lot of bubbling in the overflow tank. I thought it was just the system burping itself and getting out airpockets... but I think it is something a lot more serious.

The bubbling was continuous, and there is definitely water spitting out the tail pipe :( :(

This suggests a major problem, as in a blown head gasket or a cracked block.

Is there any other not-so-grim explanation?

I think I've diagnosed a bad radiator cap.

I don't think the system is properly pressurized - I'm getting boiling coolant at around 220 degrees. Each unit of pressure raises boiling point by 3 degrees. At 15 PSI, the boiling point of WATER would be 257 degrees, add to this the fact that I have a 50/50 mix of distlled water and dexcool .. the boiling point should be well north of 260.

Coolant is flowing in the system and both of the fans are switching on. The rad is completely clear of debris. I have removed and tested the T-stat, and it is functioning.

Boiling coolant at 220 degrees says to me that the system is not under pressure.. I have the original rad cap and the car has 45,000 miles on it. I'm gonna change it tomorrow and see what happens. Here's to hoping it's not a head gasket or cracked block.

Good luck with the repair....... :(

Sorry I don't have any guesses for you, just hope you sort it out:cheers:

Not sure but the Z06 radiator is a vacuum for grass, trash and any thing else.

Jack her up and see what's up in the space between the front bumper and the radiator. It really gets nasty in there:ack:

Here's how to safely support the car............

http://forums.corvetteforum.com/c5-g...-question.html

Jack the front of your car in the air and take the little line from your cross over line on your heads off to your rad and wait.... If you got an air lock you will get it out, in the process of doing this you will purge your heater core as well. Do all this while it is cold:) I have been stung with thinking I had overheating problems when all it was trapped air;)

So - the car is fixed. Now, I'm not a mechanic.. but the problem was...drumroll.... A BAD RADIATOR CAP .. combined with low coolant / air pockets.

Went and bought a $10 overflow tank cap and came home. Here's how I fixed it:

(make sure that heat is cranked up so the heater core is wide open)

- Idled car for a minute
- Removed old no-good cap
- Topped up Overflow tank (the level of coolant had dropped quite significantly overnight..)
- Brought the car to operating temp.. (car began to overheat)
- Replaced NEW tank cap, turned off car
- Let it sit for about half an hour
- Removed cap slowly (coolant level had dropped a lot)
- Idled car for a minute
- Topped up overflow tank again
- Started car up, brought to operating temp again.. fans came on.. and this time, when the second fan came on at 235 degrees.. IT HELD!!!
- replaced rad cap
- Checked rad hoses, upper rad hose (outlet) was VERY WARM and lower rad hose (inlet) was FAIRLY COOL!! Success! water is flowing and rad is removing heat!!

This minor problem really tested my patience.. I thought the worst: head gasket / cracked block / water pump.

There is 1 critical thing to look for that is a dead giveaway for a bad rad cap: The coolant will boil in the T-connection at the base of the tank and in the tube coming up from the water pump, just behind the t-stat housing (if you touch the hose.. you will feel the coolant boiling in the hose). The reason the coolant boils at this location is because it becomes depressurized. The radiator cap keeps the system pressurized to 15 PSI - this raises the boiling point of your coolant mixture by about 45 degrees. When the coolant gets to an unpressurized point in the system at a temperature above boiling point (say 220 degrees, even with a 50/50 mix).. it will INSTANTLY boil. If you have boiling coolant in the t-connector at the base of your overflow tank with the rad cap installed - your rad cap is NO GOOD. Also you will NEVER be able to burp a system properly if you rad cap is toast.. because it cannot maintain the negative pressure of the system to allow the coolant to displace the air pockets.

A critical giveaway for low coolant is the air vents never blowing hot air - when you open the heater core and there isn't enough coolant in the system.. the air will never blow hot. Now, this can also be a symptom of a bad water pump or blockage.. but those are easy to triage and eliminate as possible causes.

The key with this fix is patience. Burping the cooling system takes time. The system can hold a lot of fluid. If you think your coolant is full, it probably isn't.

I'm so glad I didn't take my car to a dealership - there is no dealership in the world that I would have got out of for less than $500.

Radiator caps go bad more often than you think.
I have also had a cap that would hold pressure, but would not relieve the vacuum. I noticed when my car cooled down, the lower radiator hose collapsed. I replaced the cap, and that problem went away too.

I have never had any problems getting the air out of my system when I change coolant. I just fill the reservoir, start the car with the cap off, let the pump pull down the coolant level, add coolant to at least the full mark, put the cap on and drive it. After a couple of heat/cool cycles, I can fill the reservoir to the correct level, and it is done.

Final Diagnosis:

The P1539 code which is "A/C clutch - High Voltage" is the root of the problem here.

Either a bad ground or a bad connection in the wiring harness coming from the PCM on the right hand side of the car (the plastic tube that runs adjacent to the overflow tank up to the nose of the car) was the caused of this code. This error caused several things to happen: 2 BCM codes for the left and right signals, the headlight motors and the 2 cooling fans were also affected.

So the sequence of events is: Short somewhere in the wiring harness, P1539 code, 2 BCM codes thrown.. A/C clutch, cooling fans, headlights, indicators stop working.

So, the cooling fans no operating caused the overheating, and the rest of the problems stem from that initial episode.

The problem popped up again last night and this morning.. the fix was to grab the wiring and shake it. I will need to either replace some of these connectors.. re-clean the grounds.. or just replace all the wiring in general.

:thumbs: Hope you flushed the cooling system as well.