Question: Is is necessary to bleed sytem after coolant change?

[Jim Z06]

It's time for a coolant change on my 02 Z06. I thought I would try it myself to save $100.00 Is it necessary to bleed the coolant system after the change? How would I know if there is air in the system? Thanks, Jim

 

[Toms007]

Good question, Jim. Someone will show up here and tell us the answer.

 

[catbert]

Are you going to change the 9 year old hoses while you're at it? Bleeding the system is probably a good idea in any case.

 

[TooFast]

Do a search on coolant change and you will find a full procedure in a lot of places, you do not have to "bleed" the system like the reverse flow LT-1's (C4) but you do need to "burp" it sometimes. I did mine last year and had no issues, no air, no burping. Pulled the hose off the radiator and pulled the thermostat housing. Be very careful with the radiator petcock, as it is plastic and only requires a half turn to open.

 

[Hib Halverson]

Generally, bleeding or "burping" is not necessary, however, know that it is very difficult to fully drain the system in a C5 because the engine block drains are not easily accessible.

What I do is drain the radiator, then I refilll the system with straight water, run the engine for a short time, then drain again. I do this a couple of times. Then I refill with the appropriate mix of Dexcool and distilled water.

Fill the system, then start the engine and let it idle until the thermostat opens, check the coolant level and add as necessary. Cap the system then go for a test drive driving the car around town long enough for the fans to come on. Park the car overnight then recheck the coolant level and add distilled water as necessary.

As for hoses, I would not replace all of them on GP. I'd inspect all hoses and replace any which are soft, hardened, cracked or gouged. I have found that OE hoses last a long time provided the longterm underhood temperatures have remained normal, the cooling system has received periodic maintenance and the underhood spaces are cleaned occasionally.

If the drained coolant is particularly dirty, then I'd consider an across-the-board replacement.

If you do chose to replace hoses, buy high-quality replacement parts such as Goodyear, Gates, ACDElco or OE GM. BTW, RockAuto has great prices on hoses.

 

[ernestD]

Good info as always Hib!

 

[Jim Z06]

Thanks for the info guys. I knew I could count on you.

 

[B747VET]

Bringing this thread back to life since the problem I have is similar ... I think ...

Four months ago I had the local Chevy dealer completely flush the coolant system on my 2002 Vert. I've noticed that I have a problem that may or may not be related to that work.

The problem concerns the large return hose that runs from the water pump outlet to the radiator inlet on the upper left side of the radiator.

Almost every time the system totally cools down overnight, the next morning that hose is squeezed completely flat. When I start the car in the morning, the hose remains flat until the thermostat begins to open and then it fills out and remains normal in all respects until once again the system has cooled overnight.

On the first start of the day and all subsequent starts, the engine coolant and oil temperatures seem to come up to the normal operating range at the usual rate and stay within the normal range at all times.

I'm purely guessing there is trapped air in the system and that the resulting steam/air either isn't exiting out of the port on top of the radiator and then flowing to the surge tank or, alternatively, the steam/air is getting through the port and then isn't purging out of the radiator cap.

Anyway, this is my rudimentary guess as to what might be the problem(s). My knowledge of the cooling system is minimal and I'm not sure how to trouble shoot this problem correctly.

Any help would be greatly appreciated.

 

[TooFast]

Bringing this thread back to life since the problem I have is similar ... I think ...

Four months ago I had the local Chevy dealer completely flush the coolant system on my 2002 Vert. I've noticed that I have a problem that may or may not be related to that work.

The problem concerns the large return hose that runs from the water pump outlet to the radiator inlet on the upper left side of the radiator.

Almost every time the system totally cools down overnight, the next morning that hose is squeezed completely flat. When I start the car in the morning, the hose remains flat until the thermostat begins to open and then it fills out and remains normal in all respects until once again the system has cooled overnight.

On the first start of the day and all subsequent starts, the engine coolant and oil temperatures seem to come up to the normal operating range at the usual rate and stay within the normal range at all times.

I'm purely guessing there is trapped air in the system and that the resulting steam/air either isn't exiting out of the port on top of the radiator and then flowing to the surge tank or, alternatively, the steam/air is getting through the port and then isn't purging out of the radiator cap.

Anyway, this is my rudimentary guess as to what might be the problem(s). My knowledge of the cooling system is minimal and I'm not sure how to trouble shoot this problem correctly.

Any help would be greatly appreciated.

I pulled this off another site; posted by a tech. The OP tried the cap change and then no more hose flattening problems.

The vent is stuck in the radiator cap.
It maintains system pressure when the engine runs and the coolant expands to help control the boiling point, but as the coolant cools off at night and the fluid contracts the cap should allow atmospheric air to enter the cooling system to prevent this condition.
The radiator/coolant tank cap needs to be replaced.

 

[B747VET]

Many thanks. I will give it a try tonight and report back.

 

[TooFast]

OK cool, let us know.

 

[B747VET]

I get so tired of these dealer related issues.

I bought a new radiator cap this afternoon. Got it home and it's the wrong one. 18 psi instead of 15 psi. Of course! Why do I trust anyone?

But, after the system cools down I look into the surge tank reservoir and discover that the dealership overfilled it to the tune of 2 quarts when they flushed the system. I siphoned the excess out. Again, never trust anyone ... never trust anyone ... never trust anyone.

I'm betting this was the real problem. We'll find out tomorrow.

 

[timfitz63]

... But, after the system cools down I look into the surge tank reservoir and discover that the dealership overfilled it to the tune of 2 quarts when they flushed the system. I siphoned the excess out. Again, never trust anyone ... never trust anyone ... never trust anyone.

I'm betting this was the real problem. We'll find out tomorrow.

I've had this exact same thing happen -- twice -- on two separate occasions to two separate vehicles made by two separate manufacturers (Chevrolet and MINI). Both had the coolant reservoir topped off WAAAY above the fill line (like you, to the tune of a quart or two), presumably by the guy doing all the 'courtesy' checks when the vehicle was serviced. Like you, I siphoned out the excess and set it aside for possible future use...

Now, I always double-check the fluid levels after getting a vehicle back from service. Too many people who don't know (or don't care) about cars, who do these menial 'courtesy' service tasks for the dealers...

 

[B747VET]

As always, thanks for the help. The over filling was the issue. On the plus side the service manager took this all seriously and has offered to replace the top hose and inspect the systen to be sure no damage was done to anything else includint the water pump etc.

On the worst idea I ever heard, the newest Boxster apparently doesn't have a dip stick. When you have it serviced, you have to trust the service provider that the oil really was changed and not just topped off. Only an electronic sensor at the start up tells you the quantity is full.

Sorry, but I just don't trust anyone that much.

 

[TooFast]

Well, glad you got it all sorted out!

 

[melsy]

Good catch up thread and Hib, as usual, is the man. I am fortunate to have a real old time service near my home and they are very environmentally correct. They have a coolant system "machine" that sucks out the old fluid fluid and replaces with new. They get about 14 Qts out of my '03 Z06. Very quick, very efficient and no hoses, etc to undo. They then get rid of old coolant to a recycler or some such company. The same with old refrigerant and other harmful chemicals. To answer the question I know is coming, they fill the "new" side of the "machine" with fresh coolant and water in front of my beady eyes. Hope this helps.

 

[dougelam]

Bringing this thread back to life since the problem I have is similar ... I think ...

Four months ago I had the local Chevy dealer completely flush the coolant system on my 2002 Vert. I've noticed that I have a problem that may or may not be related to that work.

The problem concerns the large return hose that runs from the water pump outlet to the radiator inlet on the upper left side of the radiator.

Almost every time the system totally cools down overnight, the next morning that hose is squeezed completely flat. When I start the car in the morning, the hose remains flat until the thermostat begins to open and then it fills out and remains normal in all respects until once again the system has cooled overnight.

On the first start of the day and all subsequent starts, the engine coolant and oil temperatures seem to come up to the normal operating range at the usual rate and stay within the normal range at all times.

I'm purely guessing there is trapped air in the system and that the resulting steam/air either isn't exiting out of the port on top of the radiator and then flowing to the surge tank or, alternatively, the steam/air is getting through the port and then isn't purging out of the radiator cap.

Anyway, this is my rudimentary guess as to what might be the problem(s). My knowledge of the cooling system is minimal and I'm not sure how to trouble shoot this problem correctly.

Any help would be greatly appreciated.

Here is what is happening to your hoses

55 gallon steel drum can crush - YouTube

Just thought you should know

 

[B747VET]

Thanks. Very informative. That's why the dealer offered to replace the top hose at my request. I'm still talking with them about the implications of all this on the water pump and radiator.