coolant change c5

[liven lg]

What is the best or easiest way to drain and refill the system?. I have read many differant ways. What is correct? Thanks Liven Lg.

[Junkman]

Originally Posted by liven lg

What is the best or easiest way to drain and refill the system?. I have read many differant ways. What is correct? Thanks Liven Lg.

Simple. Remove the overflow tank cap. Lift the car with the nose lower than the rear, insert bucket under the drain cock, turn the drain cock counter-clockwise until the fluid begins to flow heavily and then go have cold drink of your choice for a hour of so.

[ToolGuy]

And don't forget you must bleed the air out of the system while refilling.

To do this, take off the throttle body coolant hose, leave off until coolant comes out of the hose, then reconnect.

If you need the GM procedure on the location of this hose, I can get it for you tomorrow and post it. My manuals here at home are all hard copies...

[Junkman]

Originally Posted by ToolGuy

And don't forget you must bleed the air out of the system while refilling.

To do this, take off the throttle body coolant hose, leave off until coolant comes out of the hose, then reconnect.

If you need the GM procedure on the location of this hose, I can get it for you tomorrow and post it. My manuals here at home are all hard copies...

That I didn't know. However, I'm ready with a pic!

[Fixvet]

Originally Posted by Junkman

That I didn't know. However, I'm ready with a pic!

Junkman, isn't it easier to pull the small hose off the pass. side of the TB? I'm getting ready to drain mine this weekend and thought I read something somewhere to pull the pass. side hose off the TB, then burb the system until a steady stream comes out. Just curious about what you guys think.
Thanks for the pics!!

[Junkman]

Originally Posted by Fixvet

Junkman, isn't it easier to pull the small hose off the pass. side of the TB? I'm getting ready to drain mine this weekend and thought I read something somewhere to pull the pass. side hose off the TB, then burb the system until a steady stream comes out. Just curious about what you guys think.
Thanks for the pics!!

I'm not sure. I always do it exactly as the service manual states to do it and it says nothing about removing or disconnecting that hose. I have never had any issues with air being trapped in my system and I've drained and filled it quite a few times.

I've attached the instructions that I use from the service manual.

[froggy47]

FWIW when I did mine I also did the stat, if it has 50k or more miles on it I would, they get "lazy". I never bled mine just drove it with one eye on the temp & ran it hard a few gears as the temp seemed good.

You would be surprised at the amount of trapped air 6,000 rpm will move.

I also use a less than 50/50 coolant mix plus water wetter, but if it gets cold where you live stay with 50/50.

:)

[markw8]

I don't think I removed the hose when I did mine a couple of years ago. I do make sure the stat opens without overheating.

Mark

[ToolGuy]

I always bleed a cars system. One of my cars now has a screw at the thermostat housing that's made to be opened up and bleed air out, which is nice but not all have that. Many years ago I drained a system and did not bleed and watched the temp gauge go up, almost to red, then shut the car off. Learned to not do that again, better safe then sorry.

Also note, the GM service manuals are not always 100% complete/correct. Any service manual for that matter, I'm not just picking on GM here. They are guides, directing the tech to do a procedure one way. Obviously techs can learn to do things differently, or add steps that are not in the manuals as they work.

I used to write GM service manuals and noticed errors, bad illustrations and so on. I also work with a bunch of guys now that used to write them. Torque specs were a large issue, it's hard to get them from engineering at times or the correct specs. Even with the 10 years worth of GM service info I have now on CD I've seen errors, people are only human and we strive for 100% in the manuals, but there are still can be errors or omissions, sometimes due to tight deadlines. Some guys write better then others and some think the techs "know" something and dont think they have to add it to the text. I currently write service and operator manuals for military trucks and still errors are made, things are forgotten and picked up at a later date. And its easier to add or update things later being electroinc now though. Likewise, I've seen some manuals state add LocTite to intake bolts for our Vettes, others don't. Sounds like a revision to engineering info...

See these posts here where C4C5 states to bleed from the throttle body...

http://corvettemechanic.com/forum/32...e-install.html (radiator back flush "T" kit, Which hose to install?)

http://corvettemechanic.com/forum/28...-question.html

http://corvettemechanic.com/forum/16...-corvette.html (replacing coolant resevoir and thermostat in a 99' corvette)

So bleed if you want, don't if you want, its all up to you!

[Junkman]

I don't doubt you one bit in what you say ToolGuy but some forums are filled with more crap for information than all the service manual's mistakes combined (not this forum in particular). At least by going with the service manual's information, you can be rest assured that you're at least in the ball park of doing it right. Some of the stuff I've seen posted multiple times on forums is not only flat out wrong, it was borderline stupid. Some of the oil threads come to mind.