Bleeding cooling system

Bleeding the cooling system ?
I'm usually bleeding after changing the cooling hoses under the Plenum .. if that helps.

 

Have you done a pressure test on the system to verify there are no leaks?

 

I have bled the system in my 328 3 times in the 8 years I have owned the car - each time when I changed the coolant. It has never needed "re-bleeding" between coolant changes. I do it pretty much like the book says - frankly not any different than bleeding the cooling system on any car. As Thorn mentioned, do a pressure test on the system. If it's "generating" air, there's a leak.

 

I have had a similar situation with my 77 until I saw the post on the small radiator bleeder valve. As others have not seen a need for one I found it a simple fix that eliminated the bleed process that these cars seem to have. I did a coolant change (done with tee fitting under the car) and installed the little valve on the radiator. Filled the system which took 19 quarts and started it up . Let it run for a while and the system normalized . Never had a problem since.

 

I seem to recall reading that one has to jack up the front of the car or something like that to get all the air out. In fact I remember doing that once.

 

For a 308/328, you use a hand pump to fill it until it comes out of the bleed port, then you run it until no more air comes out. Close up and you are done.

I recently just bought this fill kit for my Porsche 997 and I have to tell you it makes this a bleed free refill. There are two operations, you use 90PSI air and the venturie effect to create a vacuum in the coolant system, then you use the vacuum to draw in the coolant. 10 minutes, you are done, no need to bleed. I am doing that from now on.

 

Hope all this advice cures the prob. If it doesn't, maybe you should rehash the basics, because it's easy to overlook something.
Be sure you are getting the car up to proper temp and the thermostat is fully open. Turn on the heater, as the cores can have air also.
Your car may have 2 bleeders, one on the thermo housing, and one on the radiator. (early cars had only the one on the radiator)
So after bleeding, make sure the coolant tank doesn't get low, as this may introduce more air(don't remove the cap hot).
The advise on lifting the front of the car may help also, although I never found it necessary.

 

It seems very common to find air in the radiator on an almost perpetual basis. My 328 does it, I know Rifledriver has commented that it happens a lot. People have addressed it with automatic bleeders but I have stopped worrying about it, the car runs at a constant temperature so it seems its not a problem if there is some air in there. When refilling the system I have tended to jack up the back of it & then bleed the radiator followed by the Thermostat. I did get an airlock in the heaters once & the only way to cure it was to remove the tub round the spare wheel well to get to the pipe connections at the heater cores at which point I undid one or two & let the air out there. Once I'd done that water started circulating through the cores properly.

 

Back when I worked at a reputable Ferrari shop, common practice was to open up both bleed ports until nothing but coolant came out. Tighten them back up. Run the car until hot and open the radiator bleed screw until only coolant came out. Methods are different across the board on the "proper" way to do it, but this is only a refinement of the way many other shops do it and works 100% of the time... of course, after making sure you dont have leaks anywhere else

 

EXACTLY! With a non-leaking coolant system It's a one time operation until the next time you decide to change the coolant!

 

Last time I replaced my coolant I used an Airlift tool. It was easy and worked great.

 

The air you get after a sweet ride from the "bleeding "port at the radiator is totally normal and is due to the re-distribution of the coolant throughout the engine-part of it being super hot and creating pressure/vaporisation (hence the gas escaping). i was concerned i might had a nasty leak.and kept venting after every ride...No need for that said my mechanic(Rock'restoration in Toronto).: there will always be pressurised gas coming out until the coolant cools down and everything return to liquid.
Is stopped venting and enjoy the ride a new cap every 5-8 years is more important than the bleeding.
Cheers

 

My car is stock with the exception of auto-bleeders at both the radiator and t-stat housing. It runs a notch below 195 unning down the interstate, no matter the ambient temp. It never goes above 195 in traffic unless something is wrong. I backed her out yesterday and let her idle for around 30 minutes while I cleaned it (washed with water for the first time this year) and it just sat at 195. That should be the goal. Sounds like you are there so you should be good to go.

Below is a list of the normal suspects for overheating or coolant being expelled from the expansion tank in no particular order:

1. overfilled expansion tank
2. air in the system from improper bleeding
3. failing or incorrect expansion tank cap
4. failed expansion tank....pin hole from rust
5. missing radiator foam
6. fan motors not operating at full speed due to tired brushes
7. old fuse boxes not giving proper power to fan motors
8. failing radiator mounted temp sensor
9. failing or incorrect thermostat
10. leaking peecock or other leaks within the system
11. failing water pump
12. failing water pump belt
13. clogged radiator
14. leaking bleeders
15. head gasket or cracked head