I must say however, that although I'm very happy that the leaking rad is a thing of the past, I'm still puzzled by the fact that my expansion bottle still seems to not get pressurized. I just came back from my garage to check exactly that, and no hissing sound like before when unscrewing the bottle's cap????? Could it be that since the radis not made of aluminum and plastic anymore but brass/copper, pressure dooes not build in the bottle???? the liquid in the bottle is dancing when the engine is running, and it gets hot also, showing that it does circulate in the system. Should I try to bleed the system again???. Could someone confirm the bleeding procedure that I described above???

 

Just redid the whole bleeding procedure, in case they hadn't done it properly.

 

Are you saying that at operating temp, the bottle cap has no pressure? The only thing I can think of with this is that your rad cools so well that it doesn't get hot enough to build pressure. Also means your T-stat will work overtime to keep the engine warm enough. I'm not a pro, though, ask your buddy at the rad shop. I do know that pressurized fluid has a higher boiling point, thus the reason for a pressurized system...

 

No, No ,No, I've never tried taking the cap off at operating temperature. What I mean is that I use to always wait for the engine to be cold to add fluid, about once a week on a Sunday morning, after the vehicle as had time to completely cool down overnight. This was due to the fact that I was loosing about 1/4 inch in the expansion bottle every week. When I would unscrew the cap, I would hear a hissing pressure sound being released . I donothave that sound anymore under the same conditions, meaning when the vehicle is completely cold. I noticed that yesterday, and tried again this morning just to check if pressure had built in. Nothing happened again. Soooooo, I re-bled the system again, and just got back now from a day at the parc. So, I'll see again tomorrow morning and see if the re-bleedinghad anyeffect on the expansion bottlepressure.

 

oh, ok. When my engine is cold, I don't have and puffing from the cap. I am sure that a physics geek could explain why loosing fluid in a system under pressure would cause the air in the system to pressurize, but I can't. I know water won't expand and contract under pressure and air will...I am sure it was attributed to your fluid loss....

 

Fluid loss would bean explanation, but DiscoMike seems tosay thatthere should be pressure building in the system. Could be due to the fact that the air at the top of thebottle has expandedbecause of the heatgenerated by the coolant when warm????. But then again I can't explain it either.

 

For the benefit of all, I've discussed this matter with DiscoMike trough PM, and have come to the conclusion that it is normal to not have pressure in the expansion tank when the vehicle is cold when a cooling system is sealed properly.

Thank you all for your inputs.

darover