Bubbling coolant on the reservoir

[SalvadorP]

Originally Posted by Laird Scooby

It's difficult to say this without sounding sarcastic (and i'm not being) but the clue really is in the name - expansion tank. It's designed so the coolant and any air in the system expands and contracts within certain limits, controlled by the cap. There is no need to mark the coolant level, simply top up to the minimum line on the reservoir, refit the cap tightly and leave it alone. If the HG was gone, you would have a serious amount of air/liquid being forced out at a great rate and would really know it.

You're in danger of becoming an "automotive hypochondriac" and to be honest, searching online for percieved symptoms will almost always lead to the wrong conclusions. Also Google isn't necessarily the best search engine to use for this as i've found (and proved) on many occasions that the information Google holds isn't always accurate.

As i've said several times and Mark has also pointed out above, stop opening the cap when the system is hot! It's not designed for that and will lead to problems.

In the first instance, check the level with the engine cold, top up if needed to the "MIN" mark and refit the cap tightly. Next order yourself a new cap, making sure it's the same pressure rating which should be on the current cap. When you have the new cap, remove the old one when cold, top up the coolant if needed to the "MIN" mark and fit the new cap tightly.

After that check the level visually when cold and ONLY remove the cap to top up if needed. Repeated removal of the cap in between whiles will cause more problems so unless you need to remove it when cold to top up, leave it be!

In the fullness of time, yes a full flush including reverse flushing the system is a good idea but get everything on an even keel first.

It's ok. I don't know anything about car mechanics but i want to learn. Your explanation is helpful.
You are right, one can get carried away with the self diagnosis. I don't have a tendency for hypochondria, but i expect to go through a bit of a phase until i learn enough about mechanics to start connecting the dots. And i will.