Purging air from cooling system.
 

Any way of being certain all of the air has been purged from cooling system?

Yes, start by filling the system using the Uview vacuum filler; system will be filled and totally air free in about 2 min.

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I wanted to avoid buying this tool. Not that I mind investing in good tools, I hope I would not need it too often.

The beauty of the Uview tool is that it comes with adapters to fit just about anything with a cooling system; we have used ours on everything from a lawn tractor, to a motorcycle, and even a huge John Deer harvester; worked perfectly on all of them.

without tools, I jack up the rear of the car, flip the tab on the coolant tank into the upright position, open the cap, fill the tank, start the car, run it at 2500 or so rpm and keep topping off the water as it burps. Makes a little bit of a mess but when I've had to do it at the track there is no interior in the trunk and we're only using water so it isn't that big of a deal. Takes 10 minutes or so until the fluid level stabilizes. Be sure to check it again and top off as needed after its run and cooled.

I have not looked into it on a 986 yet , but I have seen on other h2o Porsches a small tube off one of the top corners of the front radiators. .....
Accessible from the front wheel well , you can unplug it and help bleed air while the rear is jacked .
This will ensure the radiators are vented at initial filling .
Then simply run for a few minutes at 2.5k then top up and cool .
Top up again then do the same again .

There will be points where it bubbles over on idle with the cap removed so it is better to have a helper revving while you top up then replace the cap etc.

If you make the fil-point the high-point of the system it doesn't take long to get the majority of the air out .

Expect to keep your eye on levels and to-up as needed as you drive it over the next couple of weeks though ... Even with a vacuum pull you need to do this ;)

For my two cents worth, buy the uView. I started by flushing my system with distilled water. While up on stands. And used the burp method to remove air bubbles. Sorry, but it just does not get rid of all the bubbles. It takes a LOT of time driving and burping to get rid of the bubbles this way. The uView gets rid of them during the fill. Or if you have a later leak - as I did - removes the bubbles after it has coolant but is not totally filled.

It is a $100 tool. Costs much less than a replacement water pump (if it get damaged), water resovoir tank (if there is sufficient air in the system it can split the take from too much pressure), and a LOT less than an engine. It's also much cheaper than taking the car to the dealer for a flush. I find it extremely difficult to believe so many prople keep pushing the burp method rather than pay for the tool.

He asked how to do it without the tool. Simply answered his question so you don't have to beleive it. I've got a vacuum setup too but I have done it without several times after trackside repairs. With two or three people to team up on the process it can go pretty quickly.

Aknowles certainly has a valid point. It is not a terribly expensive tool when you consider the consequences of not doing a proper job.

Actually, he did not; what he asked was, "Any way of being certain all of the air has been purged from cooling system?", which the Uview most certainly is............

JFP is right. I did the burping technique but have only managed to get 4 gallons into the system leaving me to believe there may be air still in the system. I am fairly certain I completely drained the system but likely did not since the amount captured when draining was between 4 and 5 gallons. I replaced the lower radiator hoses and installed a new low temp thermostat. Thought all fluid was out but perhaps not.

Don't you need a air compressor to use this? What would be the lowest model compressor you would recommend to use with this?

Yes. With air compressors, bigger is always better, but I have seen people use small, 2 gallon home air compressors to pull vacuum, it just takes a bit longer to do it.

I thought I had a link, but couldn't seem to find it. There is another 1/2 gallon of coolant still in the system that canot be removed simply by removing a hose. It's in the heater core. To remove it, you need to find the two lines form the heater core and use compressed air at low pressure to the top hose. This will blow out the remaing 1/2 gallon.

Personally, if you flushged your system with disctilled water as I did, I wouldn't worry about it. Same if you used the same type of coolant for the fill.

I've done it Eric's method since 04.. lol The lift system works great, but I have NEVER (ever) had a car overheat. Paranoid? Buy the lift system.

The system is self burping. The two lines from the top of the radiator go into the top of the reservoir and bleed air into it.

Fill it up. Warm it up, drive it. Carry a jug of distilled water with you. Top it off up to where the white plastic meets the black plastic (look down into the reservoir)