I have used my Airlift to vacuum purge and fill my Cayenne several times (Waster pump replacement, coolant T's etc) and never had an issue getting a solid 20 inches of vacuum and a complete coolant fill in one pass. Things didn't go as well with my 997.2 Targa. I just installed new CSF center, left and right radiators. When I drained the original left and right radiators to remove them I got about 5 quarts of coolant out. I put the new radiators in empty and buttoned everything up. I then hooked up my Airlift to purge and fill the system. I only got to about 5 inches of vacuum when coolant started spitting out and by the time I got to 10 inches of vacuum (about 20 minutes) I had pulled out almost 4 more quarts through the Airlift. I shut the purge valve and it held the vacuum at 10 inches for several minutes and the hoses were mostly collapsed. At this point I figured that with so much coolant still in the system I wasn't going to be able to get a solid 20 inches of vacuum and full fill done with the Airlift. I tried and I was able to get about 5 quarts back in with the Airlift. I started the car up and let it warm at idle with the cap off hoping the air would purge out but unfortunately by the time the dash temp gauge read normal (175) the reservoir was overflowing coolant like crazy. At this point I shut it down and let it cool for a bit. A few hours later I topped up the reservoir and took it out for a drive (staying close to home) hoping this would get things flowing but by the time the temp came up I could see coolant steaming off my exhaust and my check engine light came on. Temps never rose above 175 and my oil never got above 200 by the time I pulled back into my garage. I let things cool down again and tried the Airlift one more time. This time I got to 10 inches much more quickly but again started pulling coolant more then purging air.

So I am looking for advice on what to do to get my coolant system purged at this point. I am thinking I may need to drain the engine side of the system (pull the coolant hoses) and try to purge again with a lot less coolant in the car (book says 8.3 gal) is full so about 7 gal still in) but I am open to ideas. Anyone else have an issue like this? Thanks

Jeff

 

I was told that whenever radiator flush/refill is needed, a systematic procedure involving instructing the car's computer is required, and yes unfortunately, it is typically done by Porsche dealerships for around $400-500. The procedure involves the opening and closing of several valves in series that control the flow of coolant to and from the radiator in the front of the car and the engine in the rear. I have not seen a DIY procedure to properly flush radiator fluid for a 997.2 otherwise, and if someone does know how, I'd appreciate if they could share that information.

 

 

The workshop manual says all you need is an Airlift, but they do assume you have completely drained the system before you try to pull a vacuum with the Airlift. The Airlift manual also says it is only intended for completely drained systems and not for topping off coolant. I am thinking that the completely empty radiators with 7 gallons of coolant between the airlift tool at the reservoir tank and the radiators is just too much for the tool to deal with. I am gonna just bite the bullet and drain all the the coolant and hope that does the trick unless someone else has an idea or trick to get the air out and the coolant in. Here are the steps for a 997.2 from the Workshop section WM 193817 "Draining and filling in coolant (includes bleeding the system)"

1. Remove rear underbody panelling
2. Open the cap on the expansion tank and remove it
3. Unscrew the drain plug (hexagon socket) on the coolant guide tube
4. Unscrew the drain plug on the thermostat housing
5. Collect emerging coolant
6. After draining the coolant, screw in and tighten drain plugs with new sealing rings. Tightening torque: 25 Nm (19 ftlb.)
7. Pull off large coolant hoses and heater hoses
8. Refit coolant and heater hoses after draining coolant. Coat O-rings and coolant hoses with Klüber Plus Gel (Part No. 000.043.205.93).
9. Pull a vuccum to .85 bar (Arilift says 20-25 inches) with a venturi nozzle tool (e.g. Airlift or Porsche special tool filling device 9696
10. Confirm vacuum holds for at least 30 seconds
11. Open inlet side of Airlift to pull in coolant till vacuum reaches zero
12. Test drive the vehicle. Following the test drive and when the engine is still at operating temperature, accelerate briefly to 6,000 rpm a number of times at idle speed in order to fully ventilate the system
13. Check the fluid level with the aid of the markings on the expansion tank. Correct the coolant level after the engine has cooled if necessary

 

Not every hose was collapsed (I didn't even check the ones at the engine side assuming the had coolant in them) and the ones that did collapse where not pulled nearly as tight as when I used the Airlift on my Cayanne. I am guessing that having all three radiators brand new and completely empty plus the 7 gallons of coolant still in the engine side of the system is too much for the tool. It is designed to pull air not coolant. I would love to hear I just missed something simple and I don't need to drain all the coolant but it is not looking that way now.

Jeff

 

 

Totally agree that it is nearly impossible to drain the system completely but it is an 8.35 gal system and when I emptied the radiators I drained 1.25 gal leaving 7.1 gal still in the engine side of the system and the rest of the coolant lines. I think there is a big difference between the work the airlift has to do to pull a vacuum when the system is 80% full then when it is 20% full. At least I hope that is the case or I am about to waste $160 in coolant!

Jeff

 

Did you put the heater ON to full max temperature, when running the engine?

Yves

 

 

 

I'm from the 996 side. But as a mechanic i can tell you that you cannot use an airlift with any large amount of coolant in the system. It will constantly pull coolant out of the system and you will never be able to obtain more the 20 inches. At this point you still have air in the system which is causing your issues. On the 996 it is easy to disconnect certain hoses and blow a small amount of compressed air to completely drain the system.

 

 

 

Thanks everyone for your input and ideas. Everything is all set now. and I was able to get the coolant completely filled and the air out. The solution was to pull the two drain plugs at the engine and pull the two rear main cooling hoses on either side of the transmission. This drained another 2 gallons of coolant and when I hooked the Airlift up this time I was able to get a solid 25 inches of vacuum in just a couple of minutes and 5 gallons pulled back into the system no problem. For those looking to do this here are some lessons learned from my experience and from talking this over with the shop foreman at Porsche of Tyson's Corner:

1. The 997.2 and newer models are much more difficult to purge then previous models and while you may get away with small amounts of coolant removal, air pockets created in the radiators are the hardest to get out.
2. Safest bet anytime you have to drain some coolant out for a service (especially at the front of the car) is to just to a full drain and then purge and fill with an Airlift
3. The only special tool needed is a a vacuum tool (Airlift, Porsche special tool or other venturi device)
4. Airlifts don't work well trying to pull air from the front of the car through gallons and gallons of coolant near at the back of the car near the reservoir!
5. The drain plugs on the block are both the same and are made of the same soft aluminum as other drain plugs so be careful and make sure your 6 mm hex is fully seated or they will strip.
6. The crush washers are supposed to be replaced when pulling the coolant drain plugs but once crushed they do not want to come off the plug. Porsche of Tyson's did not stock the plugs. The crush washers were so hard to get off without damaging the threads of the plug that next time I would have had new drain plugs and washers on hand before I started so i could just replace the plugs.
7. You will want to open the air purge valve on top of the coolant reservoir tank as soon as you start draining coolant and leave it open while you evacuate the system with the Airlift, filling the system with new coolant, warming up the system and test driving the car.You can close it the next day after a full heat cool cycle if it has not already closed on its own. The valve is designed to open and stay open when the coolant is at operating temps and close when the coolant cools. It is supposed to open past the manual open position when hot so it should effectively override your locking it open and self close

Thanks

Jeff