After Deer hit repair body shop has trouble getting air out of radiator system. Is there a process?

When they repaired my Boxster after the Deer hit they replaced a radiator. Since I got the car back in late October I have had two cooling fluid low alert reports and added a half gallon anti freeze each time. I brought the car back to Conestoga collision today and I think they are having trouble getting all the air out.

Is there a process for that?

Jeff Benson:

2016 Boxster, See it here: www.greatvalleyhouse.com/Boxster

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First car: 1952 Hudson Hornet

First roadster: 1962 Austin Healy 3000 III

Still have: Computer free 1974 MGB

Previous Porsches since 1982: 924, 944, 944S, and four Boxsters; 97, 03, 08 & 2012

Quote
Jeff (Philly)
When they repaired my Boxster after the Deer hit they replaced a radiator. Since I got the car back in late October I have had two cooling fluid low alert reports and added a half gallon anti freeze each time. I brought the car back to Conestoga collision today and I think they are having trouble getting all the air out.

Is there a process for that?

There are two processes. One involves repeatedly running the engine getting it hot then letting it cool and adding extra coolant until the level stays constant. A horrible process imho.

The other involves using a vacuum lift which subjects the cooling system to extremely low pressure -- the hoses collapse is what I've been told -- then switching off the vacuum source and switching to a reservoir filled with fresh coolant and open to atmospheric pressure. The pressure difference and lack of air in the system allows the fresh coolant to flow unimpeded through the system with no air pockets. I had a radiator replaced in my Boxster after I hit some road debris and when I picked up the car I was concerned about incompletely filled cooling system. I drove around Wichita KS for hours in the heat of mid-summer with no signs of any coolant level or cooling/overheating problems and then headed on west and home in CA and the system was just fine.The system refilled using the vacuum lift system -- all Porsche dealers use this -- after the water pump was replaced (Walnut Creek Porsche dealer) and again everything was just fine. And after the coolant tank was replaced. at the Livermore Porsche dealer. Again just fine.

However, I have to believe that air still in the system is not what is going on with your car. I suspect a leak.

My guess is the cap is leaking. This is not as farfetched as it sounds.

I recall my experience with my Boxster that the low coolant light came on -- out of the blue I might mention -- and the coolant tank was about a gallon low. I added distilled water and brought the level up and in about a month the light was on again. There was no sign of any leak but I happened to notice water condensation under the rear trunk lid that had me suspecting a coolant. I removed the floor of the fluid access bay and as best I could checked for leak sign. Finding none I rinsed the coolant cap in hot water and cleaned where the cap screwed to the tank and where it seals against the tank. I got the engine hot hot enough the radiator fans came on and then shut off the engine. I tended the fluid bay with aluminum foil and after a while removed the tent and spotted quite a bit of water condensation.

I suspected the cap and replaced it with a new one and that was that. No more coolant level problems.

If you want top up the coolant tank with distilled water. Do not overfill! You can just install the old cap -- making sure it is clean and the threads of the tank are clean and you tighten down the cap all the way -- then or do what I did and drive the car around with no A/C until the engine is hot enough to cause the radiator fans to come on. Back home raise RPMs until the fans come on then shut off the engine. Lay a tent of alum. foil over the fluid bay and take a 15 minute break. When you come back if there is water on the underside of the foil either the tank is leaking or the cap. You can replace the cap with a new one for $20. Be sure the tank threads are clean and you correctly install and tighten the new cap. Repeat the test. If the water is present again then suspect the tank or some other location is leaking. You'll have to get the car in the air and let an experienced Porsche tech -- or yourself -- make a careful check for any coolant leak sign.

The best solution is to draw a vacuum in the cooling system.
This serves two purposes.
If the vacuum holds steady at 5 minutes it means that there are no leaks.
Then they can slowly let the vacuum draw in the coolant.
It is very difficult to get the trapped air out of a new radiator unless they use a vacuum system or they completely drain the system.
If they don't what happens is that air is trapped between coolant in the in and out lines. This air is evacuated when the engine gets up to temperature and the air expands, forcing coolant out fo the system.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Thank you guys for the responses and

I wish everyone here very Happy Holidays.