Trying Not to Make a Splash

“Now, to put a water-cooled engine in the rear and to have a radiator in the front, that’s not very intelligent.” – Ferry Porsche (PANO, Oct. ’73).

There I was, out there just enjoying myself during the third Black Group run on Day 2 at Lime Rock, and all of a sudden I am doing a “tank-slapper” on the uphill. Holy cr#%, what the hell is going on. The tires felt a bit greasy at turn one but now all hell was breaking loose. I decided I better head to the pits and see what is going on. I get to the flagger at the bridge and see that the black flag is out (not pointing at me BTW). Further in the distance I see headlights at the end of the straight – figured some poor soul spun badly and they are calling us in. I pull into the pits and the flagger then indicates that I should pull off; I guess this run is over, oh well. My car then completely fills with white smoke and I think, MY CAR MUST BE ON FIRE. I stop the car, jump out, hear Craig Mahon yelling for me to grab my Fire Extinguisher……… then I smell the sweet smell of coolant. Trust me, it was sweet smelling on many levels as we already had one car fire that day. The other good news is that the three guys that spun as a result of my application of coolant to the track, did not bend any sheet metal. Pheww!!

It turns out that one of the coolant line couplings was backing it self out and was spraying my tires and the track from Turn 1 all the way around and into the pits. It finally gave out while in the pits. So here I am with only 3.5 track days in my new to me 2007 GT3 (20K miles) and I get the often read about and dreaded, “gonna happen eventually”, coolant coupling failure. As it turns out there are numerous couplings that can fail. Here is a bit of information about this coupling issue, what can happen and some options for dealing with it.

The issue is that Porsche bonds together metal to metal coolant pipes with an epoxy/glue, which has in numerous instances led to the metal pipes coming apart/popping out as the glue breaks down (heat-cycling) dropping coolant all over the engine, tires and the ground.

You may have this issue if you have a GT3, GT2 or Turbo (GT1 block cars, so 996/997 Turbos, GT2’s and GT3’s). GT1 based, commonly-called Mezger, engines have its roots in the air cooled 964 race engine. It was then ‘modified’ into a water-cooled engine, and water-cooled cylinder blocks were added. Coolant manifolds are ‘external’ to the engine, and plumbed differently. It is called a hybrid because it uses both oil and coolant for cooling. The M96/M97 engine, used in the regular Carrera and Carrera S, was designed as a water-cooled engine from the start, and uses different plumbing and cooling components. It is just different, and does not use these bonded couplings.

So, what is the fix? There have been a number of articles in Panorama, Excellence and others describing the factory fix (gluing the coupling/fitting back in) and third party fixes which are pinning (gluing and installing a set screw with Loctite) and welding (welding in new heavier walled fittings). Some of the fittings can be reached by removing parts and partially lowering the engine but you need to drop your engine to get to all of them (cannot do this if welding). I am having 100% of the fittings removed and new ones welded in. This work (by having my engine removed) is  being done by Powertech in Rockaway along with an additional flanged fitting that grabs one of the coolant lines better. I do not want to have the one culprit fixed and then be on the track thinking about the other 6 or 7. I am sure my track mates will like this approach as well. I am also switching over to water + Water Wetter just as a precaution since hose failures can also occur.

Seems like this problem is significant enough that there are even a couple of companies making kits (Porsche is not one of them) for this issue. One of them makes a complete refit kit similar to one pictured below.

It appears that Porsche has quietly addressed the issue of the coolant lines coming unglued from their housings in GT1 type engines. I have read that the housings have been re-engineered to increase the bonding surface area of the tubes and a new, high-strength/heat-resistant bonding material is used. Not sure when they started using these new parts but unfortunately at this point that information is not available. It does appear that 2010 and later GT3 RS’s have them, so one would assume that this would include the Turbo’s as well.

At the time I am writing this article I do not have my car back yet, but I am looking forward to getting back on track without any coolant worries (at least not coming from my car). My next event will be the advanced driver DE at NJMP on April 30 – May 1 so I will report back if anything changes.

Tom Iervolino