Dan@SharkWerks

Hi guys,
I cross-posted this from the GT3 section but this issue applies to 997 Turbo models as well so I thought it would be a good idea to post here.

Some of you may be aware of coolant pipe issues on GT1-block equipped models (GT3, GT2, Turbo), where coolant pipes come apart while driving and the rapid loss of engine coolant can cause spins/crashes at race tracks when slippery coolant sprays all over the rear tires.

The problem exists on the GT1 motor because there are a couple coolant pipes in these motors that are not a single cast piece: the larger cast pieces have extruded inlet/outlet tubes that are connected using an adhesive. There is no metal-to-metal friction or press-fit to keep these tubes in place, so after enough heat cycles the adhesive will soften/loosen up and the tube will come out of the cast block (with the hose still attached), resulting in a rapid loss of engine coolant.

Regardless of how the vehicle is driven, it seems this problem may eventually effect all 996/997 Turbo, GT2 and GT3 models including the 2010+ GT3 and GT3RS.

We have heard of many cases of this, and in fact the last time we were at Infineon Raceway, Alex and I were talking to someone about it when the exact problem happened to a 997 GT3 right in front of us -- a large steam cloud evacuated the rear of the GT3 and it spun on the hairpin! Luckily he missed the other cars and the barriers.

Here's a video showing how the tube comes apart:
http://www.youtube.com/watch?v=RH56CkzC-QE

Here's a diagram showing where the problem happens on 997 GT3 models:


Here's a picture from a 996 Turbo's coolant pipe. Both of these tubes you see are slip-fit into the cast piece and fixed in place using an adhesive:



We first saw this in early 2006 when we started building 996 Turbo engines. In fact, our 996 GT3 suffered from this exact problem earlier in its life.

James has a technique for fixing this, something we do for all 3.9L motor builds and any time a GT1 motor is removed from the car.

This week we had a 2011 GT3RS (project that was documented earlier) whose lucky owner will have plenty of track time with her. He decided that rather than wait until it might happen, he would rather be on the safe side and fix the problem now, preventing a scenario where the coolant might cause a high speed crash at a local track.

The bumper is removed exposing the Shark Werks GT3 Bypass Exhaust:


And despite the car's super low mileage, its factory fresh and perfectly running motor is removed from the car:





With the motor removed from the car, James locates each of the potential problem areas and drills a small hole through the cast piece and into the tube (that normally would come flying out at some point in the future). Then he threads a bolt through both pieces and using loctite secures the bolt in place. This locks the tube together, preventing it from coming apart regardless of heat cycles.





The coolant pipes will now act as a single piece.


All the tubes are buttoned up...



And the motor is lifted back into place, the remaining details addressed.



And here she is, now ready for an enjoyable weekend around the track at 8000 RPMs.




For more of this car, check out the whole project here.

Kerry

Thank you, Dan, for sharing that info with us.

DINOROCZ

wow that stinks, I thought this was only on the 3's....

does the motor really have to come down, or is it possible to do with the motor in place?

Lastly, thanks for the info, very informative

joyride5

no leaks from drilling holes through the coupler? Plus, any possibility with the fittings made out of soft metal + vibrations the holes can get bigger causing leaks?

Dan@SharkWerks

The holes are sealed with loctite to prevent leaking around them. The metal is a cast aluminum (soft compared to steel etc.), it's hard enough not to have the holes enlarge from vibrations.

Yes unfortunately the motor needs to come out of the car, it's pretty difficult to reach all the fittings with the motor still installed. You can get to a couple of them though,
-Dan