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  Update #1   Instructions or Technical Article / Guide
The GT1 Coolant Pipe Prevention / Fix on GT1 block (GT3, GT2, Turbo) Cars

Parts required:
bolt size: M4 x 10mm length
quantity: 6-8 depending on model
tap size: M4x0.7 pitch
sealant: Loctite 263 (p/n 1330585) or Loctite 271 -- 50ml is much more than than enough; very little is required

Please read: Unfortunately we do not have the time to support and advise on this repair via telephone and email; we cannot offer further instruction or support than what is supplied here, and recommend you consult the numerous great Porsche forums (such as Rennlist and 6 Speed Online) for further instructions. If you are interested in having us repair the car at our facility, the price to remove and re-install the engine with this repair is approximately $3500 USD (not including the cost of replacement parts).

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:

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 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...

A lesser known issue involves the plastic coolant elbow pipes that run to the oil cooler (aka heat exchanger). These pipes are molded plastic and have a very thin wall where the pipe connects to the engine with an O-ring seal. The problem is that over time and mileage, the thin plastic wall will break down at the o-ring slot (its weakest and thinnest point) causing a crack to appear. Eventually the whole engine will need to be removed in order to replace a cheap plastic tube. Both of these issues have been observed on the 997 Turbo models as well.Here's a razor blade showing where the stock piece fails. The car had approximately 40,000 miles of use in a mild climate:

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

A pair of SharkWerks coolant pipes will do the trick:

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.
  Update #2  

Welding Coolant Lines
Something that has gained a lot of popularity in recent months is the welding of these coolant lines, instead of pinning as we recommend. It might sound like an appealing solution, as a proper weld is nearly unbreakable. However we believe this is missing the point of the issue and is a riskier and possibly less reliable solution.

We've now seen at least three cars come in with welded lines that are leaking and so we discourage this practice. Each fix was done by a "top" welder or reputable independent Porsche tuner in our area. The weld fixes will show porosity (air pockets) or cracks in different places, and coolant will seep or drip, with pink cloudy residue near the welded lines. Some have lasted under 1000 miles.

We have seen welded lines that appear to be holding up fine, so we would not discredit the choice, but we also believe the pinning to be 100% reliable if done right.

We believe that welding is approaching the problem from the wrong angle: the problem is not that the coolant escapes around the tube (through the gap occupied by the glue) and it never has been: so welding and patching up the gap there is pointless.

The whole problem is the tubes eject from the engine causing massive coolant loss. Just locking those tubes in, with even the old factory glue, is sufficient to prevent a leak for the life of the vehicle. We have re-inspected our pinned lines on cars 50,000 miles later and the result is unchanged. Welds on the other hand on these pieces may eventually crack as the pipes and cast pieces heat and cool over the years at different rates.

As the temperature of the engine rises from ambient (0-40F degrees in winter perhaps) to operating temperature (210F+) the different metals in the pipe, cast piece and weld will all expand at different rates. This is where that factory glue (that is often criticized) works well: it is a great material for its expansion properties. It will expand evenly and turn softer. However if welded and fixed in place, the aluminum tubes, cast housings and weld material will contrast and expand at different rates. This may lead to cracking and failures as the pieces cannot flex or stretch evenly. Also, new weaknesses may be added to the factory pieces that were never a problem before.

Locally we have performed over 40 of the pinning fixes (probably closer to 60) and not one has leaked since the installation: we regularly see these cars for updates and inspections when doing other installations. The pins will never break and the glue should never leak.

Since it's unnecessary to weld in the first place, why make such a mess of your stock parts and permanently modify all those parts? In addition to the reasons above (missing the point of the problem) - the issue is that welding a thin metal tube (or thick in the case of the aftermarket ones) to a soft/porous cast housing is just a recipe for disaster. You simply cannot get the penetration right on both surfaces simultaneously, it's almost certain that your weld will penetrate through the cast piece easily (like a marshmallow) and have a hard time going through the tube (which is more like a very hard cheese). It will look like it's sticking to it but that's not how a weld works: unless you can inspect both sides of the weld you can't be certain it actually took. Even if it does, you cannot be sure that the weld will last, since this piece is constantly changing shape and size with temperature and each piece will change at different rates.

To reiterate, this is why as long term owners and enthusiasts for 996 and 997 GT3 and Turbo models, we do not recommend the "weld" fix for coolant repair and do not perform this repair in house.
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