Project 718 Cayman T: Part 6 – Third Radiator, Center Grill, and GT3 Vent Installation

Sorry again for the blurry picture; by sheer luck, I had exactly two nuts in my toolbox that also happened to be the correct M6x1.0 thread. The nuts where big enough to clamp down on the metal compression limiters.

The coolant connections are all quick-connect. On the vehicle side, it has a plug you need to pull out before you connect the hose from the radiator. The metal clip is pulled out to the unlocked position so I could pull out the plug. I used hose pinch clamps to minimize water leakage out of the center radiator, but I don’t think they are necessary. What happened was I pulled the plug on the car side and coolant started leaking from there of course. It took me a bit to unclamp the radiator hose all the while coolant was spilling out of the car. Once I finally got the hose inserted, I pushed closed the locking clip and did a tug test on the hose to make sure it wouldn’t pull out.

I rotated the EPDM hose on the radiator side to the proper orientation so it wasn’t twisted. The EPDM hose has an abrasion sleeve over it for durability against rubbing from the plastic retention clip that attaches to the A/C hardline. I call the yellow pull-tab on the end of the hose a grenade pin. There is a constant tension clamp glued in place on the end of the hose so as to not get lost. The yellow plastic pin thing holds the clamp in the open position so that the hose is easy to install onto the barb. Once everything is in the correct position, give the yellow pin a pull and the constant tension clamp closes shut.

This is the driver’s side for reference. After I connected the passenger side hose, I topped off the radiator with distilled water in the driver’s side hose before installing. Don’t forget to push back in that locking clip.

To snap the radiator duct into place, I loosened up the nuts holding the lower metal beam so that I could shift the beam a few millimeters for clearance.

11 comments

    1. Cool and rad. Nice article. I think I’ve accepted the fact that I will never be cool enough to understand Porsche life.

      1. Just modding for more cooling for better track reliability like my other cars. Just happens Porsche has more factory parts to use!

  1. Nice! I’m surprised you didn’t just buy the replica or OEM GT4 front bumper! You get the top vent, larger lower vent openings, and a more aggressive front splitter for maybe more front downforce. Plus you wouldn’t have had to hack up the stock front bumper. AFAIK, a GT4 front bump is pretty much a plug and play solution. Can’t wait to see even more progress on this build!

    1. Maybe it’s just me but I would not want to put an aftermarket fiberglass bumper on a Porsche daily driven street car. An OEM GT4 bumper is pretty spendy. This is a nice compromise.

    2. The reason for not doing a GT4 front end is that it would get destroyed around where I live. Lots of steep driveway entries in shopping plazas, gas stations, parking lots, etc. As it is, I scrape the air strake in front of the front tire every time I leave my complex. A couple people have done the full GT4 frontend conversion.

  2. Great job and beautifully documented!
    Fantastic final result.
    It’ll be interesting to compare temperatures with a stock car with common “control” ambients and driving, at a track day.
    I 100% agree with the perfect compromise of repurposing the stock bumper, on the grounds of cost and ground clearance. I have a 981 GT4 and conscious of the limited approach angle.
    I live in the UK where local town councils instal traffic speed calming with “sleeping policemen”, which I negotiated at an angle and crab over.
    Hotels in Europe tend to have underground car parks and on road trips I check if they are ok for low sports cars!

  3. The 997 GT3 vent looks pretty good on the 718. But, why not just use the actual GT4 radiator kit instead of the GTS?

    1. To do the GT4 center radiator right, either have to do the full GT4 front end conversion or make a custom center section to go from the base bumper opening geometry to the GT4 radiator. Neither are easy or low cost options.

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