Nutty Professor

I'm wanting to install a 3rd radiator on my 6-speed C4S. I know there are 3rd radiator kits available from various places. However, the kit offered from Suncoast Porsche states their kit will not fit on a C4S, Turbo, GT2, or GT3. See link below.

http://www.suncoastparts.com/product...96WaterCooling

I know the C4S shares the same larger L/R radiators as the Turbo. So perhaps I need to use the 3rd radiator from a Turbo? Can anyone confirm this? Has anyone installed a 3rd radiator on a C4S with a manual trans? Which kit did you use?

Thanks for your help.

ogun228

Why the need for a 3rd?

Nutty Professor

Probably not really a need, per se. But it's more of a preventative maintenance issue. I've never experienced cooling issues, at least according to the gauge. However, the gauge isn't that accurate and I do know these cars run quite warm. In the summer time, I typically make several trips from Los Angeles to Las Vegas. Driving through the desert, the outside temps can get upward of 110 degrees.

Also, I tend to be overkill on mods to my car. And there is a coolness factor to the looks of the 3rd radiator.

racer

How do you know the guage isn't that accurate? maybe a lower temp thermostat would be a "cooler" mod

I would think if the turbo had a 3rd radiator, you would need its parts, since the larger coolers on the 4S would need differently shaped connectors and perhaps connector lines as well than the unit used in the kit you mention.

I would also imagine the larger stock 4S coolers are already 10-20% larger than a C2 has, so in effect, the car has the same overall cooling capacity as a regular C2 with a 3rd cooler.

Axeman

I believe you'd have to use the Turbo center radiator for your car, that's why the one from Suncoast doesn't fit your C4S. The part # for the Turbo is 996 106 037 73 (superseded to 996 106 037 75).

ogun228

If it ain't broke...

Nutty Professor

I actually have not tested the gauge myself. I was going off what others have said on this site. I guess there have been people here who have compared the in-dash gauge to a secondary one, or to the readout when using Porsche diagnostic software. I did instal the LN Engineering low temp thermostat a couple of weeks ago, along with a new water pump. Fairly easy job. The low temp stat is a really nice piece. It came complete with the housing and all. I'm going to be doing the fan mod in the next week or two. There's a pretty good DIY on here.

I agree with you about the turbo 3rd radiator, as well as the C4S having approximately the same cooling capacity as a C2 with a 3rd radiator. I was just thinking of trying to do something different, as well as increase cooling capacity.

I agree. And I really appreciate you taking the time to track down those part numbers. I'd probably have to use the connector hoses from a turbo, as well.

Yeah, I know. But sometimes my curiosity gets the best of me.
If I can figure a way to make all of this work, I'll report back and let you guys know.

chsu74

Do the manual radiator fan switch mod. Much cheaper and more effective in stop and go traffic where you need it most.

white99c2

Do this mod for the days you are not running A/C. It bypasses the low speed radiator fan and turns on high speed by default.

http://www.ppbb.com/phorum/read.php?...04#msg-1509504

Follow these instructions for days when you use the A/C and want to turn on the fans prior to the temp reaching 205(low speed) and 215(high speed) degrees.

http://www.6speedonline.com/forums/9...-fan-mods.html

FYI - Everything I read tells me the 996 is designed to operate at 194 degrees. If you install a low temp thermostat it will open sooner and the coolant will flow from out of the engine and through the radiators but the fans will not kick on until the coolant temperature sensor reached 205. (This is where the switch mod helps). There are many posts/debates on the low temp thermostat. Your call obviously but once the car is at operating temp all you can do is improve air flow to the radiators to make it more efficient. Its a poor design that was corrected in the 997 that increases coolant flow with a better designed water pump/ plumbing system and bigger openings in the bumper to get more air on those radiators. Look up Water Wetter it helps lower the temp as well.

chsu74

My car operates at 87 degrees Celsius or 188.6F driving on the highway. 194F = 90 degrees C. Fans don't kick in until 102 degrees C or 215.6F unless you have the AC on.

Nutty Professor

Chsu, thanks for the recommendation. That's next on my list.

White, thanks so much for the detailed info. Yes, I'm going to do the fan mod. I already have a low t-stat installed. So I'm sure it'll work great with the fan mod. I didn't realize how much an improved cooling system the 997 has. I'm still debating on the 3rd radiator. What's driving me now is the challenge in making it happen.