crimony

Having been a 996 (1998 Mk I) owner for 18 months or so now, I've read a lot on this forum on various issues, done an oil change myself, and generally enjoyed the car a lot.

After a rocky start with the engine out soon after purchase, but a favourable outcome with what turned out to be a 3.6 big bore replacement short block 25,000km earlier with Nickies and JE pistons, some other weirdness has emerged, in the areas of cooling and wheels.

Having experienced higher than expected (opinions differ...) coolant temperatures, with warm but not scorching weather (low-mid 30s Celsius) showing beyond the "0" in the "80" indication on the dash, OBD App (Torque) showing mid-90s and the AC Climatronic display 6c showing approx. 5°C higher, I was investigating a centre radiator, but all the kits I could find indicate "Manual Transmission Only" and mine is a Tiptronic.

Further searching revealed a recent thread here with a statement along the lines of "All Tips have the centre radiator from the factory", and I confirmed this by reaching up under the front bumper and feeling the radiator matrix within. Why not look straight in from the front, I hear you ask? Well, this:



Centre Radiator?

Hmm. So it appears at some point my car has had its front bumper replaced and the body shop has fitted the Manual Trans unit and failed to include the centre radiator duct. Anybody got a centre duct for sale?

By the way my car also retains the AC Climatronic display of data across restarts, I have to manually change the unit back to normal display function.

My car also indicates build option M408 in the frunk lid, which decodes as "18" Techno Wheels". Whilst this would be nice, it definitely has 17" stock rims, what's more following a puncture a couple of weeks ago, I was sourcing rear tyres (I went for ContiSportContact 3's in 255/40R17 in the end), and recorded the rim markings near the air fill valve:


Front


Rear

To me that second one looks like 17x8.5 (offset 50). So it appears that not only has someone swapped out the 18" Techno wheels, but they've replaced them with what the Owner's Manual would refer to as "Winter Rims". Hmm. I once noticed the outside rear dip sharply accelerating from stop out of a T-junction corner, it felt like the tyre rolled under onto the sidewall briefly. This was on my previous tyres, P Zero asimmetrico 255/45ZR17. In my thinking this would be exacerbated by the narrower rim.

I'd like to get some 18" rims (revert to my build spec M408 ideally, they seem rare and expensive though), but I do like the low unsprung weight of the 17s.

Cheers.

P.S. Here's the puncture, a giant roofing screw. Also lucky it held pressure allowing me to drive to a garage, as the nut that holds my spare securely in the frunk was not a size that matched any of the tools in the supplied toolkit.


Screwed.

De Jeeper

There r tons of thresds.for narrow body rims. 18s r a real good idea. I have a set of hollow twists on mine, rear r 18x11" x 63 and fronts r 18x8x53. Im running 225s front and 295s rear. U want to make sure u r as close as posible on the tire diameter when u pick sizes, no more the 3-4%. Just surf the 4 sale boards for something u like.

For the center rad u cn buy the duct new from porsche there r several threads on the install. I would bet that most of your problem with cooling is debris in the reds. Pull the front bumper and clean. Also another issure is the resistor for the fans go bad so test that they r working at low and high speed.

DGI

FWIW:

My car came with 18s but the suspension was shot and the wheels were not straight. Not sure how 18s affect ride quality in these cars but from past experience, I know I like bigger side walls and lighter wheels.

De Jeeper

I can tell u that the 18's ride much better then the 19's.

dporto

Even if you don't have the "duct", you need to cut out that center portion of the bumper. It's very simply done with a utility knife as there is a depressed line all the way around it (just stick the blade right in the line and drag it around the edge - it's really that simple). The advice on the wheels is right on... Look on Ebay for the center rad duct. There are several companies that sell that stuff I've had great dealings with "Specialized German" auto parts... Good luck

TexSquirrel

I bought my duct used at a dismantler for just US$45.
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I used a Dremel to cut out the center portion of my Aerokit bumper.

Dan951Man

I was going to offer a set of sport techno’s for sale, but then saw your front plate and assumed your location is in Europe. Probably not worth shipping a set.

That is some odd things you found- my gut says the car was in an accident and repaired on the cheap with used parts, but hopefully I am incorrect? I would take the car to someone who really knows 996’s to see what else is amiss, the center radiator issue is a red flag to the quality/carelessness of who worked on the car

ps- the climate control staying in the service menu across key cycles is normal, I’d always leave my boxster coolant temp displayed and when friends would borrow the car they wondered how climate control was set so high

crimony

Thanks, I found one from a Boxster (same part #) at a local wrecker for AU$70. If should arrive shortly.

Mike Murphy

Yeah, if you have the gauge showing past 0, but your OBDII is showing mid-90s, that’s the same discrepancy I have on my 99 as well. The DME should turn the fans on at the right temps: 96.75C for stage 1 fans, low speed, and 102C for stage 2, high speed fans. If that’s happening, your are probably good. Keep in mind the center radiator only helps when you are driving. Most temp issues are caused while stuck in traffic or at speeds below 30mph.

That said, you should get more air into the center rad, as long as you have it, might as well use it.