99_Carrera

Okay, Texas heat is about to light up. I've had coolant tanks bust on me, numerous leaks appear from the line connections, and every wonderful problem I'm sure you guys have encountered. That being said, I've got to ask...what is a simple, yet feasible mod that can be done on these cars to less complicate these weather compatability problems?

LVDell

1. Take off front bumper and clean out all the crap that blocks the radiators

2. Run the proper oil

3. Make sure you do NOT have the leaks you were talking about.

I do just fine and trust me, my heat here in Vegas is much worse.

1999Porsche911

You said coolant tanks (plural) Some 996's had problems with the original tank and cap, but once replaced, it should be fine. As far as I know, there are no other problems with the cooling system, other than the around town engine temps are pretty high, but should not caused any blowing of line, etc. Specifically what other "every wonderful problem" have you had?

kilrgt

You could always install the 3rd rad option, its around $500.00 and it really does help, also an old drag racing tip, use water wetter it brings it down at least 10 degrees..

newport996

I would say 3rd radiator if you are worried about cooling.....

chris walrod

applying static pressure will also lower boiling points.

Keeping the inlet ducts clean is a great start! Water wetter also helps..

Maybe try some Liquid Cosworth...

sharkster

ALso make sure your drive side fan is coming on. Not sure what year you have but from your name I would guess it's a 99. In the past two months we've replaced the resitors for the driver's side cooling fan at least 4-5 times if I remember right. Basically the resitor had gone bad and hence the driver side fan wouldn't come on and cool properly. That and of course the leaky coolant tank in the rear. Other than that the 3rd radiator is a good good thing

Nicolaasdb

turn up the heat in the P and this will bring the engine temp down....JUST KIDDING!!!!..but it really does!!

1999Porsche911

If you want your engine to remain cooler (190F rather than 220), simply do my fan switch mod. No need for heaveier 3rd radiator.

Radiator Fan and Engine Compartment Fan Switch Mod


The 3.4 996 runs extremely hot when driving around town in temperatures higher than 75 degrees. This mod is a way to reduce coolant temps back to a safer level, helping to reduce oil temps and improving performance.

The mod consists of installing a switch that will allow you to turn on the high speed radiator fans at any time, while maintaining the automatic operation of the fans. We do the same for the engine compartment fan.

Radiator Fans

Connect a wire to the ground of the 2 high speed fan relays located on the relay carrier located in the driver’s side foot well. The relays are #20 and #22. Feed this wire to where your switch will be located. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and then connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on both radiator fans providing maximum cooling. When you turn the key off, the fans will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off.

Engine Compartment Fan

Connect a wire to the ground of the relay located in the relay carrier behind the passenger seat, driver’s side. Relay #8. . Feed this wire to where your switch will be located. I simply fed the wire along the driver’s side of the car and under the door sill. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on the fan drawing air into the engine compartment. When you turn the key off, the fan will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off. This mod helps keep the engine compartment much cooler when driving around town and is particularly beneficial to any engine that draws its intake air from inside the engine compartment, such as the EVO SC.


If you are adventurous, you can automate the operation of these switches so they will switch off at a specific speed, or operate when vacuum is present only, etc. You can choose any style switch you want and even use Porsche switches. I simply used 2 toggle switches that I installed in the batwing,

Jim

99_Carrera

Thanks everyone.

The *&^$ I've had to deal with is my car overheating. I'll be on an interstate and my car will refuse to idle. It's refreshing to know I can use my car everytime I start it.

Besides, I've never had an RMS issue. Seemingly, I'll take the cooling mods over a new eng. So this is basically what it came down to and Thx, 1999Porsche911, for your, and everyone else's input.

Later.
-99_Carrera

rickgrande

So, when I bridge the ground wire to the chasis, the fan comes on. However, during "normal" operation, the fan will not come on. How do I tell if I have a bad relay?

Macster

What Dell said. I've been in 100F+ (up to 119F) heat with my cars with no problems.

However, a properly functioning cooling system -- radiator ducts clean, radiator fans and compartment fan working right, and a pressure tight cooling system -- is a must have.

Sincerely,

Macster.

wwest

Go to home depot and buy/install a manual coolant flow shut-off valve. Your A/C uses a reheat/remix technique to moderate the temperature of the airflow exiting the system.

Until you install the valve use a bit of non-intuitiveness, turn the cabin temperature setpoint all the way down to MAXIMUM cooling and put it in recirculate mode. That will bypass the reheat/remix mode of your A/C, making it substantually more efficient. Now use the fan speed to control the cabin cooling comfort level, but being sure, certain SURE, to turn off the windshield airflow ducting path.

You don't NEED a thoroughly CHILLED windshield which might suddenly fog over outside with a high Rh.


The reheat/remix technique results in lowering the efficiency of the A/C system so much that the compresor must run continuously in a HOT climate. That adds, substantially, to the HEAT load the engine cooling radiators must operate under/with.

street rod

Macster when you ran in over 100F heat what was your temp gauge reading on average?

Macster

In the case of the Boxster in 116F heat the actual coolant temp climbed to 226F and stayed there and bear in mind at 216FR the radiator fans are running at high speed. Intake air temp was 135F and stayed there. Everytime I slowed down enough I could hear the engine compartment fan running. I think it stayed on all the way across AZ...

The coolant gage needle I can't be sure where it was but I know it was quite a ways over to the right of where it usually hanges out, but not in the red and no warning lights ever came on.

After the trip and back home and at the dealer I submitted the above to my SM and he forwarded it to factory and the word came back as long as no warning lights came on/flashed nothing bad happened.

I can't recall now what year that drive occurred, but it was either in 02 with around 25K miles on the car or in 03 with double that miles. In early 04(Feb/March) the car had around 80K miles on it but I was back in CA by then living/working here and didn't venture down into AZ for some years.

(Oh, I like to mention that at the time I encountered this heat the engine had Mobil 1 0w-40 oil in it, fresh with approx. 1000 miles on it, courtesy of the good people at Niello Porsche in Sacramento who did an oil/filter change on very short notice when i dropped in after driving down from Eugene OR!)

For the Turbo I did not collect any real data during the time I was in 119F heat with the car.

However, from some monitoring of its vitals in earlier experiences with high ambient temp driving -- 107F to 111F (in late June no less!) in places on 84 in the tri-valley area where I live -- I knew the Turbo runs quite a bit cooler than the Boxster, and hardly breaks a sweat even in high ambient temps. From what I can recall the actual coolant temp stayed in the 196F region. Now like the Boxster in AZ I had the A/C on and while the Boxster's autoclimate control labored to keep the cabin below broiling -- it is a fine system but this heat just overwhelmed it -- it was Hot! -- while the Turbo maintained 72F cabin temerature without a whimper.

I learned early on the aerodynamics of the Turbo and this includes the flow of air through the radiator ducts is light years advanced compared to the that of the Boxster and since then I really don't keep that close of tabs on the Turbo like I did the Boxster. Also, I've been testing a data logging device I've been working on now for awhile in my Turbo (and Boxster) and these logging devices need to stay connected for long periods of time during testing so I can't do a quick connect of an OBD2 data logger at various times to see what's going on with say coolant or intake air temps.

(Oh, during a long drive (coast) down a steep grade in rather cool temps I was taken aback to note the Turbo coolant gage needle had dropped a few needle widths below where it usually resides.)

Anyhow, in the case of the Turbo the coolant temp gage hardly moved from where it resides under less extreme heat driving.

Sincerely,

Macster.