JAGMAN1

Just returned from a vacation towing a 5000 lb. tandem axle trailer in 100 degree heat. The total distance I covered was about 2000 miles when it was all said and done.

The CTT did a terrific job, stopping and acceleration were never a problem. The trailer also has 4-wheel disc brakes and that adds a lot of confidence in the event of sudden stops.

I did notice that when the temps rose above about 95 or so, the coolant temperatures started to creep up. I saw as high as just shy of the 3/4 mark. Probably about 2/3's during extended slow speed driving or long uphill inclines. If I had to guess what the coolant temp was I'd say about 200-210 degrees. I think 180 or so is normal (according to the temp gauge). Oil temps remained constant, just shy of 200.

It seemed as if the CTT ran out of cooling capacity when it was hotter than 95. Keep in mind that this is with the A/C on and set to 72. Anyone have any thoughts on this?

It was never an issue, but I was watching intently hoping the temps got no hotter than where they were. Also, I do have the aluminum coolant pipes and a new T. 79K miles... Thanks!

deilenberger

It appears (from a thread on "another" forum..) that the turbo has a marginally sized cooling system (or the non-turbo V8 has an oversized one - depends on your point of view.) Other people have reported temps as high as 220F being normal on their turbos..

My experience - so far - with a lot of high-speed driving across US deserts the past month at temps in excess of 100F (110F was the highest I saw) - my S never moved off 180F. And that was with long 8% grades, and the AC keeping me fat and happy at 72F in the truck. I can imagine the extra exhaust plumbing required to get to the turbos and then the nice hot turbos themselves may create more underhood heat, and cause the truck to run hotter. Add in the extra power required for towing a 5,000lb trailer, and it's probably not unexpected to see higher temps.

f4 plt

Towed my enclosed Trailex from San Antonio to Parade and back with my 2011 Cayenne S. No issues average fuel mileage was 12mpg and coolant temp stabilized around 225. With the exception of rear visibility ( talked to Porsche AG about towing mirrors and they will work on some) the pepper is a great towing vehicle. Total towing weight was around 5500 (trailer, Cayman and stuff)

JAGMAN1

I assume normal temps for the '11 S are in the 180-190 range?

Mine too seemed to stabilize at 210-215. I was just surprised that it didn't remain in the typical operating range.

11 MPG towing a 5000 boat.

ltc

4 wheel disc brakes on a trailer?
What type of trailer was this?

JAGMAN1

Boatmate brand trailer.

JAGMAN1

I decided to remove my front license plate to let some more airflow into the radiator in a feeble attempt to help. In the process I found leaves, bugs, and dirt sandwiched in between the transmission cooler and the radiator. I cleaned out the intercoolers too. Every little bit helps.

P.S. If the screws that affix the front license plate are too long they will puncture the supply line to the headlight washers and you'll lose all your washer fluid. The end result is you'll turn a 30 minute clean out job into a 2-hour job.

RESP

JAGMAN1 -- Ouch!!

pdxjim

Jagman, you also cleaned out the intakes below the headlights?

JAGMAN1

I did. The grills below the headlights (the ones for the intercoolers) come off very easily, just by pulling them carefully. The center grill is pretty tricky as it is held in by double sided tape. I took a plastic trim removal tool (like a plastic flathead screwdriver) and separated the upper and lower edges of the center grill. Once you get the tape off the top and bottom the grill will pull out from the front.

Between the three of them I pulled out a ton of leaves and dead bugs. I think I'll do this at least once per year in the future. Should help cooling a bit.

As a side note, if you use a vacuum from the front you can avoid forcing things deeper into the cooling fins. The intercoolers can be access from inside the wheel well too. Remove that louvered piece that is in front of the tire and then use high pressure air or water and it will work well for you...

knfeparty

Some thread necromancy here, but I wanted to echo the first post:

Did some mild towing yesterday, but it was 95-100 degrees outside. A/C on the whole time.

I was towing a dual-axle aluminum trailer with a 19' outboard boat on it. I would guess the whole rig is a lot less than towing any car. It doesn't have any trailer brakes but still tows fine.

I saw the temps increase on the highway, especially accelerating up onramps, on my 04 CTT. I probably saw at most 210 degrees; it never made it to the 3/4 mark.

wrinkledpants

It's a misconception that the coolant temp should remain at 180. In almost every other VW and Audi, the coolant temp is smoothed out on the dash so people don't become alarmed if it moved like the Cayenne's does.

On the CTT - the thermostat *starts* to open at 180 degrees. With the HVAC system on, the fans will always be running, so for most daily driving, the coolant temps never move out of the 180 degree range. But, the thermostat won't be fully opened until 210 degrees. At 220 degrees, the fans hit their max speeds. If you have the AC off or in Econ mode, the fans won't start spinning until 200-210 degrees. The Cayenne doesn't have a viscous fan that is always spinning - they're are only two electric fans.

Two things that can impact cooling efficiency that aren't obvious - the water pump and the coolant reservoir cap. People have reported broken fins on other Porsches with composite impellers, though I've never actually seen a photo of a WP with broken fins on a Cayenne. But, it's a possibility, I guess.

The coolant reservoir cap as it ages, will hold less pressure. It needs that pressure to prevent the water pump from cavitating, and to help keep the boiling points lower. You might want to just replace it preemptively as it's pretty cheap.

But, in general, I think it's normal for the CTT to have temps move up to the 220 degree range. I've routinely seen temps in the 210 degree range on long mountain climbs with it's 100 degrees out, and the car is loaded. Or traffic speeds are low.

Around town with the AC on, temps never move from 180 degrees. On my old twin turbo S4, the coolant needle never moved, but the oil temps would rise 20-30 degrees on hot mountain climbs. If I read the actual temp readouts from the radiator exit sensor, the would fluctuate between 91 C to 105 C, but the needle was rock steady. My point is, when you're putting a bigger load on the motor with a turbo charged car, you should expect the oil or coolant temps to rise a bit.

If your coolant goes over the 3/4 mark (220 degrees), then I would be concerned. That's when the thermostat is fully opened, and the fans are at their peak speeds. Think of the temp range between 180 and 220 as "reserve" cooling. Once you're beyond 220, the CTT has maxed it out it's cooling performance. Once you hit 245 degrees, the ECU switches off the AC to help get the temps under control. At 255 degrees, the coolant warming light comes on.

MaxLTV

+1 on it being normal. My 2011 CTT gets to that temperature with any noticeable load fairly quickly, but then just get's stuck at that temperature, which is a clear indication of thermostat just being set for that temperature. Also, oil temp is on the lower end of operating range for synthetic oils - in fact many modern turbo engines intentionally keep oil at higher temps at all times for better fuel efficiency. So I would not worry about these temps.

Clutch-n-Throttle

These trucks can handle it. Last year, I towed my ski boat up a 6% grade for 4 miles in 122 deg. The boat weighs 6k#. I was in Lake Havasu, AZ. The water temp went up to 225. I slowed down to 25 mph. Lucky I was in a residential area when I was going up hill.

brooklynkid

I've been towing my Malibu ski boat this summer about 60 miles each way. Hot dry weather in NM 95+ degrees. Same temp reading as you, sounds like it normal