996.1 C2 - water temperature

Hi All, With my water temperature gauge being temperamental, I've been using the hack on the ac unit to read the temperature of the water. On a normal motorway run the car reads 94 and around town it reads 100 and when stuck in traffic it reads 106 and the fans kick in. Is this normal... Seems high to me?? Iceboy

That is about what I see on my C2. It does creep up when not moving. Mine has fresh radiators and coolant. MC

Thanks MC. Just wanted to be sure. Iceboy

It's a little high for cruise - from memory the standard thermostat is 85 ish. If 70 mph air and gentle cruise throttle (i.e the best conditions for cooling) can't get you down to this temperature then check your rads are not blocked, your coolant is in good condition / at the right level, and if your water pump has ever been changed. It does go high sat in traffic as you are just relying on the fans to pull air through the rad and the engine speed is low so the water has a lot of time to pick up lots of heat. The high speed fans kick in at a ridiculously high temperature. Something like 105 deg C. And then turns off at maybe 102 deg C. I normally run with A/C but always if I'm heading into traffic as it automatically turns fans on to low speed, which does help to slow or even stop your temps getting high in the first place. But even if they have gone up in traffic, 5 mins at a constant 70mph even at high ambient brings my temps back to stable at thermostat opening temp. My cooling system had a bit of a workout in M3 /M27 traffic this bank holiday weekend. I used to get a squeaky bum in the past with my temp gauge but after fixing the blown resistors the a/c trick works great and keeps me below 90 pretty much all the time. And i start from a slightly cooler temp than normal as i have a low temp stat fitted.

Like Skinny, I have my AC on all the time as it runs the fans at a lower temp.

It seems that I might have a little issue. I will look it to this.... Ive not been using the AC as it needs a new pipe and gassing. Iceboy

Mine runs around 88-90 odd off the a/c secret menu, I'm clearly not working it that hard?

Having read this thread I put the 'hack' on today as I'd some serious about town driving to do. About an hour of stop start traffic in all. I left the AC on, and found the temp peaked at 84C, even when sitting idle for over twenty minutes at one stage. Once on the open road again it dropped to and stayed at 79C. For comparison I've recently had a lower temp thermo, new rads and resistors, new coolant tank fitted, and a coolant flush.

Even if your AC is not working you can leave it switched on and the fans will run... ran mine like that for 6 years until I bit the bullet and had the AC fixed last month.

Before worrying too much, the posts seem to me in indicate a variation in "normal" temps seen by different cars. Once saw a YouTube vid were the owner was concerned about oil pressure and connected his pressure switch to another cars guage and visa versa. Turned out to be the sender was faulty. Maybe try a new temp sender first before anything more tricky and expensive? It's on the side of the water manifold near the rear engine carrier. Opposite side to the thermostat housing. Shouldn't lose too much water if you swap them quickly. Just a thought anyway. Good luck.

Just a quick note to second advice to use AC .. I've done about 500 miles in my 996 in the last week, most motorway but some in heavy city traffic. Once going steadily at 40mph or faster my temp readout stayed at 77 to 78C with or without AC fans on. In stop start traffic, AC off, the temp quickly climbs into the mid/late 90's, but staunching AC on brings the engine temp back down. Leaving AC on BEFORE hitting traffic keeps my engine at 84C max while crawling along, however lengthy the delay .. Hope this helps.