Marlon

Guys I was noticing that the cooling system seems to be somewhat overtaxed on the 996 - is this another 'duhhh....moment??? This morning I noticed that my engine bay was still warm after shutting down the car yesterday at about 5 in the afternoon. (993 or 911 would be cold as a rock by then) If the cooling system can't keep up and cool down significantly after shut down, perhaps the hot soak is contributing to a lot of the engine internal havoc. Engine core temp actually rises for a while when the car is shut down and depending on ambient etc., the hot soak temp elevations could be causing the dissimilar metals to expand and contract beyond design elasticity and contribute to some of our engine failures!?!? I don't know, but just asking.

How about engine failure trends in the C2S and C4S cars - if those cars have a heavier duty cooling system that the pedigree suggests. Or even the turbos - I'm guessing that they and the "S"'s have a larger capacity cooling system as suggested by the huge intakes in front. Can the run-of-the-mill 996's be fitted with larger capacity radiator????

cockpit temp really responds fast when you run the temp up from LO to 60's when the a/c is on:^)

Crazy thoughts I know...I'll be these cars LOVE winter time

jury_ca

Don't worry about it. These cars are extensively tested by Porsche.

Macster

to absorb heat from hotter areas of engine and convey this heat away.

Was out in up to 111F heat today in my 03 Turbo and had A/C on whole time and car ran beautifully. Stopped engine several times and when I got back in engine fired right up.

One "trick" I learned a long time ago with my Boxster is if there's a wind try to park with car heading into the wind. This helps remove engine compartment heat.

When I had a garage and would pull very hot car into garage I'd shut engine off and lower garage door and get out and turn a fan on low speed and aim it to blow air under car to help remove heat from engine/drivetrain area to cut down on heat soak.

Not engine parts per se that are affected but wiring/hoses, and fuel injectors which can build up deposits from heat soak temps.

Had my Boxster in 116F heat in southern AZ and engine suffered no harm. That was probably over 100K miles ago. Engine has been run in anywhere from near zero F to well 116F temps over the last 7+ years and for 222+K miles.

I think your car's engine and my Turbo's engine are going to be just fine.

Couple of things: Change that coolant every so often. At least every 4 years. Lifetime coolant is hooey.

Any coolant leak take care of it right away. These engines, any modern engines, do not like to overheat. You have to be careful. A leaking cooling system may not show signs of obvious overheating.

What happens is without pressure hotter parts of cooling system flash coolant into steam. This steam forms pockets that block flow of coolant and very localized hot spots in engine (heads) occur. Bad for engine.

Change that oil/filter. Oil with miles loads up with water and unburned fuel. This lowers viscosity. That 116F experience happened with fresh oil in engine: Less than 1000 miles on oil. Had oil changed in Sacramento and then drove straight down to AZ. I change oil/filter every 5000 miles.

Today in 111F heat Turbo running with fresh oil: Oil has under 1500 miles on it.

Coming in off track -- I never track my cars but for those that do -- or pulling off freeway I'd give engine some easy running to help it shed considerable heat load that builds up from high speed running.

Most of time by the time I get to a gas pump car 's been off freeway for a few minutes and engine's had time to shed heat. If not, I'll circle block or just let engine idle for a minute or so on gas station apron. Also, I try to orient car into the wind so air flowing past helps remove engine heat as I fuel car.

Keep radiator ducts clean of any debris. These can pick quite a load of trash. I've not found any overheating problems but there's a danger of corrosion if you drive car in wet conditions. This debris gets wet and salts will corrode AC condensors and radiators.

Make sure both radiator fans work at low and high speed and the engine compartment fan works.

Sincerely,

Macster.

Marlon

Oh and one other thing - the engine is blanketed on three sides by significant heat sources: two big mufflers and a couple catalytic converters. AND on the fourth side by the tranny - while not as significant as a heat generator, it certainly helps holds in heat during shutdown hot soak as well. Maybe this is the optimum engine for those big huge Artic-Cat snow machines???

ArneeA

just drive it, quit thinking about it!

Paul 996

+1 yes just go drive it.

FYI there was never a 996 C2S. The factory did have an option for a 3rd radiator which I think the tip already has. As long as you are not overheating you are fine. Make sure you cooling system if filled properly and pressurized. Also clean out those darn front radiator grills. They get packed with leaves, plastic bags, you name it.

Marlon

That's good advice - I think I will!

Tippy

Rapid cooling down is worse for parts than high temps.

tooloud10

I think y'all are overthinking it.

Dave!

Are you sure, because I've been parking my car in the pool to quench the engine and it's still running fine.

Tippy

LOL

Jake Raby

we have noted several trends in the failures, which cars they come from and what they are... Certain cylinders and areas of the heads fail in different cars as well. The differences in Boxster and 996 failures also have trends and are quite repeatable.

It will take a few more years to gather enough trend data to make the forecasts that everyone wants to hear...

That said, the cooling system is adequate, but there are ways that it can be optimized. The issues we have seen with cracked heads primarily stem from casting flash within the heads that keep coolant from flowing to certain areas of some heads..

I know of several failures that have stemmed from inadequate bleeding of the cooling system and air pockets that occur in some areas of the engine that end up being "Hot spots"... We just repaired a head crack that occurred from this and I'll be testing the repair on the track in early August on the track.

Heat soak and cool down is critical and I have noted that these engines do not cool well at all when being shut down in higher ambient temps... We have a resolution for that, we just have to perfect it.

Mica

Marlon, I'm glad you brought this up. My new-to-me C4 stays hot for a surprisingly long time after I shut down. I'm talking hours! This had been bothering me, but I feel better about it now.

gota911

I used to date a girl that was like that!

Marlon

Kinda weird - I wonder if it relates to a cooling system 'bleed' procedure that Jake mentioned???

Anybody else have a slow-to-cool car ???