So the story goes.. I own a 997.2 C4S 2010 after some semi hard driving on the highway and as I was sitting at the traffic light I noticed a steam coming from left rear side of the car. So I pulled over to check, I noticed I’ve lost quite a bit of coolant however my coolant gauge was sitting normal at 80c (175F) my initial thought was the expansion tank cap wasn’t properly shut and it was leaking from there so I waited a bit then continue to my destination which is 2-3 minutes away as I was about to park I noticed my oil and coolant temp started to climb both going at max 150c (300F) and 120c (250F) for less 10 seconds only the car was parked then engine was off and all.

So I left the car there over night and towed it in the morning to a workshop, in the morning the car started fine (no unusual noise at all) getting on flat bed.

I’m not certain if this is because of the coolant expansion cap or the bad coolant flush job (trapped air) I’m waiting for the workshop assessment but I’ll have to wait after the new year a bit later because I live in Bangkok Thailand.

This is really stressing me out especially that I have to wait a week from now and this is just the first day I got the car.. is the engine still okay, has it taken any damage from this? anything to look out for? I’m definitely going to an oil change and also assess the oil and filter for any debris.

thank you guys & gals at 6speedonline

 

Overheating an engine to max coolant temp on the gauge 80% of the time will blow the head gasket. The coolant temp gauges in these cars are very heavily buffered, which means the coolant temp can actually be as high as 215 degrees before the needle even moves from the vertical position. If you saw the needle go to the end of the gauge, the engine was very hot, especially if the oil temp also moved past 250 or 275 at the same time.

The cause of your failure was likely a failed coolant reservoir cap or a cracked coolant expansion tank as both are known fIlure points.

If you start the car in the morning and get an immediate cloud of something, that's coolant that got pushed into the cylinders from the system pressure then vaporized on start up and that cloud will smell sweet, like maple syrup. You can also put a pressure tester on the cooling system and pump it up to about 20 psi. The needle should stay there for 10 minutes or so without dropping. If the needle starts dropping find out where the noise is coming from (an ultrasonic leak detector works great for this) and that will tell you where the cooling system failure is. If it's not external to the engine, then it's the head gasket on one or both sides.

If no start up cloud and the system holds pressure, then you should still be OK with just a replacement reservoir and cap.

 

Thank you for the reply, so far no smoke from starting in the morning so I guess I could rule out head gasket failure?, I’ll pressure test the cooling system once the workshop is open (for any leaks). At least I can put my mind at ease right now, I hope I’ve not done any major damage to the engine as I’ve shut it off right away less than 10 seconds after both gauges went up.

 

Can't completely rule out a head gasket yet, but no start up cloud or burning coolant smell is a good sign. The pressure test will rule it out. How long until your next schedule spark plug change? The plugs will also tell you as a small coolant leak past the head gasket will steam clean the plug in that cylinder so it will look very clean compared to a regular ont that has some black on it.

 

I’ve only just got the car so all those maintenance stuff will come surely including spark plugs and all the fluids. I’ll keep an eye on that when I’m changing my spark plugs

 

Different cause but similar symptoms. The water pump on my -09 C4S failed at 43,000 miles. Started to see what looked like steam in the rear view mirror from the engine compartment. Also saw the coolant temp. starting to rise. I was very lucky being right next to an exit to a gas station so pulled in there and shut down. Shutting down probably about 30 seconds after seeing trouble I never got close to the temperatures the OP is mentioning.

Moral of the story though is that water pumps can fail as early as low 40K miles and you won't have much if any driving left when it happens. At least that was my experience. The coolant temp. rose very fast even though I shut the car down in 30 seconds or less after noticing problems. Turned out the water pump had seized up and trashed the serpentine belt along with it.

I have 66K miles on the current water pump so keeping a close eye on any signs of what I went through with the C4S. Tempted to replace it preemptively but it's covered by my extended warranty (about $1,200 with the belt) so I'll wait till it fails. Just hope it doesn't fail in a bad spot, like in the center lane in bumper to bumper traffic on a bridge or something like that where you can't get out of the way. Continuing to drive to a convenient exit is not an option based on what I saw.

 

when the pump failed, did you noticed any grinding noise accompanied by it? What i did noticed with mine though as soon as about to park the car (reversing slowly) I heard a grinding noise could it be the pump or the those coolant water going into the tensioner causing the noise? But the next morning those noises were gone everything start up normal (sound normal) no smoke weird smell or nothing.

I think as said our coolant gauge is heavily buffered, though could it be that as coolant temp
goes up would the oil temp start going up sort of to tell us to stop now before damages occur.

And does this car usually throw red warning message about engine heat? Cos mine certainly didn’t only low coolant.

with all this I’m going get everything checked coolant pressure tested, new engine oil, check for any debris from the oil, compression tested, and check for spark plugs.

 

I heard nothing when my pump failed. No noise of any kind. Just saw the steam/faint smoke or whatever you want to call it and a rise in coolant temp. Didn't even get any warning lights, probably because I was in a position where I could shut it down quickly. Stepping outside it was pretty obvious what had happened. A pool of coolant on the ground.

 

Could maybe be the coolant tank cracking. I'm on my third one in my 2006 and second in my 2010. The plastic get's brittle from heat and they fissure and ultimately crack and leak.