Coolant Blow-Off Spray in 996 Engine Bay?

While participating at a Sebring DE, I opened up the engine cover to cool off between runs and found a mysterious spray of dried fluid in the engine compartment. I took these pictures while I was still at the track. There were no MIL/CEL warnings coming up, voltage was fine, oil pressure was fine, etc. The car ran pretty well at 6500-7000 RPM around the track as well. A veteran driver diagnosed that it looked like coolant blow-off residue? Any one ever seen this? Have not noticed any mechanical impact, but thought I'd ask here. (Initially thought it may have been mud from the drive up, but the spray pattern appears to be coming from under the hood.) ____________________ SpeedPhreak 02 C2 - K&N Aircharger, SSK, Tubi Exhaust

There is an updated coolant resevoir cap available. I had a leak as well, but replacing the cap with the new version solved it completely. Mine is a 2003 C2.

+1 although I have not experienced it myself but heard of the problem from other track people and those that have replaced there coolant overflow tank and that is get the updated cap as well. Keep us posted on if that corrects the issue or not.

996-106-447-01-M8 Is this what you replaced?

I'm aware of that coolant cap update. But isn't it ridiculous that I've heard of people with bad caps on 02 and later cars?? Correct me if I am wrong, but that issue was on the earlier models, particularly 99 and 01? You would think they stopped using the defective caps as soon as they found out the problem.

Anyone have thoughts on Redline WaterWetter? Saw some old posts about it, but if it really drops radiator temp by 30 degrees, sounds pretty good for hot areas like South Florida and for track events. PS - didn't run into any issues with temp at track, just the leak, but I'm sure pressure build up somewhere in the pipeline must have caused it. Anyone ever delve into this area?

Was your coolant overfilled?

I saw your cap was blue....when I got my replacement it was black. I'm not absolutely sure, but are the new replacment caps black or blue? As long as it's got the 01 number on it, it should be ok. I've been thinking of adding the water wetter myself....but need to do a little more reading up on the subject. Cosmos: You are correct...the issues were with the 99-01's...and the new caps were supposedly put on the 02's and on. I'm still curious about the color of the cap. I saved my old one and it's that same blue he shows in the photo.

Mine is blue, and I remember checking the part number when I first read about the issue, and mine was like starts with 02.....or something like that, but I remember mine seemed to be the updated one when I checked back then, well, I haven't had any problems with it either.

Mine was not overfilled, and my leak was more of a seep with obvious residue around the cap. You could tell that it had sprayed a few drops here and there, but it wasn't a major leak. It was identified at tech inspection for a driving school, so I had not driven it hard prior to that (I thought I had, but I learned quickly I was mistaken!). I don't know the part numbers for what I took off or replaced it with, I relied upon my mechanic to handle it. It hasn't leaked since, so he must have done SOMETHING right. =)

Take a flashlight and look at the area under and around your coolant tank on the left side of the engine compartment. See if you can see white crusty residue on any of the cross members under or around the tank. also look at the cap and see if there's any crusty residue in the moat around the cap. Your cap should end in the numbers 01....if it ends in 00, then you have to old one and they fail regularly. Most likely you'll need to change out the coolant tank or the cap. There's a great DIY with pictures and text on How-To on RennTech.

One of the incomprehensible things that Porsche does, is NOT to change the cooling water. I talked about this with two Porsche mechanical experts and they told me that we must change it at least every 4 years. And besides the circuit must be cleaned up. They don't understand why Porsche don't replace the cooling water in their inspections in the whole life of the car. Most of wrecked engines have a beginning in this issue. It's cheap and all of watercooled users might do.

Nope. Not overfilled. Had it inspected prior to track as well.

The part number of the blue cap in the picture is 996.101.447.01. I may need to bring it in for a more thorough look...

coolant cap...I had the same issue....installed new cap and it is all okay now. The dealer might try to sell you a new reservoir!! Make sure you really need it.

Take the coolant cap off and shake it. There is a valve inside of it that should rattle around a little. Even later caps can get gummed up inside. If you can't feel it rattle a little, replace it.

ranger, that's good advice, I've never heard that before. FYI, I bought the updated cap when I changed my coolant tank about a year ago, and it was the same blue shade as the old cap. You may have a slight crack in the coolant tank, and when the pressures got high enough you had some coolant escape. You might also check the purge valve to see if it is stuck or gummed/crusted up. When the car is hot, is the vavle activated (i.e., does it spring back when you push it down?). Another thing I've noticed is that my coolant level runs pretty high when hot...perhaps you are just slightly high and the level rose to the height of the purge valve, letting some coolant escape. If that is the case, you might never have the problem again.