996.2 | Cracked head? Need help in diagnosis of video

Hi all, Well here I am again with a quick diagnosis based on experience. (cap is new and expansion tank fairly new also, no intermix present) I have noticed coolant disappearing, after which it was identified that some pipes were leaking and we proactively changed the water pump as well. Exterior leaks disappeared, however I have noticed that the coolant level keeps decreasing to MIN after longer (100km) drives. I keep refilling to the same effect. We checked radiators etc. and all seems to be fine. Pressure test as well. Mechanik stated it’s likely a cracked head. So I decided to buy the amazon head gasket kit to test. As for the results, I let the engine get to nearly operating temperature. I did some revving and there are both bubbles and apparent vacuum which I do not understand. In terms of the video; Cold (6 celsius, 42 fahrenheit) the beginning is just the end showing that there are no bubbles in the liquid whilst at near operating temp. Also for sanities sake I put the blue liquid on my hand and next to the exhaust to confirm that it works. Fluid only changes a bit in terms of color, please compare start to end. 6:55 1st rev 12:36 2nd rev reaches near operating temp. 17:10 3rd rev Is the head gasket blown? Why does the fluid keep going to the min mark after the refill? Thanks! You Tube

It is extremely rare for a head gasket to fail on a 996 engine, if ever. Some say that it is never the head gasket. Could be a cracked head. You need to perform a compression check and leak down test on each cylinder.

Most likely a cracked head from water pump impellor debris.

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Got it thanks! What worries me that in the video there are many bubbles and I guess that shouldnt be the case. Old water pump was perfect.

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If the water pump was replaced beforehand, it might be debris from the original water pump. Impellor pieces can live in the head for a long time before they come loose and move into an area in the head where they can cause a hotspot. Another possible cause of loss of coolant is from a leaking oil cooler or a faulty AOS. But that doesn't explain the exhaust in the coolant. While not impossible, blown head gaskets rarely happen on the M96 engine. Blown head gaskets are an often suspected cause that almost never turns out to be true hence the skepticism from most of us.

I think you are barking up the wrong tree..... Your combustion fluid test is inconclusive..... 1. head gaskets on these are more durable than the heads (MLS gaskets) .. 2. The test fluid is still blue . To be conclusive the test fluid must turn green ( showing slight combustion leak) or yellow ( showing large combustion leak). 3. The bubbles in the test fixture is from the coolant expanding and pushing out any air that is above the fluid level...This has to happen otherwise pressure will build in the system which is what normally occurs when the cap is on and sealed... If the oil is not milky , and the coolant shows no signs of oil in the cooling system, I think you should start over with your evaluation... I would start by filling the cooling system completely and then pressurizing the system to 20psi and check for leaks and that it holds this pressure overnight... Also test the coolant cap that it can hold 19psi pressure before it "pops off" ...Even NEW pressure caps can be defective.....

I have seen a case where the coolant leaks from the car slowly but not result in an intermix, with a Ferrari. The cause was the head nuts were just a little loose which allows the coolant to seep into the head stud hole, and out the front of the engine via another through hole. I found that issue after the first shop suggested a full rebuild. A simple head nuts retorqued solve the issue. The pressurized coolant system suggested by PorscheTech above is how that issue was identified. I hope yours is the same.

How old is your expansion tank? I had a situation where mine was leaking (weeping) when under heat/pressure and the coolant was dripping onto the exhaust header (vaporizing). It took a while for the leak to become bad enough that I started to see coolant on the floor after sitting overnight. If you expansion tank is old, grab a small mirror/flashlight and start looking around under/behind the tank for signs of dried coolant build-up.

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I had a similar issue where my coolant level would drop, maybe 3 oz every 1000 miles. I would add some every few months. I never saw a drop or smelled any coolant. Then, I came out find a puddle under the left tail pipe. It was the expansion tank. 45 minute drive home, not another drop. I replaced the expansion tank. I found no evidence of a crack on the tank. I cleaned it, scrubbed it and looked for cracks. Nothing. I pressurized it with 20 psi. Finally found the crack. It was in one of the crevices and maybe an 1/8" long. Since doing this, I've driven about 500 miles. No drop in coolant.

I had something similar to a steam mill. The coolant level would drop, and I would later find a few drops of coolant on the left side tailpipe. After replacing the tank with a factory unit, the second round of coolant issues allowed me to spout another round of spectacular Parris Island gutter vanacular to remove the new coolant tank. The culprit was finally tracked down to be a faulty return hose clamp. Since the appearance of winter weather here in the east and where inclement weather makes it difficult to negotiate around all of the soccer mom drivers who usually drive with their foot in the oil pan regardless of conditions, I am now in the process of installing new hoses, an aluminum center radiator, and replacing all of the factory radiators with CFS radiators. If I were granted one wish for the new year, it would be a lifetime coolant tank, metal, carbon fiber, or something better than that nylon plastic-looking vessel that smacks of some pointy-headed cost accountant that saved money and created this garbage that has to be constantly replaced and sold at nosebleed prices; I would be thrilled!

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Thanks! Would it also not make sense to use some UV reactive fluid? I notice around a quart after 100 miles.

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I would take an oil sample and either send it to a lab for testing, or buy some Chem-Strips that are specifically designed to test oil for antifreeze content... The oil sample/lab test is the most common and easiest to do and most accurate.. There are common places the head can crack and small amounts of coolant can get into the oil ....THIS HAS NOTHING TO DO WITH COMBUSTION TEST FLUID AND HEAD GASKETS.. Sure you can add a UV dye and drive it around for a while and look for signs, BUT modern Porsche coolant will leave a white crusty trail anywhere it leaks and dries, so I have not found the UV dye very usefull...Like I said, test the cooling system and cap like above is the first step... Have you performed the coolant system and cap pressure tests???

It sounds like there�s a very small weep in one of your radiators. I�ve had one where you couldn�t visibly see a leak or see a loss in pressure.

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I have just spend 2 hours looking for a lab in mainland europe, I have to say I miss the US for the convinience... Should I ask them to check specifically for glycol? The system was pressurized according to the mechanic with no loss but this was a half a year ago or so.

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just spoke with my mechanic and he says it held pressure 100%