996 Engine Expert Needed

[Rich69]

Any 996 engine experts out there ?

My 1999 C4 has a probable cracked head

Here is my theoretical plan...

I want to disconnect all of the coolant hoses on the engine and seal

off all of the openings...Then fill with water and add about 30 - 45 PSI air pressure from my compressor
Then pull the valve covers and see if water is dribbling out of the heads....

Is it brilliant or dumb ?

The idea is to pressure check the heads while on the engine !

your impute here thanks to all...

[JFP in PA]

Unnecessary......if you are going to pull the heads anyway, why bother?

[xtremcyber]

Dumb

[Rich69]

I won't bother asking why

[FPB111]

That sounds like a great idea. Please do it and let us know how it works.

Just some thoughts on your plan:

What will you use to hold the cams in place after you pull the "valve covers"?
Will you have to pull the engine to seal all of the coolant hoses?

What is the next step after you see water running out of the heads?
What if the water doesn't dribble out of the heads but just fills the oil sump?

Will you pull the pan to see if it dribbles out of the oil pump pickup?
What is your planned next step after you see the oil/water dribbling out?

When the engine is warmed up and running doesn't the coolant get pressurized?
Do you see water dribbling out of the heads then?

Did you change the split AOS hose with mix running out of it yet?

[JFP in PA]

Originally Posted by FPB111

That sounds like a great idea. Please do it and let us know how it works.

Just some thoughts on your plan:

What will you use to hold the cams in place after you pull the "valve covers"?
Will you have to pull the engine to seal all of the coolant hoses?

What is the next step after you see water running out of the heads?
What if the water doesn't dribble out of the heads but just fills the oil sump?

Will you pull the pan to see if it dribbles out of the oil pump pickup?
What is your planned next step after you see the oil/water dribbling out?

When the engine is warmed up and running doesn't the coolant get pressurized?
Do you see water dribbling out of the heads then?

Did you change the split AOS hose with mix running out of it yet?

And I'll bet he is still driving or running it as well..................

[Wayne 962]

If the head is cracked you will have oil and coolant mix. Very easy to see, and you have to tear apart the engine anyway to fix the issue. Unless you think you have a crack but have no symptoms? The blocks and cylinders crack way more often than the heads, as you can see in my article on engine problems:

Pelican Porsche Tech Article - Common Engine Problems on the Porsche 911 Carrera - Porsche 996 Carrera (1998-2005), Porsche 997 Carrera (2005-2008)

-Wayne

[Sapientoni]

I would limit the pressure to 15 psi which is where most radiator caps relieve. You could damage heater cores or radiators with the higher pressures. I know radiator shops used to test radiators at 30 psi, but that was before plastics, and plastic components embrittle with age and heat. Best of luck.